[PATCH] D38984: Use fopen instead of fdopen for opening GCDA files as fdopen seems to cause files to get corrupted

[Marco Castelluccio via Phabricator via llvm-commits]

marco-c created this revision.

Fixes https://bugs.llvm.org/show_bug.cgi?id=34922.

When using fdopen, the GCDA file is very often not correctly written to disk. I honestly have no idea why, perhaps somebody more familiar with Windows would know.
This doesn't only apply to the simple case from bug 34922. I have built Firefox to collect coverage and before this change most GCDA files were corrupted.


https://reviews.llvm.org/D38984

Files:
  lib/profile/GCDAProfiling.c


Index: lib/profile/GCDAProfiling.c
===================================================================
--- lib/profile/GCDAProfiling.c
+++ lib/profile/GCDAProfiling.c
@@ -263,8 +263,9 @@
    * same GCDA. This can fail if the filesystem doesn't support it, but in that
    * case we'll just carry on with the old racy behaviour and hope for the best.
    */
-  flock(fd, LOCK_EX);
-  output_file = fdopen(fd, mode);
+  close(fd);
+  output_file = fopen(filename, mode);
+  flock(fileno(output_file), LOCK_EX);
 
   /* Initialize the write buffer. */
   write_buffer = NULL;
@@ -462,7 +463,7 @@
       unmap_file();
     }
 
-    flock(fd, LOCK_UN);
+    flock(fileno(output_file), LOCK_UN);
     fclose(output_file);
     output_file = NULL;
     write_buffer = NULL;


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