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authorNicolas Pitre <nico@cam.org>2005-06-29 02:49:56 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-29 09:11:38 -0700
commitdcde55bc58ae845307efbdce3a1071f75ccd758e (patch)
treefc76dbd773c225cef239a0774304335c8116f2bc
parente5e3e0f5001f51fe388d530481e56651729add1a (diff)
downloadgit-dcde55bc58ae845307efbdce3a1071f75ccd758e.tar.gz
This is a wrap-up patch including all the cleanups I've done to the
delta code and its usage.  The most important change is the
factorization of the delta header handling code.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--count-delta.c23
-rw-r--r--delta.h22
-rw-r--r--diff-delta.c3
-rw-r--r--pack-objects.c2
-rw-r--r--patch-delta.c22
-rw-r--r--sha1_file.c21
6 files changed, 35 insertions, 58 deletions
diff --git a/count-delta.c b/count-delta.c
index 8901034188..7559ff68b1 100644
--- a/count-delta.c
+++ b/count-delta.c
@@ -6,23 +6,9 @@
 #include <stdlib.h>
 #include <string.h>
 #include <limits.h>
+#include "delta.h"
 #include "count-delta.h"
 
-static unsigned long get_hdr_size(const unsigned char **datap)
-{
-        const unsigned char *data = *datap;
-        unsigned char cmd = *data++;
-        unsigned long size = cmd & ~0x80;
-        int i = 7;
-        while (cmd & 0x80) {
-                cmd = *data++;
-                size |= (cmd & ~0x80) << i;
-                i += 7;
-        }
-        *datap = data;
-        return size;
-}
-
 /*
  * NOTE.  We do not _interpret_ delta fully.  As an approximation, we
  * just count the number of bytes that are copied from the source, and
@@ -44,15 +30,14 @@ int count_delta(void *delta_buf, unsigned long delta_size,
         unsigned char cmd;
         unsigned long src_size, dst_size, out;
 
-        /* the smallest delta size possible is 4 bytes */
-        if (delta_size < 4)
+        if (delta_size < DELTA_SIZE_MIN)
                 return -1;
 
         data = delta_buf;
         top = delta_buf + delta_size;
 
-        src_size = get_hdr_size(&data);
-        dst_size = get_hdr_size(&data);
+        src_size = get_delta_hdr_size(&data);
+        dst_size = get_delta_hdr_size(&data);
 
         added_literal = copied_from_source = out = 0;
         while (data < top) {
diff --git a/delta.h b/delta.h
index bc3a220179..31d1820f80 100644
--- a/delta.h
+++ b/delta.h
@@ -9,4 +9,26 @@ extern void *patch_delta(void *src_buf, unsigned long src_size,
                          void *delta_buf, unsigned long delta_size,
                          unsigned long *dst_size);
 
+/* the smallest possible delta size is 4 bytes */
+#define DELTA_SIZE_MIN        4
+
+/*
+ * This must be called twice on the delta data buffer, first to get the
+ * expected reference buffer size, and again to get the result buffer size.
+ */
+static inline unsigned long get_delta_hdr_size(const unsigned char **datap)
+{
+        const unsigned char *data = *datap;
+        unsigned char cmd = *data++;
+        unsigned long size = cmd & ~0x80;
+        int i = 7;
+        while (cmd & 0x80) {
+                cmd = *data++;
+                size |= (cmd & ~0x80) << i;
+                i += 7;
+        }
+        *datap = data;
+        return size;
+}
+
 #endif
diff --git a/diff-delta.c b/diff-delta.c
index 67f60814b7..b2ae7b5e6c 100644
--- a/diff-delta.c
+++ b/diff-delta.c
@@ -306,12 +306,13 @@ void *diff_delta(void *from_buf, unsigned long from_size,
                         *orig = i;
                 }
 
-                /* next time around the largest possible output is 1 + 4 + 3 */
                 if (max_size && outpos > max_size) {
                         free(out);
                         delta_cleanup(&bdf);
                         return NULL;
                 }
+
+                /* next time around the largest possible output is 1 + 4 + 3 */
                 if (outpos > outsize - 8) {
                         void *tmp = out;
                         outsize = outsize * 3 / 2;
diff --git a/pack-objects.c b/pack-objects.c
index fc969e342a..d95f45ebfe 100644
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -34,7 +34,7 @@ static void *delta_against(void *buf, unsigned long size, struct object_entry *e
         if (!otherbuf)
                 die("unable to read %s", sha1_to_hex(entry->delta->sha1));
         delta_buf = diff_delta(otherbuf, othersize,
-                               buf, size, &delta_size, ~0UL);
+                               buf, size, &delta_size, 0);
         if (!delta_buf || delta_size != entry->delta_size)
                 die("delta size changed");
         free(buf);
diff --git a/patch-delta.c b/patch-delta.c
index b68dd13c63..26281ea123 100644
--- a/patch-delta.c
+++ b/patch-delta.c
@@ -20,36 +20,20 @@ void *patch_delta(void *src_buf, unsigned long src_size,
         const unsigned char *data, *top;
         unsigned char *dst_buf, *out, cmd;
         unsigned long size;
-        int i;
 
-        /* the smallest delta size possible is 4 bytes */
-        if (delta_size < 4)
+        if (delta_size < DELTA_SIZE_MIN)
                 return NULL;
 
         data = delta_buf;
         top = delta_buf + delta_size;
 
         /* make sure the orig file size matches what we expect */
-        cmd = *data++;
-        size = cmd & ~0x80;
-        i = 7;
-        while (cmd & 0x80) {
-                cmd = *data++;
-                size |= (cmd & ~0x80) << i;
-                i += 7;
-        }
+        size = get_delta_hdr_size(&data);
         if (size != src_size)
                 return NULL;
 
         /* now the result size */
-        cmd = *data++;
-        size = cmd & ~0x80;
-        i = 7;
-        while (cmd & 0x80) {
-                cmd = *data++;
-                size |= (cmd & ~0x80) << i;
-                i += 7;
-        }
+        size = get_delta_hdr_size(&data);
         dst_buf = malloc(size);
         if (!dst_buf)
                 return NULL;
diff --git a/sha1_file.c b/sha1_file.c
index f6cf180bd4..737ecb4800 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -592,22 +592,6 @@ void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned l
         return unpack_sha1_rest(&stream, hdr, *size);
 }
 
-static unsigned long parse_delta_size(unsigned char **p)
-{
-        unsigned char c;
-        unsigned long size = 0;
-        unsigned shift = 0;
-        unsigned char *data = *p;
-
-        do {
-                c = *data++;
-                size += (c & 0x7f) << shift;
-                shift += 7;
-        } while (c & 0x80);
-        *p = data;
-        return size;
-}
-
 static int packed_delta_info(unsigned char *base_sha1,
                              unsigned long delta_size,
                              unsigned long left,
@@ -645,11 +629,12 @@ static int packed_delta_info(unsigned char *base_sha1,
          * the result size.  Verify the base size while we are at it.
          */
         data = delta_head;
-        verify_base_size = parse_delta_size(&data);
-        result_size = parse_delta_size(&data);
+        verify_base_size = get_delta_hdr_size(&data);
         if (verify_base_size != base_size)
                 die("delta base size mismatch");
 
+        /* Read the result size */
+        result_size = get_delta_hdr_size(&data);
         *sizep = result_size;
         return 0;
 }