dir: make untracked cache extension hash size independent

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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/dir.c b/dir.c
index b2cabadf2503b22cc10b3e47c548a5904d77158e..7503b56918e9ecf148c2721cd74a18c3dd7991ec 100644 (file)
--- 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;