Merge branch 'master' into jc/cache-tree

[git.git] / read-cache.c

diff --git a/read-cache.c b/read-cache.c
index 50e094e..1f71d12 100644 (file)
--- a/read-cache.c
+++ b/read-cache.c
@@ -4,11 +4,26 @@
  * Copyright (C) Linus Torvalds, 2005
  */
 #include "cache.h"
+#include "cache-tree.h"
+
+/* Index extensions.
+ *
+ * The first letter should be 'A'..'Z' for extensions that are not
+ * necessary for a correct operation (i.e. optimization data).
+ * When new extensions are added that _needs_ to be understood in
+ * order to correctly interpret the index file, pick character that
+ * is outside the range, to cause the reader to abort.
+ */
+
+#define CACHE_EXT(s) ( (s[0]<<24)|(s[1]<<16)|(s[2]<<8)|(s[3]) )
+#define CACHE_EXT_TREE 0x54524545      /* "TREE" */
 
 struct cache_entry **active_cache = NULL;
 static time_t index_file_timestamp;
 unsigned int active_nr = 0, active_alloc = 0, active_cache_changed = 0;
 
+struct cache_tree *active_cache_tree = NULL;
+
 /*
  * This only updates the "non-critical" parts of the directory
  * cache, ie the parts that aren't tracked by GIT, and only used
@@ -496,12 +511,10 @@ int add_cache_entry(struct cache_entry *ce, int option)
        return 0;
 }
 
-static int verify_hdr(struct cache_header *hdr, unsigned long size, unsigned char *sha1)
+static int verify_hdr(struct cache_header *hdr, unsigned long size)
 {
        SHA_CTX c;
-       unsigned char sha1_buf[20];
-       if (!sha1)
-               sha1 = sha1_buf;
+       unsigned char sha1[20];
 
        if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
                return error("bad signature");
@@ -515,7 +528,23 @@ static int verify_hdr(struct cache_header *hdr, unsigned long size, unsigned cha
        return 0;
 }
 
-int read_cache_1(unsigned char *cache_sha1)
+static int read_index_extension(const char *ext, void *data, unsigned long sz)
+{
+       switch (CACHE_EXT(ext)) {
+       case CACHE_EXT_TREE:
+               active_cache_tree = cache_tree_read(data, sz);
+               break;
+       default:
+               if (*ext < 'A' || 'Z' < *ext)
+                       return error("index uses %.4s extension, which we do not understand",
+                                    ext);
+               fprintf(stderr, "ignoring %.4s extension\n", ext);
+               break;
+       }
+       return 0;
+}
+
+int read_cache(void)
 {
        int fd, i;
        struct stat st;
@@ -549,7 +578,7 @@ int read_cache_1(unsigned char *cache_sha1)
                die("index file mmap failed (%s)", strerror(errno));
 
        hdr = map;
-       if (verify_hdr(hdr, size, cache_sha1) < 0)
+       if (verify_hdr(hdr, size) < 0)
                goto unmap;
 
        active_nr = ntohl(hdr->hdr_entries);
@@ -563,6 +592,22 @@ int read_cache_1(unsigned char *cache_sha1)
                active_cache[i] = ce;
        }
        index_file_timestamp = st.st_mtime;
+       while (offset <= size - 20 - 8) {
+               /* After an array of active_nr index entries,
+                * there can be arbitrary number of extended
+                * sections, each of which is prefixed with
+                * extension name (4-byte) and section length
+                * in 4-byte network byte order.
+                */
+               unsigned long extsize;
+               memcpy(&extsize, map + offset + 4, 4);
+               extsize = ntohl(extsize);
+               if (read_index_extension(map + offset,
+                                        map + offset + 8, extsize) < 0)
+                       goto unmap;
+               offset += 8;
+               offset += extsize;
+       }
        return active_nr;
 
 unmap:
@@ -597,7 +642,18 @@ static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
        return 0;
 }
 
-static int ce_flush(SHA_CTX *context, int fd, unsigned char *sha1)
+static int write_index_ext_header(SHA_CTX *context, int fd,
+                                 unsigned long ext, unsigned long sz)
+{
+       ext = htonl(ext);
+       sz = htonl(sz);
+       if ((ce_write(context, fd, &ext, 4) < 0) ||
+           (ce_write(context, fd, &sz, 4) < 0))
+               return -1;
+       return 0;
+}
+
+static int ce_flush(SHA_CTX *context, int fd)
 {
        unsigned int left = write_buffer_len;
 
@@ -614,8 +670,7 @@ static int ce_flush(SHA_CTX *context, int fd, unsigned char *sha1)
        }
 
        /* Append the SHA1 signature at the end */
-       SHA1_Final(sha1, context);
-       memcpy(write_buffer + left, sha1, 20);
+       SHA1_Final(write_buffer + left, context);
        left += 20;
        if (write(fd, write_buffer, left) != left)
                return -1;
@@ -666,14 +721,11 @@ static void ce_smudge_racily_clean_entry(struct cache_entry *ce)
        }
 }
 
-int write_cache_1(int newfd, struct cache_entry **cache, int entries,
-                 unsigned char *cache_sha1)
+int write_cache(int newfd, struct cache_entry **cache, int entries)
 {
        SHA_CTX c;
        struct cache_header hdr;
        int i, removed;
-       int status;
-       unsigned char sha1[20];
 
        for (i = removed = 0; i < entries; i++)
                if (!cache[i]->ce_mode)
@@ -697,18 +749,19 @@ int write_cache_1(int newfd, struct cache_entry **cache, int entries,
                if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
                        return -1;
        }
-       status = ce_flush(&c, newfd, sha1);
-       if (cache_sha1)
-               memcpy(cache_sha1, sha1, 20);
-       return status;
-}
 
-int read_cache(void)
-{
-       return read_cache_1(NULL);
-}
-
-int write_cache(int newfd, struct cache_entry **cache, int entries)
-{
-       return write_cache_1(newfd, cache, entries, NULL);
+       /* Write extension data here */
+       if (active_cache_tree) {
+               unsigned long sz;
+               void *data = cache_tree_write(active_cache_tree, &sz);
+               if (data &&
+                   !write_index_ext_header(&c, newfd, CACHE_EXT_TREE, sz) &&
+                   !ce_write(&c, newfd, data, sz))
+                       ;
+               else {
+                       free(data);
+                       return -1;
+               }
+       }
+       return ce_flush(&c, newfd);
 }