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Change return value of _bfd_mmap_temporary

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_bfd_mmap_temporary will return MAP_FAILED in some cases, but only one
caller was prepared for this.  This caused a couple of issues in gdb.

This patch chnages _bfd_mmap_temporary to always return NULL on
failure.  It also changes the logic to fall back to bfd_malloc if mmap
fails.

I took the opportunity to change some "(void *) -1" to MAP_FAILED
where appropriate.

Tested by "make check" in binutils, and also by applying a hack from
bug 33354 to gdb and testing something approximating the original
report.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=32542
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=33354
This commit is contained in:
Tom Tromey
2025-09-04 14:12:52 -06:00
parent e447f3a122
commit 8b50cc76f1
3 changed files with 19 additions and 21 deletions
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5
bfd/bfdio.c
View File

@@ -293,7 +293,7 @@ DESCRIPTION
. int (*bstat) (struct bfd *abfd, struct stat *sb);
. {* Mmap a part of the files. ADDR, LEN, PROT, FLAGS and OFFSET are the usual
. mmap parameter, except that LEN and OFFSET do not need to be page
. aligned. Returns (void *)-1 on failure, mmapped address on success.
. aligned. Returns MAP_FAILED on failure, mmapped address on success.
. Also write in MAP_ADDR the address of the page aligned buffer and in
. MAP_LEN the size mapped (a page multiple). Use unmap with MAP_ADDR and
. MAP_LEN to unmap. *}
@@ -732,6 +732,7 @@ DESCRIPTION
Return mmap()ed region of the file, if possible and implemented.
LEN and OFFSET do not need to be page aligned. The page aligned
address and length are written to MAP_ADDR and MAP_LEN.
Returns MAP_FAILED on failure.
*/
@@ -906,7 +907,7 @@ memory_bmmap (bfd *abfd ATTRIBUTE_UNUSED, void *addr ATTRIBUTE_UNUSED,
void **map_addr ATTRIBUTE_UNUSED,
size_t *map_len ATTRIBUTE_UNUSED)
{
return (void *)-1;
return MAP_FAILED;
}
const struct bfd_iovec _bfd_memory_iovec =

33
bfd/libbfd.c
View File

@@ -1098,24 +1098,26 @@ bfd_mmap_local (bfd *abfd, size_t rsize, void **map_addr, size_t *map_size)
/* Mmap a memory region of RSIZE bytes at the current offset.
Return mmap address and size in MAP_ADDR and MAP_SIZE. Return NULL
on invalid input and MAP_FAILED for mmap failure. */
on invalid input. */
void *
_bfd_mmap_temporary (bfd *abfd, size_t rsize, void **map_addr,
size_t *map_size)
{
/* Use mmap only if section size >= the minimum mmap section size. */
if (rsize < _bfd_minimum_mmap_size)
if (rsize >= _bfd_minimum_mmap_size)
{
void *mem = _bfd_malloc_and_read (abfd, rsize, rsize);
/* NB: Set *MAP_ADDR to MEM and *MAP_SIZE to 0 to indicate that
_bfd_malloc_and_read is called. */
*map_addr = mem;
*map_size = 0;
return mem;
void *result = bfd_mmap_local (abfd, rsize, map_addr, map_size);
if (result != MAP_FAILED)
return result;
}
return bfd_mmap_local (abfd, rsize, map_addr, map_size);
void *mem = _bfd_malloc_and_read (abfd, rsize, rsize);
/* NB: Set *MAP_ADDR to MEM and *MAP_SIZE to 0 to indicate that
_bfd_malloc_and_read is called. */
*map_addr = mem;
*map_size = 0;
return mem;
}
/* Munmap RSIZE bytes at PTR. */
@@ -1213,15 +1215,10 @@ _bfd_mmap_read_temporary (void **data_p, size_t *size_p,
if (use_mmmap)
{
void *mmaped = _bfd_mmap_temporary (abfd, size, mmap_base, size_p);
/* MAP_FAILED is returned when called from GDB on an object with
opncls_iovec. Use bfd_read in this case. */
if (mmaped != MAP_FAILED)
{
if (mmaped == NULL)
abort ();
*data_p = mmaped;
return true;
}
if (mmaped == NULL)
return false;
*data_p = mmaped;
return true;
}
#endif

2
bfd/libbfd.h
View File

@@ -1011,7 +1011,7 @@ struct bfd_iovec
int (*bstat) (struct bfd *abfd, struct stat *sb);
/* Mmap a part of the files. ADDR, LEN, PROT, FLAGS and OFFSET are the usual
mmap parameter, except that LEN and OFFSET do not need to be page
aligned. Returns (void *)-1 on failure, mmapped address on success.
aligned. Returns MAP_FAILED on failure, mmapped address on success.
Also write in MAP_ADDR the address of the page aligned buffer and in
MAP_LEN the size mapped (a page multiple). Use unmap with MAP_ADDR and
MAP_LEN to unmap. */