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/* SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0-or-later */
#include <assert.h>
#include <commonlib/bsd/cbfs_private.h>
#include <commonlib/bsd/helpers.h>
/*
* A CBFS metadata cache is an in memory data structure storing CBFS file headers (= metadata).
* It is defined by its start pointer and size. It contains a sequence of variable-length
* union mcache_entry entries. There is no overall header structure for the cache.
*
* Each mcache_entry is the raw metadata for a CBFS file (including attributes) in the same form
* as stored on flash (i.e. values in big-endian), except that the CBFS magic signature in the
* first 8 bytes ('LARCHIVE') is overwritten with mcache-internal bookkeeping data. The first 4
* bytes are a magic number (MCACHE_MAGIC_FILE) and the next 4 bytes are the absolute offset in
* bytes on the cbfs_dev_t that this metadata blob was found at. (Note that depending on the
* implementation of cbfs_dev_t, this offset may still be relative to the start of a subregion
* of the underlying storage device.)
*
* The length of an mcache_entry (i.e. length of the underlying metadata blob) is encoded in the
* metadata (entry->file.h.offset). The next mcache_entry begins at the next
* CBFS_MCACHE_ALIGNMENT boundary after that. The cache is terminated by a special 4-byte
* mcache_entry that consists only of a magic number (MCACHE_MAGIC_END or MCACHE_MAGIC_FULL).
*/
#define MCACHE_MAGIC_FILE 0x454c4946 /* 'FILE' */
#define MCACHE_MAGIC_FULL 0x4c4c5546 /* 'FULL' */
#define MCACHE_MAGIC_END 0x444e4524 /* '$END' */
union mcache_entry {
union cbfs_mdata file;
struct { /* These fields exactly overlap file.h.magic */
uint32_t magic;
uint32_t offset;
};
};
struct cbfs_mcache_build_args {
void *mcache;
void *end;
int count;
};
static enum cb_err build_walker(cbfs_dev_t dev, size_t offset, const union cbfs_mdata *mdata,
size_t already_read, void *arg)
{
struct cbfs_mcache_build_args *args = arg;
union mcache_entry *entry = args->mcache;
const uint32_t data_offset = be32toh(mdata->h.offset);
if (args->end - args->mcache < data_offset)
return CB_CBFS_CACHE_FULL;
if (cbfs_copy_fill_metadata(args->mcache, mdata, already_read, dev, offset))
return CB_CBFS_IO;
entry->magic = MCACHE_MAGIC_FILE;
entry->offset = offset;
args->mcache += ALIGN_UP(data_offset, CBFS_MCACHE_ALIGNMENT);
args->count++;
return CB_CBFS_NOT_FOUND;
}
enum cb_err cbfs_mcache_build(cbfs_dev_t dev, void *mcache, size_t size,
struct vb2_hash *metadata_hash)
{
struct cbfs_mcache_build_args args = {
.mcache = mcache,
.end = mcache + ALIGN_DOWN(size, CBFS_MCACHE_ALIGNMENT)
- sizeof(uint32_t), /* leave space for terminating magic */
.count = 0,
};
assert(size > sizeof(uint32_t) && IS_ALIGNED((uintptr_t)mcache, CBFS_MCACHE_ALIGNMENT));
enum cb_err ret = cbfs_walk(dev, build_walker, &args, metadata_hash, 0);
union mcache_entry *entry = args.mcache;
if (ret == CB_CBFS_NOT_FOUND) {
ret = CB_SUCCESS;
entry->magic = MCACHE_MAGIC_END;
} else if (ret == CB_CBFS_CACHE_FULL) {
ERROR("mcache overflow, should increase CBFS_MCACHE size!\n");
entry->magic = MCACHE_MAGIC_FULL;
}
LOG("mcache @%p built for %d files, used %#zx of %#zx bytes\n", mcache,
args.count, args.mcache + sizeof(entry->magic) - mcache, size);
return ret;
}
enum cb_err cbfs_mcache_lookup(const void *mcache, size_t mcache_size, const char *name,
union cbfs_mdata *mdata_out, size_t *data_offset_out)
{
const size_t namesize = strlen(name) + 1; /* Count trailing \0 so we can memcmp() it. */
const void *end = mcache + mcache_size;
const void *current = mcache;
while (current + sizeof(uint32_t) <= end) {
const union mcache_entry *entry = current;
if (entry->magic == MCACHE_MAGIC_END)
return CB_CBFS_NOT_FOUND;
if (entry->magic == MCACHE_MAGIC_FULL)
return CB_CBFS_CACHE_FULL;
assert(entry->magic == MCACHE_MAGIC_FILE);
const uint32_t data_offset = be32toh(entry->file.h.offset);
const uint32_t data_length = be32toh(entry->file.h.len);
if (namesize <= data_offset - offsetof(union cbfs_mdata, h.filename) &&
memcmp(name, entry->file.h.filename, namesize) == 0) {
LOG("Found '%s' @%#x size %#x in mcache @%p\n",
name, entry->offset, data_length, current);
*data_offset_out = entry->offset + data_offset;
memcpy(mdata_out, &entry->file, data_offset);
return CB_SUCCESS;
}
current += ALIGN_UP(data_offset, CBFS_MCACHE_ALIGNMENT);
}
ERROR("CBFS mcache is not terminated!\n"); /* should never happen */
return CB_ERR;
}
size_t cbfs_mcache_real_size(const void *mcache, size_t mcache_size)
{
const void *end = mcache + mcache_size;
const void *current = mcache;
while (current + sizeof(uint32_t) <= end) {
const union mcache_entry *entry = current;
if (entry->magic == MCACHE_MAGIC_FULL || entry->magic == MCACHE_MAGIC_END) {
current += sizeof(entry->magic);
break;
}
assert(entry->magic == MCACHE_MAGIC_FILE);
current += ALIGN_UP(be32toh(entry->file.h.offset), CBFS_MCACHE_ALIGNMENT);
}
return current - mcache;
}
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