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Code Issues Releases Activity

(unexec): Minor changes; clean up comments.

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This commit is contained in:
Richard M. Stallman 2001-11-05 22:17:49 +00:00
parent a6beb3d26b
commit d9d54213bc
2 changed files with 31 additions and 52 deletions
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4
src/ChangeLog
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@ -1,3 +1,7 @@
2001-11-05 Richard M. Stallman <rms@gnu.org>
* unexelf.c (unexec): Minor changes; clean up comments.
2001-11-05 Sam Steingold <sds@gnu.org>
* w32term.c (x_display_and_set_cursor): Fix w32 compilation error.

79
src/unexelf.c
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@ -404,23 +404,9 @@ Filesz Memsz Flags Align
*/
/*
* Modified by rdh@yottayotta.com of Yotta Yotta Incorporated.
*
* The code originally used mmap() to create a memory image of the new
* and old object files. This had a few handy features: (1) you get
* to use a cool system call like mmap, (2) no need to explicitly
* write out the new file before the close, and (3) no swap space
* requirements. Unfortunately, mmap() often fails to work with
* nfs-mounted file systems.
*
* So, instead of relying on the vm subsystem to do the file i/o for
* us, it's now done explicitly. A buffer of the right size for the
* file is dynamically allocated, and either the old_name is read into
* it, or it is initialized with the correct new executable contents,
* and then written to new_name.
*/
/* We do not use mmap because that fails with NFS.
Instead we read the whole file, modify it, and write it out. */
#ifndef emacs
#define fatal(a, b, c) fprintf (stderr, a, b, c), exit (1)
#include <string.h>
@ -660,17 +646,16 @@ unexec (new_name, old_name, data_start, bss_start, entry_address)
{
int new_file, old_file, new_file_size;
/* Pointers to the base of the image of the two files. */
/* Pointers to the base of the image of the two files. */
caddr_t old_base, new_base;
/* Pointers to the file, program and section headers for the old and new
* files.
*/
/* Pointers to the file, program and section headers for the old and
new files. */
ElfW(Ehdr) *old_file_h, *new_file_h;
ElfW(Phdr) *old_program_h, *new_program_h;
ElfW(Shdr) *old_section_h, *new_section_h;
/* Point to the section name table in the old file */
/* Point to the section name table in the old file. */
char *old_section_names;
ElfW(Addr) old_bss_addr, new_bss_addr;
@ -685,7 +670,7 @@ unexec (new_name, old_name, data_start, bss_start, entry_address)
struct stat stat_buf;
/* Open the old file, allocate a buffer of the right size, and read
* in the file contents. */
in the file contents. */
old_file = open (old_name, O_RDONLY);
@ -722,8 +707,7 @@ unexec (new_name, old_name, data_start, bss_start, entry_address)
old_name, old_file_h, old_section_h, 1);
/* Find the old .bss section. Figure out parameters of the new
* data2 and bss sections.
*/
data2 and bss sections. */
old_bss_index = find_section (".bss", old_section_names,
old_name, old_file_h, old_section_h, 0);
@ -778,9 +762,8 @@ unexec (new_name, old_name, data_start, bss_start, entry_address)
fatal (".bss shrank when undumping???\n", 0, 0);
/* Set the output file to the right size. Allocate a buffer to hold
* the image of the new file. Set pointers to various interesting
* objects. stat_buf still has old_file data.
*/
the image of the new file. Set pointers to various interesting
objects. stat_buf still has old_file data. */
new_file = open (new_name, O_RDWR | O_CREAT, 0666);
if (new_file < 0)
@ -807,8 +790,7 @@ unexec (new_name, old_name, data_start, bss_start, entry_address)
((byte *) new_base + old_file_h->e_shoff + new_data2_size);
/* Make our new file, program and section headers as copies of the
* originals.
*/
originals. */
memcpy (new_file_h, old_file_h, old_file_h->e_ehsize);
memcpy (new_program_h, old_program_h,
@ -818,8 +800,7 @@ unexec (new_name, old_name, data_start, bss_start, entry_address)
PATCH_INDEX (new_file_h->e_shstrndx);
/* Fix up file header. We'll add one section. Section header is
* further away now.
*/
further away now. */
new_file_h->e_shoff += new_data2_size;
new_file_h->e_shnum += 1;
@ -832,12 +813,11 @@ unexec (new_name, old_name, data_start, bss_start, entry_address)
#endif
/* Fix up a new program header. Extend the writable data segment so
* that the bss area is covered too. Find that segment by looking
* for a segment that ends just before the .bss area. Make sure
* that no segments are above the new .data2. Put a loop at the end
* to adjust the offset and address of any segment that is above
* data2, just in case we decide to allow this later.
*/
that the bss area is covered too. Find that segment by looking
for a segment that ends just before the .bss area. Make sure
that no segments are above the new .data2. Put a loop at the end
to adjust the offset and address of any segment that is above
data2, just in case we decide to allow this later. */
for (n = new_file_h->e_phnum - 1; n >= 0; n--)
{
@ -887,11 +867,10 @@ unexec (new_name, old_name, data_start, bss_start, entry_address)
#endif
/* Fix up section headers based on new .data2 section. Any section
* whose offset or virtual address is after the new .data2 section
* gets its value adjusted. .bss size becomes zero and new address
* is set. data2 section header gets added by copying the existing
* .data header and modifying the offset, address and size.
*/
whose offset or virtual address is after the new .data2 section
gets its value adjusted. .bss size becomes zero and new address
is set. data2 section header gets added by copying the existing
.data header and modifying the offset, address and size. */
for (old_data_index = 1; old_data_index < (int) old_file_h->e_shnum;
old_data_index++)
if (!strcmp (old_section_names + OLD_SECTION_H (old_data_index).sh_name,
@ -1217,26 +1196,22 @@ unexec (new_name, old_name, data_start, bss_start, entry_address)
}
}
/* Write out new_file, close it, and free the buffer containing its
* contents */
/* Write out new_file, and free the buffers. */
if (write (new_file, new_base, new_file_size) != new_file_size)
fatal ("Didn't write %d bytes to %s: errno %d\n",
new_file_size, new_base, errno);
if (close (new_file))
fatal ("Can't close (%s): errno %d\n", new_name, errno);
free (old_base);
free (new_base);
/* Close old_file, and free the corresponding buffer */
/* Close the files and make the new file executable. */
if (close (old_file))
fatal ("Can't close (%s): errno %d\n", old_name, errno);
free (old_base);
/* Make the new file executable */
if (close (new_file))
fatal ("Can't close (%s): errno %d\n", new_name, errno);
if (stat (new_name, &stat_buf) == -1)
fatal ("Can't stat (%s): errno %d\n", new_name, errno);