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[PATCH 02/16] Modify read functions to prepare for other index formats

From
Thomas Gummerer <t.gummerer@gmail.com>
Date
Aug 2, 2012, 11:01 UTC
Message-ID
<1343905326-23790-3-git-send-email-t.gummerer@gmail.com>
In-Reply-To
<1343905326-23790-1-git-send-email-t.gummerer@gmail.com>

Modify the read_index_from function, splitting it up into one function that stays the same for every index format, doing the basic operations such as verifying the header, and a function which is specific for each index version, which does the real reading of the index.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
---
 cache.h      |   1 +
 read-cache.c | 108 +++++++++++++++++++++++++++++++++++------------------------
 2 files changed, 66 insertions(+), 43 deletions(-)
diff --git a/cache.h b/cache.h
index d4028ef..3aa70d8 100644
--- a/cache.h
+++ b/cache.h
@@ -435,6 +435,7 @@ extern int init_db(const char *template_dir, unsigned int flags);
 /* Initialize and use the cache information */
 extern int read_index(struct index_state *);
 extern int read_index_preload(struct index_state *, const char **pathspec);
+extern void read_index_v2(struct index_state *, void *mmap, int);
 extern int read_index_from(struct index_state *, const char *path);
 extern int is_index_unborn(struct index_state *);
 extern int read_index_unmerged(struct index_state *);
diff --git a/read-cache.c b/read-cache.c
index c44b5f7..3d83f05 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -1247,10 +1247,8 @@ struct ondisk_cache_entry_extended {
 			    ondisk_cache_entry_extended_size(ce_namelen(ce)) : \
 			    ondisk_cache_entry_size(ce_namelen(ce)))
 
-static int verify_hdr(struct cache_version_header *hdr, unsigned long size)
+static int verify_hdr_version(struct cache_version_header *hdr, unsigned long size)
 {
-	git_SHA_CTX c;
-	unsigned char sha1[20];
 	int hdr_version;
 
 	if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
@@ -1258,6 +1256,14 @@ static int verify_hdr(struct cache_version_header *hdr, unsigned long size)
 	hdr_version = ntohl(hdr->hdr_version);
 	if (hdr_version < 2 || 4 < hdr_version)
 		return error("bad index version %d", hdr_version);
+	return 0;
+}
+
+static int verify_hdr_v2(struct cache_version_header *hdr, unsigned long size)
+{
+	git_SHA_CTX c;
+	unsigned char sha1[20];
+
 	git_SHA1_Init(&c);
 	git_SHA1_Update(&c, hdr, size - 20);
 	git_SHA1_Final(sha1, &c);
@@ -1403,50 +1409,15 @@ static struct cache_entry *create_from_disk(struct ondisk_cache_entry *ondisk,
 	return ce;
 }
 
-/* remember to discard_cache() before reading a different cache! */
-int read_index_from(struct index_state *istate, const char *path)
+void read_index_v2(struct index_state *istate, void *mmap, int mmap_size)
 {
-	int fd, i;
-	struct stat st;
+	int i;
 	unsigned long src_offset;
 	struct cache_version_header *hdr;
 	struct cache_header_v2 *hdr_v2;
-	void *mmap;
-	size_t mmap_size;
 	struct strbuf previous_name_buf = STRBUF_INIT, *previous_name;
 
-	errno = EBUSY;
-	if (istate->initialized)
-		return istate->cache_nr;
-
-	errno = ENOENT;
-	istate->timestamp.sec = 0;
-	istate->timestamp.nsec = 0;
-	fd = open(path, O_RDONLY);
-	if (fd < 0) {
-		if (errno == ENOENT)
-			return 0;
-		die_errno("index file open failed");
-	}
-
-	if (fstat(fd, &st))
-		die_errno("cannot stat the open index");
-
-	errno = EINVAL;
-	mmap_size = xsize_t(st.st_size);
-	if (mmap_size < sizeof(struct cache_version_header) + 20)
-		die("index file smaller than expected");
-
-	mmap = xmmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
-	close(fd);
-	if (mmap == MAP_FAILED)
-		die_errno("unable to map index file");
-
 	hdr = mmap;
-	hdr_v2 =  mmap + sizeof(*hdr);
-	if (verify_hdr(hdr, mmap_size) < 0)
-		goto unmap;
-
 	hdr_v2 = mmap + sizeof(*hdr);
 	istate->version = ntohl(hdr->hdr_version);
 	istate->cache_nr = ntohl(hdr_v2->hdr_entries);
@@ -1472,8 +1443,6 @@ int read_index_from(struct index_state *istate, const char *path)
 		src_offset += consumed;
 	}
 	strbuf_release(&previous_name_buf);
-	istate->timestamp.sec = st.st_mtime;
-	istate->timestamp.nsec = ST_MTIME_NSEC(st);
 
 	while (src_offset <= mmap_size - 20 - 8) {
 		/* After an array of active_nr index entries,
@@ -1493,12 +1462,65 @@ int read_index_from(struct index_state *istate, const char *path)
 		src_offset += 8;
 		src_offset += extsize;
 	}
+	return;
+unmap:
+	munmap(mmap, mmap_size);
+	die("index file corrupt");
+}
+
+/* remember to discard_cache() before reading a different cache! */
+int read_index_from(struct index_state *istate, const char *path)
+{
+	int fd;
+	struct stat st;
+	struct cache_version_header *hdr;
+	void *mmap;
+	size_t mmap_size;
+
+	errno = EBUSY;
+	if (istate->initialized)
+		return istate->cache_nr;
+
+	errno = ENOENT;
+	istate->timestamp.sec = 0;
+	istate->timestamp.nsec = 0;
+	fd = open(path, O_RDONLY);
+	if (fd < 0) {
+		if (errno == ENOENT)
+			return 0;
+		die_errno("index file open failed");
+	}
+
+	if (fstat(fd, &st))
+		die_errno("cannot stat the open index");
+
+	errno = EINVAL;
+	mmap_size = xsize_t(st.st_size);
+	if (mmap_size < sizeof(struct cache_version_header) + 20)
+		die("index file smaller than expected");
+
+	mmap = xmmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
+	close(fd);
+	if (mmap == MAP_FAILED)
+		die_errno("unable to map index file");
+
+	hdr = mmap;
+	if (verify_hdr_version(hdr, mmap_size) < 0)
+		goto unmap;
+
+	if (verify_hdr_v2(hdr, mmap_size) < 0)
+		goto unmap;
+
+	read_index_v2(istate, mmap, mmap_size);
+
+	istate->timestamp.sec = st.st_mtime;
+	istate->timestamp.nsec = ST_MTIME_NSEC(st);
+
 	munmap(mmap, mmap_size);
 	return istate->cache_nr;
 
 unmap:
 	munmap(mmap, mmap_size);
-	errno = EINVAL;
 	die("index file corrupt");
 }
 

-- 
1.7.10.886.gdf6792c.dirty
Previous: Nguyen Thai Ngoc DuyNext: Thomas Gummerer
Message 4 of 38 in “[RFC 0/16] Introduce index file format version 5”
  1. Thomas GummererAug 2, 2012
  2. 01/16 Modify cache_header to prepare for other index formatsThomas Gummerer, Aug 2, 2012
  3. Nguyen Thai Ngoc DuyAug 2, 2012
  4. 02/16 Modify read functions to prepare for other index formatsThomas Gummerer, Aug 2, 2012
  5. 03/16 Modify match_stat_basic to prepare for other index formatsThomas Gummerer, Aug 2, 2012
  6. Nguyen Thai Ngoc DuyAug 2, 2012
  7. Thomas GummererAug 2, 2012
  8. 04/16 Modify write functions to prepare for other index formatsThomas Gummerer, Aug 2, 2012
  9. Nguyen Thai Ngoc DuyAug 2, 2012
  10. Thomas GummererAug 2, 2012
  11. 05/16 t2104: Don't fail when index version is 5Thomas Gummerer, Aug 2, 2012
  12. Thomas RastAug 3, 2012
  13. Thomas GummererAug 3, 2012
  14. Junio C HamanoAug 3, 2012
  15. 06/16 t3700: sleep for 1 second, to avoid interfering with the racy codeThomas Gummerer, Aug 2, 2012
  16. 07/16 Add documentation of the index-v5 file formatThomas Gummerer, Aug 2, 2012
  17. 08/16 Make in-memory format aware of stat_crcThomas Gummerer, Aug 2, 2012
  18. 09/16 Read index-v5Thomas Gummerer, Aug 2, 2012
  19. Nguyen Thai Ngoc DuyAug 2, 2012
  20. Thomas GummererAug 2, 2012
  21. 10/16 Read resolve-undo dataThomas Gummerer, Aug 2, 2012
  22. 11/16 Read cache-tree in index-v5Thomas Gummerer, Aug 2, 2012
  23. Thomas RastAug 3, 2012
  24. Thomas GummererAug 3, 2012
  25. 12/16 Write index-v5Thomas Gummerer, Aug 2, 2012
  26. 13/16 Write index-v5 cache-tree dataThomas Gummerer, Aug 2, 2012
  27. 14/16 Write resolve-undo data for index-v5Thomas Gummerer, Aug 2, 2012
  28. 15/16 update-index.c: add a force-rewrite optionThomas Gummerer, Aug 2, 2012
  29. 16/16 p0002-index.sh: add perf test for the index formatsThomas Gummerer, Aug 2, 2012
  30. Nguyen Thai Ngoc DuyAug 2, 2012
  31. Thomas GummererAug 2, 2012
  32. Nguyen Thai Ngoc DuyAug 2, 2012
  33. Thomas GummererAug 2, 2012
  34. Nguyen Thai Ngoc DuyAug 2, 2012
  35. Nguyen Thai Ngoc DuyAug 3, 2012
  36. Thomas GummererAug 3, 2012
  37. Thomas RastAug 3, 2012
  38. Thomas GummererAug 3, 2012

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