[RFC PATCH] add a -o to only compare files that you want to compare.

[Steven Rostedt]

I'm not on the list and this not a bug report, but a feature request
(with a patch :).  Several times I like to do diffs of different source
trees without hitting all the .svn, CVS, .git, *.o and other crud that's
in the directories that I don't want to diff.  So I downloaded the
source to diffutils and made this little patch.

It adds the -o and -O which act pretty much like -x and -X but opposite.
It also should only work for recursive searches and it doesn't
exclude/include directory names.

Basically what the -o option does is allows the user to put in a regexpr
for the files that they want to compare.  The -x still works with this
and takes precedence.  It also doesn't effect directories, so it will
still descend  into directories that doesn't match the -o regexpr.

So -o allows the user to only compare files within directories that
match the regexpr name given by the user in a recursive diff.

For example I can do the following:

diff -ur -o '*.[ch]' linux-2.6.16/ linux-2.6.17/

and this will give me a diff of all the *.c and *.h files that changed
between the two directories.

If anyone is interested, the patch is below. For comments, please CC me
since I'm not on the list.

This was a quick patch, it probably needs a little more clean up to add
it.  But it works for what I want to use it for, and that's all that I
wanted, and all that I did :)

Thanks,

-- Steve

Signed-off-by: Steven Rostedt <address@hidden>

Index: diffutils-2.8.1/src/diff.c
===================================================================
--- diffutils-2.8.1.orig/src/diff.c     2006-08-23 09:42:38.000000000 -0400
+++ diffutils-2.8.1/src/diff.c  2006-08-23 10:27:28.000000000 -0400
@@ -139,7 +139,7 @@ exclude_options (void)
 }
 
 static char const shortopts[] =
-"0123456789abBcC:dD:eEfF:hHiI:lL:nNpPqrsS:tTuU:vwW:x:X:y";
+"0123456789abBcC:dD:eEfF:hHiI:lL:nNpPqrsS:tTuU:vwW:x:X:yo:O:";
 
 /* Values for long options that do not have single-letter equivalents.  */
 enum
@@ -428,6 +428,20 @@ main (int argc, char **argv)
          new_file = 1;
          break;
 
+       case 'o':
+         if (!included)
+           included = new_exclude ();
+         add_exclude (included, optarg, exclude_options ());
+         break;
+
+       case 'O':
+         if (!included)
+           included = new_exclude ();
+         if (add_exclude_file (add_exclude, included, optarg,
+                               exclude_options (), '\n'))
+           pfatal_with_name (optarg);
+         break;
+
        case 'p':
          show_c_function = 1;
          add_regexp (&function_regexp_list, "^[[:alpha:]$_]");
@@ -1066,6 +1080,9 @@ compare_files (struct comparison const *
       char const *name = name0 == 0 ? name1 : name0;
       char const *dir = parent->file[name0 == 0].name;
 
+      if (included && !excluded_filename (included, name))
+             return EXIT_SUCCESS;
+
       /* See POSIX 1003.1-2001 for this format.  */
       message ("Only in %s: %s\n", dir, name);
 
@@ -1278,13 +1295,20 @@ compare_files (struct comparison const *
           && (cmp.file[0].desc == NONEXISTENT
               || S_ISREG (cmp.file[0].stat.st_mode))
           && (cmp.file[1].desc == NONEXISTENT
-              || S_ISREG (cmp.file[1].stat.st_mode)))
+              || S_ISREG (cmp.file[1].stat.st_mode))
+          && (!included || excluded_filename (included, cmp.file[0].name))
+         )
     {
       message ("Files %s and %s differ\n",
               file_label[0] ? file_label[0] : cmp.file[0].name,
               file_label[1] ? file_label[1] : cmp.file[1].name);
       status = EXIT_FAILURE;
     }
+  else if (included && !excluded_filename (included, cmp.file[0].name))
+    {
+           /* this does not match the "only" flag */
+           status = EXIT_SUCCESS;
+    }
   else
     {
       /* Both exist and neither is a directory.  */
Index: diffutils-2.8.1/src/diff.h
===================================================================
--- diffutils-2.8.1.orig/src/diff.h     2006-08-23 09:42:40.000000000 -0400
+++ diffutils-2.8.1/src/diff.h  2006-08-23 09:44:07.000000000 -0400
@@ -191,6 +191,9 @@ XTERN bool speed_large_files;
 /* Patterns that match file names to be excluded.  */
 XTERN struct exclude *excluded;
 
+/* Patterns that match file names to only include.  */
+XTERN struct exclude *included;
+
 /* Don't discard lines.  This makes things slower (sometimes much
    slower) but will find a guaranteed minimal set of changes.  */
 XTERN bool minimal;