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2005-10-17 Roland McGrath <roland@redhat.com> 

* elf/dl-load.c (MAP_COPY): When undefined, define to
	MAP_PRIVATE|MAP_DENYWRITE instead of just MAP_PRIVATE.
	(_dl_map_object_from_fd): Don't use MAP_DENYWRITE explicitly.
This commit is contained in:
Roland McGrath 2005-10-17 20:59:28 +00:00
parent 4fa64d66fe
commit a3fcd5e8a4
1 changed files with 12 additions and 10 deletions
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22
elf/dl-load.c
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@ -50,15 +50,17 @@
overwritten. Some losing VM systems like Linux's lack MAP_COPY. All we
get is MAP_PRIVATE, which copies each page when it is modified; this
means if the file is overwritten, we may at some point get some pages
from the new version after starting with pages from the old version. */
#ifndef MAP_COPY
# define MAP_COPY MAP_PRIVATE
#endif
from the new version after starting with pages from the old version.
/* We want to prevent people from modifying DSOs which are currently in
use. This is what MAP_DENYWRITE is for. */
#ifndef MAP_DENYWRITE
# define MAP_DENYWRITE 0
To make up for the lack and avoid the overwriting problem,
what Linux does have is MAP_DENYWRITE. This prevents anyone
from modifying the file while we have it mapped. */
#ifndef MAP_COPY
# ifdef MAP_DENYWRITE
# define MAP_COPY (MAP_PRIVATE | MAP_DENYWRITE)
# else
# define MAP_COPY MAP_PRIVATE
# endif
#endif
/* Some systems link their relocatable objects for another base address
@ -1181,7 +1183,7 @@ cannot allocate TLS data structures for initial thread");
/* Remember which part of the address space this object uses. */
l->l_map_start = (ElfW(Addr)) __mmap ((void *) mappref, maplength,
c->prot,
MAP_COPY|MAP_FILE|MAP_DENYWRITE,
MAP_COPY|MAP_FILE,
fd, c->mapoff);
if (__builtin_expect ((void *) l->l_map_start == MAP_FAILED, 0))
{
@ -1229,7 +1231,7 @@ cannot allocate TLS data structures for initial thread");
/* Map the segment contents from the file. */
&& (__mmap ((void *) (l->l_addr + c->mapstart),
c->mapend - c->mapstart, c->prot,
MAP_FIXED|MAP_COPY|MAP_FILE|MAP_DENYWRITE,
MAP_FIXED|MAP_COPY|MAP_FILE,
fd, c->mapoff)
== MAP_FAILED))
goto map_error;