mirror of
https://git.proxmox.com/git/libgit2
synced 2025-05-28 00:25:29 +00:00
delta: move delta application to delta.c
Move the delta application functions into `delta.c`, next to the similar delta creation functions. Make the `git__delta_apply` functions adhere to other naming and parameter style within the library.
This commit is contained in:
Edward Thomson
Edward Thomson
parent
0004386f29
commit
6a2d2f8aa1
@ -1,166 +0,0 @@
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/*
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* Copyright (C) the libgit2 contributors. All rights reserved.
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*
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* This file is part of libgit2, distributed under the GNU GPL v2 with
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* a Linking Exception. For full terms see the included COPYING file.
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*/
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#include "common.h"
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#include "git2/odb.h"
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#include "delta-apply.h"
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/*
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* This file was heavily cribbed from BinaryDelta.java in JGit, which
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* itself was heavily cribbed from <code>patch-delta.c</code> in the
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* GIT project. The original delta patching code was written by
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* Nicolas Pitre <nico@cam.org>.
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*/
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static int hdr_sz(
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size_t *size,
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const unsigned char **delta,
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const unsigned char *end)
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{
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const unsigned char *d = *delta;
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size_t r = 0;
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unsigned int c, shift = 0;
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do {
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if (d == end)
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return -1;
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c = *d++;
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r |= (c & 0x7f) << shift;
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shift += 7;
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} while (c & 0x80);
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*delta = d;
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*size = r;
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return 0;
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}
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int git__delta_read_header(
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const unsigned char *delta,
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size_t delta_len,
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size_t *base_sz,
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size_t *res_sz)
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{
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const unsigned char *delta_end = delta + delta_len;
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if ((hdr_sz(base_sz, &delta, delta_end) < 0) ||
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(hdr_sz(res_sz, &delta, delta_end) < 0))
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return -1;
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return 0;
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}
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#define DELTA_HEADER_BUFFER_LEN 16
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int git__delta_read_header_fromstream(size_t *base_sz, size_t *res_sz, git_packfile_stream *stream)
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{
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static const size_t buffer_len = DELTA_HEADER_BUFFER_LEN;
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unsigned char buffer[DELTA_HEADER_BUFFER_LEN];
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const unsigned char *delta, *delta_end;
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size_t len;
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ssize_t read;
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len = read = 0;
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while (len < buffer_len) {
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read = git_packfile_stream_read(stream, &buffer[len], buffer_len - len);
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if (read == 0)
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break;
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if (read == GIT_EBUFS)
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continue;
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len += read;
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}
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delta = buffer;
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delta_end = delta + len;
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if ((hdr_sz(base_sz, &delta, delta_end) < 0) ||
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(hdr_sz(res_sz, &delta, delta_end) < 0))
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return -1;
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return 0;
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}
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int git__delta_apply(
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git_rawobj *out,
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const unsigned char *base,
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size_t base_len,
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const unsigned char *delta,
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size_t delta_len)
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{
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const unsigned char *delta_end = delta + delta_len;
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size_t base_sz, res_sz, alloc_sz;
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unsigned char *res_dp;
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/* Check that the base size matches the data we were given;
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* if not we would underflow while accessing data from the
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* base object, resulting in data corruption or segfault.
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*/
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if ((hdr_sz(&base_sz, &delta, delta_end) < 0) || (base_sz != base_len)) {
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giterr_set(GITERR_INVALID, "Failed to apply delta. Base size does not match given data");
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return -1;
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}
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if (hdr_sz(&res_sz, &delta, delta_end) < 0) {
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giterr_set(GITERR_INVALID, "Failed to apply delta. Base size does not match given data");
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return -1;
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}
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GITERR_CHECK_ALLOC_ADD(&alloc_sz, res_sz, 1);
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res_dp = git__malloc(alloc_sz);
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GITERR_CHECK_ALLOC(res_dp);
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res_dp[res_sz] = '\0';
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out->data = res_dp;
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out->len = res_sz;
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while (delta < delta_end) {
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unsigned char cmd = *delta++;
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if (cmd & 0x80) {
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/* cmd is a copy instruction; copy from the base.
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*/
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size_t off = 0, len = 0;
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if (cmd & 0x01) off = *delta++;
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if (cmd & 0x02) off |= *delta++ << 8UL;
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if (cmd & 0x04) off |= *delta++ << 16UL;
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if (cmd & 0x08) off |= *delta++ << 24UL;
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if (cmd & 0x10) len = *delta++;
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if (cmd & 0x20) len |= *delta++ << 8UL;
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if (cmd & 0x40) len |= *delta++ << 16UL;
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if (!len) len = 0x10000;
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if (base_len < off + len || res_sz < len)
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goto fail;
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memcpy(res_dp, base + off, len);
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res_dp += len;
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res_sz -= len;
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} else if (cmd) {
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/* cmd is a literal insert instruction; copy from
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* the delta stream itself.
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*/
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if (delta_end - delta < cmd || res_sz < cmd)
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goto fail;
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memcpy(res_dp, delta, cmd);
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delta += cmd;
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res_dp += cmd;
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res_sz -= cmd;
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} else {
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/* cmd == 0 is reserved for future encodings.
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*/
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goto fail;
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}
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}
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if (delta != delta_end || res_sz)
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goto fail;
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return 0;
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fail:
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git__free(out->data);
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out->data = NULL;
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giterr_set(GITERR_INVALID, "Failed to apply delta");
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return -1;
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}
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@ -1,62 +0,0 @@
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/*
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* Copyright (C) the libgit2 contributors. All rights reserved.
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*
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* This file is part of libgit2, distributed under the GNU GPL v2 with
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* a Linking Exception. For full terms see the included COPYING file.
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*/
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#ifndef INCLUDE_delta_apply_h__
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#define INCLUDE_delta_apply_h__
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#include "odb.h"
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#include "pack.h"
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/**
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* Apply a git binary delta to recover the original content.
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*
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* @param out the output buffer to receive the original data.
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* Only out->data and out->len are populated, as this is
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* the only information available in the delta.
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* @param base the base to copy from during copy instructions.
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* @param base_len number of bytes available at base.
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* @param delta the delta to execute copy/insert instructions from.
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* @param delta_len total number of bytes in the delta.
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* @return
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* - 0 on a successful delta unpack.
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* - GIT_ERROR if the delta is corrupt or doesn't match the base.
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*/
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extern int git__delta_apply(
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git_rawobj *out,
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const unsigned char *base,
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size_t base_len,
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const unsigned char *delta,
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size_t delta_len);
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/**
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* Read the header of a git binary delta.
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*
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* @param delta the delta to execute copy/insert instructions from.
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* @param delta_len total number of bytes in the delta.
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* @param base_sz pointer to store the base size field.
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* @param res_sz pointer to store the result size field.
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* @return
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* - 0 on a successful decoding the header.
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* - GIT_ERROR if the delta is corrupt.
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*/
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extern int git__delta_read_header(
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const unsigned char *delta,
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size_t delta_len,
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size_t *base_sz,
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size_t *res_sz);
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/**
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* Read the header of a git binary delta
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*
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* This variant reads just enough from the packfile stream to read the
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* delta header.
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*/
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extern int git__delta_read_header_fromstream(
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size_t *base_sz,
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size_t *res_sz,
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git_packfile_stream *stream);
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#endif
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167
src/delta.c
167
src/delta.c
@ -441,3 +441,170 @@ git_delta_create(
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*delta_size = outpos;
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return out;
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}
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/*
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* Delta application was heavily cribbed from BinaryDelta.java in JGit, which
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* itself was heavily cribbed from <code>patch-delta.c</code> in the
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* GIT project. The original delta patching code was written by
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* Nicolas Pitre <nico@cam.org>.
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*/
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static int hdr_sz(
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size_t *size,
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const unsigned char **delta,
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const unsigned char *end)
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{
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const unsigned char *d = *delta;
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size_t r = 0;
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unsigned int c, shift = 0;
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do {
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if (d == end)
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return -1;
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c = *d++;
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r |= (c & 0x7f) << shift;
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shift += 7;
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} while (c & 0x80);
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*delta = d;
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*size = r;
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return 0;
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}
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int git_delta_read_header(
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size_t *base_out,
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size_t *result_out,
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const unsigned char *delta,
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size_t delta_len)
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{
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const unsigned char *delta_end = delta + delta_len;
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if ((hdr_sz(base_out, &delta, delta_end) < 0) ||
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(hdr_sz(result_out, &delta, delta_end) < 0))
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return -1;
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return 0;
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}
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#define DELTA_HEADER_BUFFER_LEN 16
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int git_delta_read_header_fromstream(
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size_t *base_sz, size_t *res_sz, git_packfile_stream *stream)
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{
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static const size_t buffer_len = DELTA_HEADER_BUFFER_LEN;
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unsigned char buffer[DELTA_HEADER_BUFFER_LEN];
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const unsigned char *delta, *delta_end;
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size_t len;
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ssize_t read;
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len = read = 0;
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while (len < buffer_len) {
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read = git_packfile_stream_read(stream, &buffer[len], buffer_len - len);
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if (read == 0)
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break;
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if (read == GIT_EBUFS)
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continue;
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len += read;
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}
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delta = buffer;
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delta_end = delta + len;
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if ((hdr_sz(base_sz, &delta, delta_end) < 0) ||
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(hdr_sz(res_sz, &delta, delta_end) < 0))
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return -1;
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return 0;
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}
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int git_delta_apply(
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void **out,
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size_t *out_len,
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const unsigned char *base,
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size_t base_len,
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const unsigned char *delta,
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size_t delta_len)
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{
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const unsigned char *delta_end = delta + delta_len;
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size_t base_sz, res_sz, alloc_sz;
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unsigned char *res_dp;
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*out = NULL;
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*out_len = 0;
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/* Check that the base size matches the data we were given;
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* if not we would underflow while accessing data from the
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* base object, resulting in data corruption or segfault.
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*/
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if ((hdr_sz(&base_sz, &delta, delta_end) < 0) || (base_sz != base_len)) {
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giterr_set(GITERR_INVALID, "Failed to apply delta. Base size does not match given data");
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return -1;
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}
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if (hdr_sz(&res_sz, &delta, delta_end) < 0) {
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giterr_set(GITERR_INVALID, "Failed to apply delta. Base size does not match given data");
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return -1;
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}
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GITERR_CHECK_ALLOC_ADD(&alloc_sz, res_sz, 1);
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res_dp = git__malloc(alloc_sz);
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GITERR_CHECK_ALLOC(res_dp);
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res_dp[res_sz] = '\0';
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*out = res_dp;
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*out_len = res_sz;
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while (delta < delta_end) {
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unsigned char cmd = *delta++;
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if (cmd & 0x80) {
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/* cmd is a copy instruction; copy from the base.
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*/
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size_t off = 0, len = 0;
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if (cmd & 0x01) off = *delta++;
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if (cmd & 0x02) off |= *delta++ << 8UL;
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if (cmd & 0x04) off |= *delta++ << 16UL;
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if (cmd & 0x08) off |= *delta++ << 24UL;
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if (cmd & 0x10) len = *delta++;
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if (cmd & 0x20) len |= *delta++ << 8UL;
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if (cmd & 0x40) len |= *delta++ << 16UL;
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if (!len) len = 0x10000;
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if (base_len < off + len || res_sz < len)
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goto fail;
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memcpy(res_dp, base + off, len);
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res_dp += len;
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res_sz -= len;
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}
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else if (cmd) {
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/* cmd is a literal insert instruction; copy from
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* the delta stream itself.
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*/
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if (delta_end - delta < cmd || res_sz < cmd)
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goto fail;
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memcpy(res_dp, delta, cmd);
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delta += cmd;
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res_dp += cmd;
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res_sz -= cmd;
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}
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else {
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/* cmd == 0 is reserved for future encodings.
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*/
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goto fail;
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}
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}
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if (delta != delta_end || res_sz)
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goto fail;
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return 0;
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fail:
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git__free(*out);
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*out = NULL;
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*out_len = 0;
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giterr_set(GITERR_INVALID, "Failed to apply delta");
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return -1;
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}
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51
src/delta.h
51
src/delta.h
@ -6,6 +6,7 @@
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#define INCLUDE_git_delta_h__
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#include "common.h"
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#include "pack.h"
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/* opaque object for delta index */
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struct git_delta_index;
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@ -19,8 +20,8 @@ struct git_delta_index;
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* before free_delta_index() is called. The returned pointer must be freed
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* using free_delta_index().
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*/
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extern struct git_delta_index *
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git_delta_create_index(const void *buf, unsigned long bufsize);
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extern struct git_delta_index *git_delta_create_index(
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const void *buf, unsigned long bufsize);
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/*
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* free_delta_index: free the index created by create_delta_index()
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@ -111,4 +112,50 @@ GIT_INLINE(unsigned long) git_delta_get_hdr_size(
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return size;
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}
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/**
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* Apply a git binary delta to recover the original content.
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* The caller is responsible for freeing the returned buffer.
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*
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* @param out the output buffer
|
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* @param out_len the length of the output buffer
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* @param base the base to copy from during copy instructions.
|
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* @param base_len number of bytes available at base.
|
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* @param delta the delta to execute copy/insert instructions from.
|
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* @param delta_len total number of bytes in the delta.
|
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* @return 0 on success or an error code
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*/
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extern int git_delta_apply(
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void **out,
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size_t *out_len,
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const unsigned char *base,
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size_t base_len,
|
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const unsigned char *delta,
|
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size_t delta_len);
|
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|
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/**
|
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* Read the header of a git binary delta.
|
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*
|
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* @param base_out pointer to store the base size field.
|
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* @param result_out pointer to store the result size field.
|
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* @param delta the delta to execute copy/insert instructions from.
|
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* @param delta_len total number of bytes in the delta.
|
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* @return 0 on success or an error code
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*/
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extern int git_delta_read_header(
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size_t *base_out,
|
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size_t *result_out,
|
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const unsigned char *delta,
|
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size_t delta_len);
|
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|
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/**
|
||||
* Read the header of a git binary delta
|
||||
*
|
||||
* This variant reads just enough from the packfile stream to read the
|
||||
* delta header.
|
||||
*/
|
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extern int git_delta_read_header_fromstream(
|
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size_t *base_out,
|
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size_t *result_out,
|
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git_packfile_stream *stream);
|
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|
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#endif
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@ -12,7 +12,7 @@
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#include "fileops.h"
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#include "hash.h"
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#include "odb.h"
|
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#include "delta-apply.h"
|
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#include "delta.h"
|
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#include "filter.h"
|
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#include "repository.h"
|
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|
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|
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@ -12,7 +12,7 @@
|
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#include "fileops.h"
|
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#include "hash.h"
|
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#include "odb.h"
|
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#include "delta-apply.h"
|
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#include "delta.h"
|
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#include "filebuf.h"
|
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|
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#include "git2/odb_backend.h"
|
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|
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@ -13,7 +13,7 @@
|
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#include "fileops.h"
|
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#include "hash.h"
|
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#include "odb.h"
|
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#include "delta-apply.h"
|
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#include "delta.h"
|
||||
#include "sha1_lookup.h"
|
||||
#include "mwindow.h"
|
||||
#include "pack.h"
|
||||
|
||||
@ -8,7 +8,7 @@
|
||||
#include "common.h"
|
||||
#include "odb.h"
|
||||
#include "pack.h"
|
||||
#include "delta-apply.h"
|
||||
#include "delta.h"
|
||||
#include "sha1_lookup.h"
|
||||
#include "mwindow.h"
|
||||
#include "fileops.h"
|
||||
@ -505,7 +505,7 @@ int git_packfile_resolve_header(
|
||||
git_mwindow_close(&w_curs);
|
||||
if ((error = git_packfile_stream_open(&stream, p, curpos)) < 0)
|
||||
return error;
|
||||
error = git__delta_read_header_fromstream(&base_size, size_p, &stream);
|
||||
error = git_delta_read_header_fromstream(&base_size, size_p, &stream);
|
||||
git_packfile_stream_free(&stream);
|
||||
if (error < 0)
|
||||
return error;
|
||||
@ -730,8 +730,9 @@ int git_packfile_unpack(
|
||||
obj->len = 0;
|
||||
obj->type = GIT_OBJ_BAD;
|
||||
|
||||
error = git__delta_apply(obj, base.data, base.len, delta.data, delta.len);
|
||||
error = git_delta_apply(&obj->data, &obj->len, base.data, base.len, delta.data, delta.len);
|
||||
obj->type = base_type;
|
||||
|
||||
/*
|
||||
* We usually don't want to free the base at this
|
||||
* point, as we put it into the cache in the previous
|
||||
|
||||
Loading…
Reference in New Issue
Block a user