mirror of
https://github.com/tildearrow/furnace.git
synced 2024-12-05 18:57:27 +00:00
504 lines
17 KiB
C
504 lines
17 KiB
C
/* 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;
|
|
}
|