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#include <zlib.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
void usage(char *exe) {
fprintf(stderr,"usage: %s <file>\n", exe);
exit(-1);
}
char *slurp(char *file, size_t *flen) {
struct stat stats;
char *out;
int fd;
if (stat(file, &stats) == -1) {
fprintf(stderr, "can't stat %s: %s\n", file, strerror(errno));
exit(-1);
}
*flen = stats.st_size;
if (flen == 0) {
fprintf(stderr, "file %s is zero length\n", file);
exit(-1);
}
if ( (out = malloc(stats.st_size)) == NULL) {
fprintf(stderr, "can't malloc space for %s\n", file);
exit(-1);
}
if ( (fd = open(file,O_RDONLY)) == -1) {
fprintf(stderr, "can't open %s: %s\n", file, strerror(errno));
exit(-1);
}
if ( read(fd, out, stats.st_size) != stats.st_size) {
fprintf(stderr, "short read on %s\n", file);
exit(-1);
}
close(fd);
return out;
}
int main( int argc, char *argv[]) {
if (argc < 2) usage(argv[0]);
int rc;
size_t flen;
char *file = argv[1];
char *data = slurp(file, &flen);
/* minimal required initialization of z_stream prior to inflateInit2 */
z_stream zs = {.next_in = data, .avail_in=flen, .zalloc=Z_NULL, .zfree=Z_NULL,
.opaque=NULL};
#define want_gzip 16
#define def_windowbits (15 + want_gzip)
rc = inflateInit2(&zs, def_windowbits);
if (rc != Z_OK) {
fprintf(stderr, "inflateInit failed: %s\n", zs.msg);
exit(-1);
}
/* start with a guess of the space needed to uncompress */
size_t gzmax = flen * 3;
char *out = malloc(gzmax);
if (out == NULL) {
fprintf(stderr, "could not allocate %u bytes for uncompressed file\n",
(unsigned)gzmax);
exit(-1);
}
/* initialize the remaining parts of z_stream prior to actual deflate */
zs.next_out = out;
zs.avail_out = gzmax;
/* inflate it .. cannot do this in one pass since final size unknown */
keepgoing:
rc = inflate(&zs, Z_NO_FLUSH);
if ((rc == Z_OK) || (rc == Z_BUF_ERROR)) { /* need to grow buffer */
/* fprintf(stderr,"inflate loop..\n"); */
off_t cur = (char*)zs.next_out - out; /* save offset */
out = realloc(out, gzmax*2);
if (out == NULL) {
fprintf(stderr,"realloc failed\n");
exit(-1);
}
zs.next_out = out + cur;
zs.avail_out += gzmax;
gzmax *= 2;
goto keepgoing;
}
if (rc != Z_STREAM_END) {
if (rc == Z_DATA_ERROR) fprintf(stderr,"input data corrupted\n");
else if (rc == Z_STREAM_ERROR) fprintf(stderr,"stream error\n");
else if (rc == Z_MEM_ERROR) fprintf(stderr,"insufficient memory\n");
else fprintf(stderr,"unknown error\n");
exit(-1);
}
rc = inflateEnd(&zs);
if (rc != Z_OK) fprintf(stderr,"inflateEnd error: %s\n", zs.msg);
fprintf(stderr,"Original size: %u\n", (unsigned)flen);
fprintf(stderr,"Inflated size: %u\n", (unsigned)zs.total_out);
if (write(STDOUT_FILENO, out, zs.total_out) != zs.total_out) {
fprintf(stderr,"error: partial write\n");
exit(-1);
}
return 0;
}
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