zapret/tpws/gzip.c
2021-03-04 14:30:38 +03:00

83 lines
1.4 KiB
C

#include "gzip.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define ZCHUNK 16384
#define BUFMIN 128
#define BUFCHUNK (1024*128)
int z_readfile(FILE *F, char **buf, size_t *size)
{
z_stream zs;
int r;
unsigned char in[ZCHUNK];
size_t bufsize;
void *newbuf;
memset(&zs, 0, sizeof(zs));
*buf = NULL;
bufsize = *size = 0;
r = inflateInit2(&zs, 47);
if (r != Z_OK) return r;
do
{
zs.avail_in = fread(in, 1, sizeof(in), F);
if (ferror(F))
{
r = Z_ERRNO;
goto zerr;
}
if (!zs.avail_in) break;
zs.next_in = in;
do
{
if ((bufsize - *size) < BUFMIN)
{
bufsize += BUFCHUNK;
newbuf = *buf ? realloc(*buf, bufsize) : malloc(bufsize);
if (!newbuf)
{
r = Z_MEM_ERROR;
goto zerr;
}
*buf = newbuf;
}
zs.avail_out = bufsize - *size;
zs.next_out = (unsigned char*)(*buf + *size);
r = inflate(&zs, Z_NO_FLUSH);
if (r != Z_OK && r != Z_STREAM_END) goto zerr;
*size = bufsize - zs.avail_out;
} while (r == Z_OK && zs.avail_in);
} while (r == Z_OK);
if (*size < bufsize)
{
// free extra space
if ((newbuf = realloc(*buf, *size))) *buf = newbuf;
}
inflateEnd(&zs);
return Z_OK;
zerr:
inflateEnd(&zs);
if (*buf)
{
free(*buf);
*buf = NULL;
}
return r;
}
bool is_gzip(FILE* F)
{
unsigned char magic[2];
bool b = !fseek(F, 0, SEEK_SET) && fread(magic, 1, 2, F) == 2 && magic[0] == 0x1F && magic[1] == 0x8B;
fseek(F, 0, SEEK_SET);
return b;
}