add support for reading MTD partitions to applypatch
Allow an MTD partition so serve as a source "file" in applypatch,
using a magically-formatted 'filename' that specifies the partition
name, size of data to read, and expected hash. Build incremental OTAs
that update the recovery image via a patch.
diff --git a/tools/applypatch/applypatch.c b/tools/applypatch/applypatch.c
index b9f28a2..6559533 100644
--- a/tools/applypatch/applypatch.c
+++ b/tools/applypatch/applypatch.c
@@ -25,12 +25,22 @@
#include "mincrypt/sha.h"
#include "applypatch.h"
+#include "mtdutils/mtdutils.h"
+
+int LoadMTDContents(const char* filename, FileContents* file);
+int ParseSha1(const char* str, uint8_t* digest);
// Read a file into memory; store it and its associated metadata in
// *file. Return 0 on success.
int LoadFileContents(const char* filename, FileContents* file) {
file->data = NULL;
+ // A special 'filename' beginning with "MTD:" means to load the
+ // contents of an MTD partition.
+ if (strncmp(filename, "MTD:", 4) == 0) {
+ return LoadMTDContents(filename, file);
+ }
+
if (stat(filename, &file->st) != 0) {
fprintf(stderr, "failed to stat \"%s\": %s\n", filename, strerror(errno));
return -1;
@@ -61,6 +71,178 @@
return 0;
}
+static size_t* size_array;
+// comparison function for qsort()ing an int array of indexes into
+// size_array[].
+static int compare_size_indices(const void* a, const void* b) {
+ int aa = *(int*)a;
+ int bb = *(int*)b;
+ if (size_array[aa] < size_array[bb]) {
+ return -1;
+ } else if (size_array[aa] > size_array[bb]) {
+ return 1;
+ } else {
+ return 0;
+ }
+}
+
+// Load the contents of an MTD partition into the provided
+// FileContents. filename should be a string of the form
+// "MTD:<partition_name>:<size_1>:<sha1_1>:<size_2>:<sha1_2>:...".
+// The smallest size_n bytes for which that prefix of the mtd contents
+// has the corresponding sha1 hash will be loaded. It is acceptable
+// for a size value to be repeated with different sha1s. Will return
+// 0 on success.
+//
+// This complexity is needed because if an OTA installation is
+// interrupted, the partition might contain either the source or the
+// target data, which might be of different lengths. We need to know
+// the length in order to read from MTD (there is no "end-of-file"
+// marker), so the caller must specify the possible lengths and the
+// hash of the data, and we'll do the load expecting to find one of
+// those hashes.
+int LoadMTDContents(const char* filename, FileContents* file) {
+ char* copy = strdup(filename);
+ const char* magic = strtok(copy, ":");
+ if (strcmp(magic, "MTD") != 0) {
+ fprintf(stderr, "LoadMTDContents called with bad filename (%s)\n",
+ filename);
+ return -1;
+ }
+ const char* partition = strtok(NULL, ":");
+
+ int i;
+ int colons = 0;
+ for (i = 0; filename[i] != '\0'; ++i) {
+ if (filename[i] == ':') {
+ ++colons;
+ }
+ }
+ if (colons < 3 || colons%2 == 0) {
+ fprintf(stderr, "LoadMTDContents called with bad filename (%s)\n",
+ filename);
+ }
+
+ int pairs = (colons-1)/2; // # of (size,sha1) pairs in filename
+ int* index = malloc(pairs * sizeof(int));
+ size_t* size = malloc(pairs * sizeof(size_t));
+ char** sha1sum = malloc(pairs * sizeof(char*));
+
+ for (i = 0; i < pairs; ++i) {
+ const char* size_str = strtok(NULL, ":");
+ size[i] = strtol(size_str, NULL, 10);
+ if (size[i] == 0) {
+ fprintf(stderr, "LoadMTDContents called with bad size (%s)\n", filename);
+ return -1;
+ }
+ sha1sum[i] = strtok(NULL, ":");
+ index[i] = i;
+ }
+
+ // sort the index[] array so it indexs the pairs in order of
+ // increasing size.
+ size_array = size;
+ qsort(index, pairs, sizeof(int), compare_size_indices);
+
+ static int partitions_scanned = 0;
+ if (!partitions_scanned) {
+ mtd_scan_partitions();
+ partitions_scanned = 1;
+ }
+
+ const MtdPartition* mtd = mtd_find_partition_by_name(partition);
+ if (mtd == NULL) {
+ fprintf(stderr, "mtd partition \"%s\" not found (loading %s)\n",
+ partition, filename);
+ return -1;
+ }
+
+ MtdReadContext* ctx = mtd_read_partition(mtd);
+ if (ctx == NULL) {
+ fprintf(stderr, "failed to initialize read of mtd partition \"%s\"\n",
+ partition);
+ return -1;
+ }
+
+ SHA_CTX sha_ctx;
+ SHA_init(&sha_ctx);
+ uint8_t parsed_sha[SHA_DIGEST_SIZE];
+
+ // allocate enough memory to hold the largest size.
+ file->data = malloc(size[index[pairs-1]]);
+ char* p = (char*)file->data;
+ file->size = 0; // # bytes read so far
+
+ for (i = 0; i < pairs; ++i) {
+ // Read enough additional bytes to get us up to the next size
+ // (again, we're trying the possibilities in order of increasing
+ // size).
+ size_t next = size[index[i]] - file->size;
+ size_t read = 0;
+ if (next > 0) {
+ read = mtd_read_data(ctx, p, next);
+ if (next != read) {
+ fprintf(stderr, "short read (%d bytes of %d) for partition \"%s\"\n",
+ read, next, partition);
+ free(file->data);
+ file->data = NULL;
+ return -1;
+ }
+ SHA_update(&sha_ctx, p, read);
+ file->size += read;
+ }
+
+ // Duplicate the SHA context and finalize the duplicate so we can
+ // check it against this pair's expected hash.
+ SHA_CTX temp_ctx;
+ memcpy(&temp_ctx, &sha_ctx, sizeof(SHA_CTX));
+ const uint8_t* sha_so_far = SHA_final(&temp_ctx);
+
+ if (ParseSha1(sha1sum[index[i]], parsed_sha) != 0) {
+ fprintf(stderr, "failed to parse sha1 %s in %s\n",
+ sha1sum[index[i]], filename);
+ free(file->data);
+ file->data = NULL;
+ return -1;
+ }
+
+ if (memcmp(sha_so_far, parsed_sha, SHA_DIGEST_SIZE) == 0) {
+ // we have a match. stop reading the partition; we'll return
+ // the data we've read so far.
+ printf("mtd read matched size %d sha %s\n",
+ size[index[i]], sha1sum[index[i]]);
+ break;
+ }
+
+ p += read;
+ }
+
+ mtd_read_close(ctx);
+
+ if (i == pairs) {
+ // Ran off the end of the list of (size,sha1) pairs without
+ // finding a match.
+ fprintf(stderr, "contents of MTD partition \"%s\" didn't match %s\n",
+ partition, filename);
+ free(file->data);
+ file->data = NULL;
+ return -1;
+ }
+
+ const uint8_t* sha_final = SHA_final(&sha_ctx);
+ for (i = 0; i < SHA_DIGEST_SIZE; ++i) {
+ file->sha1[i] = sha_final[i];
+ }
+
+ free(copy);
+ free(index);
+ free(size);
+ free(sha1sum);
+
+ return 0;
+}
+
+
// Save the contents of the given FileContents object under the given
// filename. Return 0 on success.
int SaveFileContents(const char* filename, FileContents file) {
@@ -178,8 +360,13 @@
FileContents file;
file.data = NULL;
+ // It's okay to specify no sha1s; the check will pass if the
+ // LoadFileContents is successful. (Useful for reading MTD
+ // partitions, where the filename encodes the sha1s; no need to
+ // check them twice.)
if (LoadFileContents(argv[2], &file) != 0 ||
- FindMatchingPatch(file.sha1, patches, num_patches) == NULL) {
+ (num_patches > 0 &&
+ FindMatchingPatch(file.sha1, patches, num_patches) == NULL)) {
fprintf(stderr, "file \"%s\" doesn't have any of expected "
"sha1 sums; checking cache\n", argv[2]);
@@ -241,14 +428,24 @@
//
// - otherwise, or if any error is encountered, exits with non-zero
// status.
+//
+// <src-file> (or <file> in check mode) may refer to an MTD partition
+// to read the source data. See the comments for the
+// LoadMTDContents() function above for the format of such a filename.
int main(int argc, char** argv) {
if (argc < 2) {
usage:
- fprintf(stderr, "usage: %s <src-file> <tgt-file> <tgt-sha1> <tgt-size> [<src-sha1>:<patch> ...]\n"
- " or %s -c <file> [<sha1> ...]\n"
- " or %s -s <bytes>\n"
- " or %s -l\n",
+ fprintf(stderr,
+ "usage: %s <src-file> <tgt-file> <tgt-sha1> <tgt-size> "
+ "[<src-sha1>:<patch> ...]\n"
+ " or %s -c <file> [<sha1> ...]\n"
+ " or %s -s <bytes>\n"
+ " or %s -l\n"
+ "\n"
+ "<src-file> or <file> may be of the form\n"
+ " MTD:<partition>:<len_1>:<sha1_1>:<len_2>:<sha1_2>:...\n"
+ "to specify reading from an MTD partition.\n\n",
argv[0], argv[0], argv[0], argv[0]);
return 1;
}
@@ -370,6 +567,15 @@
// Using the original source, but not enough free space. First
// copy the source file to cache, then delete it from the original
// location.
+
+ if (strncmp(source_filename, "MTD:", 4) == 0) {
+ // It's impossible to free space on the target filesystem by
+ // deleting the source if the source is an MTD partition. If
+ // we're ever in a state where we need to do this, fail.
+ fprintf(stderr, "not enough free space for target but source is MTD\n");
+ return 1;
+ }
+
if (MakeFreeSpaceOnCache(source_file.size) < 0) {
fprintf(stderr, "not enough free space on /cache\n");
return 1;