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[PATCH v2 32/35] dir: make untracked cache extension hash size independent

From
brian m. carlson <sandals@crustytoothpaste.net>
Date
Feb 19, 2019, 00:05 UTC
Message-ID
<20190219000526.476553-33-sandals@crustytoothpaste.net>
In-Reply-To
<20190219000526.476553-1-sandals@crustytoothpaste.net>

Instead of using a struct with a flex array member to read and write the untracked cache extension, use a shorter, fixed-length struct and add the name and hash data explicitly.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
---
 dir.c | 28 ++++++++++++++--------------
 1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/dir.c b/dir.c
index b2cabadf25..7503b56918 100644
--- a/dir.c
+++ b/dir.c
@@ -2545,13 +2545,9 @@ struct ondisk_untracked_cache {
 	struct stat_data info_exclude_stat;
 	struct stat_data excludes_file_stat;
 	uint32_t dir_flags;
-	unsigned char info_exclude_sha1[20];
-	unsigned char excludes_file_sha1[20];
-	char exclude_per_dir[FLEX_ARRAY];
 };
 
 #define ouc_offset(x) offsetof(struct ondisk_untracked_cache, x)
-#define ouc_size(len) (ouc_offset(exclude_per_dir) + len + 1)
 
 struct write_data {
 	int index;	   /* number of written untracked_cache_dir */
@@ -2634,20 +2630,21 @@ void write_untracked_extension(struct strbuf *out, struct untracked_cache *untra
 	struct write_data wd;
 	unsigned char varbuf[16];
 	int varint_len;
-	size_t len = strlen(untracked->exclude_per_dir);
+	const unsigned hashsz = the_hash_algo->rawsz;
 
-	FLEX_ALLOC_MEM(ouc, exclude_per_dir, untracked->exclude_per_dir, len);
+	ouc = xcalloc(1, sizeof(*ouc));
 	stat_data_to_disk(&ouc->info_exclude_stat, &untracked->ss_info_exclude.stat);
 	stat_data_to_disk(&ouc->excludes_file_stat, &untracked->ss_excludes_file.stat);
-	hashcpy(ouc->info_exclude_sha1, untracked->ss_info_exclude.oid.hash);
-	hashcpy(ouc->excludes_file_sha1, untracked->ss_excludes_file.oid.hash);
 	ouc->dir_flags = htonl(untracked->dir_flags);
 
 	varint_len = encode_varint(untracked->ident.len, varbuf);
 	strbuf_add(out, varbuf, varint_len);
 	strbuf_addbuf(out, &untracked->ident);
 
-	strbuf_add(out, ouc, ouc_size(len));
+	strbuf_add(out, ouc, sizeof(*ouc));
+	strbuf_add(out, untracked->ss_info_exclude.oid.hash, hashsz);
+	strbuf_add(out, untracked->ss_excludes_file.oid.hash, hashsz);
+	strbuf_add(out, untracked->exclude_per_dir, strlen(untracked->exclude_per_dir) + 1);
 	FREE_AND_NULL(ouc);
 
 	if (!untracked->root) {
@@ -2834,6 +2831,9 @@ struct untracked_cache *read_untracked_extension(const void *data, unsigned long
 	int ident_len;
 	ssize_t len;
 	const char *exclude_per_dir;
+	const unsigned hashsz = the_hash_algo->rawsz;
+	const unsigned offset = sizeof(struct ondisk_untracked_cache);
+	const unsigned exclude_per_dir_offset = offset + 2 * hashsz;
 
 	if (sz <= 1 || end[-1] != '\0')
 		return NULL;
@@ -2845,7 +2845,7 @@ struct untracked_cache *read_untracked_extension(const void *data, unsigned long
 	ident = (const char *)next;
 	next += ident_len;
 
-	if (next + ouc_size(0) > end)
+	if (next + exclude_per_dir_offset + 1 > end)
 		return NULL;
 
 	uc = xcalloc(1, sizeof(*uc));
@@ -2853,15 +2853,15 @@ struct untracked_cache *read_untracked_extension(const void *data, unsigned long
 	strbuf_add(&uc->ident, ident, ident_len);
 	load_oid_stat(&uc->ss_info_exclude,
 		      next + ouc_offset(info_exclude_stat),
-		      next + ouc_offset(info_exclude_sha1));
+		      next + offset);
 	load_oid_stat(&uc->ss_excludes_file,
 		      next + ouc_offset(excludes_file_stat),
-		      next + ouc_offset(excludes_file_sha1));
+		      next + offset + hashsz);
 	uc->dir_flags = get_be32(next + ouc_offset(dir_flags));
-	exclude_per_dir = (const char *)next + ouc_offset(exclude_per_dir);
+	exclude_per_dir = (const char *)next + exclude_per_dir_offset;
 	uc->exclude_per_dir = xstrdup(exclude_per_dir);
 	/* NUL after exclude_per_dir is covered by sizeof(*ouc) */
-	next += ouc_size(strlen(exclude_per_dir));
+	next += exclude_per_dir_offset + strlen(exclude_per_dir) + 1;
 	if (next >= end)
 		goto done2;
 
Previous: brian m. carlsonNext: brian m. carlson
Message 31 of 36 in “Hash function transition part 16”
  1. 00/35 Hash function transition part 16brian m. carlson, Feb 19, 2019
  2. 01/35 t/lib-submodule-update: use appropriate length constantbrian m. carlson, Feb 19, 2019
  3. 02/35 khash: move oid hash table definitionbrian m. carlson, Feb 19, 2019
  4. 03/35 pack-bitmap: make bitmap header handling hash agnosticbrian m. carlson, Feb 19, 2019
  5. 06/35 pack-bitmap: switch hard-coded constants to the_hash_algobrian m. carlson, Feb 19, 2019
  6. 05/35 pack-bitmap: replace sha1_to_hexbrian m. carlson, Feb 19, 2019
  7. 07/35 pack-bitmap: switch hash tables to use struct object_idbrian m. carlson, Feb 19, 2019
  8. 09/35 notes-merge: switch to use the_hash_algobrian m. carlson, Feb 19, 2019
  9. 08/35 submodule: avoid hard-coded constantsbrian m. carlson, Feb 19, 2019
  10. 11/35 notes: replace sha1_to_hexbrian m. carlson, Feb 19, 2019
  11. 14/35 fast-import: make hash-size independentbrian m. carlson, Feb 19, 2019
  12. 17/35 builtin/pull: make hash-size independentbrian m. carlson, Feb 19, 2019
  13. 15/35 fast-import: replace sha1_to_hexbrian m. carlson, Feb 19, 2019
  14. 12/35 object-store: rename and expand packed_git's sha1 memberbrian m. carlson, Feb 19, 2019
  15. 19/35 http-backend: allow 64-character hex namesbrian m. carlson, Feb 19, 2019
  16. 18/35 http-push: convert to use the_hash_algobrian m. carlson, Feb 19, 2019
  17. 21/35 http-walker: replace sha1_to_hexbrian m. carlson, Feb 19, 2019
  18. 22/35 http: replace hard-coded constant with the_hash_algobrian m. carlson, Feb 19, 2019
  19. 20/35 http-push: remove remaining uses of sha1_to_hexbrian m. carlson, Feb 19, 2019
  20. 23/35 http: compute hash of downloaded objects using the_hash_algobrian m. carlson, Feb 19, 2019
  21. 24/35 http: replace sha1_to_hexbrian m. carlson, Feb 19, 2019
  22. 25/35 remote-curl: make hash size independentbrian m. carlson, Feb 19, 2019
  23. 26/35 hash: add a function to lookup hash algorithm by lengthbrian m. carlson, Feb 19, 2019
  24. 30/35 refspec: make hash size independentbrian m. carlson, Feb 19, 2019
  25. 27/35 get-tar-commit-id: parse comment recordbrian m. carlson, Feb 19, 2019
  26. 29/35 archive: convert struct archiver_args to object_idbrian m. carlson, Feb 19, 2019
  27. 34/35 Git.pm: make hash size independentbrian m. carlson, Feb 19, 2019
  28. 33/35 read-cache: read data in a hash-independent waybrian m. carlson, Feb 19, 2019
  29. 31/35 builtin/difftool: use parse_oid_hexbrian m. carlson, Feb 19, 2019
  30. 35/35 gitweb: make hash size independentbrian m. carlson, Feb 19, 2019
  31. 32/35 dir: make untracked cache extension hash size independentbrian m. carlson, Feb 19, 2019
  32. 16/35 builtin/am: make hash size independentbrian m. carlson, Feb 19, 2019
  33. 28/35 builtin/get-tar-commit-id: make hash size independentbrian m. carlson, Feb 19, 2019
  34. 13/35 builtin/name-rev: make hash-size independentbrian m. carlson, Feb 19, 2019
  35. 04/35 pack-bitmap: convert struct stored_bitmap to object_idbrian m. carlson, Feb 19, 2019
  36. 10/35 notes: make hash size independentbrian m. carlson, Feb 19, 2019

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