[llvm] r276017 - Use posix_fallocate instead of ftruncate.

[Rafael Espindola via llvm-commits]

Author: rafael
Date: Tue Jul 19 15:19:56 2016
New Revision: 276017

URL: http://llvm.org/viewvc/llvm-project?rev=276017&view=rev
Log:
Use posix_fallocate instead of ftruncate.

This makes sure that space is actually available. With this change
running lld on a full file system causes it to exit with

failed to open foo: No space left on device

instead of crashing with a sigbus.

Modified:
    llvm/trunk/cmake/config-ix.cmake
    llvm/trunk/include/llvm/Config/config.h.cmake
    llvm/trunk/lib/Support/Unix/Path.inc

Modified: llvm/trunk/cmake/config-ix.cmake
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/cmake/config-ix.cmake?rev=276017&r1=276016&r2=276017&view=diff
==============================================================================
--- llvm/trunk/cmake/config-ix.cmake (original)
+++ llvm/trunk/cmake/config-ix.cmake Tue Jul 19 15:19:56 2016
@@ -162,6 +162,7 @@ check_symbol_exists(setrlimit sys/resour
 check_symbol_exists(isatty unistd.h HAVE_ISATTY)
 check_symbol_exists(futimens sys/stat.h HAVE_FUTIMENS)
 check_symbol_exists(futimes sys/time.h HAVE_FUTIMES)
+check_symbol_exists(posix_fallocate fcntl.h HAVE_POSIX_FALLOCATE)
 if( HAVE_SETJMP_H )
   check_symbol_exists(longjmp setjmp.h HAVE_LONGJMP)
   check_symbol_exists(setjmp setjmp.h HAVE_SETJMP)

Modified: llvm/trunk/include/llvm/Config/config.h.cmake
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Config/config.h.cmake?rev=276017&r1=276016&r2=276017&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Config/config.h.cmake (original)
+++ llvm/trunk/include/llvm/Config/config.h.cmake Tue Jul 19 15:19:56 2016
@@ -585,4 +585,6 @@
 /* Define to 1 if you have the `_chsize_s' function. */
 #cmakedefine HAVE__CHSIZE_S ${HAVE__CHSIZE_S}
 
+#cmakedefine HAVE_POSIX_FALLOCATE ${HAVE_POSIX_FALLOCATE}
+
 #endif

Modified: llvm/trunk/lib/Support/Unix/Path.inc
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Unix/Path.inc?rev=276017&r1=276016&r2=276017&view=diff
==============================================================================
--- llvm/trunk/lib/Support/Unix/Path.inc (original)
+++ llvm/trunk/lib/Support/Unix/Path.inc Tue Jul 19 15:19:56 2016
@@ -329,8 +329,17 @@ std::error_code rename(const Twine &from
 }
 
 std::error_code resize_file(int FD, uint64_t Size) {
+#if defined(HAVE_POSIX_FALLOCATE)
+  // If we have posix_fallocate use it. Unlike ftruncate it always allocates
+  // space, so we get an error if the disk is full.
+  if (int Err = ::posix_fallocate(FD, 0, Size))
+    return std::error_code(Err, std::generic_category());
+#else
+  // Use ftruncate as a fallback. It may or may not allocate space. At least on
+  // OS X with HFS+ it does.
   if (::ftruncate(FD, Size) == -1)
     return std::error_code(errno, std::generic_category());
+#endif
 
   return std::error_code();
 }