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Re: comparing file contents in is_exact_match?

From
Alex Riesen <fork0@t-online.de>
Date
Jul 17, 2006, 20:20 UTC
Message-ID
<20060717202046.GA8119@steel.home>
In-Reply-To
<Pine.LNX.4.64.0607171055230.15611@evo.osdl.org>
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
Previous: Martin WaitzNext: Geert Bosch
Message 19 of 32 in “comparing file contents in is_exact_match?”
  1. Martin WaitzJul 6, 2006
  2. Junio C HamanoJul 6, 2006
  3. Martin WaitzJul 6, 2006
  4. Junio C HamanoJul 6, 2006
  5. Martin WaitzJul 6, 2006
  6. Martin WaitzJul 6, 2006
  7. Florian WeimerJul 7, 2006
  8. Johannes SchindelinJul 8, 2006
  9. Florian WeimerJul 16, 2006
  10. Johannes SchindelinJul 16, 2006
  11. Yakov LernerJul 16, 2006
  12. Alex RiesenJul 16, 2006
  13. Florian WeimerJul 17, 2006
  14. Johannes SchindelinJul 17, 2006
  15. Linus TorvaldsJul 17, 2006
  16. Johannes SchindelinJul 17, 2006
  17. Linus TorvaldsJul 17, 2006
  18. Martin WaitzJul 17, 2006
  19. Alex RiesenJul 17, 2006
  20. Geert BoschJul 17, 2006
  21. Linus TorvaldsJul 17, 2006
  22. Yakov LernerJul 18, 2006
  23. Johannes SchindelinJul 18, 2006
  24. Linus TorvaldsJul 18, 2006
  25. Alex RiesenJul 18, 2006
  26. Juergen RuehleJul 17, 2006
  27. Johannes SchindelinJul 17, 2006
  28. Juergen RuehleJul 17, 2006
  29. Yakov LernerJul 17, 2006
  30. Juergen RuehleJul 17, 2006
  31. Yakov LernerJul 18, 2006
  32. Yakov LernerJul 17, 2006

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