fs/jffs2/compr_zlib.c

Source file repositories/reference/linux-study-clean/fs/jffs2/compr_zlib.c

File Facts

System
Linux kernel
Corpus path
fs/jffs2/compr_zlib.c
Extension
.c
Size
5633 bytes
Lines
223
Domain
Core OS
Bucket
VFS And Filesystem Core
Inferred role
Core OS: implementation source
Status
source implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

if (ret != Z_OK) {
			jffs2_dbg(1, "deflate in loop returned %d\n", ret);
			zlib_deflateEnd(&def_strm);
			mutex_unlock(&deflate_mutex);
			return -1;
		}
	}
	def_strm.avail_out += STREAM_END_SPACE;
	def_strm.avail_in = 0;
	ret = zlib_deflate(&def_strm, Z_FINISH);
	zlib_deflateEnd(&def_strm);

	if (ret != Z_STREAM_END) {
		jffs2_dbg(1, "final deflate returned %d\n", ret);
		ret = -1;
		goto out;
	}

	if (def_strm.total_out >= def_strm.total_in) {
		jffs2_dbg(1, "zlib compressed %ld bytes into %ld; failing\n",
			  def_strm.total_in, def_strm.total_out);
		ret = -1;
		goto out;
	}

	jffs2_dbg(1, "zlib compressed %ld bytes into %ld\n",
		  def_strm.total_in, def_strm.total_out);

	*dstlen = def_strm.total_out;
	*sourcelen = def_strm.total_in;
	ret = 0;
 out:
	mutex_unlock(&deflate_mutex);
	return ret;
}

static int jffs2_zlib_decompress(unsigned char *data_in,
				 unsigned char *cpage_out,
				 uint32_t srclen, uint32_t destlen)
{
	int ret;
	int wbits = MAX_WBITS;

	mutex_lock(&inflate_mutex);

	inf_strm.next_in = data_in;
	inf_strm.avail_in = srclen;
	inf_strm.total_in = 0;

	inf_strm.next_out = cpage_out;
	inf_strm.avail_out = destlen;
	inf_strm.total_out = 0;

	/* If it's deflate, and it's got no preset dictionary, then
	   we can tell zlib to skip the adler32 check. */
	if (srclen > 2 && !(data_in[1] & PRESET_DICT) &&
	    ((data_in[0] & 0x0f) == Z_DEFLATED) &&
	    !(((data_in[0]<<8) + data_in[1]) % 31)) {

		jffs2_dbg(2, "inflate skipping adler32\n");
		wbits = -((data_in[0] >> 4) + 8);
		inf_strm.next_in += 2;
		inf_strm.avail_in -= 2;
	} else {
		/* Let this remain D1 for now -- it should never happen */
		jffs2_dbg(1, "inflate not skipping adler32\n");
	}


	if (Z_OK != zlib_inflateInit2(&inf_strm, wbits)) {
		pr_warn("inflateInit failed\n");
		mutex_unlock(&inflate_mutex);
		return 1;
	}

	while((ret = zlib_inflate(&inf_strm, Z_FINISH)) == Z_OK)
		;
	if (ret != Z_STREAM_END) {
		pr_notice("inflate returned %d\n", ret);
	}
	zlib_inflateEnd(&inf_strm);
	mutex_unlock(&inflate_mutex);
	return 0;
}

static struct jffs2_compressor jffs2_zlib_comp = {
    .priority = JFFS2_ZLIB_PRIORITY,
    .name = "zlib",
    .compr = JFFS2_COMPR_ZLIB,
    .compress = &jffs2_zlib_compress,

Annotation

Implementation Notes