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(AC_FUNC_MMAP): Use fixed version from development
autoconf.
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Dave Love
parent
53c94d4d99
commit
8b05edb34e
146
aclocal.m4
vendored
146
aclocal.m4
vendored
@ -355,4 +355,150 @@ AC_DEFUN(AC_SYS_LARGEFILE,
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fi
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])
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undefine([AC_FUNC_MMAP])dnl
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dnl The autoconf 2.13 version loses on OSF, at least,
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dnl by messing up the declaration of malloc.
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AC_DEFUN([AC_FUNC_MMAP],
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[AC_CHECK_HEADERS(stdlib.h unistd.h sys/stat.h)
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AC_CHECK_FUNCS(getpagesize)
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AC_CACHE_CHECK(for working mmap, ac_cv_func_mmap_fixed_mapped,
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[AC_TRY_RUN(
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[/* Thanks to Mike Haertel and Jim Avera for this test.
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Here is a matrix of mmap possibilities:
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mmap private not fixed
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mmap private fixed at somewhere currently unmapped
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mmap private fixed at somewhere already mapped
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mmap shared not fixed
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mmap shared fixed at somewhere currently unmapped
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mmap shared fixed at somewhere already mapped
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For private mappings, we should verify that changes cannot be read()
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back from the file, nor mmap's back from the file at a different
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address. (There have been systems where private was not correctly
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implemented like the infamous i386 svr4.0, and systems where the
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VM page cache was not coherent with the file system buffer cache
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like early versions of FreeBSD and possibly contemporary NetBSD.)
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For shared mappings, we should conversely verify that changes get
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propogated back to all the places they're supposed to be.
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Grep wants private fixed already mapped.
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The main things grep needs to know about mmap are:
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* does it exist and is it safe to write into the mmap'd area
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* how to use it (BSD variants) */
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#include <sys/types.h>
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#include <fcntl.h>
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#include <sys/mman.h>
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#if STDC_HEADERS || HAVE_STDLIB_H
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# include <stdlib.h>
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#else
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char *malloc ();
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#endif
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#if HAVE_UNISTD_H
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# include <unistd.h>
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#endif
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#if HAVE_SYS_STAT_H
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# include <sys/stat.h>
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#endif
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/* This mess was copied from the GNU getpagesize.h. */
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#if !HAVE_GETPAGESIZE
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/* Assume that all systems that can run configure have sys/param.h. */
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# if !HAVE_SYS_PARAM_H
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# define HAVE_SYS_PARAM_H 1
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# endif
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# ifdef _SC_PAGESIZE
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# define getpagesize() sysconf(_SC_PAGESIZE)
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# else /* no _SC_PAGESIZE */
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# if HAVE_SYS_PARAM_H
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# include <sys/param.h>
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# ifdef EXEC_PAGESIZE
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# define getpagesize() EXEC_PAGESIZE
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# else /* no EXEC_PAGESIZE */
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# ifdef NBPG
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# define getpagesize() NBPG * CLSIZE
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# ifndef CLSIZE
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# define CLSIZE 1
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# endif /* no CLSIZE */
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# else /* no NBPG */
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# ifdef NBPC
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# define getpagesize() NBPC
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# else /* no NBPC */
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# ifdef PAGESIZE
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# define getpagesize() PAGESIZE
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# endif /* PAGESIZE */
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# endif /* no NBPC */
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# endif /* no NBPG */
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# endif /* no EXEC_PAGESIZE */
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# else /* no HAVE_SYS_PARAM_H */
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# define getpagesize() 8192 /* punt totally */
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# endif /* no HAVE_SYS_PARAM_H */
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# endif /* no _SC_PAGESIZE */
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#endif /* no HAVE_GETPAGESIZE */
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int
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main ()
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{
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char *data, *data2, *data3;
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int i, pagesize;
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int fd;
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pagesize = getpagesize ();
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/* First, make a file with some known garbage in it. */
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data = (char *) malloc (pagesize);
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if (!data)
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exit (1);
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for (i = 0; i < pagesize; ++i)
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*(data + i) = rand ();
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umask (0);
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fd = creat ("conftestmmap", 0600);
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if (fd < 0)
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exit (1);
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if (write (fd, data, pagesize) != pagesize)
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exit (1);
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close (fd);
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/* Next, try to mmap the file at a fixed address which already has
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something else allocated at it. If we can, also make sure that
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we see the same garbage. */
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fd = open ("conftestmmap", O_RDWR);
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if (fd < 0)
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exit (1);
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data2 = (char *) malloc (2 * pagesize);
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if (!data2)
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exit (1);
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data2 += (pagesize - ((int) data2 & (pagesize - 1))) & (pagesize - 1);
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if (data2 != mmap (data2, pagesize, PROT_READ | PROT_WRITE,
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MAP_PRIVATE | MAP_FIXED, fd, 0L))
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exit (1);
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for (i = 0; i < pagesize; ++i)
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if (*(data + i) != *(data2 + i))
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exit (1);
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/* Finally, make sure that changes to the mapped area do not
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percolate back to the file as seen by read(). (This is a bug on
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some variants of i386 svr4.0.) */
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for (i = 0; i < pagesize; ++i)
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*(data2 + i) = *(data2 + i) + 1;
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data3 = (char *) malloc (pagesize);
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if (!data3)
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exit (1);
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if (read (fd, data3, pagesize) != pagesize)
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exit (1);
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for (i = 0; i < pagesize; ++i)
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if (*(data + i) != *(data3 + i))
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exit (1);
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close (fd);
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unlink ("conftestmmap");
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exit (0);
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}], ac_cv_func_mmap_fixed_mapped=yes, ac_cv_func_mmap_fixed_mapped=no,
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ac_cv_func_mmap_fixed_mapped=no)])
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if test $ac_cv_func_mmap_fixed_mapped = yes; then
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AC_DEFINE(HAVE_MMAP, 1,
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[Define if you have a working `mmap' system call.])
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fi
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])# AC_FUNC_MMAP
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) dnl ifelse
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