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