From b5b81136da11638bdf1e336d9ec371b820fbf412 Mon Sep 17 00:00:00 2001
From: Jeff King <peff@peff.net>
Date: Tue, 14 Feb 2017 01:05:55 -0500
Subject: grep: fix "--" rev/pathspec disambiguation

If we see "git grep pattern rev -- file" then we apply the
usual rev/pathspec disambiguation rules: any "rev" before
the "--" must be a revision, and we do not need to apply the
verify_non_filename() check.

But there are two bugs here:

  1. We keep a seen_dashdash flag to handle this case, but
     we set it in the same left-to-right pass over the
     arguments in which we parse "rev".

     So when we see "rev", we do not yet know that there is
     a "--", and we mistakenly complain if there is a
     matching file.

     We can fix this by making a preliminary pass over the
     arguments to find the "--", and only then checking the rev
     arguments.

  2. If we can't resolve "rev" but there isn't a dashdash,
     that's OK. We treat it like a path, and complain later
     if it doesn't exist.

     But if there _is_ a dashdash, then we know it must be a
     rev, and should treat it as such, complaining if it
     does not resolve. The current code instead ignores it
     and tries to treat it like a path.

This patch fixes both bugs, and tries to comment the parsing
flow a bit better.

It adds tests that cover the two bugs, but also some related
situations (which already worked, but this confirms that our
fixes did not break anything).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin/grep.c | 29 ++++++++++++++++++++++++-----
 1 file changed, 24 insertions(+), 5 deletions(-)

(limited to 'builtin/grep.c')

diff --git a/builtin/grep.c b/builtin/grep.c
index 461347adb0..e83b33bdaa 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -1149,7 +1149,22 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 
 	compile_grep_patterns(&opt);
 
-	/* Check revs and then paths */
+	/*
+	 * We have to find "--" in a separate pass, because its presence
+	 * influences how we will parse arguments that come before it.
+	 */
+	for (i = 0; i < argc; i++) {
+		if (!strcmp(argv[i], "--")) {
+			seen_dashdash = 1;
+			break;
+		}
+	}
+
+	/*
+	 * Resolve any rev arguments. If we have a dashdash, then everything up
+	 * to it must resolve as a rev. If not, then we stop at the first
+	 * non-rev and assume everything else is a path.
+	 */
 	for (i = 0; i < argc; i++) {
 		const char *arg = argv[i];
 		unsigned char sha1[20];
@@ -1158,13 +1173,14 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 
 		if (!strcmp(arg, "--")) {
 			i++;
-			seen_dashdash = 1;
 			break;
 		}
 
-		/* Stop at the first non-rev */
-		if (get_sha1_with_context(arg, 0, sha1, &oc))
+		if (get_sha1_with_context(arg, 0, sha1, &oc)) {
+			if (seen_dashdash)
+				die(_("unable to resolve revision: %s"), arg);
 			break;
+		}
 
 		object = parse_object_or_die(sha1, arg);
 		if (!seen_dashdash)
@@ -1172,7 +1188,10 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		add_object_array_with_path(object, arg, &list, oc.mode, oc.path);
 	}
 
-	/* The rest are paths */
+	/*
+	 * Anything left over is presumed to be a path. But in the non-dashdash
+	 * "do what I mean" case, we verify and complain when that isn't true.
+	 */
 	if (!seen_dashdash) {
 		int j;
 		for (j = i; j < argc; j++)
-- 
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