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-rw-r--r--fs/jffs2/read.c228
1 files changed, 228 insertions, 0 deletions
diff --git a/fs/jffs2/read.c b/fs/jffs2/read.c
new file mode 100644
index 00000000..0b042b1f
--- /dev/null
+++ b/fs/jffs2/read.c
@@ -0,0 +1,228 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2001-2007 Red Hat, Inc.
+ *
+ * Created by David Woodhouse <dwmw2@infradead.org>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/crc32.h>
+#include <linux/pagemap.h>
+#include <linux/mtd/mtd.h>
+#include <linux/compiler.h>
+#include "nodelist.h"
+#include "compr.h"
+
+int jffs2_read_dnode(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
+ struct jffs2_full_dnode *fd, unsigned char *buf,
+ int ofs, int len)
+{
+ struct jffs2_raw_inode *ri;
+ size_t readlen;
+ uint32_t crc;
+ unsigned char *decomprbuf = NULL;
+ unsigned char *readbuf = NULL;
+ int ret = 0;
+
+ ri = jffs2_alloc_raw_inode();
+ if (!ri)
+ return -ENOMEM;
+
+ ret = jffs2_flash_read(c, ref_offset(fd->raw), sizeof(*ri), &readlen, (char *)ri);
+ if (ret) {
+ jffs2_free_raw_inode(ri);
+ pr_warn("Error reading node from 0x%08x: %d\n",
+ ref_offset(fd->raw), ret);
+ return ret;
+ }
+ if (readlen != sizeof(*ri)) {
+ jffs2_free_raw_inode(ri);
+ pr_warn("Short read from 0x%08x: wanted 0x%zx bytes, got 0x%zx\n",
+ ref_offset(fd->raw), sizeof(*ri), readlen);
+ return -EIO;
+ }
+ crc = crc32(0, ri, sizeof(*ri)-8);
+
+ jffs2_dbg(1, "Node read from %08x: node_crc %08x, calculated CRC %08x. dsize %x, csize %x, offset %x, buf %p\n",
+ ref_offset(fd->raw), je32_to_cpu(ri->node_crc),
+ crc, je32_to_cpu(ri->dsize), je32_to_cpu(ri->csize),
+ je32_to_cpu(ri->offset), buf);
+ if (crc != je32_to_cpu(ri->node_crc)) {
+ pr_warn("Node CRC %08x != calculated CRC %08x for node at %08x\n",
+ je32_to_cpu(ri->node_crc), crc, ref_offset(fd->raw));
+ ret = -EIO;
+ goto out_ri;
+ }
+ /* There was a bug where we wrote hole nodes out with csize/dsize
+ swapped. Deal with it */
+ if (ri->compr == JFFS2_COMPR_ZERO && !je32_to_cpu(ri->dsize) &&
+ je32_to_cpu(ri->csize)) {
+ ri->dsize = ri->csize;
+ ri->csize = cpu_to_je32(0);
+ }
+
+ D1(if(ofs + len > je32_to_cpu(ri->dsize)) {
+ pr_warn("jffs2_read_dnode() asked for %d bytes at %d from %d-byte node\n",
+ len, ofs, je32_to_cpu(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 == je32_to_cpu(ri->dsize)) {
+ readbuf = buf;
+ } else {
+ readbuf = kmalloc(je32_to_cpu(ri->csize), GFP_KERNEL);
+ if (!readbuf) {
+ ret = -ENOMEM;
+ goto out_ri;
+ }
+ }
+ if (ri->compr != JFFS2_COMPR_NONE) {
+ if (len < je32_to_cpu(ri->dsize)) {
+ decomprbuf = kmalloc(je32_to_cpu(ri->dsize), GFP_KERNEL);
+ if (!decomprbuf) {
+ ret = -ENOMEM;
+ goto out_readbuf;
+ }
+ } else {
+ decomprbuf = buf;
+ }
+ } else {
+ decomprbuf = readbuf;
+ }
+
+ jffs2_dbg(2, "Read %d bytes to %p\n", je32_to_cpu(ri->csize),
+ readbuf);
+ ret = jffs2_flash_read(c, (ref_offset(fd->raw)) + sizeof(*ri),
+ je32_to_cpu(ri->csize), &readlen, readbuf);
+
+ if (!ret && readlen != je32_to_cpu(ri->csize))
+ ret = -EIO;
+ if (ret)
+ goto out_decomprbuf;
+
+ crc = crc32(0, readbuf, je32_to_cpu(ri->csize));
+ if (crc != je32_to_cpu(ri->data_crc)) {
+ pr_warn("Data CRC %08x != calculated CRC %08x for node at %08x\n",
+ je32_to_cpu(ri->data_crc), crc, ref_offset(fd->raw));
+ ret = -EIO;
+ goto out_decomprbuf;
+ }
+ jffs2_dbg(2, "Data CRC matches calculated CRC %08x\n", crc);
+ if (ri->compr != JFFS2_COMPR_NONE) {
+ jffs2_dbg(2, "Decompress %d bytes from %p to %d bytes at %p\n",
+ je32_to_cpu(ri->csize), readbuf,
+ je32_to_cpu(ri->dsize), decomprbuf);
+ ret = jffs2_decompress(c, f, ri->compr | (ri->usercompr << 8), readbuf, decomprbuf, je32_to_cpu(ri->csize), je32_to_cpu(ri->dsize));
+ if (ret) {
+ pr_warn("Error: jffs2_decompress returned %d\n", ret);
+ goto out_decomprbuf;
+ }
+ }
+
+ if (len < je32_to_cpu(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;
+}
+
+int jffs2_read_inode_range(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
+ unsigned char *buf, uint32_t offset, uint32_t len)
+{
+ uint32_t end = offset + len;
+ struct jffs2_node_frag *frag;
+ int ret;
+
+ jffs2_dbg(1, "%s(): ino #%u, range 0x%08x-0x%08x\n",
+ __func__, f->inocache->ino, offset, offset + len);
+
+ frag = jffs2_lookup_node_frag(&f->fragtree, offset);
+
+ /* XXX FIXME: Where a single physical node actually shows up in two
+ frags, we read it twice. Don't do that. */
+ /* Now we're pointing at the first frag which overlaps our page
+ * (or perhaps is before it, if we've been asked to read off the
+ * end of the file). */
+ while(offset < end) {
+ jffs2_dbg(2, "%s(): offset %d, end %d\n",
+ __func__, offset, end);
+ if (unlikely(!frag || frag->ofs > offset ||
+ frag->ofs + frag->size <= offset)) {
+ uint32_t holesize = end - offset;
+ if (frag && frag->ofs > offset) {
+ jffs2_dbg(1, "Eep. Hole in ino #%u fraglist. frag->ofs = 0x%08x, offset = 0x%08x\n",
+ f->inocache->ino, frag->ofs, offset);
+ holesize = min(holesize, frag->ofs - offset);
+ }
+ jffs2_dbg(1, "Filling non-frag hole from %d-%d\n",
+ offset, offset + holesize);
+ memset(buf, 0, holesize);
+ buf += holesize;
+ offset += holesize;
+ continue;
+ } else if (unlikely(!frag->node)) {
+ uint32_t holeend = min(end, frag->ofs + frag->size);
+ jffs2_dbg(1, "Filling frag hole from %d-%d (frag 0x%x 0x%x)\n",
+ offset, holeend, frag->ofs,
+ frag->ofs + frag->size);
+ memset(buf, 0, holeend - offset);
+ buf += holeend - offset;
+ offset = holeend;
+ frag = frag_next(frag);
+ continue;
+ } else {
+ uint32_t readlen;
+ uint32_t fragofs; /* offset within the frag to start reading */
+
+ fragofs = offset - frag->ofs;
+ readlen = min(frag->size - fragofs, end - offset);
+ jffs2_dbg(1, "Reading %d-%d from node at 0x%08x (%d)\n",
+ frag->ofs+fragofs,
+ frag->ofs + fragofs+readlen,
+ ref_offset(frag->node->raw),
+ ref_flags(frag->node->raw));
+ ret = jffs2_read_dnode(c, f, frag->node, buf, fragofs + frag->ofs - frag->node->ofs, readlen);
+ jffs2_dbg(2, "node read done\n");
+ if (ret) {
+ jffs2_dbg(1, "%s(): error %d\n",
+ __func__, ret);
+ memset(buf, 0, readlen);
+ return ret;
+ }
+ buf += readlen;
+ offset += readlen;
+ frag = frag_next(frag);
+ jffs2_dbg(2, "node read was OK. Looping\n");
+ }
+ }
+ return 0;
+}
+
generated by cgit (git 2.34.1) at 2024-12-20 08:19:29 +0000