Error correction: Add libfec to read encoded data

Add libfec to read files or partitions with error-correcting codes
appended to them. Uses verity metadata to speed up I/O and improve
error correction effectiveness.

Bug: 21893453
Change-Id: I94b95058b084418019fc96595bb6055df36e2c2b

1 files changed, 176 insertions, 0 deletions

diff --git a/libfec/fec_private.h b/libfec/fec_private.h
new file mode 100644
index 00000000..fab81cfe
--- /dev/null
+++ b/libfec/fec_private.h
@@ -0,0 +1,176 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __FEC_PRIVATE_H__
+#define __FEC_PRIVATE_H__
+
+#include <errno.h>
+#include <fcntl.h>
+#include <list>
+#include <memory>
+#include <new>
+#include <pthread.h>
+#include <stdio.h>
+#include <string>
+#include <string.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <unordered_map>
+#include <vector>
+
+#include <mincrypt/rsa.h>
+#include <openssl/sha.h>
+#include <fec/io.h>
+#include <fec/ecc.h>
+
+/* processing parameters */
+#define WORK_MIN_THREADS 1
+#define WORK_MAX_THREADS 64
+
+/* verity parameters */
+#define VERITY_CACHE_BLOCKS 4096
+#define VERITY_NO_CACHE UINT64_MAX
+
+/* verity definitions */
+#define VERITY_METADATA_SIZE (8 * FEC_BLOCKSIZE)
+#define VERITY_TABLE_ARGS 10 /* mandatory arguments */
+#define VERITY_MIN_TABLE_SIZE (VERITY_TABLE_ARGS * 2) /* for a sanity check */
+#define VERITY_MAX_TABLE_SIZE (VERITY_METADATA_SIZE - sizeof(verity_header))
+
+/* verity header and metadata */
+#define VERITY_MAGIC 0xB001B001
+#define VERITY_MAGIC_DISABLE 0x46464F56
+#define VERITY_VERSION 0
+#define VERITY_TABLE_FIELDS 10
+#define VERITY_TABLE_VERSION 1
+
+struct verity_header {
+    uint32_t magic;
+    uint32_t version;
+    uint8_t signature[RSANUMBYTES];
+    uint32_t length;
+};
+
+/* file handle */
+struct ecc_info {
+    bool valid;
+    int roots;
+    int rsn;
+    uint32_t size;
+    uint64_t blocks;
+    uint64_t rounds;
+    uint64_t start; /* offset in file */
+};
+
+struct verity_info {
+    bool disabled;
+    char *table;
+    uint32_t hash_data_blocks;
+    uint32_t hash_size;
+    uint64_t hash_data_offset;
+    uint64_t hash_start;
+    uint8_t *hash;
+    uint32_t salt_size;
+    uint8_t *salt;
+    uint64_t data_blocks;
+    uint64_t metadata_start; /* offset in file */
+    uint8_t zero_hash[SHA256_DIGEST_LENGTH];
+    verity_header header;
+};
+
+struct verity_block_info {
+    uint64_t index;
+    bool valid;
+};
+
+struct fec_handle {
+    ecc_info ecc;
+    int fd;
+    int flags; /* additional flags passed to fec_open */
+    int mode; /* mode for open(2) */
+    pthread_mutex_t mutex;
+    std::list<verity_block_info> lru;
+    std::unordered_map<uint64_t, std::list<verity_block_info>::iterator> cache;
+    uint64_t errors;
+    uint64_t data_size;
+    uint64_t pos;
+    uint64_t size;
+    verity_info verity;
+};
+
+/* I/O helpers */
+extern bool raw_pread(fec_handle *f, void *buf, size_t count,
+        uint64_t offset);
+extern bool raw_pwrite(fec_handle *f, const void *buf, size_t count,
+        uint64_t offset);
+
+/* processing functions */
+typedef ssize_t (*read_func)(fec_handle *f, uint8_t *dest, size_t count,
+        uint64_t offset, size_t *errors);
+
+extern ssize_t process(fec_handle *f, uint8_t *buf, size_t count,
+        uint64_t offset, read_func func);
+
+/* verity functions */
+extern uint64_t verity_get_size(uint64_t file_size, uint32_t *verity_levels,
+        uint32_t *level_hashes);
+
+extern int verity_parse_header(fec_handle *f, uint64_t offset);
+
+extern bool verity_check_block(fec_handle *f, uint64_t index,
+        const uint8_t *expected, const uint8_t *block);
+
+/* helper macros */
+#ifndef unlikely
+    #define unlikely(x) __builtin_expect(!!(x), 0)
+    #define likely(x)   __builtin_expect(!!(x), 1)
+#endif
+
+#ifndef stringify
+    #define __stringify(x) #x
+    #define stringify(x) __stringify(x)
+#endif
+
+/*  warnings, errors, debug output */
+#ifdef FEC_NO_KLOG
+    #define __log(func, type, format, args...) \
+        fprintf(stderr, "fec: <%d> " type ": %s: " format "\n", \
+            (int)syscall(SYS_gettid), __FUNCTION__,  ##args)
+#else
+    #include <cutils/klog.h>
+
+    #define __log(func, type, format, args...) \
+        KLOG_##func("fec", "<%d> " type ": %s: " format "\n", \
+            (int)syscall(SYS_gettid), __FUNCTION__, ##args)
+#endif
+
+#ifdef NDEBUG
+    #define debug(format, args...)
+#else
+    #define debug(format, args...) __log(DEBUG, "debug", format, ##args)
+#endif
+
+#define warn(format, args...) __log(WARNING, "warning", format, ##args)
+#define error(format, args...) __log(ERROR, "error", format, ##args)
+
+#define check(p) \
+    if (unlikely(!(p))) { \
+        error("`%s' failed", #p); \
+        errno = EFAULT; \
+        return -1; \
+    }
+
+#endif /* __FEC_PRIVATE_H__ */