Allow custom "comment char"

Some users do want to write a line that begin with a pound sign, #,
in their commit log message.  Many tracking system recognise
a token of #<bugid> form, for example.

The support we offer these use cases is not very friendly to the end
users.  They have a choice between

 - Don't do it.  Avoid such a line by rewrapping or indenting; and

 - Use --cleanup=whitespace but remove all the hint lines we add.

Give them a way to set a custom comment char, e.g.

    $ git -c core.commentchar="%" commit

so that they do not have to do either of the two workarounds.

[jc: although I started the topic, all the tests and documentation
updates, many of the call sites of the new strbuf_add_commented_*()
functions, and the change to git-submodule.sh scripted Porcelain are
from Ralf.]

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

7 files changed, 86 insertions, 60 deletions

diff --git a/builtin/branch.c b/builtin/branch.c
index 873f624d1c..3548271c47 100644
--- a/builtin/branch.c
+++ b/builtin/branch.c
@@ -706,11 +706,11 @@ static int edit_branch_description(const char *branch_name)
 	read_branch_desc(&buf, branch_name);
 	if (!buf.len || buf.buf[buf.len-1] != '\n')
 		strbuf_addch(&buf, '\n');
-	strbuf_addf(&buf,
-		    "# Please edit the description for the branch\n"
-		    "#   %s\n"
-		    "# Lines starting with '#' will be stripped.\n",
-		    branch_name);
+	strbuf_commented_addf(&buf,
+		    "Please edit the description for the branch\n"
+		    "  %s\n"
+		    "Lines starting with '%c' will be stripped.\n",
+		    branch_name, comment_line_char);
 	fp = fopen(git_path(edit_description), "w");
 	if ((fwrite(buf.buf, 1, buf.len, fp) < buf.len) || fclose(fp)) {
 		strbuf_release(&buf);
diff --git a/builtin/commit.c b/builtin/commit.c
index d6dd3df8b1..f95f64abff 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -733,15 +733,15 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 		if (cleanup_mode == CLEANUP_ALL)
 			status_printf(s, GIT_COLOR_NORMAL,
 				_("Please enter the commit message for your changes."
-				" Lines starting\nwith '#' will be ignored, and an empty"
-				" message aborts the commit.\n"));
+				  " Lines starting\nwith '%c' will be ignored, and an empty"
+				  " message aborts the commit.\n"), comment_line_char);
 		else /* CLEANUP_SPACE, that is. */
 			status_printf(s, GIT_COLOR_NORMAL,
 				_("Please enter the commit message for your changes."
-				" Lines starting\n"
-				"with '#' will be kept; you may remove them"
-				" yourself if you want to.\n"
-				"An empty message aborts the commit.\n"));
+				  " Lines starting\n"
+				  "with '%c' will be kept; you may remove them"
+				  " yourself if you want to.\n"
+				  "An empty message aborts the commit.\n"), comment_line_char);
 		if (only_include_assumed)
 			status_printf_ln(s, GIT_COLOR_NORMAL,
 					"%s", only_include_assumed);
diff --git a/builtin/fmt-merge-msg.c b/builtin/fmt-merge-msg.c
index e2e27b2c40..d6d2e1b6c0 100644
--- a/builtin/fmt-merge-msg.c
+++ b/builtin/fmt-merge-msg.c
@@ -464,7 +464,7 @@ static void fmt_tag_signature(struct strbuf *tagbuf,
 	strbuf_complete_line(tagbuf);
 	if (sig->len) {
 		strbuf_addch(tagbuf, '\n');
-		strbuf_add_lines(tagbuf, "# ", sig->buf, sig->len);
+		strbuf_add_commented_lines(tagbuf, sig->buf, sig->len);
 	}
 }
 
diff --git a/builtin/merge.c b/builtin/merge.c
index 3a31c4bc25..d7baa2683c 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -788,17 +788,16 @@ static const char merge_editor_comment[] =
 N_("Please enter a commit message to explain why this merge is necessary,\n"
    "especially if it merges an updated upstream into a topic branch.\n"
    "\n"
-   "Lines starting with '#' will be ignored, and an empty message aborts\n"
+   "Lines starting with '%c' will be ignored, and an empty message aborts\n"
    "the commit.\n");
 
 static void prepare_to_commit(struct commit_list *remoteheads)
 {
 	struct strbuf msg = STRBUF_INIT;
-	const char *comment = _(merge_editor_comment);
 	strbuf_addbuf(&msg, &merge_msg);
 	strbuf_addch(&msg, '\n');
 	if (0 < option_edit)
-		strbuf_add_lines(&msg, "# ", comment, strlen(comment));
+		strbuf_commented_addf(&msg, _(merge_editor_comment), comment_line_char);
 	write_merge_msg(&msg);
 	if (run_hook(get_index_file(), "prepare-commit-msg",
 		     git_path("MERGE_MSG"), "merge", NULL, NULL))
diff --git a/builtin/notes.c b/builtin/notes.c
index 453457adb9..57748a6fb6 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -92,10 +92,7 @@ static const char * const git_notes_get_ref_usage[] = {
 };
 
 static const char note_template[] =
-	"\n"
-	"#\n"
-	"# Write/edit the notes for the following object:\n"
-	"#\n";
+	"\nWrite/edit the notes for the following object:\n";
 
 struct msg_arg {
 	int given;
@@ -129,7 +126,7 @@ static void write_commented_object(int fd, const unsigned char *object)
 		{"show", "--stat", "--no-notes", sha1_to_hex(object), NULL};
 	struct child_process show;
 	struct strbuf buf = STRBUF_INIT;
-	FILE *show_out;
+	struct strbuf cbuf = STRBUF_INIT;
 
 	/* Invoke "git show --stat --no-notes $object" */
 	memset(&show, 0, sizeof(show));
@@ -142,21 +139,14 @@ static void write_commented_object(int fd, const unsigned char *object)
 		die(_("unable to start 'show' for object '%s'"),
 		    sha1_to_hex(object));
 
-	/* Open the output as FILE* so strbuf_getline() can be used. */
-	show_out = xfdopen(show.out, "r");
-	if (show_out == NULL)
-		die_errno(_("can't fdopen 'show' output fd"));
+	if (strbuf_read(&buf, show.out, 0) < 0)
+		die_errno(_("could not read 'show' output"));
+	strbuf_add_commented_lines(&cbuf, buf.buf, buf.len);
+	write_or_die(fd, cbuf.buf, cbuf.len);
 
-	/* Prepend "# " to each output line and write result to 'fd' */
-	while (strbuf_getline(&buf, show_out, '\n') != EOF) {
-		write_or_die(fd, "# ", 2);
-		write_or_die(fd, buf.buf, buf.len);
-		write_or_die(fd, "\n", 1);
-	}
+	strbuf_release(&cbuf);
 	strbuf_release(&buf);
-	if (fclose(show_out))
-		die_errno(_("failed to close pipe to 'show' for object '%s'"),
-			  sha1_to_hex(object));
+
 	if (finish_command(&show))
 		die(_("failed to finish 'show' for object '%s'"),
 		    sha1_to_hex(object));
@@ -170,6 +160,7 @@ static void create_note(const unsigned char *object, struct msg_arg *msg,
 
 	if (msg->use_editor || !msg->given) {
 		int fd;
+		struct strbuf buf = STRBUF_INIT;
 
 		/* write the template message before editing: */
 		path = git_pathdup("NOTES_EDITMSG");
@@ -181,11 +172,16 @@ static void create_note(const unsigned char *object, struct msg_arg *msg,
 			write_or_die(fd, msg->buf.buf, msg->buf.len);
 		else if (prev && !append_only)
 			write_note_data(fd, prev);
-		write_or_die(fd, note_template, strlen(note_template));
+
+		strbuf_addch(&buf, '\n');
+		strbuf_add_commented_lines(&buf, note_template, strlen(note_template));
+		strbuf_addch(&buf, '\n');
+		write_or_die(fd, buf.buf, buf.len);
 
 		write_commented_object(fd, object);
 
 		close(fd);
+		strbuf_release(&buf);
 		strbuf_reset(&(msg->buf));
 
 		if (launch_editor(path, &(msg->buf), NULL)) {
diff --git a/builtin/stripspace.c b/builtin/stripspace.c
index f16986c0ae..e981dfb9f0 100644
--- a/builtin/stripspace.c
+++ b/builtin/stripspace.c
@@ -30,7 +30,8 @@ static size_t cleanup(char *line, size_t len)
  *
  * If last line does not have a newline at the end, one is added.
  *
- * Enable skip_comments to skip every line starting with "#".
+ * Enable skip_comments to skip every line starting with comment
+ * character.
  */
 void stripspace(struct strbuf *sb, int skip_comments)
 {
@@ -45,7 +46,7 @@ void stripspace(struct strbuf *sb, int skip_comments)
 		eol = memchr(sb->buf + i, '\n', sb->len - i);
 		len = eol ? eol - (sb->buf + i) + 1 : sb->len - i;
 
-		if (skip_comments && len && sb->buf[i] == '#') {
+		if (skip_comments && len && sb->buf[i] == comment_line_char) {
 			newlen = 0;
 			continue;
 		}
@@ -66,21 +67,53 @@ void stripspace(struct strbuf *sb, int skip_comments)
 	strbuf_setlen(sb, j);
 }
 
+static void comment_lines(struct strbuf *buf)
+{
+	char *msg;
+	size_t len;
+
+	msg = strbuf_detach(buf, &len);
+	strbuf_add_commented_lines(buf, msg, len);
+	free(msg);
+}
+
+static const char *usage_msg = "\n"
+"  git stripspace [-s | --strip-comments] < input\n"
+"  git stripspace [-c | --comment-lines] < input";
+
 int cmd_stripspace(int argc, const char **argv, const char *prefix)
 {
 	struct strbuf buf = STRBUF_INIT;
 	int strip_comments = 0;
+	enum { INVAL = 0, STRIP_SPACE = 1, COMMENT_LINES = 2 } mode = STRIP_SPACE;
+
+	if (argc == 2) {
+		if (!strcmp(argv[1], "-s") ||
+			!strcmp(argv[1], "--strip-comments")) {
+			 strip_comments = 1;
+		} else if (!strcmp(argv[1], "-c") ||
+					 !strcmp(argv[1], "--comment-lines")) {
+			 mode = COMMENT_LINES;
+		} else {
+			mode = INVAL;
+		}
+	} else if (argc > 1) {
+		mode = INVAL;
+	}
+
+	if (mode == INVAL)
+		usage(usage_msg);
 
-	if (argc == 2 && (!strcmp(argv[1], "-s") ||
-				!strcmp(argv[1], "--strip-comments")))
-		strip_comments = 1;
-	else if (argc > 1)
-		usage("git stripspace [-s | --strip-comments] < input");
+	if (strip_comments || mode == COMMENT_LINES)
+		git_config(git_default_config, NULL);
 
 	if (strbuf_read(&buf, 0, 1024) < 0)
 		die_errno("could not read the input");
 
-	stripspace(&buf, strip_comments);
+	if (mode == STRIP_SPACE)
+		stripspace(&buf, strip_comments);
+	else
+		comment_lines(&buf);
 
 	write_or_die(1, buf.buf, buf.len);
 	strbuf_release(&buf);
diff --git a/builtin/tag.c b/builtin/tag.c
index 9c3e0673d5..f8266888cc 100644
--- a/builtin/tag.c
+++ b/builtin/tag.c
@@ -246,19 +246,13 @@ static int do_sign(struct strbuf *buffer)
 }
 
 static const char tag_template[] =
-	N_("\n"
-	"#\n"
-	"# Write a tag message\n"
-	"# Lines starting with '#' will be ignored.\n"
-	"#\n");
+	N_("\nWrite a tag message\n"
+	"Lines starting with '%c' will be ignored.\n");
 
 static const char tag_template_nocleanup[] =
-	N_("\n"
-	"#\n"
-	"# Write a tag message\n"
-	"# Lines starting with '#' will be kept; you may remove them"
-	" yourself if you want to.\n"
-	"#\n");
+	N_("\nWrite a tag message\n"
+	"Lines starting with '%c' will be kept; you may remove them"
+	" yourself if you want to.\n");
 
 static int git_tag_config(const char *var, const char *value, void *cb)
 {
@@ -346,14 +340,18 @@ static void create_tag(const unsigned char *object, const char *tag,
 		if (fd < 0)
 			die_errno(_("could not create file '%s'"), path);
 
-		if (!is_null_sha1(prev))
+		if (!is_null_sha1(prev)) {
 			write_tag_body(fd, prev);
-		else if (opt->cleanup_mode == CLEANUP_ALL)
-			write_or_die(fd, _(tag_template),
-					strlen(_(tag_template)));
-		else
-			write_or_die(fd, _(tag_template_nocleanup),
-					strlen(_(tag_template_nocleanup)));
+		} else {
+			struct strbuf buf = STRBUF_INIT;
+			strbuf_addch(&buf, '\n');
+			if (opt->cleanup_mode == CLEANUP_ALL)
+				strbuf_commented_addf(&buf, _(tag_template), comment_line_char);
+			else
+				strbuf_commented_addf(&buf, _(tag_template_nocleanup), comment_line_char);
+			write_or_die(fd, buf.buf, buf.len);
+			strbuf_release(&buf);
+		}
 		close(fd);
 
 		if (launch_editor(path, buf, NULL)) {