[PATCH 4/8] revert: separate out parse errors logically

[Ramkumar Ramachandra <artagnon@gmail.com>]

Three kinds of errors can arise from parsing the instruction sheet:
1. Unrecognized action
2. Malformed object name
3. Object name does not refer to a valid commit

The next patch makes an attempt to make the parser report meaningful
errors by replacing the "return -1" with "return error(...)"
appropriately.  For the first kind of error, it is insufficient to
check if the buffer beings with a "pick" or "revert", otherwise the
following insn sheet would be interpreted as having a malformed object
name:

pickle a1fe57~2

In reality, the issue is that "pickle" is an unrecognized instruction.
So, check that the buffer starts with ("pick " or "pick\t") and
("revert " or "revert\t").

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 builtin/revert.c |   15 ++++++---------
 1 files changed, 6 insertions(+), 9 deletions(-)

diff --git a/builtin/revert.c b/builtin/revert.c
index 1841ffa..9a09471 100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -736,22 +736,19 @@ static int parse_insn_line(char *bol, char *eol, struct replay_insn_list *item)
 {
 	unsigned char commit_sha1[20];
 	char *end_of_object_name;
-	int saved, status, padding;
+	int saved, status;
 
-	if (!prefixcmp(bol, "pick")) {
+	if (!prefixcmp(bol, "pick ") || !prefixcmp(bol, "pick\t")) {
 		item->action = REPLAY_PICK;
-		bol += strlen("pick");
-	} else if (!prefixcmp(bol, "revert")) {
+		bol += strlen("pick ");
+	} else if (!prefixcmp(bol, "revert ") || !prefixcmp(bol, "revert\t")) {
 		item->action = REPLAY_REVERT;
-		bol += strlen("revert");
+		bol += strlen("revert ");
 	} else
 		return -1;
 
 	/* Eat up extra spaces/ tabs before object name */
-	padding = strspn(bol, " \t");
-	if (!padding)
-		return -1;
-	bol += padding;
+	bol += strspn(bol, " \t");
 
 	end_of_object_name = bol + strcspn(bol, " \t\n");
 	saved = *end_of_object_name;
-- 
1.7.8.2