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// gzip2deflate by Piotr Fusik <fox@scene.pl>
// http://xasm.atari.org
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#ifdef __WIN32
#include <fcntl.h>
#endif
static int get_byte(void)
{
int b = getchar();
if (b == EOF) {
fputs("gzip2deflate: unexpected end of stream\n", stderr);
exit(1);
}
return b;
}
static void skip_bytes(int n)
{
while (--n >= 0)
get_byte();
}
static void skip_string(void)
{
while (get_byte() != 0);
}
int main (int argc, char *argv[])
{
int flg;
char buf[8 + 4096];
size_t len;
#ifdef __WIN32
_setmode(_fileno(stdin), _O_BINARY);
_setmode(_fileno(stdout), _O_BINARY);
#endif
if (get_byte() != 0x1f || get_byte() != 0x8b || get_byte() != 8) {
fputs("gzip2deflate: not a gzip file on stdin\n", stderr);
return 1;
}
flg = get_byte();
skip_bytes(6);
if ((flg & 4) != 0) {
int xlen = get_byte();
xlen += get_byte() << 8;
skip_bytes(xlen);
}
if ((flg & 8) != 0)
skip_string();
if ((flg & 16) != 0)
skip_string();
if ((flg & 2) != 0)
skip_bytes(2);
/* copy everything except the last 8 bytes */
len = 0;
for (;;) {
len += fread(buf + len, 1, sizeof(buf) - len, stdin);
if (len != sizeof(buf))
break;
fwrite(buf, 1, sizeof(buf) - 8, stdout);
memcpy(buf, buf + sizeof(buf) - 8, 8);
len = 8;
}
if (ferror(stdin)) {
fputs("gzip2deflate: read error\n", stderr);
return 1;
}
if (len < 8) {
fputs("gzip2deflate: unexpected end of stream\n", stderr);
return 1;
}
fwrite(buf, 1, len - 8, stdout);
return 0;
}
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