From: Elfyn McBratney <beu@gentoo.org>
To: Git Mailing List <git@vger.kernel.org>
Cc: Linus Torvalds <torvalds@osdl.org>,
Alex Riesen <fork0@users.sourceforge.net>,
Chuck Lever <cel@citi.umich.edu>,
Git Mailing List <git@vger.kernel.org>,
Junio C Hamano <junkio@cox.net>, Christopher Faylor <me@cgf.cx>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: First cut at git port to Cygwin
Date: Sat, 8 Oct 2005 18:38:13 +0100 [thread overview]
Message-ID: <20051008173812.GA20870@gentoo.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0510080900510.31407@g5.osdl.org>
[-- Attachment #1: Type: text/plain, Size: 2779 bytes --]
On Sat, Oct 08, 2005 at 09:11:03AM -0700, Linus Torvalds wrote:
>
> On Fri, 7 Oct 2005, Alex Riesen wrote:
> >
> > Make read_cache copy the index into memory, to improve portability on
> > other OS's which have mmap too, tend to use it less commonly.
>
> I really think that you should just get rid of the mmap.
>
> As it is, you're just slowing the code down on sane architectures. That's
> not good.
>
> So I'd suggest something like this instead.
>
> Totally untested, of course.
>
> Linus
Slightly adjusted diff below so it compiles ;) (Note: only the second
die() un hunk #1 was changed.)
Best,
Elfyn
----
diff --git a/read-cache.c b/read-cache.c
--- a/read-cache.c
+++ b/read-cache.c
@@ -454,13 +454,39 @@ static int verify_hdr(struct cache_heade
return 0;
}
+static void *map_index_file(int fd, size_t size)
+{
+ void *map;
+#ifdef NO_MMAP
+ map = malloc(size);
+ if (!map)
+ die("Unable to allocate index file mapping");
+ if (read(fd, map, size) != size)
+ die("Unable to read %z bytes from index", size);
+#else
+ map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+ if (map == MAP_FAILED)
+ die("index file mmap failed (%s)", strerror(errno));
+#endif
+ return map;
+}
+
+static void unmap_index_file(void *map, size_t size)
+{
+#ifdef NO_MMAP
+ free(map);
+#else
+ munmap(map, size);
+#endif
+}
+
int read_cache(void)
{
int fd, i;
struct stat st;
unsigned long size, offset;
- void *map;
struct cache_header *hdr;
+ void *map;
errno = EBUSY;
if (active_cache)
@@ -475,16 +501,15 @@ int read_cache(void)
}
size = 0; // avoid gcc warning
- map = MAP_FAILED;
- if (!fstat(fd, &st)) {
- size = st.st_size;
- errno = EINVAL;
- if (size >= sizeof(struct cache_header) + 20)
- map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
- }
+ if (fstat(fd, &st))
+ die("unable to fstat index file");
+
+ size = st.st_size;
+ errno = EINVAL;
+ if (size < sizeof(struct cache_header) + 20)
+ goto corrupt;
+ map = map_index_file(fd, size);
close(fd);
- if (map == MAP_FAILED)
- die("index file mmap failed (%s)", strerror(errno));
hdr = map;
if (verify_hdr(hdr, size) < 0)
@@ -503,8 +528,9 @@ int read_cache(void)
return active_nr;
unmap:
- munmap(map, size);
+ unmap_index_file(map, size);
errno = EINVAL;
+corrupt:
die("index file corrupt");
}
--
Elfyn McBratney
Gentoo Developer/Perl Team Lead
beu/irc.freenode.net http://dev.gentoo.org/~beu/
+------------O.o--------------------- http://dev.gentoo.org/~beu/pubkey.asc
PGP Key ID: 0x69DF17AD
PGP Key Fingerprint:
DBD3 B756 ED58 B1B4 47B9 B3BD 8D41 E597 69DF 17AD
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next prev parent reply other threads:[~2005-10-08 17:38 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-09-29 0:53 First cut at git port to Cygwin H. Peter Anvin
2005-09-29 4:30 ` Junio C Hamano
2005-09-29 5:07 ` H. Peter Anvin
2005-09-29 4:46 ` Martin Langhoff
2005-09-29 5:13 ` Junio C Hamano
2005-09-29 6:19 ` H. Peter Anvin
2005-09-29 8:46 ` Johannes Schindelin
2005-09-29 16:11 ` H. Peter Anvin
2005-09-29 17:25 ` H. Peter Anvin
2005-09-30 10:02 ` Junio C Hamano
2005-09-30 17:01 ` H. Peter Anvin
2005-09-30 19:08 ` H. Peter Anvin
2005-10-04 12:31 ` Alex Riesen
2005-10-04 13:06 ` Alex Riesen
2005-10-04 14:06 ` H. Peter Anvin
2005-10-05 3:15 ` Christopher Faylor
2005-10-04 15:03 ` H. Peter Anvin
2005-10-05 3:16 ` Christopher Faylor
2005-10-05 5:25 ` H. Peter Anvin
2005-10-05 11:24 ` Alex Riesen
2005-10-05 15:46 ` Alex Riesen
2005-10-05 15:54 ` Christopher Faylor
2005-10-05 16:09 ` Davide Libenzi
2005-10-05 16:15 ` Christopher Faylor
2005-10-05 16:23 ` H. Peter Anvin
2005-10-05 16:28 ` Christopher Faylor
2005-10-05 17:29 ` Davide Libenzi
2005-10-05 19:17 ` Alex Riesen
2005-10-05 20:29 ` Christopher Faylor
2005-10-06 9:05 ` Alex Riesen
2005-10-06 10:07 ` Alex Riesen
2005-10-07 12:44 ` Alex Riesen
2005-10-07 15:34 ` Linus Torvalds
2005-10-07 20:54 ` Alex Riesen
2005-10-07 21:22 ` Alex Riesen
2005-10-07 21:29 ` Chuck Lever
2005-10-07 21:39 ` Alex Riesen
2005-10-08 16:11 ` Linus Torvalds
2005-10-08 17:38 ` Elfyn McBratney [this message]
2005-10-08 17:43 ` Elfyn McBratney
2005-10-08 18:27 ` Johannes Schindelin
2005-10-08 18:44 ` Junio C Hamano
2005-10-08 19:04 ` Johannes Schindelin
2005-10-08 21:10 ` Junio C Hamano
2005-10-08 22:06 ` Johannes Schindelin
2005-10-10 18:43 ` H. Peter Anvin
2005-10-10 19:01 ` Johannes Schindelin
2005-10-10 19:26 ` H. Peter Anvin
2005-10-10 19:42 ` Johannes Schindelin
2005-10-10 20:21 ` Junio C Hamano
2005-10-10 20:34 ` Junio C Hamano
2005-10-10 20:52 ` H. Peter Anvin
2005-10-10 20:27 ` Daniel Barkalow
2005-10-08 18:49 ` Alex Riesen
2005-10-09 20:40 ` Commit text BEFORE the dashes (Re: First cut at git port to Cygwin) Matthias Urlichs
[not found] ` <7vfyrdyre5.fsf@assigned-by-dhcp.cox.net>
2005-10-07 23:45 ` First cut at git port to Cygwin Alex Riesen
2005-10-08 1:00 ` Elfyn McBratney
2005-10-10 18:45 ` H. Peter Anvin
2005-10-05 13:16 ` Jonas Fonseca
2005-10-05 13:58 ` Johannes Schindelin
2005-10-05 15:52 ` [PATCH] Fix symbolic ref validation Jonas Fonseca
2005-10-05 16:54 ` Junio C Hamano
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