feat: support log file truncation on windows (#960)

CMakeLists.txt

@@ -131,6 +131,7 @@ check_function_exists (sigaltstack HAVE_SIGALTSTACK)
 check_cxx_symbol_exists (backtrace execinfo.h HAVE_EXECINFO_BACKTRACE)
 check_cxx_symbol_exists (backtrace_symbols execinfo.h
   HAVE_EXECINFO_BACKTRACE_SYMBOLS)
+check_cxx_symbol_exists (_chsize_s io.h HAVE__CHSIZE_S)
 
 # NOTE gcc does not fail if you pass a non-existent -Wno-* option as an
 # argument. However, it will happily fail if you pass the corresponding -W*

bazel/glog.bzl

@@ -114,6 +114,7 @@ def glog_library(namespace = "google", with_gflags = 1, **kwargs):
         "-DGLOG_EXPORT=__declspec(dllexport)",
         "-DGLOG_NO_ABBREVIATED_SEVERITIES",
         "-DHAVE_SNPRINTF",
+        "-DHAVE__CHSIZE_S",
         "-I" + src_windows,
     ]
 

src/config.h.cmake.in

@@ -130,6 +130,9 @@
 /* define if gmtime_r is available in time.h */
 #cmakedefine HAVE_GMTIME_R
 
+/* define if _chsize_s is available in io.h */
+#cmakedefine HAVE__CHSIZE_S
+
 /* Define to the sub-directory in which libtool stores uninstalled libraries.
    */
 #cmakedefine LT_OBJDIR

src/logging.cc

@@ -58,6 +58,9 @@
 #ifdef HAVE_SYSLOG_H
 # include <syslog.h>
 #endif
+#ifdef HAVE__CHSIZE_S
+#include <io.h> // for truncate log file
+#endif
 #include <vector>
 #include <cerrno>                   // for errno
 #include <sstream>
@@ -2425,7 +2428,7 @@ void GetExistingTempDirectories(vector<string>* list) {
 }
 
 void TruncateLogFile(const char *path, uint64 limit, uint64 keep) {
-#ifdef HAVE_UNISTD_H
+#if defined(HAVE_UNISTD_H) || defined(HAVE__CHSIZE_S)
   struct stat statbuf;
   const int kCopyBlockSize = 8 << 10;
   char copybuf[kCopyBlockSize];
@@ -2446,7 +2449,11 @@ void TruncateLogFile(const char *path, uint64 limit, uint64 keep) {
       // all of base/...) with -D_FILE_OFFSET_BITS=64 but that's
       // rather scary.
       // Instead just truncate the file to something we can manage
+#ifdef HAVE__CHSIZE_S
+      if (_chsize_s(fd, 0) != 0) {
+#else
       if (truncate(path, 0) == -1) {
+#endif
         PLOG(ERROR) << "Unable to truncate " << path;
       } else {
         LOG(ERROR) << "Truncated " << path << " due to EFBIG error";
@@ -2491,7 +2498,11 @@ void TruncateLogFile(const char *path, uint64 limit, uint64 keep) {
   // Truncate the remainder of the file. If someone else writes to the
   // end of the file after our last read() above, we lose their latest
   // data. Too bad ...
+#ifdef HAVE__CHSIZE_S
+  if (_chsize_s(fd, write_offset) != 0) {
+#else
   if (ftruncate(fd, write_offset) == -1) {
+#endif
     PLOG(ERROR) << "Unable to truncate " << path;
   }