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authorGravatar Andy Getzendanner <durandal@google.com>2022-05-04 20:58:05 -0700
committerGravatar Copybara-Service <copybara-worker@google.com>2022-05-04 20:58:54 -0700
commit173dfe4a4c70f294a512aae4d0d0f5fc7db39241 (patch)
tree69713a45f8fb1ad3874a0f7e1e0a50b40f7d001a /absl/base/internal
parente8cda74967d1fa43182f88396e9030e93501e1a1 (diff)
raw_logging: Rename SafeWriteToStderr to indicate what about it is safe (answer: it's async-signal-safe).
Also, preserve errno across calls to make it actually signal-safe. PiperOrigin-RevId: 446620926 Change-Id: I875fbec02b909e8424ddf763303b0d6007f8548f
Diffstat (limited to 'absl/base/internal')
-rw-r--r--absl/base/internal/raw_logging.cc8
-rw-r--r--absl/base/internal/raw_logging.h9
2 files changed, 9 insertions, 8 deletions
diff --git a/absl/base/internal/raw_logging.cc b/absl/base/internal/raw_logging.cc
index acf20f2a..ca2a75f3 100644
--- a/absl/base/internal/raw_logging.cc
+++ b/absl/base/internal/raw_logging.cc
@@ -24,6 +24,7 @@
#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/base/internal/atomic_hook.h"
+#include "absl/base/internal/errno_saver.h"
#include "absl/base/log_severity.h"
// We know how to perform low-level writes to stderr in POSIX and Windows. For
@@ -169,7 +170,7 @@ void RawLogVA(absl::LogSeverity severity, const char* file, int line,
} else {
DoRawLog(&buf, &size, "%s", kTruncated);
}
- SafeWriteToStderr(buffer, strlen(buffer));
+ AsyncSignalSafeWriteToStderr(buffer, strlen(buffer));
}
#else
static_cast<void>(format);
@@ -196,8 +197,11 @@ void DefaultInternalLog(absl::LogSeverity severity, const char* file, int line,
} // namespace
-void SafeWriteToStderr(const char *s, size_t len) {
+void AsyncSignalSafeWriteToStderr(const char* s, size_t len) {
+ absl::base_internal::ErrnoSaver errno_saver;
#if defined(ABSL_HAVE_SYSCALL_WRITE)
+ // We prefer calling write via `syscall` to minimize the risk of libc doing
+ // something "helpful".
syscall(SYS_write, STDERR_FILENO, s, len);
#elif defined(ABSL_HAVE_POSIX_WRITE)
write(STDERR_FILENO, s, len);
diff --git a/absl/base/internal/raw_logging.h b/absl/base/internal/raw_logging.h
index efe28dac..68a8bf21 100644
--- a/absl/base/internal/raw_logging.h
+++ b/absl/base/internal/raw_logging.h
@@ -109,12 +109,9 @@ namespace raw_logging_internal {
void RawLog(absl::LogSeverity severity, const char* file, int line,
const char* format, ...) ABSL_PRINTF_ATTRIBUTE(4, 5);
-// Writes the provided buffer directly to stderr, in a safe, low-level manner.
-//
-// In POSIX this means calling write(), which is async-signal safe and does
-// not malloc. If the platform supports the SYS_write syscall, we invoke that
-// directly to side-step any libc interception.
-void SafeWriteToStderr(const char *s, size_t len);
+// Writes the provided buffer directly to stderr, in a signal-safe, low-level
+// manner.
+void AsyncSignalSafeWriteToStderr(const char* s, size_t len);
// compile-time function to get the "base" filename, that is, the part of
// a filename after the last "/" or "\" path separator. The search starts at