am: add --show-current-patch

Pointing the user to $GIT_DIR/rebase-apply may encourage them to mess
around in there, which is not a good thing. With this, the user does
not have to keep the path around somewhere (because after a couple of
commands, the path may be out of scrollback buffer) when they need to
look at the patch.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-am.txt

@@ -16,7 +16,7 @@ SYNOPSIS
 	 [--exclude=<path>] [--include=<path>] [--reject] [-q | --quiet]
 	 [--[no-]scissors] [-S[<keyid>]] [--patch-format=<format>]
 	 [(<mbox> | <Maildir>)...]
-'git am' (--continue | --skip | --abort)
+'git am' (--continue | --skip | --abort | --show-current-patch)
 
 DESCRIPTION
 -----------
@@ -167,6 +167,10 @@ default.   You can use `--no-utf8` to override this.
 --abort::
 	Restore the original branch and abort the patching operation.
 
+--show-current-patch::
+	Show the patch being applied when "git am" is stopped because
+	of conflicts.
+
 DISCUSSION
 ----------
 

builtin/am.c

@@ -1831,8 +1831,7 @@ static void am_run(struct am_state *state, int resume)
 			git_config_get_bool("advice.amworkdir", &advice_amworkdir);
 
 			if (advice_amworkdir)
-				printf_ln(_("The copy of the patch that failed is found in: %s"),
-						am_path(state, "patch"));
+				printf_ln(_("Use 'git am --show-current-patch' to see the failed patch"));
 
 			die_user_resolve(state);
 		}
@@ -2121,6 +2120,23 @@ static void am_abort(struct am_state *state)
 	am_destroy(state);
 }
 
+static int show_patch(struct am_state *state)
+{
+	struct strbuf sb = STRBUF_INIT;
+	const char *patch_path;
+	int len;
+
+	patch_path = am_path(state, msgnum(state));
+	len = strbuf_read_file(&sb, patch_path, 0);
+	if (len < 0)
+		die_errno(_("failed to read '%s'"), patch_path);
+
+	setup_pager();
+	write_in_full(1, sb.buf, sb.len);
+	strbuf_release(&sb);
+	return 0;
+}
+
 /**
  * parse_options() callback that validates and sets opt->value to the
  * PATCH_FORMAT_* enum value corresponding to `arg`.
@@ -2149,7 +2165,8 @@ enum resume_mode {
 	RESUME_APPLY,
 	RESUME_RESOLVED,
 	RESUME_SKIP,
-	RESUME_ABORT
+	RESUME_ABORT,
+	RESUME_SHOW_PATCH
 };
 
 static int git_am_config(const char *k, const char *v, void *cb)
@@ -2171,6 +2188,7 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 	int patch_format = PATCH_FORMAT_UNKNOWN;
 	enum resume_mode resume = RESUME_FALSE;
 	int in_progress;
+	int ret = 0;
 
 	const char * const usage[] = {
 		N_("git am [<options>] [(<mbox> | <Maildir>)...]"),
@@ -2249,6 +2267,9 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 		OPT_CMDMODE(0, "abort", &resume,
 			N_("restore the original branch and abort the patching operation."),
 			RESUME_ABORT),
+		OPT_CMDMODE(0, "show-current-patch", &resume,
+			N_("show the patch being applied."),
+			RESUME_SHOW_PATCH),
 		OPT_BOOL(0, "committer-date-is-author-date",
 			&state.committer_date_is_author_date,
 			N_("lie about committer date")),
@@ -2359,11 +2380,14 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 	case RESUME_ABORT:
 		am_abort(&state);
 		break;
+	case RESUME_SHOW_PATCH:
+		ret = show_patch(&state);
+		break;
 	default:
 		die("BUG: invalid resume value");
 	}
 
 	am_state_release(&state);
 
-	return 0;
+	return ret;
 }

contrib/completion/git-completion.bash

@@ -1077,7 +1077,7 @@ _git_am ()
 {
 	__git_find_repo_path
 	if [ -d "$__git_repo_path"/rebase-apply ]; then
-		__gitcomp "--skip --continue --resolved --abort"
+		__gitcomp "--skip --continue --resolved --abort --show-current-patch"
 		return
 	fi
 	case "$cur" in

t/t4150-am.sh

@@ -662,6 +662,11 @@ test_expect_success 'am pauses on conflict' '
 	test -d .git/rebase-apply
 '
 
+test_expect_success 'am --show-current-patch' '
+	git am --show-current-patch >actual.patch &&
+	test_cmp .git/rebase-apply/0001 actual.patch
+'
+
 test_expect_success 'am --skip works' '
 	echo goodbye >expected &&
 	git am --skip &&