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Make dlerror(3) thread-safe.

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I gave up trying to use the usual thread-local buffer idiom; calls to
calloc(3) and free(3) from any of the "dl" functions -- which live in
the dynamic linker -- end up resolving to the dynamic linker's stubs.
I tried to work around that, but was just making things more complicated.
This alternative costs us a well-known TLS slot (instead of the
dynamically-allocated TLS slot we'd have used otherwise, so no difference
there), plus an extra buffer inside every pthread_internal_t.

Bug: 5404023
Change-Id: Ie9614edd05b6d1eeaf7bf9172792d616c6361767
This commit is contained in:
Elliott Hughes
2012-10-16 15:54:46 -07:00
parent a9944cfe9e
commit 5419b94747
10 changed files with 124 additions and 94 deletions
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15
linker/linker.cpp
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@@ -168,16 +168,15 @@ static char __linker_dl_err_buf[768];
ERROR(fmt "\n", ##x); \
} while(0)
const char *linker_get_error(void)
{
return (const char *)&__linker_dl_err_buf[0];
const char* linker_get_error() {
return &__linker_dl_err_buf[0];
}
/*
* This function is an empty stub where GDB locates a breakpoint to get notified
* about linker activity.
*/
extern "C" void __attribute__((noinline)) __attribute__((visibility("default"))) rtld_db_dlactivity(void);
extern "C" void __attribute__((noinline)) __attribute__((visibility("default"))) rtld_db_dlactivity();
static r_debug _r_debug = {1, NULL, &rtld_db_dlactivity,
RT_CONSISTENT, 0};
@@ -1363,8 +1362,7 @@ static void call_destructors(soinfo *si)
/* Force any of the closed stdin, stdout and stderr to be associated with
/dev/null. */
static int nullify_closed_stdio (void)
{
static int nullify_closed_stdio() {
int dev_null, i, status;
int return_value = 0;
@@ -2056,5 +2054,8 @@ extern "C" unsigned __linker_init(unsigned **elfdata) {
// We have successfully fixed our own relocations. It's safe to run
// the main part of the linker now.
return __linker_init_post_relocation(elfdata, linker_addr);
unsigned start_address = __linker_init_post_relocation(elfdata, linker_addr);
// Return the address that the calling assembly stub should jump to.
return start_address;
}