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