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1433 lines
49 KiB
Plaintext
1433 lines
49 KiB
Plaintext
@c -*-texinfo-*-
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@c This is part of the GNU Emacs Lisp Reference Manual.
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@c Copyright (C) 1990, 1991, 1992, 1993, 1998, 1999
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@c Free Software Foundation, Inc.
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@c See the file elisp.texi for copying conditions.
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@setfilename ../info/internals
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@node GNU Emacs Internals, Standard Errors, Tips, Top
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@comment node-name, next, previous, up
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@appendix GNU Emacs Internals
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This chapter describes how the runnable Emacs executable is dumped with
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the preloaded Lisp libraries in it, how storage is allocated, and some
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internal aspects of GNU Emacs that may be of interest to C programmers.
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@menu
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* Building Emacs:: How to the dumped Emacs is made.
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* Pure Storage:: A kludge to make preloaded Lisp functions sharable.
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* Garbage Collection:: Reclaiming space for Lisp objects no longer used.
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* Memory Usage:: Info about total size of Lisp objects made so far.
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* Writing Emacs Primitives:: Writing C code for Emacs.
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* Object Internals:: Data formats of buffers, windows, processes.
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@end menu
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@node Building Emacs
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@appendixsec Building Emacs
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@cindex building Emacs
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@pindex temacs
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This section explains the steps involved in building the Emacs
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executable. You don't have to know this material to build and install
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Emacs, since the makefiles do all these things automatically. This
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information is pertinent to Emacs maintenance.
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Compilation of the C source files in the @file{src} directory
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produces an executable file called @file{temacs}, also called a
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@dfn{bare impure Emacs}. It contains the Emacs Lisp interpreter and I/O
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routines, but not the editing commands.
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@cindex @file{loadup.el}
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The command @w{@samp{temacs -l loadup}} uses @file{temacs} to create
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the real runnable Emacs executable. These arguments direct
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@file{temacs} to evaluate the Lisp files specified in the file
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@file{loadup.el}. These files set up the normal Emacs editing
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environment, resulting in an Emacs that is still impure but no longer
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bare.
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It takes a substantial time to load the standard Lisp files. Luckily,
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you don't have to do this each time you run Emacs; @file{temacs} can
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dump out an executable program called @file{emacs} that has these files
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preloaded. @file{emacs} starts more quickly because it does not need to
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load the files. This is the Emacs executable that is normally
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installed.
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To create @file{emacs}, use the command @samp{temacs -batch -l loadup
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dump}. The purpose of @samp{-batch} here is to prevent @file{temacs}
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from trying to initialize any of its data on the terminal; this ensures
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that the tables of terminal information are empty in the dumped Emacs.
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The argument @samp{dump} tells @file{loadup.el} to dump a new executable
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named @file{emacs}.
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Some operating systems don't support dumping. On those systems, you
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must start Emacs with the @samp{temacs -l loadup} command each time you
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use it. This takes a substantial time, but since you need to start
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Emacs once a day at most---or once a week if you never log out---the
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extra time is not too severe a problem.
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@cindex @file{site-load.el}
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You can specify additional files to preload by writing a library named
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@file{site-load.el} that loads them. You may need to add a definition
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@example
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#define SITELOAD_PURESIZE_EXTRA @var{n}
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@end example
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@noindent
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to make @var{n} added bytes of pure space to hold the additional files.
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(Try adding increments of 20000 until it is big enough.) However, the
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advantage of preloading additional files decreases as machines get
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faster. On modern machines, it is usually not advisable.
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After @file{loadup.el} reads @file{site-load.el}, it finds the
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documentation strings for primitive and preloaded functions (and
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variables) in the file @file{etc/DOC} where they are stored, by calling
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@code{Snarf-documentation} (@pxref{Accessing Documentation}).
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@cindex @file{site-init.el}
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You can specify other Lisp expressions to execute just before dumping
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by putting them in a library named @file{site-init.el}. This file is
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executed after the documentation strings are found.
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If you want to preload function or variable definitions, there are
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three ways you can do this and make their documentation strings
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accessible when you subsequently run Emacs:
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@itemize @bullet
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@item
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Arrange to scan these files when producing the @file{etc/DOC} file,
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and load them with @file{site-load.el}.
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@item
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Load the files with @file{site-init.el}, then copy the files into the
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installation directory for Lisp files when you install Emacs.
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@item
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Specify a non-@code{nil} value for
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@code{byte-compile-dynamic-docstrings} as a local variable in each of these
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files, and load them with either @file{site-load.el} or
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@file{site-init.el}. (This method has the drawback that the
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documentation strings take up space in Emacs all the time.)
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@end itemize
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It is not advisable to put anything in @file{site-load.el} or
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@file{site-init.el} that would alter any of the features that users
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expect in an ordinary unmodified Emacs. If you feel you must override
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normal features for your site, do it with @file{default.el}, so that
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users can override your changes if they wish. @xref{Startup Summary}.
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@defun dump-emacs to-file from-file
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@cindex unexec
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This function dumps the current state of Emacs into an executable file
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@var{to-file}. It takes symbols from @var{from-file} (this is normally
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the executable file @file{temacs}).
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If you want to use this function in an Emacs that was already dumped,
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you must run Emacs with @samp{-batch}.
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@end defun
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@node Pure Storage
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@appendixsec Pure Storage
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@cindex pure storage
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Emacs Lisp uses two kinds of storage for user-created Lisp objects:
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@dfn{normal storage} and @dfn{pure storage}. Normal storage is where
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all the new data created during an Emacs session are kept; see the
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following section for information on normal storage. Pure storage is
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used for certain data in the preloaded standard Lisp files---data that
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should never change during actual use of Emacs.
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Pure storage is allocated only while @file{temacs} is loading the
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standard preloaded Lisp libraries. In the file @file{emacs}, it is
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marked as read-only (on operating systems that permit this), so that
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the memory space can be shared by all the Emacs jobs running on the
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machine at once. Pure storage is not expandable; a fixed amount is
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allocated when Emacs is compiled, and if that is not sufficient for the
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preloaded libraries, @file{temacs} crashes. If that happens, you must
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increase the compilation parameter @code{PURESIZE} in the file
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@file{src/puresize.h}. This normally won't happen unless you try to
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preload additional libraries or add features to the standard ones.
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@defun purecopy object
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This function makes a copy in pure storage of @var{object}, and returns
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it. It copies a string by simply making a new string with the same
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characters in pure storage. It recursively copies the contents of
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vectors and cons cells. It does not make copies of other objects such
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as symbols, but just returns them unchanged. It signals an error if
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asked to copy markers.
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This function is a no-op except while Emacs is being built and dumped;
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it is usually called only in the file @file{emacs/lisp/loaddefs.el}, but
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a few packages call it just in case you decide to preload them.
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@end defun
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@defvar pure-bytes-used
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The value of this variable is the number of bytes of pure storage
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allocated so far. Typically, in a dumped Emacs, this number is very
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close to the total amount of pure storage available---if it were not,
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we would preallocate less.
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@end defvar
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@defvar purify-flag
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This variable determines whether @code{defun} should make a copy of the
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function definition in pure storage. If it is non-@code{nil}, then the
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function definition is copied into pure storage.
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This flag is @code{t} while loading all of the basic functions for
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building Emacs initially (allowing those functions to be sharable and
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non-collectible). Dumping Emacs as an executable always writes
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@code{nil} in this variable, regardless of the value it actually has
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before and after dumping.
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You should not change this flag in a running Emacs.
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@end defvar
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@node Garbage Collection
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@appendixsec Garbage Collection
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@cindex garbage collector
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@cindex memory allocation
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When a program creates a list or the user defines a new function (such
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as by loading a library), that data is placed in normal storage. If
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normal storage runs low, then Emacs asks the operating system to
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allocate more memory in blocks of 1k bytes. Each block is used for one
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type of Lisp object, so symbols, cons cells, markers, etc., are
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segregated in distinct blocks in memory. (Vectors, long strings,
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buffers and certain other editing types, which are fairly large, are
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allocated in individual blocks, one per object, while small strings are
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packed into blocks of 8k bytes.)
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It is quite common to use some storage for a while, then release it by
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(for example) killing a buffer or deleting the last pointer to an
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object. Emacs provides a @dfn{garbage collector} to reclaim this
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abandoned storage. (This name is traditional, but ``garbage recycler''
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might be a more intuitive metaphor for this facility.)
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The garbage collector operates by finding and marking all Lisp objects
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that are still accessible to Lisp programs. To begin with, it assumes
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all the symbols, their values and associated function definitions, and
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any data presently on the stack, are accessible. Any objects that can
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be reached indirectly through other accessible objects are also
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accessible.
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When marking is finished, all objects still unmarked are garbage. No
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matter what the Lisp program or the user does, it is impossible to refer
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to them, since there is no longer a way to reach them. Their space
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might as well be reused, since no one will miss them. The second
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(``sweep'') phase of the garbage collector arranges to reuse them.
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@c ??? Maybe add something describing weak hash tables here?
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@cindex free list
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The sweep phase puts unused cons cells onto a @dfn{free list}
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for future allocation; likewise for symbols and markers. It compacts
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the accessible strings so they occupy fewer 8k blocks; then it frees the
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other 8k blocks. Vectors, buffers, windows, and other large objects are
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individually allocated and freed using @code{malloc} and @code{free}.
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@cindex CL note---allocate more storage
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@quotation
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@b{Common Lisp note:} Unlike other Lisps, GNU Emacs Lisp does not
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call the garbage collector when the free list is empty. Instead, it
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simply requests the operating system to allocate more storage, and
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processing continues until @code{gc-cons-threshold} bytes have been
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used.
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This means that you can make sure that the garbage collector will not
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run during a certain portion of a Lisp program by calling the garbage
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collector explicitly just before it (provided that portion of the
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program does not use so much space as to force a second garbage
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collection).
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@end quotation
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@deffn Command garbage-collect
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This command runs a garbage collection, and returns information on
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the amount of space in use. (Garbage collection can also occur
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spontaneously if you use more than @code{gc-cons-threshold} bytes of
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Lisp data since the previous garbage collection.)
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@code{garbage-collect} returns a list containing the following
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information:
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@example
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@group
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((@var{used-conses} . @var{free-conses})
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(@var{used-syms} . @var{free-syms})
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@end group
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(@var{used-miscs} . @var{free-miscs})
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@var{used-string-chars}
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@var{used-vector-slots}
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(@var{used-floats} . @var{free-floats})
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(@var{used-intervals} . @var{free-intervals})
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(@var{used-strings} . @var{free-strings}))
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@end example
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Here is an example:
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@example
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@group
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(garbage-collect)
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@result{} ((106886 . 13184) (9769 . 0)
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(7731 . 4651) 347543 121628
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(31 . 94) (1273 . 168)
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(25474 . 3569))
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@end group
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@end example
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Here is a table explaining each element:
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@table @var
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@item used-conses
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The number of cons cells in use.
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@item free-conses
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The number of cons cells for which space has been obtained from the
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operating system, but that are not currently being used.
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@item used-syms
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The number of symbols in use.
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@item free-syms
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The number of symbols for which space has been obtained from the
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operating system, but that are not currently being used.
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@item used-miscs
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The number of miscellaneous objects in use. These include markers and
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overlays, plus certain objects not visible to users.
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@item free-miscs
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The number of miscellaneous objects for which space has been obtained
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from the operating system, but that are not currently being used.
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@item used-string-chars
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The total size of all strings, in characters.
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@item used-vector-slots
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The total number of elements of existing vectors.
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@item used-floats
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@c Emacs 19 feature
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The number of floats in use.
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@item free-floats
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@c Emacs 19 feature
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The number of floats for which space has been obtained from the
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operating system, but that are not currently being used.
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@item used-intervals
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The number of intervals in use. Intervals are an internal
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data structure used for representing text properties.
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@item free-intervals
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The number of intervals for which space has been obtained
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from the operating system, but that are not currently being used.
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@item used-strings
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The number of strings in use.
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@item free-strings
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The number of string headers for which the space was obtained from the
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operating system, but which are currently not in use. (A string
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object consists of a header and the storage for the string text
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itself; the latter is only allocated when the string is created.)
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@end table
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@end deffn
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@defopt garbage-collection-messages
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If this variable is non-@code{nil}, Emacs displays a message at the
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beginning and end of garbage collection. The default value is
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@code{nil}, meaning there are no such messages.
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@end defopt
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@defopt gc-cons-threshold
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The value of this variable is the number of bytes of storage that must
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be allocated for Lisp objects after one garbage collection in order to
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trigger another garbage collection. A cons cell counts as eight bytes,
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a string as one byte per character plus a few bytes of overhead, and so
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on; space allocated to the contents of buffers does not count. Note
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that the subsequent garbage collection does not happen immediately when
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the threshold is exhausted, but only the next time the Lisp evaluator is
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called.
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The initial threshold value is 400,000. If you specify a larger
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value, garbage collection will happen less often. This reduces the
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amount of time spent garbage collecting, but increases total memory use.
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You may want to do this when running a program that creates lots of
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Lisp data.
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You can make collections more frequent by specifying a smaller value,
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down to 10,000. A value less than 10,000 will remain in effect only
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until the subsequent garbage collection, at which time
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@code{garbage-collect} will set the threshold back to 10,000.
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@end defopt
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The value return by @code{garbage-collect} describes the amount of
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memory used by Lisp data, broken down by data type. By contrast, the
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function @code{memory-limit} provides information on the total amount of
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memory Emacs is currently using.
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@c Emacs 19 feature
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@defun memory-limit
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This function returns the address of the last byte Emacs has allocated,
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divided by 1024. We divide the value by 1024 to make sure it fits in a
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Lisp integer.
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You can use this to get a general idea of how your actions affect the
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memory usage.
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@end defun
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@node Memory Usage
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@section Memory Usage
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These functions and variables give information about the total amount
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of memory allocation that Emacs has done, broken down by data type.
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Note the difference between these and the values returned by
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@code{(garbage-collect)}; those count objects that currently exist, but
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these count the number or size of all allocations, including those for
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objects that have since been freed.
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@defvar cons-cells-consed
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The total number of cons cells that have been allocated so far
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in this Emacs session.
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@end defvar
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@defvar floats-consed
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The total number of floats that have been allocated so far
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in this Emacs session.
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@end defvar
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@defvar vector-cells-consed
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The total number of vector cells that have been allocated so far
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in this Emacs session.
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@end defvar
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@defvar symbols-consed
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The total number of symbols that have been allocated so far
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in this Emacs session.
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@end defvar
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@defvar string-chars-consed
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The total number of string characters that have been allocated so far
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in this Emacs session.
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@end defvar
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@defvar misc-objects-consed
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The total number of miscellaneous objects that have been allocated so
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far in this Emacs session. These include markers and overlays, plus
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certain objects not visible to users.
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@end defvar
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@defvar intervals-consed
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The total number of intervals that have been allocated so far
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in this Emacs session.
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@end defvar
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@defvar strings-consed
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The total number of strings that have been allocated so far in this
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Emacs session.
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@end defvar
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@node Writing Emacs Primitives
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@appendixsec Writing Emacs Primitives
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@cindex primitive function internals
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Lisp primitives are Lisp functions implemented in C. The details of
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interfacing the C function so that Lisp can call it are handled by a few
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C macros. The only way to really understand how to write new C code is
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to read the source, but we can explain some things here.
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An example of a special form is the definition of @code{or}, from
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@file{eval.c}. (An ordinary function would have the same general
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appearance.)
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@cindex garbage collection protection
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@smallexample
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@group
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DEFUN ("or", For, Sor, 0, UNEVALLED, 0,
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doc: /* Eval args until one of them yields non-nil, then return that value.
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The remaining args are not evalled at all.
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If all args return nil, return nil.
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@end group
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@group
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usage: (or CONDITIONS ...) */)
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(args)
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Lisp_Object args;
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@{
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register Lisp_Object val;
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Lisp_Object args_left;
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struct gcpro gcpro1;
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@end group
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@group
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if (NILP (args))
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return Qnil;
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args_left = args;
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GCPRO1 (args_left);
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@end group
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@group
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do
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@{
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val = Feval (Fcar (args_left));
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if (!NILP (val))
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break;
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args_left = Fcdr (args_left);
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@}
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while (!NILP (args_left));
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@end group
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@group
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UNGCPRO;
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return val;
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@}
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@end group
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@end smallexample
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Let's start with a precise explanation of the arguments to the
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@code{DEFUN} macro. Here is a template for them:
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@example
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DEFUN (@var{lname}, @var{fname}, @var{sname}, @var{min}, @var{max}, @var{interactive}, @var{doc})
|
|
@end example
|
|
|
|
@table @var
|
|
@item lname
|
|
This is the name of the Lisp symbol to define as the function name; in
|
|
the example above, it is @code{or}.
|
|
|
|
@item fname
|
|
This is the C function name for this function. This is
|
|
the name that is used in C code for calling the function. The name is,
|
|
by convention, @samp{F} prepended to the Lisp name, with all dashes
|
|
(@samp{-}) in the Lisp name changed to underscores. Thus, to call this
|
|
function from C code, call @code{For}. Remember that the arguments must
|
|
be of type @code{Lisp_Object}; various macros and functions for creating
|
|
values of type @code{Lisp_Object} are declared in the file
|
|
@file{lisp.h}.
|
|
|
|
@item sname
|
|
This is a C variable name to use for a structure that holds the data for
|
|
the subr object that represents the function in Lisp. This structure
|
|
conveys the Lisp symbol name to the initialization routine that will
|
|
create the symbol and store the subr object as its definition. By
|
|
convention, this name is always @var{fname} with @samp{F} replaced with
|
|
@samp{S}.
|
|
|
|
@item min
|
|
This is the minimum number of arguments that the function requires. The
|
|
function @code{or} allows a minimum of zero arguments.
|
|
|
|
@item max
|
|
This is the maximum number of arguments that the function accepts, if
|
|
there is a fixed maximum. Alternatively, it can be @code{UNEVALLED},
|
|
indicating a special form that receives unevaluated arguments, or
|
|
@code{MANY}, indicating an unlimited number of evaluated arguments (the
|
|
equivalent of @code{&rest}). Both @code{UNEVALLED} and @code{MANY} are
|
|
macros. If @var{max} is a number, it may not be less than @var{min} and
|
|
it may not be greater than seven.
|
|
|
|
@item interactive
|
|
This is an interactive specification, a string such as might be used as
|
|
the argument of @code{interactive} in a Lisp function. In the case of
|
|
@code{or}, it is 0 (a null pointer), indicating that @code{or} cannot be
|
|
called interactively. A value of @code{""} indicates a function that
|
|
should receive no arguments when called interactively.
|
|
|
|
@item doc
|
|
This is the documentation string. It uses C comment syntax rather
|
|
than C string syntax because comment syntax requires nothing special
|
|
to include multiple lines. The @samp{doc:} identifies the comment
|
|
that follows as the documentation string. The @samp{/*} and @samp{*/}
|
|
delimiters that begin and end the comment are not part of the
|
|
documentation string.
|
|
|
|
If the last line of the documentation string begins with the keyword
|
|
@samp{usage:}, the rest of the line is treated as the argument list
|
|
for documentation purposes. This way, you can use different argument
|
|
names in the documentation string from the ones used in the C code.
|
|
|
|
All the usual rules for documentation strings in Lisp code
|
|
(@pxref{Documentation Tips}) apply to C code documentation strings
|
|
too.
|
|
@end table
|
|
|
|
After the call to the @code{DEFUN} macro, you must write the argument
|
|
name list that every C function must have, followed by ordinary C
|
|
declarations for the arguments. For a function with a fixed maximum
|
|
number of arguments, declare a C argument for each Lisp argument, and
|
|
give them all type @code{Lisp_Object}. When a Lisp function has no
|
|
upper limit on the number of arguments, its implementation in C actually
|
|
receives exactly two arguments: the first is the number of Lisp
|
|
arguments, and the second is the address of a block containing their
|
|
values. They have types @code{int} and @w{@code{Lisp_Object *}}.
|
|
|
|
Within the function @code{For} itself, note the use of the macros
|
|
@code{GCPRO1} and @code{UNGCPRO}. @code{GCPRO1} is used to ``protect''
|
|
a variable from garbage collection---to inform the garbage collector that
|
|
it must look in that variable and regard its contents as an accessible
|
|
object. This is necessary whenever you call @code{Feval} or anything
|
|
that can directly or indirectly call @code{Feval}. At such a time, any
|
|
Lisp object that you intend to refer to again must be protected somehow.
|
|
@code{UNGCPRO} cancels the protection of the variables that are
|
|
protected in the current function. It is necessary to do this explicitly.
|
|
|
|
For most data types, it suffices to protect at least one pointer to
|
|
the object; as long as the object is not recycled, all pointers to it
|
|
remain valid. This is not so for strings, because the garbage collector
|
|
can move them. When the garbage collector moves a string, it relocates
|
|
all the pointers it knows about; any other pointers become invalid.
|
|
Therefore, you must protect all pointers to strings across any point
|
|
where garbage collection may be possible.
|
|
|
|
The macro @code{GCPRO1} protects just one local variable. If you want
|
|
to protect two, use @code{GCPRO2} instead; repeating @code{GCPRO1} will
|
|
not work. Macros @code{GCPRO3} and @code{GCPRO4} also exist.
|
|
|
|
These macros implicitly use local variables such as @code{gcpro1}; you
|
|
must declare these explicitly, with type @code{struct gcpro}. Thus, if
|
|
you use @code{GCPRO2}, you must declare @code{gcpro1} and @code{gcpro2}.
|
|
Alas, we can't explain all the tricky details here.
|
|
|
|
You must not use C initializers for static or global variables unless
|
|
the variables are never written once Emacs is dumped. These variables
|
|
with initializers are allocated in an area of memory that becomes
|
|
read-only (on certain operating systems) as a result of dumping Emacs.
|
|
@xref{Pure Storage}.
|
|
|
|
Do not use static variables within functions---place all static
|
|
variables at top level in the file. This is necessary because Emacs on
|
|
some operating systems defines the keyword @code{static} as a null
|
|
macro. (This definition is used because those systems put all variables
|
|
declared static in a place that becomes read-only after dumping, whether
|
|
they have initializers or not.)
|
|
|
|
Defining the C function is not enough to make a Lisp primitive
|
|
available; you must also create the Lisp symbol for the primitive and
|
|
store a suitable subr object in its function cell. The code looks like
|
|
this:
|
|
|
|
@example
|
|
defsubr (&@var{subr-structure-name});
|
|
@end example
|
|
|
|
@noindent
|
|
Here @var{subr-structure-name} is the name you used as the third
|
|
argument to @code{DEFUN}.
|
|
|
|
If you add a new primitive to a file that already has Lisp primitives
|
|
defined in it, find the function (near the end of the file) named
|
|
@code{syms_of_@var{something}}, and add the call to @code{defsubr}
|
|
there. If the file doesn't have this function, or if you create a new
|
|
file, add to it a @code{syms_of_@var{filename}} (e.g.,
|
|
@code{syms_of_myfile}). Then find the spot in @file{emacs.c} where all
|
|
of these functions are called, and add a call to
|
|
@code{syms_of_@var{filename}} there.
|
|
|
|
@vindex byte-boolean-vars
|
|
The function @code{syms_of_@var{filename}} is also the place to define
|
|
any C variables that are to be visible as Lisp variables.
|
|
@code{DEFVAR_LISP} makes a C variable of type @code{Lisp_Object} visible
|
|
in Lisp. @code{DEFVAR_INT} makes a C variable of type @code{int}
|
|
visible in Lisp with a value that is always an integer.
|
|
@code{DEFVAR_BOOL} makes a C variable of type @code{int} visible in Lisp
|
|
with a value that is either @code{t} or @code{nil}. Note that variables
|
|
defined with @code{DEFVAR_BOOL} are automatically added to the list
|
|
@code{byte-boolean-vars} used by the byte compiler.
|
|
|
|
If you define a file-scope C variable of type @code{Lisp_Object},
|
|
you must protect it from garbage-collection by calling @code{staticpro}
|
|
in @code{syms_of_@var{filename}}, like this:
|
|
|
|
@example
|
|
staticpro (&@var{variable});
|
|
@end example
|
|
|
|
Here is another example function, with more complicated arguments.
|
|
This comes from the code in @file{window.c}, and it demonstrates the use
|
|
of macros and functions to manipulate Lisp objects.
|
|
|
|
@smallexample
|
|
@group
|
|
DEFUN ("coordinates-in-window-p", Fcoordinates_in_window_p,
|
|
Scoordinates_in_window_p, 2, 2,
|
|
"xSpecify coordinate pair: \nXExpression which evals to window: ",
|
|
"Return non-nil if COORDINATES is in WINDOW.\n\
|
|
COORDINATES is a cons of the form (X . Y), X and Y being distances\n\
|
|
...
|
|
@end group
|
|
@group
|
|
If they are on the border between WINDOW and its right sibling,\n\
|
|
`vertical-line' is returned.")
|
|
(coordinates, window)
|
|
register Lisp_Object coordinates, window;
|
|
@{
|
|
int x, y;
|
|
@end group
|
|
|
|
@group
|
|
CHECK_LIVE_WINDOW (window, 0);
|
|
CHECK_CONS (coordinates, 1);
|
|
x = XINT (Fcar (coordinates));
|
|
y = XINT (Fcdr (coordinates));
|
|
@end group
|
|
|
|
@group
|
|
switch (coordinates_in_window (XWINDOW (window), &x, &y))
|
|
@{
|
|
case 0: /* NOT in window at all. */
|
|
return Qnil;
|
|
@end group
|
|
|
|
@group
|
|
case 1: /* In text part of window. */
|
|
return Fcons (make_number (x), make_number (y));
|
|
@end group
|
|
|
|
@group
|
|
case 2: /* In mode line of window. */
|
|
return Qmode_line;
|
|
@end group
|
|
|
|
@group
|
|
case 3: /* On right border of window. */
|
|
return Qvertical_line;
|
|
@end group
|
|
|
|
@group
|
|
default:
|
|
abort ();
|
|
@}
|
|
@}
|
|
@end group
|
|
@end smallexample
|
|
|
|
Note that C code cannot call functions by name unless they are defined
|
|
in C. The way to call a function written in Lisp is to use
|
|
@code{Ffuncall}, which embodies the Lisp function @code{funcall}. Since
|
|
the Lisp function @code{funcall} accepts an unlimited number of
|
|
arguments, in C it takes two: the number of Lisp-level arguments, and a
|
|
one-dimensional array containing their values. The first Lisp-level
|
|
argument is the Lisp function to call, and the rest are the arguments to
|
|
pass to it. Since @code{Ffuncall} can call the evaluator, you must
|
|
protect pointers from garbage collection around the call to
|
|
@code{Ffuncall}.
|
|
|
|
The C functions @code{call0}, @code{call1}, @code{call2}, and so on,
|
|
provide handy ways to call a Lisp function conveniently with a fixed
|
|
number of arguments. They work by calling @code{Ffuncall}.
|
|
|
|
@file{eval.c} is a very good file to look through for examples;
|
|
@file{lisp.h} contains the definitions for some important macros and
|
|
functions.
|
|
|
|
If you define a function which is side-effect free, update the code in
|
|
@file{byte-opt.el} which binds @code{side-effect-free-fns} and
|
|
@code{side-effect-and-error-free-fns} to include it. This will help the
|
|
optimizer.
|
|
|
|
@node Object Internals
|
|
@appendixsec Object Internals
|
|
@cindex object internals
|
|
|
|
GNU Emacs Lisp manipulates many different types of data. The actual
|
|
data are stored in a heap and the only access that programs have to it
|
|
is through pointers. Pointers are thirty-two bits wide in most
|
|
implementations. Depending on the operating system and type of machine
|
|
for which you compile Emacs, twenty-eight bits are used to address the
|
|
object, and the remaining four bits are used for a GC mark bit and the
|
|
tag that identifies the object's type.
|
|
|
|
Because Lisp objects are represented as tagged pointers, it is always
|
|
possible to determine the Lisp data type of any object. The C data type
|
|
@code{Lisp_Object} can hold any Lisp object of any data type. Ordinary
|
|
variables have type @code{Lisp_Object}, which means they can hold any
|
|
type of Lisp value; you can determine the actual data type only at run
|
|
time. The same is true for function arguments; if you want a function
|
|
to accept only a certain type of argument, you must check the type
|
|
explicitly using a suitable predicate (@pxref{Type Predicates}).
|
|
@cindex type checking internals
|
|
|
|
@menu
|
|
* Buffer Internals:: Components of a buffer structure.
|
|
* Window Internals:: Components of a window structure.
|
|
* Process Internals:: Components of a process structure.
|
|
@end menu
|
|
|
|
@node Buffer Internals
|
|
@appendixsubsec Buffer Internals
|
|
@cindex internals, of buffer
|
|
@cindex buffer internals
|
|
|
|
Buffers contain fields not directly accessible by the Lisp programmer.
|
|
We describe them here, naming them by the names used in the C code.
|
|
Many are accessible indirectly in Lisp programs via Lisp primitives.
|
|
|
|
Two structures are used to represent buffers in C. The
|
|
@code{buffer_text} structure contains fields describing the text of a
|
|
buffer; the @code{buffer} structure holds other fields. In the case
|
|
of indirect buffers, two or more @code{buffer} structures reference
|
|
the same @code{buffer_text} structure.
|
|
|
|
Here is a list of the @code{struct buffer_text} fields:
|
|
|
|
@table @code
|
|
@item beg
|
|
This field contains the actual address of the buffer contents.
|
|
|
|
@item gpt
|
|
This holds the character position of the gap in the buffer.
|
|
|
|
@item z
|
|
This field contains the character position of the end of the buffer
|
|
text.
|
|
|
|
@item gpt_byte
|
|
Contains the byte position of the gap.
|
|
|
|
@item z_byte
|
|
Holds the byte position of the end of the buffer text.
|
|
|
|
@item gap_size
|
|
Contains the size of buffer's gap.
|
|
|
|
@item modiff
|
|
This field counts buffer-modification events for this buffer. It is
|
|
incremented for each such event, and never otherwise changed.
|
|
|
|
@item save_modiff
|
|
Contains the previous value of @code{modiff}, as of the last time a
|
|
buffer was visited or saved in a file.
|
|
|
|
@item overlay_modiff
|
|
Counts modifications to overlays analogous to @code{modiff}.
|
|
|
|
@item beg_unchanged
|
|
Holds the number of characters at the start of the text that are known
|
|
to be unchanged since the last redisplay that finished.
|
|
|
|
@item end_unchanged
|
|
Holds the number of characters at the end of the text that are known to
|
|
be unchanged since the last redisplay that finished.
|
|
|
|
@item unchanged_modified
|
|
Contains the value of @code{modiff} at the time of the last redisplay
|
|
that finished. If this value matches @code{modiff},
|
|
@code{beg_unchanged} and @code{end_unchanged} contain no useful
|
|
information.
|
|
|
|
@item overlay_unchanged_modified
|
|
Contains the value of @code{overlay_modiff} at the time of the last
|
|
redisplay that finished. If this value matches @code{overlay_modiff},
|
|
@code{beg_unchanged} and @code{end_unchanged} contain no useful
|
|
information.
|
|
|
|
@item markers
|
|
The markers that refer to this buffer. This is actually a single
|
|
marker, and successive elements in its marker @code{chain} are the other
|
|
markers referring to this buffer text.
|
|
|
|
@item intervals
|
|
Contains the interval tree which records the text properties of this
|
|
buffer.
|
|
@end table
|
|
|
|
The fields of @code{struct buffer} are:
|
|
|
|
@table @code
|
|
@item next
|
|
Points to the next buffer, in the chain of all buffers including killed
|
|
buffers. This chain is used only for garbage collection, in order to
|
|
collect killed buffers properly. Note that vectors, and most kinds of
|
|
objects allocated as vectors, are all on one chain, but buffers are on a
|
|
separate chain of their own.
|
|
|
|
@item own_text
|
|
This is a @code{struct buffer_text} structure. In an ordinary buffer,
|
|
it holds the buffer contents. In indirect buffers, this field is not
|
|
used.
|
|
|
|
@item text
|
|
This points to the @code{buffer_text} structure that is used for this
|
|
buffer. In an ordinary buffer, this is the @code{own_text} field above.
|
|
In an indirect buffer, this is the @code{own_text} field of the base
|
|
buffer.
|
|
|
|
@item pt
|
|
Contains the character position of point in a buffer.
|
|
|
|
@item pt_byte
|
|
Contains the byte position of point in a buffer.
|
|
|
|
@item begv
|
|
This field contains the character position of the beginning of the
|
|
accessible range of text in the buffer.
|
|
|
|
@item begv_byte
|
|
This field contains the byte position of the beginning of the
|
|
accessible range of text in the buffer.
|
|
|
|
@item zv
|
|
This field contains the character position of the end of the
|
|
accessible range of text in the buffer.
|
|
|
|
@item zv_byte
|
|
This field contains the byte position of the end of the
|
|
accessible range of text in the buffer.
|
|
|
|
@item base_buffer
|
|
In an indirect buffer, this points to the base buffer. In an ordinary
|
|
buffer, it is null.
|
|
|
|
@item local_var_flags
|
|
This field contains flags indicating that certain variables are local in
|
|
this buffer. Such variables are declared in the C code using
|
|
@code{DEFVAR_PER_BUFFER}, and their buffer-local bindings are stored in
|
|
fields in the buffer structure itself. (Some of these fields are
|
|
described in this table.)
|
|
|
|
@item modtime
|
|
This field contains the modification time of the visited file. It is
|
|
set when the file is written or read. Before writing the buffer into a
|
|
file, this field is compared to the modification time of the file to see
|
|
if the file has changed on disk. @xref{Buffer Modification}.
|
|
|
|
@item auto_save_modified
|
|
This field contains the time when the buffer was last auto-saved.
|
|
|
|
@item auto_save_failure_time
|
|
The time at which we detected a failure to auto-save, or -1 if we didn't
|
|
have a failure.
|
|
|
|
@item last_window_start
|
|
This field contains the @code{window-start} position in the buffer as of
|
|
the last time the buffer was displayed in a window.
|
|
|
|
@item clip_changed
|
|
This flag is set when narrowing changes in a buffer.
|
|
|
|
@item prevent_redisplay_optimizations_p
|
|
this flag indicates that redisplay optimizations should not be used
|
|
to display this buffer.
|
|
|
|
@item undo_list
|
|
This field points to the buffer's undo list. @xref{Undo}.
|
|
|
|
@item name
|
|
The buffer name is a string that names the buffer. It is guaranteed to
|
|
be unique. @xref{Buffer Names}.
|
|
|
|
@item filename
|
|
The name of the file visited in this buffer, or @code{nil}.
|
|
|
|
@item directory
|
|
The directory for expanding relative file names.
|
|
|
|
@item save_length
|
|
Length of the file this buffer is visiting, when last read or saved.
|
|
This and other fields concerned with saving are not kept in the
|
|
@code{buffer_text} structure because indirect buffers are never saved.
|
|
|
|
@item auto_save_file_name
|
|
File name used for auto-saving this buffer. This is not in the
|
|
@code{buffer_text} because it's not used in indirect buffers at all.
|
|
|
|
@item read_only
|
|
Non-@code{nil} means this buffer is read-only.
|
|
|
|
@item mark
|
|
This field contains the mark for the buffer. The mark is a marker,
|
|
hence it is also included on the list @code{markers}. @xref{The Mark}.
|
|
|
|
@item local_var_alist
|
|
This field contains the association list describing the buffer-local
|
|
variable bindings of this buffer, not including the built-in
|
|
buffer-local bindings that have special slots in the buffer object.
|
|
(Those slots are omitted from this table.) @xref{Buffer-Local
|
|
Variables}.
|
|
|
|
@item major_mode
|
|
Symbol naming the major mode of this buffer, e.g., @code{lisp-mode}.
|
|
|
|
@item mode_name
|
|
Pretty name of major mode, e.g., @code{"Lisp"}.
|
|
|
|
@item mode_line_format
|
|
Mode line element that controls the format of the mode line. If this
|
|
is @code{nil}, no mode line will be displayed.
|
|
|
|
@item header_line_format
|
|
This field is analoguous to @code{mode_line_format} for the mode
|
|
line displayed at the top of windows.
|
|
|
|
@item keymap
|
|
This field holds the buffer's local keymap. @xref{Keymaps}.
|
|
|
|
@item abbrev_table
|
|
This buffer's local abbrevs.
|
|
|
|
@item syntax_table
|
|
This field contains the syntax table for the buffer. @xref{Syntax Tables}.
|
|
|
|
@item category_table
|
|
This field contains the category table for the buffer.
|
|
|
|
@item case_fold_search
|
|
The value of @code{case-fold-search} in this buffer.
|
|
|
|
@item tab_width
|
|
The value of @code{tab-width} in this buffer.
|
|
|
|
@item fill_column
|
|
The value of @code{fill-column} in this buffer.
|
|
|
|
@item left_margin
|
|
The value of @code{left-margin} in this buffer.
|
|
|
|
@item auto_fill_function
|
|
The value of @code{auto-fill-function} in this buffer.
|
|
|
|
@item downcase_table
|
|
This field contains the conversion table for converting text to lower case.
|
|
@xref{Case Tables}.
|
|
|
|
@item upcase_table
|
|
This field contains the conversion table for converting text to upper case.
|
|
@xref{Case Tables}.
|
|
|
|
@item case_canon_table
|
|
This field contains the conversion table for canonicalizing text for
|
|
case-folding search. @xref{Case Tables}.
|
|
|
|
@item case_eqv_table
|
|
This field contains the equivalence table for case-folding search.
|
|
@xref{Case Tables}.
|
|
|
|
@item truncate_lines
|
|
The value of @code{truncate-lines} in this buffer.
|
|
|
|
@item ctl_arrow
|
|
The value of @code{ctl-arrow} in this buffer.
|
|
|
|
@item selective_display
|
|
The value of @code{selective-display} in this buffer.
|
|
|
|
@item selective_display_ellipsis
|
|
The value of @code{selective-display-ellipsis} in this buffer.
|
|
|
|
@item minor_modes
|
|
An alist of the minor modes of this buffer.
|
|
|
|
@item overwrite_mode
|
|
The value of @code{overwrite_mode} in this buffer.
|
|
|
|
@item abbrev_mode
|
|
The value of @code{abbrev-mode} in this buffer.
|
|
|
|
@item display_table
|
|
This field contains the buffer's display table, or @code{nil} if it doesn't
|
|
have one. @xref{Display Tables}.
|
|
|
|
@item save_modified
|
|
This field contains the time when the buffer was last saved, as an integer.
|
|
@xref{Buffer Modification}.
|
|
|
|
@item mark_active
|
|
This field is non-@code{nil} if the buffer's mark is active.
|
|
|
|
@item overlays_before
|
|
This field holds a list of the overlays in this buffer that end at or
|
|
before the current overlay center position. They are sorted in order of
|
|
decreasing end position.
|
|
|
|
@item overlays_after
|
|
This field holds a list of the overlays in this buffer that end after
|
|
the current overlay center position. They are sorted in order of
|
|
increasing beginning position.
|
|
|
|
@item overlay_center
|
|
This field holds the current overlay center position. @xref{Overlays}.
|
|
|
|
@item enable_multibyte_characters
|
|
This field holds the buffer's local value of
|
|
@code{enable-multibyte-characters}---either @code{t} or @code{nil}.
|
|
|
|
@item buffer_file_coding_system
|
|
The value of @code{buffer-file-coding-system} in this buffer.
|
|
|
|
@item file_format
|
|
The value of @code{buffer-file-format} in this buffer.
|
|
|
|
@item pt_marker
|
|
In an indirect buffer, or a buffer that is the base of an indirect
|
|
buffer, this holds a marker that records point for this buffer when the
|
|
buffer is not current.
|
|
|
|
@item begv_marker
|
|
In an indirect buffer, or a buffer that is the base of an indirect
|
|
buffer, this holds a marker that records @code{begv} for this buffer
|
|
when the buffer is not current.
|
|
|
|
@item zv_marker
|
|
In an indirect buffer, or a buffer that is the base of an indirect
|
|
buffer, this holds a marker that records @code{zv} for this buffer when
|
|
the buffer is not current.
|
|
|
|
@item file_truename
|
|
The truename of the visited file, or @code{nil}.
|
|
|
|
@item invisibility_spec
|
|
The value of @code{buffer-invisibility-spec} in this buffer.
|
|
|
|
@item last_selected_window
|
|
This is the last window that was selected with this buffer in it, or @code{nil}
|
|
if that window no longer displays this buffer.
|
|
|
|
@item display_count
|
|
This field is incremented each time the buffer is displayed in a window.
|
|
|
|
@item left_margin_width
|
|
The value of @code{left-margin-width} in this buffer.
|
|
|
|
@item right_margin_width
|
|
The value of @code{right-margin-width} in this buffer.
|
|
|
|
@item indicate_empty_lines
|
|
Non-@code{nil} means indicate empty lines (lines with no text) with a
|
|
small bitmap in the fringe, when using a window system that can do it.
|
|
|
|
@item display_time
|
|
This holds a time stamp that is updated each time this buffer is
|
|
displayed in a window.
|
|
|
|
@item scroll_up_aggressively
|
|
The value of @code{scroll-up-aggressively} in this buffer.
|
|
|
|
@item scroll_down_aggressively
|
|
The value of @code{scroll-down-aggressively} in this buffer.
|
|
@end table
|
|
|
|
@node Window Internals
|
|
@appendixsubsec Window Internals
|
|
@cindex internals, of window
|
|
@cindex window internals
|
|
|
|
Windows have the following accessible fields:
|
|
|
|
@table @code
|
|
@item frame
|
|
The frame that this window is on.
|
|
|
|
@item mini_p
|
|
Non-@code{nil} if this window is a minibuffer window.
|
|
|
|
@item parent
|
|
Internally, Emacs arranges windows in a tree; each group of siblings has
|
|
a parent window whose area includes all the siblings. This field points
|
|
to a window's parent.
|
|
|
|
Parent windows do not display buffers, and play little role in display
|
|
except to shape their child windows. Emacs Lisp programs usually have
|
|
no access to the parent windows; they operate on the windows at the
|
|
leaves of the tree, which actually display buffers.
|
|
|
|
The following four fields also describe the window tree structure.
|
|
|
|
@item hchild
|
|
In a window subdivided horizontally by child windows, the leftmost child.
|
|
Otherwise, @code{nil}.
|
|
|
|
@item vchild
|
|
In a window subdivided vertically by child windows, the topmost child.
|
|
Otherwise, @code{nil}.
|
|
|
|
@item next
|
|
The next sibling of this window. It is @code{nil} in a window that is
|
|
the rightmost or bottommost of a group of siblings.
|
|
|
|
@item prev
|
|
The previous sibling of this window. It is @code{nil} in a window that
|
|
is the leftmost or topmost of a group of siblings.
|
|
|
|
@item left
|
|
This is the left-hand edge of the window, measured in columns. (The
|
|
leftmost column on the screen is @w{column 0}.)
|
|
|
|
@item top
|
|
This is the top edge of the window, measured in lines. (The top line on
|
|
the screen is @w{line 0}.)
|
|
|
|
@item height
|
|
The height of the window, measured in lines.
|
|
|
|
@item width
|
|
The width of the window, measured in columns. This width includes the
|
|
scroll bar and fringes, and/or the separator line on the right of the
|
|
window (if any).
|
|
|
|
@item buffer
|
|
The buffer that the window is displaying. This may change often during
|
|
the life of the window.
|
|
|
|
@item start
|
|
The position in the buffer that is the first character to be displayed
|
|
in the window.
|
|
|
|
@item pointm
|
|
@cindex window point internals
|
|
This is the value of point in the current buffer when this window is
|
|
selected; when it is not selected, it retains its previous value.
|
|
|
|
@item force_start
|
|
If this flag is non-@code{nil}, it says that the window has been
|
|
scrolled explicitly by the Lisp program. This affects what the next
|
|
redisplay does if point is off the screen: instead of scrolling the
|
|
window to show the text around point, it moves point to a location that
|
|
is on the screen.
|
|
|
|
@item frozen_window_start_p
|
|
This field is set temporarily to 1 to indicate to redisplay that
|
|
@code{start} of this window should not be changed, even if point
|
|
gets invisible.
|
|
|
|
@item start_at_line_beg
|
|
Non-@code{nil} means current value of @code{start} was the beginning of a line
|
|
when it was chosen.
|
|
|
|
@item too_small_ok
|
|
Non-@code{nil} means don't delete this window for becoming ``too small''.
|
|
|
|
@item height_fixed_p
|
|
This field is temporarily set to 1 to fix the height of the selected
|
|
window when the echo area is resized.
|
|
|
|
@item use_time
|
|
This is the last time that the window was selected. The function
|
|
@code{get-lru-window} uses this field.
|
|
|
|
@item sequence_number
|
|
A unique number assigned to this window when it was created.
|
|
|
|
@item last_modified
|
|
The @code{modiff} field of the window's buffer, as of the last time
|
|
a redisplay completed in this window.
|
|
|
|
@item last_overlay_modified
|
|
The @code{overlay_modiff} field of the window's buffer, as of the last
|
|
time a redisplay completed in this window.
|
|
|
|
@item last_point
|
|
The buffer's value of point, as of the last time a redisplay completed
|
|
in this window.
|
|
|
|
@item last_had_star
|
|
A non-@code{nil} value means the window's buffer was ``modified'' when the
|
|
window was last updated.
|
|
|
|
@item vertical_scroll_bar
|
|
This window's vertical scroll bar.
|
|
|
|
@item left_margin_width
|
|
The width of the left margin in this window, or @code{nil} not to
|
|
specify it (in which case the buffer's value of @code{left-margin-width}
|
|
is used.
|
|
|
|
@item right_margin_width
|
|
Likewise for the right margin.
|
|
|
|
@ignore
|
|
@item last_mark_x
|
|
@item last_mark_y
|
|
???Not used.
|
|
@end ignore
|
|
|
|
@item window_end_pos
|
|
This is computed as @code{z} minus the buffer position of the last glyph
|
|
in the current matrix of the window. The value is only valid if
|
|
@code{window_end_valid} is not @code{nil}.
|
|
|
|
@item window_end_bytepos
|
|
The byte position corresponding to @code{window_end_pos}.
|
|
|
|
@item window_end_vpos
|
|
The window-relative vertical position of the line containing
|
|
@code{window_end_pos}.
|
|
|
|
@item window_end_valid
|
|
This field is set to a non-@code{nil} value if @code{window_end_pos} is truly
|
|
valid. This is @code{nil} if nontrivial redisplay is preempted since in that
|
|
case the display that @code{window_end_pos} was computed for did not get
|
|
onto the screen.
|
|
|
|
@item redisplay_end_trigger
|
|
If redisplay in this window goes beyond this buffer position, it runs
|
|
run the @code{redisplay-end-trigger-hook}.
|
|
|
|
@ignore
|
|
@item orig_height
|
|
@item orig_top
|
|
??? Are temporary storage areas.
|
|
@end ignore
|
|
|
|
@item cursor
|
|
A structure describing where the cursor is in this window.
|
|
|
|
@item last_cursor
|
|
The value of @code{cursor} as of the last redisplay that finished.
|
|
|
|
@item phys_cursor
|
|
A structure describing where the cursor of this window physically is.
|
|
|
|
@item phys_cursor_type
|
|
The type of cursor that was last displayed on this window.
|
|
|
|
@item phys_cursor_on_p
|
|
This field is non-zero if the cursor is physically on.
|
|
|
|
@item cursor_off_p
|
|
Non-zero means the cursor in this window is logically on.
|
|
|
|
@item last_cursor_off_p
|
|
This field contains the value of @code{cursor_off_p} as of the time of
|
|
the last redisplay.
|
|
|
|
@item must_be_updated_p
|
|
This is set to 1 during redisplay when this window must be updated.
|
|
|
|
@item hscroll
|
|
This is the number of columns that the display in the window is scrolled
|
|
horizontally to the left. Normally, this is 0.
|
|
|
|
@item vscroll
|
|
Vertical scroll amount, in pixels. Normally, this is 0.
|
|
|
|
@item dedicated
|
|
Non-@code{nil} if this window is dedicated to its buffer.
|
|
|
|
@item display_table
|
|
The window's display table, or @code{nil} if none is specified for it.
|
|
|
|
@item update_mode_line
|
|
Non-@code{nil} means this window's mode line needs to be updated.
|
|
|
|
@item base_line_number
|
|
The line number of a certain position in the buffer, or @code{nil}.
|
|
This is used for displaying the line number of point in the mode line.
|
|
|
|
@item base_line_pos
|
|
The position in the buffer for which the line number is known, or
|
|
@code{nil} meaning none is known.
|
|
|
|
@item region_showing
|
|
If the region (or part of it) is highlighted in this window, this field
|
|
holds the mark position that made one end of that region. Otherwise,
|
|
this field is @code{nil}.
|
|
|
|
@item column_number_displayed
|
|
The column number currently displayed in this window's mode line, or @code{nil}
|
|
if column numbers are not being displayed.
|
|
|
|
@item current_matrix
|
|
A glyph matrix describing the current display of this window.
|
|
|
|
@item desired_matrix
|
|
A glyph matrix describing the desired display of this window.
|
|
@end table
|
|
|
|
@node Process Internals
|
|
@appendixsubsec Process Internals
|
|
@cindex internals, of process
|
|
@cindex process internals
|
|
|
|
The fields of a process are:
|
|
|
|
@table @code
|
|
@item name
|
|
A string, the name of the process.
|
|
|
|
@item command
|
|
A list containing the command arguments that were used to start this
|
|
process.
|
|
|
|
@item filter
|
|
A function used to accept output from the process instead of a buffer,
|
|
or @code{nil}.
|
|
|
|
@item sentinel
|
|
A function called whenever the process receives a signal, or @code{nil}.
|
|
|
|
@item buffer
|
|
The associated buffer of the process.
|
|
|
|
@item pid
|
|
An integer, the Unix process @sc{id}.
|
|
|
|
@item childp
|
|
A flag, non-@code{nil} if this is really a child process.
|
|
It is @code{nil} for a network connection.
|
|
|
|
@item mark
|
|
A marker indicating the position of the end of the last output from this
|
|
process inserted into the buffer. This is often but not always the end
|
|
of the buffer.
|
|
|
|
@item kill_without_query
|
|
If this is non-@code{nil}, killing Emacs while this process is still
|
|
running does not ask for confirmation about killing the process.
|
|
|
|
@item raw_status_low
|
|
@itemx raw_status_high
|
|
These two fields record 16 bits each of the process status returned by
|
|
the @code{wait} system call.
|
|
|
|
@item status
|
|
The process status, as @code{process-status} should return it.
|
|
|
|
@item tick
|
|
@itemx update_tick
|
|
If these two fields are not equal, a change in the status of the process
|
|
needs to be reported, either by running the sentinel or by inserting a
|
|
message in the process buffer.
|
|
|
|
@item pty_flag
|
|
Non-@code{nil} if communication with the subprocess uses a @sc{pty};
|
|
@code{nil} if it uses a pipe.
|
|
|
|
@item infd
|
|
The file descriptor for input from the process.
|
|
|
|
@item outfd
|
|
The file descriptor for output to the process.
|
|
|
|
@item subtty
|
|
The file descriptor for the terminal that the subprocess is using. (On
|
|
some systems, there is no need to record this, so the value is
|
|
@code{nil}.)
|
|
|
|
@item tty_name
|
|
The name of the terminal that the subprocess is using,
|
|
or @code{nil} if it is using pipes.
|
|
|
|
@item decode_coding_system
|
|
Coding-system for decoding the input from this process.
|
|
|
|
@item decoding_buf
|
|
A working buffer for decoding.
|
|
|
|
@item decoding_carryover
|
|
Size of carryover in decoding.
|
|
|
|
@item encode_coding_system
|
|
Coding-system for encoding the output to this process.
|
|
|
|
@item encoding_buf
|
|
A working buffer for enecoding.
|
|
|
|
@item encoding_carryover
|
|
Size of carryover in encoding.
|
|
|
|
@item inherit_coding_system_flag
|
|
Flag to set @code{coding-system} of the process buffer from the
|
|
coding system used to decode process output.
|
|
@end table
|