sequencer: use read_author_script()

Use the new function added in the last commit to read the author
script, updating read_env_script() and read_author_ident(). We now
have a single code path that reads the author script for am and all
flavors of rebase. This changes the behavior of read_env_script() as
previously it would set any environment variables that were in the
author-script file. Now it is an error if the file contains other
variables or any of GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL and
GIT_AUTHOR_DATE are missing. This is what am and the non interactive
version of rebase have been doing for several years so hopefully it
will not cause a problem for interactive rebase users. The advantage
is that we are reusing existing code from am which uses sq_dequote()
to properly dequote variables. This fixes potential problems with user
edited scripts as read_env_script() which did not track quotes
properly.

This commit also removes the fallback code for checking for a broken
author script after git is upgraded when a rebase is stopped. Now that
the parsing uses sq_dequote() it will reliably return an error if the
quoting is broken and the user will have to abort the rebase and
restart. This isn't ideal but it's a corner case and the detection of
the broken quoting could be confused by user edited author scripts.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer.c

@@ -771,53 +771,24 @@ finish:
 }
 
 /*
- * write_author_script() used to fail to terminate the last line with a "'" and
- * also escaped "'" incorrectly as "'\\\\''" rather than "'\\''". We check for
- * the terminating "'" on the last line to see how "'" has been escaped in case
- * git was upgraded while rebase was stopped.
- */
-static int quoting_is_broken(const char *s, size_t n)
-{
-	/* Skip any empty lines in case the file was hand edited */
-	while (n > 0 && s[--n] == '\n')
-		; /* empty */
-	if (n > 0 && s[n] != '\'')
-		return 1;
-
-	return 0;
-}
-
-/*
- * Read a list of environment variable assignments (such as the author-script
- * file) into an environment block. Returns -1 on error, 0 otherwise.
+ * Read a GIT_AUTHOR_NAME, GIT_AUTHOR_EMAIL AND GIT_AUTHOR_DATE from a
+ * file with shell quoting into struct argv_array. Returns -1 on
+ * error, 0 otherwise.
  */
 static int read_env_script(struct argv_array *env)
 {
-	struct strbuf script = STRBUF_INIT;
-	int i, count = 0, sq_bug;
-	const char *p2;
-	char *p;
+	char *name, *email, *date;
 
-	if (strbuf_read_file(&script, rebase_path_author_script(), 256) <= 0)
+	if (read_author_script(rebase_path_author_script(),
+			       &name, &email, &date, 0))
 		return -1;
-	/* write_author_script() used to quote incorrectly */
-	sq_bug = quoting_is_broken(script.buf, script.len);
-	for (p = script.buf; *p; p++)
-		if (sq_bug && skip_prefix(p, "'\\\\''", &p2))
-			strbuf_splice(&script, p - script.buf, p2 - p, "'", 1);
-		else if (skip_prefix(p, "'\\''", &p2))
-			strbuf_splice(&script, p - script.buf, p2 - p, "'", 1);
-		else if (*p == '\'')
-			strbuf_splice(&script, p-- - script.buf, 1, "", 0);
-		else if (*p == '\n') {
-			*p = '\0';
-			count++;
-		}
 
-	for (i = 0, p = script.buf; i < count; i++) {
-		argv_array_push(env, p);
-		p += strlen(p) + 1;
-	}
+	argv_array_pushf(env, "GIT_AUTHOR_NAME=%s", name);
+	argv_array_pushf(env, "GIT_AUTHOR_EMAIL=%s", email);
+	argv_array_pushf(env, "GIT_AUTHOR_DATE=%s", date);
+	free(name);
+	free(email);
+	free(date);
 
 	return 0;
 }
@@ -837,54 +808,28 @@ static char *get_author(const char *message)
 /* Read author-script and return an ident line (author <email> timestamp) */
 static const char *read_author_ident(struct strbuf *buf)
 {
-	const char *keys[] = {
-		"GIT_AUTHOR_NAME=", "GIT_AUTHOR_EMAIL=", "GIT_AUTHOR_DATE="
-	};
 	struct strbuf out = STRBUF_INIT;
-	char *in, *eol;
-	const char *val[3];
-	int i = 0;
+	char *name, *email, *date;
 
-	if (strbuf_read_file(buf, rebase_path_author_script(), 256) <= 0)
+	if (read_author_script(rebase_path_author_script(),
+			       &name, &email, &date, 0))
 		return NULL;
 
-	/* dequote values and construct ident line in-place */
-	for (in = buf->buf; i < 3 && in - buf->buf < buf->len; i++) {
-		if (!skip_prefix(in, keys[i], (const char **)&in)) {
-			warning(_("could not parse '%s' (looking for '%s')"),
-				rebase_path_author_script(), keys[i]);
-			return NULL;
-		}
-
-		eol = strchrnul(in, '\n');
-		*eol = '\0';
-		if (!sq_dequote(in)) {
-			warning(_("bad quoting on %s value in '%s'"),
-				keys[i], rebase_path_author_script());
-			return NULL;
-		}
-		val[i] = in;
-		in = eol + 1;
-	}
-
-	if (i < 3) {
-		warning(_("could not parse '%s' (looking for '%s')"),
-			rebase_path_author_script(), keys[i]);
-		return NULL;
-	}
-
 	/* validate date since fmt_ident() will die() on bad value */
-	if (parse_date(val[2], &out)){
+	if (parse_date(date, &out)){
 		warning(_("invalid date format '%s' in '%s'"),
-			val[2], rebase_path_author_script());
+			date, rebase_path_author_script());
 		strbuf_release(&out);
 		return NULL;
 	}
 
 	strbuf_reset(&out);
-	strbuf_addstr(&out, fmt_ident(val[0], val[1], val[2], 0));
+	strbuf_addstr(&out, fmt_ident(name, email, date, 0));
 	strbuf_swap(buf, &out);
 	strbuf_release(&out);
+	free(name);
+	free(email);
+	free(date);
 	return buf->buf;
 }