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// SPDX-License-Identifier: GPL-2.0
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <zlib.h>
#include <linux/compiler.h>
#include <internal/lib.h>
#include "util/compress.h"
#define CHUNK_SIZE 16384
int gzip_decompress_to_file(const char *input, int output_fd)
{
int ret = Z_STREAM_ERROR;
int input_fd;
void *ptr;
int len;
struct stat stbuf;
unsigned char buf[CHUNK_SIZE];
z_stream zs = {
.zalloc = Z_NULL,
.zfree = Z_NULL,
.opaque = Z_NULL,
.avail_in = 0,
.next_in = Z_NULL,
};
input_fd = open(input, O_RDONLY);
if (input_fd < 0)
return -1;
if (fstat(input_fd, &stbuf) < 0)
goto out_close;
ptr = mmap(NULL, stbuf.st_size, PROT_READ, MAP_PRIVATE, input_fd, 0);
if (ptr == MAP_FAILED)
goto out_close;
if (inflateInit2(&zs, 16 + MAX_WBITS) != Z_OK)
goto out_unmap;
zs.next_in = ptr;
zs.avail_in = stbuf.st_size;
do {
zs.next_out = buf;
zs.avail_out = CHUNK_SIZE;
ret = inflate(&zs, Z_NO_FLUSH);
switch (ret) {
case Z_NEED_DICT:
ret = Z_DATA_ERROR;
/* fall through */
case Z_DATA_ERROR:
case Z_MEM_ERROR:
goto out;
default:
break;
}
len = CHUNK_SIZE - zs.avail_out;
if (writen(output_fd, buf, len) != len) {
ret = Z_DATA_ERROR;
goto out;
}
} while (ret != Z_STREAM_END);
out:
inflateEnd(&zs);
out_unmap:
munmap(ptr, stbuf.st_size);
out_close:
close(input_fd);
return ret == Z_STREAM_END ? 0 : -1;
}
bool gzip_is_compressed(const char *input)
{
int fd = open(input, O_RDONLY);
const uint8_t magic[2] = { 0x1f, 0x8b };
char buf[2] = { 0 };
ssize_t rc;
if (fd < 0)
return -1;
rc = read(fd, buf, sizeof(buf));
close(fd);
return rc == sizeof(buf) ?
memcmp(buf, magic, sizeof(buf)) == 0 : false;
}
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