Re: [PATCH 14/16] fetch-pack: refactor parsing in get_ack

2014-06-19 Thread Eric Sunshine
On Wed, Jun 18, 2014 at 3:56 PM, Jeff King  wrote:
> There are several uses of the magic number "line+45" when
> parsing ACK lines from the server, and it's rather unclear
> why 45 is the correct number. We can make this more clear by
> keeping a running pointer as we parse, using skip_prefix to
> jump past the first "ACK ", then adding 40 to jump past
> get_sha1_hex (which is still magical, but hopefully 40 is
> less magical to readers of git code).
>
> Note that this actually puts us at line+44. The original
> required some character between the sha1 and further ACK
> flags (it is supposed to be a space, but we never enforced
> that). We start our search for flags at line+44, which
> meanas we are slightly more liberal than the old code.

s/meanas/means/

> Signed-off-by: Jeff King 
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[PATCH 14/16] fetch-pack: refactor parsing in get_ack

2014-06-18 Thread Jeff King
There are several uses of the magic number "line+45" when
parsing ACK lines from the server, and it's rather unclear
why 45 is the correct number. We can make this more clear by
keeping a running pointer as we parse, using skip_prefix to
jump past the first "ACK ", then adding 40 to jump past
get_sha1_hex (which is still magical, but hopefully 40 is
less magical to readers of git code).

Note that this actually puts us at line+44. The original
required some character between the sha1 and further ACK
flags (it is supposed to be a space, but we never enforced
that). We start our search for flags at line+44, which
meanas we are slightly more liberal than the old code.

Signed-off-by: Jeff King 
---
I actually think we could tighten this even more and drop the strstrs,
too, like:

  arg += 40;
  if (*arg++ != ' ')
return ACK;
  if (!strcmp(arg, "continue"))
return ACK_continue;

and so on. But I wasn't sure if there was a reason for the use of
strstr. According to pack-protocol.txt, we would only get one at a time,
and always with a single space between them.

 fetch-pack.c | 15 +--
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/fetch-pack.c b/fetch-pack.c
index 3de3bd5..72ec520 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -189,20 +189,23 @@ static enum ack_type get_ack(int fd, unsigned char 
*result_sha1)
 {
int len;
char *line = packet_read_line(fd, &len);
+   const char *arg;
 
if (!len)
die("git fetch-pack: expected ACK/NAK, got EOF");
if (!strcmp(line, "NAK"))
return NAK;
-   if (starts_with(line, "ACK ")) {
-   if (!get_sha1_hex(line+4, result_sha1)) {
-   if (len < 45)
+   if (skip_prefix(line, "ACK ", &arg)) {
+   if (!get_sha1_hex(arg, result_sha1)) {
+   arg += 40;
+   len -= arg - line;
+   if (len < 1)
return ACK;
-   if (strstr(line+45, "continue"))
+   if (strstr(arg, "continue"))
return ACK_continue;
-   if (strstr(line+45, "common"))
+   if (strstr(arg, "common"))
return ACK_common;
-   if (strstr(line+45, "ready"))
+   if (strstr(arg, "ready"))
return ACK_ready;
return ACK;
}
-- 
2.0.0.566.gfe3e6b2

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