Bug: OS::MemoryMappedFile::open() should not truncate a pre-existing file.

Patch by Mark Lam from Hewlett-Packard Development Company, LP

Review URL: http://codereview.chromium.org/6543039

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@6872 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/platform-cygwin.cc

@@ -209,7 +209,7 @@ class PosixMemoryMappedFile : public OS::MemoryMappedFile {
 
 
 OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
-  FILE* file = fopen(name, "w+");
+  FILE* file = fopen(name, "r+");
   if (file == NULL) return NULL;
 
   fseek(file, 0, SEEK_END);

src/platform-freebsd.cc

@@ -224,7 +224,7 @@ class PosixMemoryMappedFile : public OS::MemoryMappedFile {
 
 
 OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
-  FILE* file = fopen(name, "w+");
+  FILE* file = fopen(name, "r+");
   if (file == NULL) return NULL;
 
   fseek(file, 0, SEEK_END);

src/platform-linux.cc

@@ -327,7 +327,7 @@ class PosixMemoryMappedFile : public OS::MemoryMappedFile {
 
 
 OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
-  FILE* file = fopen(name, "w+");
+  FILE* file = fopen(name, "r+");
   if (file == NULL) return NULL;
 
   fseek(file, 0, SEEK_END);

src/platform-macos.cc

@@ -205,7 +205,7 @@ class PosixMemoryMappedFile : public OS::MemoryMappedFile {
 
 
 OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
-  FILE* file = fopen(name, "w+");
+  FILE* file = fopen(name, "r+");
   if (file == NULL) return NULL;
 
   fseek(file, 0, SEEK_END);

src/platform-openbsd.cc

@@ -222,7 +222,7 @@ class PosixMemoryMappedFile : public OS::MemoryMappedFile {
 
 
 OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
-  FILE* file = fopen(name, "w+");
+  FILE* file = fopen(name, "r+");
   if (file == NULL) return NULL;
 
   fseek(file, 0, SEEK_END);

src/platform-solaris.cc

@@ -235,7 +235,7 @@ class PosixMemoryMappedFile : public OS::MemoryMappedFile {
 
 
 OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
-  FILE* file = fopen(name, "w+");
+  FILE* file = fopen(name, "r+");
   if (file == NULL) return NULL;
 
   fseek(file, 0, SEEK_END);

src/platform-win32.cc

@@ -939,7 +939,7 @@ OS::MemoryMappedFile* OS::MemoryMappedFile::open(const char* name) {
   // Open a physical file
   HANDLE file = CreateFileA(name, GENERIC_READ | GENERIC_WRITE,
       FILE_SHARE_READ | FILE_SHARE_WRITE, NULL, OPEN_EXISTING, 0, NULL);
-  if (file == NULL) return NULL;
+  if (file == INVALID_HANDLE_VALUE) return NULL;
 
   int size = static_cast<int>(GetFileSize(file, NULL));