builtin-grep: workaround for non GNU grep.

Of course, it still ignores the fact that not all grep's support some of
the flags like -F/-L/-A/-C etc, but for those cases, the external grep
itself will happily just say "unrecognized option -F" or similar.

So with this change, "git grep" should handle all the flags the native
grep handles, which is really quite fine. We don't _need_ to expose
anything more, and if you do want our extensions, you can get them with
"--uncached" and an up-to-date index.

No configuration necessary, and we automatically take advantage of any
native grep we have, if possible.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/builtin-grep.c b/builtin-grep.c
index 66111de..d09ddf0 100644 (file)
--- a/builtin-grep.c
+++ b/builtin-grep.c
@@ -453,7 +453,6 @@ static int external_grep(struct grep_opt *opt, const char **paths, int cached)
 
        len = nr = 0;
        push_arg("grep");
-       push_arg("-H");
        if (opt->fixed)
                push_arg("-F");
        if (opt->linenum)
@@ -503,17 +502,35 @@ static int external_grep(struct grep_opt *opt, const char **paths, int cached)
                push_arg("-e");
                push_arg(p->pattern);
        }
-       push_arg("--");
+
+       /*
+        * To make sure we get the header printed out when we want it,
+        * add /dev/null to the paths to grep.  This is unnecessary
+        * (and wrong) with "-l" or "-L", which always print out the
+        * name anyway.
+        *
+        * GNU grep has "-H", but this is portable.
+        */
+       if (!opt->name_only && !opt->unmatch_name_only)
+               push_arg("/dev/null");
 
        hit = 0;
        argc = nr;
        for (i = 0; i < active_nr; i++) {
                struct cache_entry *ce = active_cache[i];
+               const char *name;
                if (ce_stage(ce) || !S_ISREG(ntohl(ce->ce_mode)))
                        continue;
                if (!pathspec_matches(paths, ce->name))
                        continue;
-               argv[argc++] = ce->name;
+               name = ce->name;
+               if (name[0] == '-') {
+                       int len = ce_namelen(ce);
+                       name = xmalloc(len + 3);
+                       memcpy(name, "./", 2);
+                       memcpy(name + 2, ce->name, len + 1);
+               }
+               argv[argc++] = name;
                if (argc < MAXARGS)
                        continue;
                hit += exec_grep(argc, argv);