[PATCH 3/4] am: support --show-current-patch=raw as a synonym for--show-current-patch

[pbonzini@redhat.com]

From: Paolo Bonzini <pbonzini@redhat.com>

When "git am --show-current-patch" was added in commit 984913a210 ("am:
add --show-current-patch", 2018-02-12), "git am" started recommending it
as a replacement for .git/rebase-merge/patch.  Unfortunately the suggestion
is misguided, for example the output "git am --show-current-patch" cannot
be passed to "git apply" if it is encoded as quoted-printable or base64.

We would like therefore to add a new mode to "git am" that copies
.git/rebase-merge/patch to stdout.  In order to preserve backwards
compatibility, "git am --show-current-patch"'s behavior as to stay as
is, and the new functionality will be added as an optional
argument to --show-current-patch.  As a start, add the code to parse
submodes.  For now "raw" is the only valid submode, and it prints
the full e-mail message just like "git am --show-current-patch".

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 Documentation/git-am.txt               |  4 +-
 builtin/am.c                           | 59 +++++++++++++++++++++++---
 contrib/completion/git-completion.bash |  5 +++
 t/t4150-am.sh                          | 10 +++++
 4 files changed, 70 insertions(+), 8 deletions(-)

diff --git a/Documentation/git-am.txt b/Documentation/git-am.txt
index 11ca61b00b..bafb491ede 100644
--- a/Documentation/git-am.txt
+++ b/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 | --quit | --show-current-patch)
+'git am' (--continue | --skip | --abort | --quit | --show-current-patch[=raw])
 
 DESCRIPTION
 -----------
@@ -176,7 +176,7 @@ default.   You can use `--no-utf8` to override this.
 	Abort the patching operation but keep HEAD and the index
 	untouched.
 
---show-current-patch::
+--show-current-patch[=raw]::
 	Show the entire e-mail message "git am" has stopped at, because
 	of conflicts.
 
diff --git a/builtin/am.c b/builtin/am.c
index a89e1a96ed..ec4c743556 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -81,6 +81,10 @@ enum signoff_type {
 	SIGNOFF_EXPLICIT /* --signoff was set on the command-line */
 };
 
+enum show_patch_type {
+	SHOW_PATCH_RAW = 0,
+};
+
 struct am_state {
 	/* state directory path */
 	char *dir;
@@ -2061,7 +2065,7 @@ static void am_abort(struct am_state *state)
 	am_destroy(state);
 }
 
-static int show_patch(struct am_state *state)
+static int show_patch(struct am_state *state, enum show_patch_type sub_mode)
 {
 	struct strbuf sb = STRBUF_INIT;
 	const char *patch_path;
@@ -2078,7 +2082,14 @@ static int show_patch(struct am_state *state)
 		return ret;
 	}
 
-	patch_path = am_path(state, msgnum(state));
+	switch (sub_mode) {
+	case SHOW_PATCH_RAW:
+		patch_path = am_path(state, msgnum(state));
+		break;
+	default:
+		abort();
+	}
+
 	len = strbuf_read_file(&sb, patch_path, 0);
 	if (len < 0)
 		die_errno(_("failed to read '%s'"), patch_path);
@@ -2130,8 +2141,42 @@ enum resume_type {
 
 struct resume_mode {
 	enum resume_type mode;
+	enum show_patch_type sub_mode;
 };
 
+static int parse_opt_show_current_patch(const struct option *opt, const char *arg, int unset)
+{
+	int *opt_value = opt->value;
+	struct resume_mode *resume = container_of(opt_value, struct resume_mode, mode);
+
+	/*
+	 * Please update $__git_showcurrentpatch in git-completion.bash
+	 * when you add new options
+	 */
+	const char *valid_modes[] = {
+		[SHOW_PATCH_RAW] = "raw"
+	};
+	int new_value = SHOW_PATCH_RAW;
+
+	if (arg) {
+		for (new_value = 0; new_value < ARRAY_SIZE(valid_modes); new_value++) {
+			if (!strcmp(arg, valid_modes[new_value]))
+				break;
+		}
+		if (new_value >= ARRAY_SIZE(valid_modes))
+			return error(_("Invalid value for --show-current-patch: %s"), arg);
+	}
+
+	if (resume->mode == RESUME_SHOW_PATCH && new_value != resume->sub_mode)
+		return error(_("--show-current-patch=%s is incompatible with "
+			       "--show-current-patch=%s"),
+			     arg, valid_modes[resume->sub_mode]);
+
+	resume->mode = RESUME_SHOW_PATCH;
+	resume->sub_mode = new_value;
+	return 0;
+}
+
 static int git_am_config(const char *k, const char *v, void *cb)
 {
 	int status;
@@ -2233,9 +2278,11 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 		OPT_CMDMODE(0, "quit", &resume.mode,
 			N_("abort the patching operation but keep HEAD where it is."),
 			RESUME_QUIT),
-		OPT_CMDMODE(0, "show-current-patch", &resume.mode,
-			N_("show the patch being applied."),
-			RESUME_SHOW_PATCH),
+		{ OPTION_CALLBACK, 0, "show-current-patch", &resume.mode,
+		  "raw",
+		  N_("show the patch being applied"),
+		  PARSE_OPT_CMDMODE | PARSE_OPT_OPTARG | PARSE_OPT_NONEG | PARSE_OPT_LITERAL_ARGHELP,
+		  parse_opt_show_current_patch, RESUME_SHOW_PATCH },
 		OPT_BOOL(0, "committer-date-is-author-date",
 			&state.committer_date_is_author_date,
 			N_("lie about committer date")),
@@ -2354,7 +2401,7 @@ int cmd_am(int argc, const char **argv, const char *prefix)
 		am_destroy(&state);
 		break;
 	case RESUME_SHOW_PATCH:
-		ret = show_patch(&state);
+		ret = show_patch(&state, resume.sub_mode);
 		break;
 	default:
 		BUG("invalid resume value");
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 1aac5a56c0..247f34f1fa 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -1197,6 +1197,7 @@ __git_count_arguments ()
 
 __git_whitespacelist="nowarn warn error error-all fix"
 __git_patchformat="mbox stgit stgit-series hg mboxrd"
+__git_showcurrentpatch="raw"
 __git_am_inprogress_options="--skip --continue --resolved --abort --quit --show-current-patch"
 
 _git_am ()
@@ -1215,6 +1216,10 @@ _git_am ()
 		__gitcomp "$__git_patchformat" "" "${cur##--patch-format=}"
 		return
 		;;
+	--show-current-patch=*)
+		__gitcomp "$__git_showcurrentpatch" "" "${cur##--show-current-patch=}"
+		return
+		;;
 	--*)
 		__gitcomp_builtin am "" \
 			"$__git_am_inprogress_options"
diff --git a/t/t4150-am.sh b/t/t4150-am.sh
index 4f1e24ecbe..afe456e75e 100755
--- a/t/t4150-am.sh
+++ b/t/t4150-am.sh
@@ -666,6 +666,16 @@ test_expect_success 'am --show-current-patch' '
 	test_cmp .git/rebase-apply/0001 actual.patch
 '
 
+test_expect_success 'am --show-current-patch=raw' '
+	git am --show-current-patch=raw >actual.patch &&
+	test_cmp .git/rebase-apply/0001 actual.patch
+'
+
+test_expect_success 'am accepts repeated --show-current-patch' '
+	git am --show-current-patch --show-current-patch=raw >actual.patch &&
+	test_cmp .git/rebase-apply/0001 actual.patch
+'
+
 test_expect_success 'am --skip works' '
 	echo goodbye >expected &&
 	git am --skip &&
-- 
2.21.1