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Replace snprintf calls in linker.

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When enabling debug malloc, the snprintf calls in the linker fails to
update the buffer.

The problem is that snprintf makes a call to pthread_getspecific that
returns a valid pointer, but the data it points to is zero. This should
never happen and causes the snprintf to stop and do nothing.

Temporarily replace snprintf with a different implementation to work
around this issue.

Bug: 16874447
Bug: 17302493
Change-Id: I7a500f28adf153150cf2812fae745ff41f1c48d3
This commit is contained in:
Christopher Ferris 2014-08-26 20:48:11 -07:00 committed by The Android Automerger
parent 54a6221cc2
commit 20dc3f8fa4
2 changed files with 17 additions and 3 deletions
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4
linker/debugger.cpp
View File

@ -170,9 +170,9 @@ static void log_signal_summary(int signum, const siginfo_t* info) {
if (info != NULL) {
// For a rethrown signal, this si_code will be right and the one debuggerd shows will
// always be SI_TKILL.
snprintf(code_desc, sizeof(code_desc), ", code %d", info->si_code);
__libc_format_buffer(code_desc, sizeof(code_desc), ", code %d", info->si_code);
if (has_address) {
snprintf(addr_desc, sizeof(addr_desc), ", fault addr %p", info->si_addr);
__libc_format_buffer(addr_desc, sizeof(addr_desc), ", fault addr %p", info->si_addr);
}
}
__libc_format_log(ANDROID_LOG_FATAL, "libc",

16
linker/linker.cpp
View File

@ -866,7 +866,21 @@ static void soinfo_unload(soinfo* si) {
}
void do_android_get_LD_LIBRARY_PATH(char* buffer, size_t buffer_size) {
snprintf(buffer, buffer_size, "%s:%s", kDefaultLdPaths[0], kDefaultLdPaths[1]);
// Use basic string manipulation calls to avoid snprintf.
// snprintf indirectly calls pthread_getspecific to get the size of a buffer.
// When debug malloc is enabled, this call returns 0. This in turn causes
// snprintf to do nothing, which causes libraries to fail to load.
// See b/17302493 for further details.
// Once the above bug is fixed, this code can be modified to use
// snprintf again.
size_t required_len = strlen(kDefaultLdPaths[0]) + strlen(kDefaultLdPaths[1]) + 2;
if (buffer_size < required_len) {
__libc_fatal("android_get_LD_LIBRARY_PATH failed, buffer too small: buffer len %zu, required len %zu",
buffer_size, required_len);
}
char* end = stpcpy(buffer, kDefaultLdPaths[0]);
*end = ':';
strcpy(end + 1, kDefaultLdPaths[1]);
}
void do_android_update_LD_LIBRARY_PATH(const char* ld_library_path) {