commit 4198fa4c23fc8a1895808a597bb153530f6ea515
author Elliott Hughes <enh@google.com> Mon Sep 17 15:23:35 2012 -0700
committer Elliott Hughes <enh@google.com> Mon Sep 17 15:23:35 2012 -0700
tree 79a050550930720fba3886064bd95acc10944f11
parent 4e9d953a0e9334c0f3519f470b97973c31da5bb6

Don't copy strerror(3) or strsignal(3) strings if we can share.

Change-Id: Ic405269f63b945c6fb347e7c4346cd6f104aff35

libc/bionic/strerror.cpp

diff --git a/libc/bionic/strerror.cpp b/libc/bionic/strerror.cpp
index 036ec8d..455dc52 100644
--- a/libc/bionic/strerror.cpp
+++ b/libc/bionic/strerror.cpp
@@ -29,9 +29,17 @@
 #include <string.h>
 #include "ThreadLocalBuffer.h"
 
+extern "C" const char* __strerror_lookup(int);
+
 GLOBAL_INIT_THREAD_LOCAL_BUFFER(strerror);
 
 char* strerror(int error_number) {
+  // Just return the original constant in the easy cases.
+  char* result = const_cast<char*>(__strerror_lookup(error_number));
+  if (result != NULL) {
+    return result;
+  }
+
   LOCAL_INIT_THREAD_LOCAL_BUFFER(char*, strerror, NL_TEXTMAX);
   strerror_r(error_number, strerror_buffer, strerror_buffer_size);
   return strerror_buffer;

libc/bionic/strerror_r.cpp

diff --git a/libc/bionic/strerror_r.cpp b/libc/bionic/strerror_r.cpp
index 92235a5..a00ebe5 100644
--- a/libc/bionic/strerror_r.cpp
+++ b/libc/bionic/strerror_r.cpp
@@ -27,11 +27,25 @@
   { 0, NULL }
 };
 
+extern "C" const char* __strerror_lookup(int error_number) {
+  return __code_string_lookup(_sys_error_strings, error_number);
+}
+
+static const Pair _sys_signal_strings[] = {
+#define  __BIONIC_SIGDEF(x,y,z)  { y, z },
+#include <sys/_sigdefs.h>
+  { 0, NULL }
+};
+
+extern "C" const char* __strsignal_lookup(int signal_number) {
+  return __code_string_lookup(_sys_signal_strings, signal_number);
+}
+
 int strerror_r(int error_number, char* buf, size_t buf_len) {
   int saved_errno = errno;
   size_t length;
 
-  const char* error_name = __code_string_lookup(_sys_error_strings, error_number);
+  const char* error_name = __strerror_lookup(error_number);
   if (error_name != NULL) {
     length = snprintf(buf, buf_len, "%s", error_name);
   } else {
@@ -46,14 +60,8 @@
   return 0;
 }
 
-static const Pair _sys_signal_strings[] = {
-#define  __BIONIC_SIGDEF(x,y,z)  { y, z },
-#include <sys/_sigdefs.h>
-  { 0, NULL }
-};
-
 extern "C" const char* __strsignal(int signal_number, char* buf, size_t buf_len) {
-  const char* signal_name = __code_string_lookup(_sys_signal_strings, signal_number);
+  const char* signal_name = __strsignal_lookup(signal_number);
   if (signal_name != NULL) {
     return signal_name;
   }

libc/bionic/strsignal.cpp

diff --git a/libc/bionic/strsignal.cpp b/libc/bionic/strsignal.cpp
index 1cbec9b..9b046d4 100644
--- a/libc/bionic/strsignal.cpp
+++ b/libc/bionic/strsignal.cpp
@@ -29,11 +29,18 @@
 #include <string.h>
 #include "ThreadLocalBuffer.h"
 
+extern "C" const char* __strsignal_lookup(int);
 extern "C" const char* __strsignal(int, char*, size_t);
 
 GLOBAL_INIT_THREAD_LOCAL_BUFFER(strsignal);
 
 char* strsignal(int signal_number) {
+  // Just return the original constant in the easy cases.
+  char* result = const_cast<char*>(__strsignal_lookup(signal_number));
+  if (result != NULL) {
+    return result;
+  }
+
   LOCAL_INIT_THREAD_LOCAL_BUFFER(char*, strsignal, NL_TEXTMAX);
   return const_cast<char*>(__strsignal(signal_number, strsignal_buffer, strsignal_buffer_size));
 }