1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * uncompress.c 4 * 5 * (C) Copyright 1999 Linus Torvalds 6 * 7 * cramfs interfaces to the uncompression library. There's really just 8 * three entrypoints: 9 * 10 * - cramfs_uncompress_init() - called to initialize the thing. 11 * - cramfs_uncompress_exit() - tell me when you're done 12 * - cramfs_uncompress_block() - uncompress a block. 13 * 14 * NOTE NOTE NOTE! The uncompression is entirely single-threaded. We 15 * only have one stream, and we'll initialize it only once even if it 16 * then is used by multiple filesystems. 17 */ 18 19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 20 21 #include <linux/kernel.h> 22 #include <linux/errno.h> 23 #include <linux/vmalloc.h> 24 #include <linux/zlib.h> 25 #include "internal.h" 26 27 static z_stream stream; 28 static int initialized; 29 30 /* Returns length of decompressed data. */ 31 int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen) 32 { 33 int err; 34 35 stream.next_in = src; 36 stream.avail_in = srclen; 37 38 stream.next_out = dst; 39 stream.avail_out = dstlen; 40 41 err = zlib_inflateReset(&stream); 42 if (err != Z_OK) { 43 pr_err("zlib_inflateReset error %d\n", err); 44 zlib_inflateEnd(&stream); 45 zlib_inflateInit(&stream); 46 } 47 48 err = zlib_inflate(&stream, Z_FINISH); 49 if (err != Z_STREAM_END) 50 goto err; 51 return stream.total_out; 52 53 err: 54 pr_err("Error %d while decompressing!\n", err); 55 pr_err("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen); 56 return -EIO; 57 } 58 59 int cramfs_uncompress_init(void) 60 { 61 if (!initialized++) { 62 stream.workspace = vmalloc(zlib_inflate_workspacesize()); 63 if (!stream.workspace) { 64 initialized = 0; 65 return -ENOMEM; 66 } 67 stream.next_in = NULL; 68 stream.avail_in = 0; 69 zlib_inflateInit(&stream); 70 } 71 return 0; 72 } 73 74 void cramfs_uncompress_exit(void) 75 { 76 if (!--initialized) { 77 zlib_inflateEnd(&stream); 78 vfree(stream.workspace); 79 } 80 } 81