Use strerror_r(3) for the printf family %m.

There's TLS space used for unknown errno values, and a call to printf
shouldn't clobber that. No-one will ever hit this in real life, but
since it's easily fixed...

Bug: http://b/112776560
Test: ran tests
Change-Id: I8c2437f2e5214e652119791d4e162a197b049d5b

1 files changed, 20 insertions, 0 deletions

diff --git a/tests/stdio_test.cpp b/tests/stdio_test.cpp
index 4107a7490..54b913add 100644
--- a/tests/stdio_test.cpp
+++ b/tests/stdio_test.cpp
@@ -2369,6 +2369,16 @@ TEST(STDIO_TEST, printf_m) {
   ASSERT_STREQ("<Invalid argument>", buf);
 }
 
+TEST(STDIO_TEST, printf_m_does_not_clobber_strerror) {
+  char buf[BUFSIZ];
+  const char* m = strerror(-1);
+  ASSERT_STREQ("Unknown error -1", m);
+  errno = -2;
+  snprintf(buf, sizeof(buf), "<%m>");
+  ASSERT_STREQ("<Unknown error -2>", buf);
+  ASSERT_STREQ("Unknown error -1", m);
+}
+
 TEST(STDIO_TEST, wprintf_m) {
   wchar_t buf[BUFSIZ];
   errno = 0;
@@ -2382,6 +2392,16 @@ TEST(STDIO_TEST, wprintf_m) {
   ASSERT_EQ(std::wstring(L"<Invalid argument>"), buf);
 }
 
+TEST(STDIO_TEST, wprintf_m_does_not_clobber_strerror) {
+  wchar_t buf[BUFSIZ];
+  const char* m = strerror(-1);
+  ASSERT_STREQ("Unknown error -1", m);
+  errno = -2;
+  swprintf(buf, sizeof(buf), L"<%m>");
+  ASSERT_EQ(std::wstring(L"<Unknown error -2>"), buf);
+  ASSERT_STREQ("Unknown error -1", m);
+}
+
 TEST(STDIO_TEST, fopen_append_mode_and_ftell) {
   TemporaryFile tf;
   SetFileTo(tf.filename, "0123456789");