binary patch.
[git.git] / apply.c
diff --git a/apply.c b/apply.c
index 269210a..e37c4eb 100644 (file)
--- a/apply.c
+++ b/apply.c
@@ -10,6 +10,7 @@
 #include "cache.h"
 #include "quote.h"
 #include "blob.h"
+#include "delta.h"
 
 //  --check turns on checking that the working tree matches the
 //    files that are being modified, but doesn't apply the patch
@@ -966,6 +967,70 @@ static inline int metadata_changes(struct patch *patch)
                 patch->old_mode != patch->new_mode);
 }
 
+static int parse_binary(char *buffer, unsigned long size, struct patch *patch)
+{
+       /* We have read "GIT binary patch\n"; what follows is a
+        * sequence of 'length-byte' followed by base-85 encoded
+        * delta data.
+        *
+        * Each 5-byte sequence of base-85 encodes up to 4 bytes,
+        * and we would limit the patch line to 66 characters,
+        * so one line can fit up to 13 groups that would decode
+        * to 52 bytes max.  The length byte 'A'-'Z' corresponds
+        * to 1-26 bytes, and 'a'-'z' corresponds to 27-52 bytes.
+        * The end of binary is signalled with an empty line.
+        */
+       int llen, used;
+       struct fragment *fragment;
+       char *delta = NULL;
+
+       patch->is_binary = 1;
+       patch->fragments = fragment = xcalloc(1, sizeof(*fragment));
+       used = 0;
+       while (1) {
+               int byte_length, max_byte_length, newsize;
+               llen = linelen(buffer, size);
+               used += llen;
+               linenr++;
+               if (llen == 1)
+                       break;
+               /* Minimum line is "A00000\n" which is 7-byte long,
+                * and the line length must be multiple of 5 plus 2.
+                */
+               if ((llen < 7) || (llen-2) % 5)
+                       goto corrupt;
+               max_byte_length = (llen - 2) / 5 * 4;
+               byte_length = *buffer;
+               if ('A' <= byte_length && byte_length <= 'Z')
+                       byte_length = byte_length - 'A' + 1;
+               else if ('a' <= byte_length && byte_length <= 'z')
+                       byte_length = byte_length - 'a' + 27;
+               else
+                       goto corrupt;
+               /* if the input length was not multiple of 4, we would
+                * have filler at the end but the filler should never
+                * exceed 3 bytes
+                */
+               if (max_byte_length < byte_length ||
+                   byte_length <= max_byte_length - 4)
+                       goto corrupt;
+               newsize = fragment->size + byte_length;
+               delta = xrealloc(delta, newsize);
+               if (decode_85(delta + fragment->size,
+                             buffer + 1,
+                             byte_length))
+                       goto corrupt;
+               fragment->size = newsize;
+               buffer += llen;
+               size -= llen;
+       }
+       fragment->patch = delta;
+       return used;
+ corrupt:
+       return error("corrupt binary patch at line %d: %.*s",
+                    linenr-1, llen-1, buffer);
+}
+
 static int parse_chunk(char *buffer, unsigned long size, struct patch *patch)
 {
        int hdrsize, patchsize;
@@ -982,19 +1047,34 @@ static int parse_chunk(char *buffer, unsigned long size, struct patch *patch)
                        "Files ",
                        NULL,
                };
+               static const char git_binary[] = "GIT binary patch\n";
                int i;
                int hd = hdrsize + offset;
                unsigned long llen = linelen(buffer + hd, size - hd);
 
-               if (!memcmp(" differ\n", buffer + hd + llen - 8, 8))
+               if (llen == sizeof(git_binary) - 1 &&
+                   !memcmp(git_binary, buffer + hd, llen)) {
+                       int used;
+                       linenr++;
+                       used = parse_binary(buffer + hd + llen,
+                                           size - hd - llen, patch);
+                       if (used)
+                               patchsize = used + llen;
+                       else
+                               patchsize = 0;
+               }
+               else if (!memcmp(" differ\n", buffer + hd + llen - 8, 8)) {
                        for (i = 0; binhdr[i]; i++) {
                                int len = strlen(binhdr[i]);
                                if (len < size - hd &&
                                    !memcmp(binhdr[i], buffer + hd, len)) {
+                                       linenr++;
                                        patch->is_binary = 1;
+                                       patchsize = llen;
                                        break;
                                }
                        }
+               }
 
                /* Empty patch cannot be applied if:
                 * - it is a binary patch and we do not do binary_replace, or
@@ -1345,76 +1425,108 @@ static int apply_one_fragment(struct buffer_desc *desc, struct fragment *frag)
        return offset;
 }
 
-static int apply_fragments(struct buffer_desc *desc, struct patch *patch)
+static int apply_binary(struct buffer_desc *desc, struct patch *patch)
 {
-       struct fragment *frag = patch->fragments;
        const char *name = patch->old_name ? patch->old_name : patch->new_name;
+       unsigned char sha1[20];
+       unsigned char hdr[50];
+       int hdrlen;
 
-       if (patch->is_binary) {
-               unsigned char sha1[20];
+       if (!allow_binary_replacement)
+               return error("cannot apply binary patch to '%s' "
+                            "without --allow-binary-replacement",
+                            name);
 
-               if (!allow_binary_replacement)
-                       return error("cannot apply binary patch to '%s' "
-                                    "without --allow-binary-replacement",
-                                    name);
+       /* For safety, we require patch index line to contain
+        * full 40-byte textual SHA1 for old and new, at least for now.
+        */
+       if (strlen(patch->old_sha1_prefix) != 40 ||
+           strlen(patch->new_sha1_prefix) != 40 ||
+           get_sha1_hex(patch->old_sha1_prefix, sha1) ||
+           get_sha1_hex(patch->new_sha1_prefix, sha1))
+               return error("cannot apply binary patch to '%s' "
+                            "without full index line", name);
 
-               /* For safety, we require patch index line to contain
-                * full 40-byte textual SHA1 for old and new, at least for now.
+       if (patch->old_name) {
+               /* See if the old one matches what the patch
+                * applies to.
                 */
-               if (strlen(patch->old_sha1_prefix) != 40 ||
-                   strlen(patch->new_sha1_prefix) != 40 ||
-                   get_sha1_hex(patch->old_sha1_prefix, sha1) ||
-                   get_sha1_hex(patch->new_sha1_prefix, sha1))
-                       return error("cannot apply binary patch to '%s' "
-                                    "without full index line", name);
-
-               if (patch->old_name) {
-                       unsigned char hdr[50];
-                       int hdrlen;
-
-                       /* See if the old one matches what the patch
-                        * applies to.
-                        */
-                       write_sha1_file_prepare(desc->buffer, desc->size,
-                                               blob_type, sha1, hdr, &hdrlen);
-                       if (strcmp(sha1_to_hex(sha1), patch->old_sha1_prefix))
-                               return error("the patch applies to '%s' (%s), "
-                                            "which does not match the "
-                                            "current contents.",
-                                            name, sha1_to_hex(sha1));
-               }
-               else {
-                       /* Otherwise, the old one must be empty. */
-                       if (desc->size)
-                               return error("the patch applies to an empty "
-                                            "'%s' but it is not empty", name);
-               }
+               write_sha1_file_prepare(desc->buffer, desc->size,
+                                       blob_type, sha1, hdr, &hdrlen);
+               if (strcmp(sha1_to_hex(sha1), patch->old_sha1_prefix))
+                       return error("the patch applies to '%s' (%s), "
+                                    "which does not match the "
+                                    "current contents.",
+                                    name, sha1_to_hex(sha1));
+       }
+       else {
+               /* Otherwise, the old one must be empty. */
+               if (desc->size)
+                       return error("the patch applies to an empty "
+                                    "'%s' but it is not empty", name);
+       }
+
+       if (desc->buffer) {
+               free(desc->buffer);
+               desc->alloc = desc->size = 0;
+       }
+       get_sha1_hex(patch->new_sha1_prefix, sha1);
+       if (!memcmp(sha1, null_sha1, 20))
+               return 0; /* deletion patch */
+
+       if (has_sha1_file(sha1)) {
+               char type[10];
+               unsigned long size;
 
-               /* For now, we do not record post-image data in the patch,
-                * and require the object already present in the recipient's
-                * object database.
+               desc->buffer = read_sha1_file(sha1, type, &size);
+               if (!desc->buffer)
+                       return error("the necessary postimage %s for "
+                                    "'%s' cannot be read",
+                                    patch->new_sha1_prefix, name);
+               desc->alloc = desc->size = size;
+       }
+       else {
+               char type[10];
+               unsigned long src_size, dst_size;
+               void *src;
+
+               get_sha1_hex(patch->old_sha1_prefix, sha1);
+               src = read_sha1_file(sha1, type, &src_size);
+               if (!src)
+                       return error("the necessary preimage %s for "
+                                    "'%s' cannot be read",
+                                    patch->old_sha1_prefix, name);
+
+               /* patch->fragment->patch has the delta data and
+                * we should apply it to the preimage.
                 */
-               if (desc->buffer) {
-                       free(desc->buffer);
-                       desc->alloc = desc->size = 0;
-               }
-               get_sha1_hex(patch->new_sha1_prefix, sha1);
-
-               if (memcmp(sha1, null_sha1, 20)) {
-                       char type[10];
-                       unsigned long size;
-
-                       desc->buffer = read_sha1_file(sha1, type, &size);
-                       if (!desc->buffer)
-                               return error("the necessary postimage %s for "
-                                            "'%s' does not exist",
-                                            patch->new_sha1_prefix, name);
-                       desc->alloc = desc->size = size;
-               }
+               desc->buffer = patch_delta(src, src_size,
+                                          (void*) patch->fragments->patch,
+                                          patch->fragments->size,
+                                          &dst_size);
+               if (!desc->buffer)
+                       return error("binary patch does not apply to '%s'",
+                                    name);
+               desc->size = desc->alloc = dst_size;
 
-               return 0;
+               /* verify that the result matches */
+               write_sha1_file_prepare(desc->buffer, desc->size, blob_type,
+                                       sha1, hdr, &hdrlen);
+               if (strcmp(sha1_to_hex(sha1), patch->new_sha1_prefix))
+                       return error("binary patch to '%s' creates incorrect result", name);
        }
 
+       return 0;
+}
+
+static int apply_fragments(struct buffer_desc *desc, struct patch *patch)
+{
+       struct fragment *frag = patch->fragments;
+       const char *name = patch->old_name ? patch->old_name : patch->new_name;
+
+       if (patch->is_binary)
+               return apply_binary(desc, patch);
+
        while (frag) {
                if (apply_one_fragment(desc, frag) < 0)
                        return error("patch failed: %s:%ld",