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Replace __libc_multiple_libcs with __libc_initial flag

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Change sbrk to fail for !__libc_initial (in the generic
implementation).  As a result, sbrk is (relatively) safe to use
for the __libc_initial case (from the main libc).  It is therefore
no longer necessary to avoid using it in that case (or updating the
brk cache), and the __libc_initial flag does not need to be updated
as part of dlmopen or static dlopen.

As before, direct brk system calls on Linux may lead to memory
corruption.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer
2020-12-16 15:09:52 +01:00
parent 9459fe9da0
commit e7570f4131
9 changed files with 52 additions and 39 deletions
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9
elf/libc_early_init.c
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@ -18,8 +18,13 @@
#include <ctype.h>
#include <libc-early-init.h>
#include <libc-internal.h>
#include <sys/single_threaded.h>
#ifdef SHARED
_Bool __libc_initial;
#endif
void
__libc_early_init (_Bool initial)
{
@ -28,4 +33,8 @@ __libc_early_init (_Bool initial)
/* Only the outer namespace is marked as single-threaded. */
__libc_single_threaded = initial;
#ifdef SHARED
__libc_initial = initial;
#endif
}