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![René Scharfe](/assets/img/avatar_default.png)
We use the function git_deflate_init() -- which wraps the zlib function deflateInit() -- to initialize compression of ZIP file entries. This results in compressed data prefixed with a two-bytes long header and followed by a four-bytes trailer. ZIP file entries consist of ZIP headers and raw compressed data instead, so we remove the zlib wrapper before writing the result. We can ask zlib for the the raw compressed data without the unwanted parts in the first place by using deflateInit2() and specifying a negative number of bits to size the window. For that purpose, factor out the function do_git_deflate_init() and add git_deflate_init_raw(), which wraps it. Then use the latter in archive-zip.c and get rid of the code that stripped the zlib header and trailer. Also rename the helper function zlib_deflate() to zlib_deflate_raw() to reflect the change. Thus we avoid generating data that we throw away anyway, the code becomes shorter and some magic constants are removed. Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <gitster@pobox.com>
272 lines
6.1 KiB
C
272 lines
6.1 KiB
C
/*
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* zlib wrappers to make sure we don't silently miss errors
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* at init time.
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*/
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#include "cache.h"
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static const char *zerr_to_string(int status)
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{
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switch (status) {
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case Z_MEM_ERROR:
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return "out of memory";
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case Z_VERSION_ERROR:
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return "wrong version";
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case Z_NEED_DICT:
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return "needs dictionary";
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case Z_DATA_ERROR:
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return "data stream error";
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case Z_STREAM_ERROR:
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return "stream consistency error";
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default:
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return "unknown error";
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}
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}
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/*
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* avail_in and avail_out in zlib are counted in uInt, which typically
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* limits the size of the buffer we can use to 4GB when interacting
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* with zlib in a single call to inflate/deflate.
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*/
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/* #define ZLIB_BUF_MAX ((uInt)-1) */
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#define ZLIB_BUF_MAX ((uInt) 1024 * 1024 * 1024) /* 1GB */
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static inline uInt zlib_buf_cap(unsigned long len)
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{
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return (ZLIB_BUF_MAX < len) ? ZLIB_BUF_MAX : len;
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}
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static void zlib_pre_call(git_zstream *s)
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{
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s->z.next_in = s->next_in;
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s->z.next_out = s->next_out;
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s->z.total_in = s->total_in;
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s->z.total_out = s->total_out;
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s->z.avail_in = zlib_buf_cap(s->avail_in);
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s->z.avail_out = zlib_buf_cap(s->avail_out);
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}
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static void zlib_post_call(git_zstream *s)
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{
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unsigned long bytes_consumed;
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unsigned long bytes_produced;
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bytes_consumed = s->z.next_in - s->next_in;
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bytes_produced = s->z.next_out - s->next_out;
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if (s->z.total_out != s->total_out + bytes_produced)
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die("BUG: total_out mismatch");
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if (s->z.total_in != s->total_in + bytes_consumed)
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die("BUG: total_in mismatch");
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s->total_out = s->z.total_out;
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s->total_in = s->z.total_in;
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s->next_in = s->z.next_in;
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s->next_out = s->z.next_out;
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s->avail_in -= bytes_consumed;
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s->avail_out -= bytes_produced;
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}
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void git_inflate_init(git_zstream *strm)
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{
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int status;
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zlib_pre_call(strm);
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status = inflateInit(&strm->z);
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zlib_post_call(strm);
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if (status == Z_OK)
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return;
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die("inflateInit: %s (%s)", zerr_to_string(status),
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strm->z.msg ? strm->z.msg : "no message");
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}
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void git_inflate_init_gzip_only(git_zstream *strm)
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{
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/*
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* Use default 15 bits, +16 is to accept only gzip and to
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* yield Z_DATA_ERROR when fed zlib format.
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*/
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const int windowBits = 15 + 16;
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int status;
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zlib_pre_call(strm);
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status = inflateInit2(&strm->z, windowBits);
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zlib_post_call(strm);
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if (status == Z_OK)
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return;
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die("inflateInit2: %s (%s)", zerr_to_string(status),
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strm->z.msg ? strm->z.msg : "no message");
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}
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void git_inflate_end(git_zstream *strm)
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{
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int status;
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zlib_pre_call(strm);
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status = inflateEnd(&strm->z);
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zlib_post_call(strm);
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if (status == Z_OK)
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return;
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error("inflateEnd: %s (%s)", zerr_to_string(status),
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strm->z.msg ? strm->z.msg : "no message");
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}
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int git_inflate(git_zstream *strm, int flush)
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{
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int status;
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for (;;) {
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zlib_pre_call(strm);
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/* Never say Z_FINISH unless we are feeding everything */
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status = inflate(&strm->z,
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(strm->z.avail_in != strm->avail_in)
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? 0 : flush);
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if (status == Z_MEM_ERROR)
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die("inflate: out of memory");
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zlib_post_call(strm);
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/*
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* Let zlib work another round, while we can still
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* make progress.
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*/
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if ((strm->avail_out && !strm->z.avail_out) &&
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(status == Z_OK || status == Z_BUF_ERROR))
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continue;
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break;
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}
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switch (status) {
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/* Z_BUF_ERROR: normal, needs more space in the output buffer */
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case Z_BUF_ERROR:
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case Z_OK:
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case Z_STREAM_END:
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return status;
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default:
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break;
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}
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error("inflate: %s (%s)", zerr_to_string(status),
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strm->z.msg ? strm->z.msg : "no message");
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return status;
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}
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#if defined(NO_DEFLATE_BOUND) || ZLIB_VERNUM < 0x1200
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#define deflateBound(c,s) ((s) + (((s) + 7) >> 3) + (((s) + 63) >> 6) + 11)
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#endif
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unsigned long git_deflate_bound(git_zstream *strm, unsigned long size)
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{
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return deflateBound(&strm->z, size);
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}
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void git_deflate_init(git_zstream *strm, int level)
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{
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int status;
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zlib_pre_call(strm);
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status = deflateInit(&strm->z, level);
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zlib_post_call(strm);
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if (status == Z_OK)
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return;
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die("deflateInit: %s (%s)", zerr_to_string(status),
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strm->z.msg ? strm->z.msg : "no message");
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}
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static void do_git_deflate_init(git_zstream *strm, int level, int windowBits)
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{
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int status;
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zlib_pre_call(strm);
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status = deflateInit2(&strm->z, level,
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Z_DEFLATED, windowBits,
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8, Z_DEFAULT_STRATEGY);
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zlib_post_call(strm);
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if (status == Z_OK)
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return;
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die("deflateInit2: %s (%s)", zerr_to_string(status),
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strm->z.msg ? strm->z.msg : "no message");
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}
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void git_deflate_init_gzip(git_zstream *strm, int level)
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{
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/*
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* Use default 15 bits, +16 is to generate gzip header/trailer
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* instead of the zlib wrapper.
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*/
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return do_git_deflate_init(strm, level, 15 + 16);
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}
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void git_deflate_init_raw(git_zstream *strm, int level)
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{
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/*
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* Use default 15 bits, negate the value to get raw compressed
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* data without zlib header and trailer.
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*/
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return do_git_deflate_init(strm, level, -15);
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}
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int git_deflate_abort(git_zstream *strm)
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{
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int status;
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zlib_pre_call(strm);
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status = deflateEnd(&strm->z);
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zlib_post_call(strm);
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return status;
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}
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void git_deflate_end(git_zstream *strm)
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{
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int status = git_deflate_abort(strm);
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if (status == Z_OK)
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return;
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error("deflateEnd: %s (%s)", zerr_to_string(status),
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strm->z.msg ? strm->z.msg : "no message");
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}
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int git_deflate_end_gently(git_zstream *strm)
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{
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int status;
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zlib_pre_call(strm);
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status = deflateEnd(&strm->z);
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zlib_post_call(strm);
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return status;
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}
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int git_deflate(git_zstream *strm, int flush)
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{
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int status;
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for (;;) {
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zlib_pre_call(strm);
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/* Never say Z_FINISH unless we are feeding everything */
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status = deflate(&strm->z,
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(strm->z.avail_in != strm->avail_in)
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? 0 : flush);
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if (status == Z_MEM_ERROR)
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die("deflate: out of memory");
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zlib_post_call(strm);
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/*
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* Let zlib work another round, while we can still
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* make progress.
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*/
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if ((strm->avail_out && !strm->z.avail_out) &&
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(status == Z_OK || status == Z_BUF_ERROR))
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continue;
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break;
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}
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switch (status) {
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/* Z_BUF_ERROR: normal, needs more space in the output buffer */
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case Z_BUF_ERROR:
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case Z_OK:
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case Z_STREAM_END:
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return status;
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default:
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break;
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}
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error("deflate: %s (%s)", zerr_to_string(status),
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strm->z.msg ? strm->z.msg : "no message");
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return status;
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}
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