Added new ReadFileToString API with a max_size argument

base/file_util.cc

Index: base/file_util.cc
diff --git a/base/file_util.cc b/base/file_util.cc
index e44f713cdb31828010ad9be92739a3d021dc4685..5301e74a485dea2f6b236281dec1dcaa4947c323 100644
--- a/base/file_util.cc
+++ b/base/file_util.cc
@@ -126,7 +126,9 @@ bool TextContentsEqual(const FilePath& filename1, const FilePath& filename2) {
   return true;
 }
 
-bool ReadFileToString(const FilePath& path, std::string* contents) {
+bool ReadFileToString(const FilePath& path,
+                             std::string* contents,

[bartfab (slow), 2014/02/11 12:51:12]

Nit: Align the arguments.

[kaliamoorthi, 2014/02/11 16:29:16]

Done.

+                             size_t maxsize) {
   if (path.ReferencesParent())
     return false;
   FILE* file = OpenFile(path, "rb");
@@ -136,7 +138,18 @@ bool ReadFileToString(const FilePath& path, std::string* contents) {
 
   char buf[1 << 16];
   size_t len;
+  size_t size = 0;
+
+  // Many files supplied in path have incorrect size (proc files, streams etc)

[bartfab (slow), 2014/02/11 12:51:12]

Nit: What do you mean by incorrect size? IIUC, the size is not incorrect, it
just cannot reliably be determined because it may change at any time.

[kaliamoorthi, 2014/02/11 16:29:16]

Some files especially procfs have incorrect size (reported as 0)

+  // hence the file is read sequentially as opposed to one-shot read.
   while ((len = fread(buf, 1, sizeof(buf), file)) > 0) {
+    if ((maxsize - size) < len) {

[bartfab (slow), 2014/02/11 12:51:12]

Nit: A matter of taste but I think |len > maxsize - size| would be easier to
parse: "If the amount of data read (len) is larger than the amount still
permitted (maxsize - size), report an error."

[kaliamoorthi, 2014/02/11 16:29:16]

Since it is not a coding guideline, I think the current one is fine

+      if (contents)
+        contents->clear();
+      CloseFile(file);
+      return false;
+    }
+    size += len;
     if (contents)
       contents->append(buf, len);
   }
@@ -145,6 +158,10 @@ bool ReadFileToString(const FilePath& path, std::string* contents) {
   return true;
 }
 
+bool ReadFileToString(const FilePath& path, std::string* contents) {
+  return ReadFileToString(path, contents, std::numeric_limits<size_t>::max());

[bartfab (slow), 2014/02/11 12:51:12]

Nit: #include <limits>

[kaliamoorthi, 2014/02/11 16:29:16]

Done.

+}
+
 bool IsDirectoryEmpty(const FilePath& dir_path) {
   FileEnumerator files(dir_path, false,
       FileEnumerator::FILES | FileEnumerator::DIRECTORIES);