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[sanitizer] Use runtime checks instead of API level for Android logging 

Summary:
Recent Bionic have a slew of `async_safe_*` logging functions that are
basically the liblog ones but included within the libc. They have the advantage
of not allocating memory. `async_safe_write_log` does no formatting and is
likely the best candidate for logging.

Use a weak definition to try and use it. Also, avoid API level checks (as
the toolchain is compiled at a rather low API level) for `__android_log_write`
in favor of a weak definition as well.

Keep the fallback to `syslog` if nothing else was found.

I tried to overhaul the code block to only have a single #if SANITIZER_ANDROID
but I am not particularly attached to the form. LMKWYT.

Reviewers: eugenis

Reviewed By: eugenis

Subscribers: srhines, kubamracek, llvm-commits

Differential Revision: https://reviews.llvm.org/D40100

llvm-svn: 318410
This commit is contained in:
Kostya Kortchinsky 2017-11-16 16:19:44 +00:00
parent c43622642a
commit 8562eb32c9
1 changed files with 38 additions and 27 deletions
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65
compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cc
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@ -48,10 +48,6 @@
#include <android/api-level.h>
#endif
#if SANITIZER_ANDROID && __ANDROID_API__ < 21
#include <android/log.h>
#endif
#if !SANITIZER_ANDROID
#include <elf.h>
#include <unistd.h>
@ -538,12 +534,9 @@ uptr GetRSS() {
return rss * GetPageSizeCached();
}
// 64-bit Android targets don't provide the deprecated __android_log_write.
// Starting with the L release, syslog() works and is preferable to
// __android_log_write.
#if SANITIZER_LINUX
#if SANITIZER_ANDROID
# if SANITIZER_ANDROID
static atomic_uint8_t android_log_initialized;
void AndroidLogInit() {
@ -554,35 +547,53 @@ void AndroidLogInit() {
static bool ShouldLogAfterPrintf() {
return atomic_load(&android_log_initialized, memory_order_acquire);
}
#else
extern "C" SANITIZER_WEAK_ATTRIBUTE
int async_safe_write_log(int pri, const char* tag, const char* msg);
extern "C" SANITIZER_WEAK_ATTRIBUTE
int __android_log_write(int prio, const char* tag, const char* msg);
// ANDROID_LOG_INFO is 4, but can't be resolved at runtime.
#define SANITIZER_ANDROID_LOG_INFO 4
// async_safe_write_log is basically __android_log_write but is only available
// in recent versions of Bionic. __android_log_write was deprecated along the
// way, so fallback to syslog if neither exists. The non-syslog alternatives
// do not allocate memory and are preferable. Also syslog is broken pre-L, this
// is another reason why we prefer __android_log_write if available.
void WriteOneLineToSyslog(const char *s) {
if (&async_safe_write_log) {
async_safe_write_log(SANITIZER_ANDROID_LOG_INFO, GetProcessName(), s);
} else if (&__android_log_write) {
__android_log_write(SANITIZER_ANDROID_LOG_INFO, nullptr, s);
} else {
syslog(LOG_INFO, "%s", s);
}
}
extern "C" SANITIZER_WEAK_ATTRIBUTE
void android_set_abort_message(const char *);
void SetAbortMessage(const char *str) {
if (&android_set_abort_message)
android_set_abort_message(str);
}
# else
void AndroidLogInit() {}
static bool ShouldLogAfterPrintf() { return true; }
#endif // SANITIZER_ANDROID
void WriteOneLineToSyslog(const char *s) {
#if SANITIZER_ANDROID &&__ANDROID_API__ < 21
__android_log_write(ANDROID_LOG_INFO, NULL, s);
#else
syslog(LOG_INFO, "%s", s);
#endif
}
void WriteOneLineToSyslog(const char *s) { syslog(LOG_INFO, "%s", s); }
void SetAbortMessage(const char *str) {}
# endif // SANITIZER_ANDROID
void LogMessageOnPrintf(const char *str) {
if (common_flags()->log_to_syslog && ShouldLogAfterPrintf())
WriteToSyslog(str);
}
#if SANITIZER_ANDROID
extern "C" __attribute__((weak)) void android_set_abort_message(const char *);
void SetAbortMessage(const char *str) {
if (&android_set_abort_message) android_set_abort_message(str);
}
#else
void SetAbortMessage(const char *str) {}
#endif
#endif // SANITIZER_LINUX
#endif // SANITIZER_LINUX
} // namespace __sanitizer