crash-reporter: Avoid writing through symlinks.

crash_collector.h

Index: crash_collector.h
diff --git a/crash_collector.h b/crash_collector.h
index e5eddcdd5d5aa08563e26378a6563d07800a4b6a..219c8af6ec85d2d03937dd0779db081faaa3cac8 100644
--- a/crash_collector.h
+++ b/crash_collector.h
@@ -39,15 +39,25 @@ class CrashCollector {
   FRIEND_TEST(CrashCollectorTest, CheckHasCapacityUsual);
   FRIEND_TEST(CrashCollectorTest, GetCrashDirectoryInfo);
   FRIEND_TEST(CrashCollectorTest, GetCrashPath);
+  FRIEND_TEST(CrashCollectorTest, ForkExecAndPipe);
   FRIEND_TEST(CrashCollectorTest, FormatDumpBasename);
   FRIEND_TEST(CrashCollectorTest, Initialize);
   FRIEND_TEST(CrashCollectorTest, MetaData);
   FRIEND_TEST(CrashCollectorTest, ReadKeyValueFile);
   FRIEND_TEST(CrashCollectorTest, Sanitize);
+  FRIEND_TEST(CrashCollectorTest, WriteNewFile);
 
   // Set maximum enqueued crashes in a crash directory.
   static const int kMaxCrashDirectorySize;
 
+  // Writes |data| of |size| to |filename|, which must be a new file.
+  // If the file already exists or writing fails, return a negative value.
+  // Otherwise returns the number of bytes written.
+  int WriteNewFile(const FilePath &filename, const char *data, int size);
+
+  int ForkExecAndPipe(std::vector<const char *> &arguments,
+                      const char *output_file);
+
   // Return a filename that has only [a-z0-1_] characters by mapping
   // all others into '_'.
   std::string Sanitize(const std::string &name);