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Diffstat (limited to 'zlib/examples/gzappend.c')
| -rw-r--r-- | zlib/examples/gzappend.c | 504 |
1 files changed, 0 insertions, 504 deletions
diff --git a/zlib/examples/gzappend.c b/zlib/examples/gzappend.c deleted file mode 100644 index 662dec3..0000000 --- a/zlib/examples/gzappend.c +++ /dev/null @@ -1,504 +0,0 @@ -/* gzappend -- command to append to a gzip file - - Copyright (C) 2003, 2012 Mark Adler, all rights reserved - version 1.2, 11 Oct 2012 - - This software is provided 'as-is', without any express or implied - warranty. In no event will the author be held liable for any damages - arising from the use of this software. - - Permission is granted to anyone to use this software for any purpose, - including commercial applications, and to alter it and redistribute it - freely, subject to the following restrictions: - - 1. The origin of this software must not be misrepresented; you must not - claim that you wrote the original software. If you use this software - in a product, an acknowledgment in the product documentation would be - appreciated but is not required. - 2. Altered source versions must be plainly marked as such, and must not be - misrepresented as being the original software. - 3. This notice may not be removed or altered from any source distribution. - - Mark Adler madler@alumni.caltech.edu - */ - -/* - * Change history: - * - * 1.0 19 Oct 2003 - First version - * 1.1 4 Nov 2003 - Expand and clarify some comments and notes - * - Add version and copyright to help - * - Send help to stdout instead of stderr - * - Add some preemptive typecasts - * - Add L to constants in lseek() calls - * - Remove some debugging information in error messages - * - Use new data_type definition for zlib 1.2.1 - * - Simplfy and unify file operations - * - Finish off gzip file in gztack() - * - Use deflatePrime() instead of adding empty blocks - * - Keep gzip file clean on appended file read errors - * - Use in-place rotate instead of auxiliary buffer - * (Why you ask? Because it was fun to write!) - * 1.2 11 Oct 2012 - Fix for proper z_const usage - * - Check for input buffer malloc failure - */ - -/* - gzappend takes a gzip file and appends to it, compressing files from the - command line or data from stdin. The gzip file is written to directly, to - avoid copying that file, in case it's large. Note that this results in the - unfriendly behavior that if gzappend fails, the gzip file is corrupted. - - This program was written to illustrate the use of the new Z_BLOCK option of - zlib 1.2.x's inflate() function. This option returns from inflate() at each - block boundary to facilitate locating and modifying the last block bit at - the start of the final deflate block. Also whether using Z_BLOCK or not, - another required feature of zlib 1.2.x is that inflate() now provides the - number of unusued bits in the last input byte used. gzappend will not work - with versions of zlib earlier than 1.2.1. - - gzappend first decompresses the gzip file internally, discarding all but - the last 32K of uncompressed data, and noting the location of the last block - bit and the number of unused bits in the last byte of the compressed data. - The gzip trailer containing the CRC-32 and length of the uncompressed data - is verified. This trailer will be later overwritten. - - Then the last block bit is cleared by seeking back in the file and rewriting - the byte that contains it. Seeking forward, the last byte of the compressed - data is saved along with the number of unused bits to initialize deflate. - - A deflate process is initialized, using the last 32K of the uncompressed - data from the gzip file to initialize the dictionary. If the total - uncompressed data was less than 32K, then all of it is used to initialize - the dictionary. The deflate output bit buffer is also initialized with the - last bits from the original deflate stream. From here on, the data to - append is simply compressed using deflate, and written to the gzip file. - When that is complete, the new CRC-32 and uncompressed length are written - as the trailer of the gzip file. - */ - -#include <stdio.h> -#include <stdlib.h> -#include <string.h> -#include <fcntl.h> -#include <unistd.h> -#include "zlib.h" - -#define local static -#define LGCHUNK 14 -#define CHUNK (1U << LGCHUNK) -#define DSIZE 32768U - -/* print an error message and terminate with extreme prejudice */ -local void bye(char *msg1, char *msg2) -{ - fprintf(stderr, "gzappend error: %s%s\n", msg1, msg2); - exit(1); -} - -/* return the greatest common divisor of a and b using Euclid's algorithm, - modified to be fast when one argument much greater than the other, and - coded to avoid unnecessary swapping */ -local unsigned gcd(unsigned a, unsigned b) -{ - unsigned c; - - while (a && b) - if (a > b) { - c = b; - while (a - c >= c) - c <<= 1; - a -= c; - } - else { - c = a; - while (b - c >= c) - c <<= 1; - b -= c; - } - return a + b; -} - -/* rotate list[0..len-1] left by rot positions, in place */ -local void rotate(unsigned char *list, unsigned len, unsigned rot) -{ - unsigned char tmp; - unsigned cycles; - unsigned char *start, *last, *to, *from; - - /* normalize rot and handle degenerate cases */ - if (len < 2) return; - if (rot >= len) rot %= len; - if (rot == 0) return; - - /* pointer to last entry in list */ - last = list + (len - 1); - - /* do simple left shift by one */ - if (rot == 1) { - tmp = *list; - memcpy(list, list + 1, len - 1); - *last = tmp; - return; - } - - /* do simple right shift by one */ - if (rot == len - 1) { - tmp = *last; - memmove(list + 1, list, len - 1); - *list = tmp; - return; - } - - /* otherwise do rotate as a set of cycles in place */ - cycles = gcd(len, rot); /* number of cycles */ - do { - start = from = list + cycles; /* start index is arbitrary */ - tmp = *from; /* save entry to be overwritten */ - for (;;) { - to = from; /* next step in cycle */ - from += rot; /* go right rot positions */ - if (from > last) from -= len; /* (pointer better not wrap) */ - if (from == start) break; /* all but one shifted */ - *to = *from; /* shift left */ - } - *to = tmp; /* complete the circle */ - } while (--cycles); -} - -/* structure for gzip file read operations */ -typedef struct { - int fd; /* file descriptor */ - int size; /* 1 << size is bytes in buf */ - unsigned left; /* bytes available at next */ - unsigned char *buf; /* buffer */ - z_const unsigned char *next; /* next byte in buffer */ - char *name; /* file name for error messages */ -} file; - -/* reload buffer */ -local int readin(file *in) -{ - int len; - - len = read(in->fd, in->buf, 1 << in->size); - if (len == -1) bye("error reading ", in->name); - in->left = (unsigned)len; - in->next = in->buf; - return len; -} - -/* read from file in, exit if end-of-file */ -local int readmore(file *in) -{ - if (readin(in) == 0) bye("unexpected end of ", in->name); - return 0; -} - -#define read1(in) (in->left == 0 ? readmore(in) : 0, \ - in->left--, *(in->next)++) - -/* skip over n bytes of in */ -local void skip(file *in, unsigned n) -{ - unsigned bypass; - - if (n > in->left) { - n -= in->left; - bypass = n & ~((1U << in->size) - 1); - if (bypass) { - if (lseek(in->fd, (off_t)bypass, SEEK_CUR) == -1) - bye("seeking ", in->name); - n -= bypass; - } - readmore(in); - if (n > in->left) - bye("unexpected end of ", in->name); - } - in->left -= n; - in->next += n; -} - -/* read a four-byte unsigned integer, little-endian, from in */ -unsigned long read4(file *in) -{ - unsigned long val; - - val = read1(in); - val += (unsigned)read1(in) << 8; - val += (unsigned long)read1(in) << 16; - val += (unsigned long)read1(in) << 24; - return val; -} - -/* skip over gzip header */ -local void gzheader(file *in) -{ - int flags; - unsigned n; - - if (read1(in) != 31 || read1(in) != 139) bye(in->name, " not a gzip file"); - if (read1(in) != 8) bye("unknown compression method in", in->name); - flags = read1(in); - if (flags & 0xe0) bye("unknown header flags set in", in->name); - skip(in, 6); - if (flags & 4) { - n = read1(in); - n += (unsigned)(read1(in)) << 8; - skip(in, n); - } - if (flags & 8) while (read1(in) != 0) ; - if (flags & 16) while (read1(in) != 0) ; - if (flags & 2) skip(in, 2); -} - -/* decompress gzip file "name", return strm with a deflate stream ready to - continue compression of the data in the gzip file, and return a file - descriptor pointing to where to write the compressed data -- the deflate - stream is initialized to compress using level "level" */ -local int gzscan(char *name, z_stream *strm, int level) -{ - int ret, lastbit, left, full; - unsigned have; - unsigned long crc, tot; - unsigned char *window; - off_t lastoff, end; - file gz; - - /* open gzip file */ - gz.name = name; - gz.fd = open(name, O_RDWR, 0); - if (gz.fd == -1) bye("cannot open ", name); - gz.buf = malloc(CHUNK); - if (gz.buf == NULL) bye("out of memory", ""); - gz.size = LGCHUNK; - gz.left = 0; - - /* skip gzip header */ - gzheader(&gz); - - /* prepare to decompress */ - window = malloc(DSIZE); - if (window == NULL) bye("out of memory", ""); - strm->zalloc = Z_NULL; - strm->zfree = Z_NULL; - strm->opaque = Z_NULL; - ret = inflateInit2(strm, -15); - if (ret != Z_OK) bye("out of memory", " or library mismatch"); - - /* decompress the deflate stream, saving append information */ - lastbit = 0; - lastoff = lseek(gz.fd, 0L, SEEK_CUR) - gz.left; - left = 0; - strm->avail_in = gz.left; - strm->next_in = gz.next; - crc = crc32(0L, Z_NULL, 0); - have = full = 0; - do { - /* if needed, get more input */ - if (strm->avail_in == 0) { - readmore(&gz); - strm->avail_in = gz.left; - strm->next_in = gz.next; - } - - /* set up output to next available section of sliding window */ - strm->avail_out = DSIZE - have; - strm->next_out = window + have; - - /* inflate and check for errors */ - ret = inflate(strm, Z_BLOCK); - if (ret == Z_STREAM_ERROR) bye("internal stream error!", ""); - if (ret == Z_MEM_ERROR) bye("out of memory", ""); - if (ret == Z_DATA_ERROR) - bye("invalid compressed data--format violated in", name); - - /* update crc and sliding window pointer */ - crc = crc32(crc, window + have, DSIZE - have - strm->avail_out); - if (strm->avail_out) - have = DSIZE - strm->avail_out; - else { - have = 0; - full = 1; - } - - /* process end of block */ - if (strm->data_type & 128) { - if (strm->data_type & 64) - left = strm->data_type & 0x1f; - else { - lastbit = strm->data_type & 0x1f; - lastoff = lseek(gz.fd, 0L, SEEK_CUR) - strm->avail_in; - } - } - } while (ret != Z_STREAM_END); - inflateEnd(strm); - gz.left = strm->avail_in; - gz.next = strm->next_in; - - /* save the location of the end of the compressed data */ - end = lseek(gz.fd, 0L, SEEK_CUR) - gz.left; - - /* check gzip trailer and save total for deflate */ - if (crc != read4(&gz)) - bye("invalid compressed data--crc mismatch in ", name); - tot = strm->total_out; - if ((tot & 0xffffffffUL) != read4(&gz)) - bye("invalid compressed data--length mismatch in", name); - - /* if not at end of file, warn */ - if (gz.left || readin(&gz)) - fprintf(stderr, - "gzappend warning: junk at end of gzip file overwritten\n"); - - /* clear last block bit */ - lseek(gz.fd, lastoff - (lastbit != 0), SEEK_SET); - if (read(gz.fd, gz.buf, 1) != 1) bye("reading after seek on ", name); - *gz.buf = (unsigned char)(*gz.buf ^ (1 << ((8 - lastbit) & 7))); - lseek(gz.fd, -1L, SEEK_CUR); - if (write(gz.fd, gz.buf, 1) != 1) bye("writing after seek to ", name); - - /* if window wrapped, build dictionary from window by rotating */ - if (full) { - rotate(window, DSIZE, have); - have = DSIZE; - } - - /* set up deflate stream with window, crc, total_in, and leftover bits */ - ret = deflateInit2(strm, level, Z_DEFLATED, -15, 8, Z_DEFAULT_STRATEGY); - if (ret != Z_OK) bye("out of memory", ""); - deflateSetDictionary(strm, window, have); - strm->adler = crc; - strm->total_in = tot; - if (left) { - lseek(gz.fd, --end, SEEK_SET); - if (read(gz.fd, gz.buf, 1) != 1) bye("reading after seek on ", name); - deflatePrime(strm, 8 - left, *gz.buf); - } - lseek(gz.fd, end, SEEK_SET); - - /* clean up and return */ - free(window); - free(gz.buf); - return gz.fd; -} - -/* append file "name" to gzip file gd using deflate stream strm -- if last - is true, then finish off the deflate stream at the end */ -local void gztack(char *name, int gd, z_stream *strm, int last) -{ - int fd, len, ret; - unsigned left; - unsigned char *in, *out; - - /* open file to compress and append */ - fd = 0; - if (name != NULL) { - fd = open(name, O_RDONLY, 0); - if (fd == -1) - fprintf(stderr, "gzappend warning: %s not found, skipping ...\n", - name); - } - - /* allocate buffers */ - in = malloc(CHUNK); - out = malloc(CHUNK); - if (in == NULL || out == NULL) bye("out of memory", ""); - - /* compress input file and append to gzip file */ - do { - /* get more input */ - len = read(fd, in, CHUNK); - if (len == -1) { - fprintf(stderr, - "gzappend warning: error reading %s, skipping rest ...\n", - name); - len = 0; - } - strm->avail_in = (unsigned)len; - strm->next_in = in; - if (len) strm->adler = crc32(strm->adler, in, (unsigned)len); - - /* compress and write all available output */ - do { - strm->avail_out = CHUNK; - strm->next_out = out; - ret = deflate(strm, last && len == 0 ? Z_FINISH : Z_NO_FLUSH); - left = CHUNK - strm->avail_out; - while (left) { - len = write(gd, out + CHUNK - strm->avail_out - left, left); - if (len == -1) bye("writing gzip file", ""); - left -= (unsigned)len; - } - } while (strm->avail_out == 0 && ret != Z_STREAM_END); - } while (len != 0); - - /* write trailer after last entry */ - if (last) { - deflateEnd(strm); - out[0] = (unsigned char)(strm->adler); - out[1] = (unsigned char)(strm->adler >> 8); - out[2] = (unsigned char)(strm->adler >> 16); - out[3] = (unsigned char)(strm->adler >> 24); - out[4] = (unsigned char)(strm->total_in); - out[5] = (unsigned char)(strm->total_in >> 8); - out[6] = (unsigned char)(strm->total_in >> 16); - out[7] = (unsigned char)(strm->total_in >> 24); - len = 8; - do { - ret = write(gd, out + 8 - len, len); - if (ret == -1) bye("writing gzip file", ""); - len -= ret; - } while (len); - close(gd); - } - - /* clean up and return */ - free(out); - free(in); - if (fd > 0) close(fd); -} - -/* process the compression level option if present, scan the gzip file, and - append the specified files, or append the data from stdin if no other file - names are provided on the command line -- the gzip file must be writable - and seekable */ -int main(int argc, char **argv) -{ - int gd, level; - z_stream strm; - - /* ignore command name */ - argc--; argv++; - - /* provide usage if no arguments */ - if (*argv == NULL) { - printf( - "gzappend 1.2 (11 Oct 2012) Copyright (C) 2003, 2012 Mark Adler\n" - ); - printf( - "usage: gzappend [-level] file.gz [ addthis [ andthis ... ]]\n"); - return 0; - } - - /* set compression level */ - level = Z_DEFAULT_COMPRESSION; - if (argv[0][0] == '-') { - if (argv[0][1] < '0' || argv[0][1] > '9' || argv[0][2] != 0) - bye("invalid compression level", ""); - level = argv[0][1] - '0'; - if (*++argv == NULL) bye("no gzip file name after options", ""); - } - - /* prepare to append to gzip file */ - gd = gzscan(*argv++, &strm, level); - - /* append files on command line, or from stdin if none */ - if (*argv == NULL) - gztack(NULL, gd, &strm, 1); - else - do { - gztack(*argv, gd, &strm, argv[1] == NULL); - } while (*++argv != NULL); - return 0; -} |