diff options
Diffstat (limited to 'fs/jffs2/read.c')
| -rw-r--r-- | fs/jffs2/read.c | 246 |
1 files changed, 246 insertions, 0 deletions
diff --git a/fs/jffs2/read.c b/fs/jffs2/read.c new file mode 100644 index 000000000000..eb493dc06db7 --- /dev/null +++ b/fs/jffs2/read.c @@ -0,0 +1,246 @@ +/* + * JFFS2 -- Journalling Flash File System, Version 2. + * + * Copyright (C) 2001-2003 Red Hat, Inc. + * + * Created by David Woodhouse <dwmw2@infradead.org> + * + * For licensing information, see the file 'LICENCE' in this directory. + * + * $Id: read.c,v 1.38 2004/11/16 20:36:12 dwmw2 Exp $ + * + */ + +#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); + printk(KERN_WARNING "Error reading node from 0x%08x: %d\n", ref_offset(fd->raw), ret); + return ret; + } + if (readlen != sizeof(*ri)) { + jffs2_free_raw_inode(ri); + printk(KERN_WARNING "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); + + D1(printk(KERN_DEBUG "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)) { + printk(KERN_WARNING "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)) { + printk(KERN_WARNING "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; + } + + D2(printk(KERN_DEBUG "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)) { + printk(KERN_WARNING "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; + } + 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", + 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) { + printk(KERN_WARNING "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; + + D1(printk(KERN_DEBUG "jffs2_read_inode_range: ino #%u, range 0x%08x-0x%08x\n", + 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 */ + while(offset < end) { + D2(printk(KERN_DEBUG "jffs2_read_inode_range: offset %d, end %d\n", offset, end)); + if (unlikely(!frag || frag->ofs > offset)) { + uint32_t holesize = end - offset; + if (frag) { + D1(printk(KERN_NOTICE "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); + D2(jffs2_print_frag_list(f)); + } + D1(printk(KERN_DEBUG "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); + D1(printk(KERN_DEBUG "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); + D1(printk(KERN_DEBUG "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); + D2(printk(KERN_DEBUG "node read done\n")); + if (ret) { + D1(printk(KERN_DEBUG"jffs2_read_inode_range error %d\n",ret)); + memset(buf, 0, readlen); + return ret; + } + buf += readlen; + offset += readlen; + frag = frag_next(frag); + D2(printk(KERN_DEBUG "node read was OK. Looping\n")); + } + } + return 0; +} + +/* Core function to read symlink target. */ +char *jffs2_getlink(struct jffs2_sb_info *c, struct jffs2_inode_info *f) +{ + char *buf; + int ret; + + down(&f->sem); + + if (!f->metadata) { + printk(KERN_NOTICE "No metadata for symlink inode #%u\n", f->inocache->ino); + up(&f->sem); + return ERR_PTR(-EINVAL); + } + buf = kmalloc(f->metadata->size+1, GFP_USER); + if (!buf) { + up(&f->sem); + return ERR_PTR(-ENOMEM); + } + buf[f->metadata->size]=0; + + ret = jffs2_read_dnode(c, f, f->metadata, buf, 0, f->metadata->size); + + up(&f->sem); + + if (ret) { + kfree(buf); + return ERR_PTR(ret); + } + return buf; +} |