Add logging macros that automatically append the last system error in string form.

Also add thread-safe, portable variants for strerror() and strerror_r() on POSIX so that existing error logging code that calls strerror() for something other than LOG, LOG_IF, or CHECK can be changed to use safe versions too. After this CL I will eliminate all unsafe uses of strerror() in our code.

TEST=Linux: tested PLOG and DPLOG with both a valid error and invalid error on a dbg build with both the default strerror_r implementation (GNU) and the other one (POSIX) via some throw-away macro evilness, and also tested the default strerror_r again on an opt build to verify DPLOG is a no-op; Windows: tested PLOG and DPLOG with both a valid error and invalid error on a dbg build; also tested LOG_GETLASTERROR_MODULE with winhttp and ERROR_WINHTTP_CANNOT_CONNECT and verified that it prints the correct system message and that it doesn't with PLOG; also tested LOG_GETLASTERROR_MODULE with a bogus module name and verified that it prints an error that it can't find the module, and the original error; Mac: none (implicitly tested via the Linux POSIX tests); trybots for Win, Mac, and Linux 32-bit; built locally for Linux 32-bit and 64-bit and tested base_unittests and also running Chromium itself; wrote the upcoming CL that switches strerror() calls to use PLOG and verified that it builds and works for both Linux 32-bit and Linux 64-bit; lint
BUG=none

Review URL: http://codereview.chromium.org/265052

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@28632 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 36 insertions, 0 deletions

diff --git a/base/safe_strerror_posix.h b/base/safe_strerror_posix.h
new file mode 100644
index 0000000..ecf3a78
--- /dev/null
+++ b/base/safe_strerror_posix.h
@@ -0,0 +1,36 @@
+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_SAFE_STRERROR_POSIX_H_
+#define BASE_SAFE_STRERROR_POSIX_H_
+
+#include <string>
+
+// BEFORE using anything from this file, first look at PLOG and friends in
+// logging.h and use them instead if applicable.
+//
+// This file declares safe, portable alternatives to the POSIX strerror()
+// function. strerror() is inherently unsafe in multi-threaded apps and should
+// never be used. Doing so can cause crashes. Additionally, the thread-safe
+// alternative strerror_r varies in semantics across platforms. Use these
+// functions instead.
+
+// Thread-safe strerror function with dependable semantics that never fails.
+// It will write the string form of error "err" to buffer buf of length len.
+// If there is an error calling the OS's strerror_r() function then a message to
+// that effect will be printed into buf, truncating if necessary. The final
+// result is always null-terminated. The value of errno is never changed.
+//
+// Use this instead of strerror_r().
+void safe_strerror_r(int err, char *buf, size_t len);
+
+// Calls safe_strerror_r with a buffer of suitable size and returns the result
+// in a C++ string.
+//
+// Use this instead of strerror(). Note though that safe_strerror_r will be
+// more robust in the case of heap corruption errors, since it doesn't need to
+// allocate a string.
+std::string safe_strerror(int err);
+
+#endif  // BASE_SAFE_STRERROR_POSIX_H_