patch-2.4.10 linux/fs/jffs2/read.c

• Lines: 158
• Date: Fri Sep 14 14:04:07 2001
• Orig file: v2.4.9/linux/fs/jffs2/read.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.4.9/linux/fs/jffs2/read.c linux/fs/jffs2/read.c
@@ -0,0 +1,157 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright (C) 2001 Red Hat, Inc.
+ *
+ * Created by David Woodhouse <dwmw2@cambridge.redhat.com>
+ *
+ * The original JFFS, from which the design for JFFS2 was derived,
+ * was designed and implemented by Axis Communications AB.
+ *
+ * The contents of this file are subject to the Red Hat eCos Public
+ * License Version 1.1 (the "Licence"); you may not use this file
+ * except in compliance with the Licence.  You may obtain a copy of
+ * the Licence at http://www.redhat.com/
+ *
+ * Software distributed under the Licence is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
+ * See the Licence for the specific language governing rights and
+ * limitations under the Licence.
+ *
+ * The Original Code is JFFS2 - Journalling Flash File System, version 2
+ *
+ * Alternatively, the contents of this file may be used under the
+ * terms of the GNU General Public License version 2 (the "GPL"), in
+ * which case the provisions of the GPL are applicable instead of the
+ * above.  If you wish to allow the use of your version of this file
+ * only under the terms of the GPL and not to allow others to use your
+ * version of this file under the RHEPL, indicate your decision by
+ * deleting the provisions above and replace them with the notice and
+ * other provisions required by the GPL.  If you do not delete the
+ * provisions above, a recipient may use your version of this file
+ * under either the RHEPL or the GPL.
+ *
+ * $Id: read.c,v 1.13 2001/05/01 16:24:44 dwmw2 Exp $
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/jffs2.h>
+#include <linux/mtd/mtd.h>
+#include "nodelist.h"
+#include "crc32.h"
+
+int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_full_dnode *fd, unsigned char *buf, int ofs, int len)
+{
+	struct jffs2_raw_inode *ri;
+	size_t readlen;
+	__u32 crc;
+	unsigned char *decomprbuf = NULL;
+	unsigned char *readbuf = NULL;
+	int ret = 0;
+
+	ri = jffs2_alloc_raw_inode();
+	if (!ri)
+		return -ENOMEM;
+
+	ret = c->mtd->read(c->mtd, fd->raw->flash_offset & ~3, sizeof(*ri), &readlen, (char *)ri);
+	if (ret) {
+		jffs2_free_raw_inode(ri);
+		printk(KERN_WARNING "Error reading node from 0x%08x: %d\n", fd->raw->flash_offset & ~3, ret);
+		return ret;
+	}
+	if (readlen != sizeof(*ri)) {
+		jffs2_free_raw_inode(ri);
+		printk(KERN_WARNING "Short read from 0x%08x: wanted 0x%x bytes, got 0x%x\n", 
+		       fd->raw->flash_offset & ~3, sizeof(*ri), readlen);
+		return -EIO;
+	}
+	crc = crc32(0, ri, sizeof(*ri)-8);
+
+	D1(printk(KERN_DEBUG "Node read from %08x: node_crc %08x, calculated CRC %08x. dsize %x, csize %x, offset %x, buf %p\n", fd->raw->flash_offset & ~3, ri->node_crc, crc, ri->dsize, ri->csize, ri->offset, buf));
+	if (crc != ri->node_crc) {
+		printk(KERN_WARNING "Node CRC %08x != calculated CRC %08x for node at %08x\n", ri->node_crc, crc, fd->raw->flash_offset & ~3);
+		ret = -EIO;
+		goto out_ri;
+	}
+
+	D1(if(ofs + len > ri->dsize) {
+		printk(KERN_WARNING "jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n", len, ofs, ri->dsize);
+		ret = -EINVAL;
+		goto out_ri;
+	});
+
+	
+	if (ri->compr == JFFS2_COMPR_ZERO) {
+		memset(buf, 0, len);
+		goto out_ri;
+	}
+
+	/* Cases:
+	   Reading whole node and it's uncompressed - read directly to buffer provided, check CRC.
+	   Reading whole node and it's compressed - read into comprbuf, check CRC and decompress to buffer provided 
+	   Reading partial node and it's uncompressed - read into readbuf, check CRC, and copy 
+	   Reading partial node and it's compressed - read into readbuf, check checksum, decompress to decomprbuf and copy
+	*/
+	if (ri->compr == JFFS2_COMPR_NONE && len == ri->dsize) {
+		readbuf = buf;
+	} else {
+		readbuf = kmalloc(ri->csize, GFP_KERNEL);
+		if (!readbuf) {
+			ret = -ENOMEM;
+			goto out_ri;
+		}
+	}
+	if (ri->compr != JFFS2_COMPR_NONE) {
+		if (len < ri->dsize) {
+			decomprbuf = kmalloc(ri->dsize, GFP_KERNEL);
+			if (!decomprbuf) {
+				ret = -ENOMEM;
+				goto out_readbuf;
+			}
+		} else {
+			decomprbuf = buf;
+		}
+	} else {
+		decomprbuf = readbuf;
+	}
+
+	D2(printk(KERN_DEBUG "Read %d bytes to %p\n", ri->csize, readbuf));
+	ret = c->mtd->read(c->mtd, (fd->raw->flash_offset &~3) + sizeof(*ri), ri->csize, &readlen, readbuf);
+
+	if (!ret && readlen != ri->csize)
+		ret = -EIO;
+	if (ret)
+		goto out_decomprbuf;
+
+	crc = crc32(0, readbuf, ri->csize);
+	if (crc != ri->data_crc) {
+		printk(KERN_WARNING "Data CRC %08x != calculated CRC %08x for node at %08x\n", ri->data_crc, crc, fd->raw->flash_offset & ~3);
+		ret = -EIO;
+		goto out_decomprbuf;
+	}
+	D2(printk(KERN_DEBUG "Data CRC matches calculated CRC %08x\n", crc));
+	if (ri->compr != JFFS2_COMPR_NONE) {
+		D2(printk(KERN_DEBUG "Decompress %d bytes from %p to %d bytes at %p\n", ri->csize, readbuf, ri->dsize, decomprbuf)); 
+		ret = jffs2_decompress(ri->compr, readbuf, decomprbuf, ri->csize, ri->dsize);
+		if (ret) {
+			printk(KERN_WARNING "Error: jffs2_decompress returned %d\n", ret);
+			goto out_decomprbuf;
+		}
+	}
+
+	if (len < ri->dsize) {
+		memcpy(buf, decomprbuf+ofs, len);
+	}
+ out_decomprbuf:
+	if(decomprbuf != buf && decomprbuf != readbuf)
+		kfree(decomprbuf);
+ out_readbuf:
+	if(readbuf != buf)
+		kfree(readbuf);
+ out_ri:
+	jffs2_free_raw_inode(ri);
+
+	return ret;
+}