files.c (_cpp_find_file): If returning early...

	* files.c (_cpp_find_file): If returning early, before storing
	something to *hash_slot and *hash_slot is NULL, call htab_clear_slot
	on it.  Access *hash_slot using void * type rather than
	struct file_hash_entry * to avoid aliasing issues.

From-SVN: r196356

diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index 7a94c90b6d3152450ce92ed3986948951e4b53a8..934db6a08cd332793afe97a82ccddfd7ed941630 100644 (file)
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,5 +1,10 @@
 2013-02-28  Jakub Jelinek  <jakub@redhat.com>
 
+       * files.c (_cpp_find_file): If returning early, before storing
+       something to *hash_slot and *hash_slot is NULL, call htab_clear_slot
+       on it.  Access *hash_slot using void * type rather than
+       struct file_hash_entry * to avoid aliasing issues.
+
        * configure.ac: Don't define ENABLE_CHECKING whenever
        --enable-checking is seen, instead use similar --enable-checking=yes
        vs. --enable-checking=release default as gcc/ subdir has and

diff --git a/libcpp/files.c b/libcpp/files.c
index 105cd96974847a69235d4f34f85f6201f001cb4e..a614b7cebeddbec6ed750ae851c43331f88b5f6f 100644 (file)
--- a/libcpp/files.c
+++ b/libcpp/files.c
@@ -492,7 +492,8 @@ _cpp_file *
 _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir,
                bool fake, int angle_brackets, bool implicit_preinclude)
 {
-  struct file_hash_entry *entry, **hash_slot;
+  struct file_hash_entry *entry;
+  void **hash_slot;
   _cpp_file *file;
   bool invalid_pch = false;
   bool saw_bracket_include = false;
@@ -503,13 +504,12 @@ _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir,
   if (start_dir == NULL)
     cpp_error (pfile, CPP_DL_ICE, "NULL directory in find_file");
 
-  hash_slot = (struct file_hash_entry **)
-    htab_find_slot_with_hash (pfile->file_hash, fname,
-                             htab_hash_string (fname),
-                             INSERT);
+  hash_slot
+    = htab_find_slot_with_hash (pfile->file_hash, fname,
+                               htab_hash_string (fname), INSERT);
 
   /* First check the cache before we resort to memory allocation.  */
-  entry = search_cache (*hash_slot, start_dir);
+  entry = search_cache ((struct file_hash_entry *) *hash_slot, start_dir);
   if (entry)
     return entry->u.file;
 
@@ -533,6 +533,17 @@ _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir,
                 the list of all files so that #import works.  */
              file->next_file = pfile->all_files;
              pfile->all_files = file;
+             if (*hash_slot == NULL)
+               {
+                 /* If *hash_slot is NULL, the above htab_find_slot_with_hash
+                    call just created the slot, but we aren't going to store
+                    there anything, so need to remove the newly created entry.
+                    htab_clear_slot requires that it is non-NULL, so store
+                    there some non-NULL pointer, htab_clear_slot will
+                    overwrite it immediately.  */
+                 *hash_slot = file;
+                 htab_clear_slot (pfile->file_hash, hash_slot);
+               }
              return file;
            }
 
@@ -548,6 +559,12 @@ _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir,
            {
              free ((char *) file->name);
              free (file);
+             if (*hash_slot == NULL)
+               {
+                 /* See comment on the above htab_clear_slot call.  */
+                 *hash_slot = file;
+                 htab_clear_slot (pfile->file_hash, hash_slot);
+               }
              return NULL;
            }
          else
@@ -565,7 +582,7 @@ _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir,
       else
        continue;
 
-      entry = search_cache (*hash_slot, file->dir);
+      entry = search_cache ((struct file_hash_entry *) *hash_slot, file->dir);
       if (entry)
        {
          found_in_cache = file->dir;
@@ -589,11 +606,11 @@ _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir,
 
   /* Store this new result in the hash table.  */
   entry = new_file_hash_entry (pfile);
-  entry->next = *hash_slot;
+  entry->next = (struct file_hash_entry *) *hash_slot;
   entry->start_dir = start_dir;
   entry->location = pfile->line_table->highest_location;
   entry->u.file = file;
-  *hash_slot = entry;
+  *hash_slot = (void *) entry;
 
   /* If we passed the quote or bracket chain heads, cache them also.
      This speeds up processing if there are lots of -I options.  */
@@ -602,22 +619,22 @@ _cpp_find_file (cpp_reader *pfile, const char *fname, cpp_dir *start_dir,
       && found_in_cache != pfile->bracket_include)
     {
       entry = new_file_hash_entry (pfile);
-      entry->next = *hash_slot;
+      entry->next = (struct file_hash_entry *) *hash_slot;
       entry->start_dir = pfile->bracket_include;
       entry->location = pfile->line_table->highest_location;
       entry->u.file = file;
-      *hash_slot = entry;
+      *hash_slot = (void *) entry;
     }
   if (saw_quote_include
       && pfile->quote_include != start_dir
       && found_in_cache != pfile->quote_include)
     {
       entry = new_file_hash_entry (pfile);
-      entry->next = *hash_slot;
+      entry->next = (struct file_hash_entry *) *hash_slot;
       entry->start_dir = pfile->quote_include;
       entry->location = pfile->line_table->highest_location;
       entry->u.file = file;
-      *hash_slot = entry;
+      *hash_slot = (void *) entry;
     }
 
   return file;