Re: comparing file contents in is_exact_match?
Linus Torvalds, Mon, Jul 17, 2006 19:56:04 +0200:
Show 9 quoted lines
> > So we could introduce a second mmap() which is normally the same as
> > mmap(), except for windows, where it is a rename() and unlink() safe
> > version of mmap() by reading the thing into RAM. Not very pretty.
>
> Well, not too ugly either.
>
> Imagine having a "map_packfile()" interface, and letting different targets
> just implement their own version. That doesn't sound too bad, does it?
>
Maybe the patch below will at least help to identify the place where the interface could be used. It's a bit more than packfiles. I use it since march (I really meant to post it, but probably forgot). But careful, it has an ugly piece in git-compat-util.h, which probably makes the patch only useful on cygwin and nowhere else (is there any other platform which has NO_MMAP defined?).
---
Makefile | 2 +-
compat/realmmap.c | 26 ++++++++++++++++++++++++++
diff.c | 4 ++--
git-compat-util.h | 10 ++++++++--
sha1_file.c | 24 ++++++++++++------------
5 files changed, 49 insertions(+), 17 deletions(-)
diff --git a/Makefile b/Makefile
index 01fb9cf..f16b466 100644
--- a/Makefile
+++ b/Makefile
@@ -432,7 +432,7 @@ ifdef NO_SETENV
endif
ifdef NO_MMAP
COMPAT_CFLAGS += -DNO_MMAP
- COMPAT_OBJS += compat/mmap.o
+ COMPAT_OBJS += compat/mmap.o compat/realmmap.o
endif
ifdef NO_IPV6
ALL_CFLAGS += -DNO_IPV6
diff --git a/compat/realmmap.c b/compat/realmmap.c
new file mode 100644
index 0000000..8f26641
--- /dev/null
+++ b/compat/realmmap.c
@@ -0,0 +1,26 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include "../git-compat-util.h"
+
+#undef mmap
+#undef munmap
+
+void *realmmap(void *start, size_t length, int prot , int flags, int fd, off_t offset)
+{
+ if (start != NULL || !(flags & MAP_PRIVATE)) {
+ errno = ENOTSUP;
+ return MAP_FAILED;
+ }
+ start = mmap(start, length, prot, flags, fd, offset);
+ return start;
+}
+
+int realmunmap(void *start, size_t length)
+{
+ return munmap(start, length);
+}
+
+
diff --git a/diff.c b/diff.c
index 8b44756..831bf82 100644
--- a/diff.c
+++ b/diff.c
@@ -1094,7 +1094,7 @@ int diff_populate_filespec(struct diff_f
fd = open(s->path, O_RDONLY);
if (fd < 0)
goto err_empty;
- s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
+ s->data = realmmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (s->data == MAP_FAILED)
goto err_empty;
@@ -1126,7 +1126,7 @@ void diff_free_filespec_data(struct diff
if (s->should_free)
free(s->data);
else if (s->should_munmap)
- munmap(s->data, s->size);
+ realmunmap(s->data, s->size);
s->should_free = s->should_munmap = 0;
s->data = NULL;
free(s->cnt_data);
diff --git a/git-compat-util.h b/git-compat-util.h
index 93f5580..503b8e4 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -46,22 +46,28 @@ extern void set_error_routine(void (*rou
#ifdef NO_MMAP
-#ifndef PROT_READ
+#include <sys/mman.h>
+/*#ifndef PROT_READ
#define PROT_READ 1
#define PROT_WRITE 2
#define MAP_PRIVATE 1
#define MAP_FAILED ((void*)-1)
-#endif
+#endif*/
#define mmap gitfakemmap
#define munmap gitfakemunmap
extern void *gitfakemmap(void *start, size_t length, int prot , int flags, int fd, off_t offset);
extern int gitfakemunmap(void *start, size_t length);
+extern void *realmmap(void *start, size_t length, int prot , int flags, int fd, off_t offset);
+extern int realmunmap(void *start, size_t length);
+
#else /* NO_MMAP */
#include <sys/mman.h>
+#define realmmap mmap
+#define realmunmap munmap
#endif /* NO_MMAP */
#ifdef NO_SETENV
diff --git a/sha1_file.c b/sha1_file.c
index e666aec..38ab710 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -331,14 +331,14 @@ static void read_info_alternates(const c
close(fd);
return;
}
- map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+ map = realmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (map == MAP_FAILED)
return;
link_alt_odb_entries(map, map + st.st_size, '\n', relative_base, depth);
- munmap(map, st.st_size);
+ realmunmap(map, st.st_size);
}
void prepare_alt_odb(void)
@@ -394,7 +394,7 @@ static int check_packed_git_idx(const ch
return -1;
}
idx_size = st.st_size;
- idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
+ idx_map = realmmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (idx_map == MAP_FAILED)
return -1;
@@ -439,7 +439,7 @@ static int unuse_one_packed_git(void)
}
if (!lru)
return 0;
- munmap(lru->pack_base, lru->pack_size);
+ realmunmap(lru->pack_base, lru->pack_size);
lru->pack_base = NULL;
return 1;
}
@@ -476,7 +476,7 @@ int use_packed_git(struct packed_git *p)
}
if (st.st_size != p->pack_size)
die("packfile %s size mismatch.", p->pack_name);
- map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
+ map = realmmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (map == MAP_FAILED)
die("packfile %s cannot be mapped.", p->pack_name);
@@ -511,7 +511,7 @@ struct packed_git *add_packed_git(char *
/* do we have a corresponding .pack file? */
strcpy(path + path_len - 4, ".pack");
if (stat(path, &st) || !S_ISREG(st.st_mode)) {
- munmap(idx_map, idx_size);
+ realmunmap(idx_map, idx_size);
return NULL;
}
/* ok, it looks sane as far as we can check without
@@ -676,7 +676,7 @@ static void *map_sha1_file_internal(cons
*/
sha1_file_open_flag = 0;
}
- map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+ map = realmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (map == MAP_FAILED)
return NULL;
@@ -1220,7 +1220,7 @@ int sha1_object_info(const unsigned char
*sizep = size;
}
inflateEnd(&stream);
- munmap(map, mapsize);
+ realmunmap(map, mapsize);
return status;
}
@@ -1246,7 +1246,7 @@ void * read_sha1_file(const unsigned cha
map = map_sha1_file_internal(sha1, &mapsize);
if (map) {
buf = unpack_sha1_file(map, mapsize, type, size);
- munmap(map, mapsize);
+ realmunmap(map, mapsize);
return buf;
}
reprepare_packed_git();
@@ -1543,7 +1543,7 @@ int write_sha1_to_fd(int fd, const unsig
if (buf) {
retval = write_buffer(fd, buf, objsize);
- munmap(buf, objsize);
+ realmunmap(buf, objsize);
return retval;
}
@@ -1726,7 +1726,7 @@ int index_fd(unsigned char *sha1, int fd
buf = "";
if (size)
- buf = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
+ buf = realmmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
if (buf == MAP_FAILED)
return -1;
@@ -1740,7 +1740,7 @@ int index_fd(unsigned char *sha1, int fd
ret = 0;
}
if (size)
- munmap(buf, size);
+ realmunmap(buf, size);
return ret;
}
--
1.4.1.gb944
Martin Waitz
