Add "unpack_sha1_header()" helper function
It's for people who aren't necessarily interested in the whole unpacked file, but do want to know the header information (size, type, etc..) For example, the delta code can use this to figure out whether an object is already a delta object, and what it is a delta against, without actually bothering to unpack all of the actual data in the delta.
This commit is contained in:
27
sha1_file.c
27
sha1_file.c
@ -307,6 +307,19 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
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return map;
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}
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int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
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{
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/* Get the data stream */
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memset(stream, 0, sizeof(*stream));
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stream->next_in = map;
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stream->avail_in = mapsize;
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stream->next_out = buffer;
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stream->avail_out = size;
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inflateInit(stream);
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return inflate(stream, 0);
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}
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void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
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{
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int ret, bytes;
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@ -314,18 +327,8 @@ void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned l
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char buffer[8192];
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unsigned char *buf;
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/* Get the data stream */
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memset(&stream, 0, sizeof(stream));
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stream.next_in = map;
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stream.avail_in = mapsize;
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stream.next_out = (unsigned char *)buffer;
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stream.avail_out = sizeof(buffer);
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inflateInit(&stream);
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ret = inflate(&stream, 0);
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if (ret < Z_OK)
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return NULL;
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if (sscanf(buffer, "%10s %lu", type, size) != 2)
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ret = unpack_sha1_header(&stream, map, mapsize, buffer, sizeof(buffer));
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if (ret < Z_OK || sscanf(buffer, "%10s %lu", type, size) != 2)
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return NULL;
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bytes = strlen(buffer) + 1;
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