new image diffing tool and support for image patches in applypatch
Images (like boot and recovery) consist of large sections of gzipped
data interspersed with other data. To do effective binary patching of
these files, we need to apply patches to the gzipped parts in
'uncompressed space', that is, we decompress, apply a patch, then
recompress to obtain the desired output.
This change defines a new format with these patches, which is
basically a description of how the source and target files are to be
divided up into chunks and a bsdiff patch for each chunk. We add a
new host executable, "imgdiff", for generating these patches from
source and target images, and add support in applypatch for
recognizing this format and applying it on the device.
diff --git a/tools/applypatch/bsdiff.c b/tools/applypatch/bsdiff.c
index a2851f9..9d55f3b 100644
--- a/tools/applypatch/bsdiff.c
+++ b/tools/applypatch/bsdiff.c
@@ -29,6 +29,7 @@
#include <bzlib.h>
#include "mincrypt/sha.h"
+#include "applypatch.h"
void ShowBSDiffLicense() {
puts("The bsdiff library used herein is:\n"
@@ -80,10 +81,34 @@
return y;
}
+
int ApplyBSDiffPatch(const unsigned char* old_data, ssize_t old_size,
- const char* patch_filename,
+ const char* patch_filename, ssize_t patch_offset,
FILE* output, SHA_CTX* ctx) {
+ unsigned char* new_data;
+ ssize_t new_size;
+ if (ApplyBSDiffPatchMem(old_data, old_size, patch_filename, patch_offset,
+ &new_data, &new_size) != 0) {
+ return -1;
+ }
+
+ if (fwrite(new_data, 1, new_size, output) < new_size) {
+ fprintf(stderr, "short write of output: %d (%s)\n", errno, strerror(errno));
+ return 1;
+ }
+ if (ctx) {
+ SHA_update(ctx, new_data, new_size);
+ }
+ free(new_data);
+
+ return 0;
+}
+
+int ApplyBSDiffPatchMem(const unsigned char* old_data, ssize_t old_size,
+ const char* patch_filename, ssize_t patch_offset,
+ unsigned char** new_data, ssize_t* new_size) {
+
FILE* f;
if ((f = fopen(patch_filename, "rb")) == NULL) {
fprintf(stderr, "failed to open patch file\n");
@@ -102,6 +127,8 @@
// from oldfile to x bytes from the diff block; copy y bytes from the
// extra block; seek forwards in oldfile by z bytes".
+ fseek(f, patch_offset, SEEK_SET);
+
unsigned char header[32];
if (fread(header, 1, 32, f) < 32) {
fprintf(stderr, "failed to read patch file header\n");
@@ -109,17 +136,16 @@
}
if (memcmp(header, "BSDIFF40", 8) != 0) {
- fprintf(stderr, "corrupt patch file header (magic number)\n");
+ fprintf(stderr, "corrupt bsdiff patch file header (magic number)\n");
return 1;
}
ssize_t ctrl_len, data_len;
- ssize_t new_size;
ctrl_len = offtin(header+8);
data_len = offtin(header+16);
- new_size = offtin(header+24);
+ *new_size = offtin(header+24);
- if (ctrl_len < 0 || data_len < 0 || new_size < 0) {
+ if (ctrl_len < 0 || data_len < 0 || *new_size < 0) {
fprintf(stderr, "corrupt patch file header (data lengths)\n");
return 1;
}
@@ -135,7 +161,7 @@
fprintf(stderr, "failed to open patch file\n"); \
return 1; \
} \
- if (fseeko(f, offset, SEEK_SET)) { \
+ if (fseeko(f, offset+patch_offset, SEEK_SET)) { \
fprintf(stderr, "failed to seek in patch file\n"); \
return 1; \
} \
@@ -150,9 +176,10 @@
#undef OPEN_AT
- unsigned char* new_data = malloc(new_size);
- if (new_data == NULL) {
- fprintf(stderr, "failed to allocate memory for output file\n");
+ *new_data = malloc(*new_size);
+ if (*new_data == NULL) {
+ fprintf(stderr, "failed to allocate %d bytes of memory for output file\n",
+ (int)*new_size);
return 1;
}
@@ -161,7 +188,7 @@
off_t len_read;
int i;
unsigned char buf[8];
- while (newpos < new_size) {
+ while (newpos < *new_size) {
// Read control data
for (i = 0; i < 3; ++i) {
len_read = BZ2_bzRead(&bzerr, cpfbz2, buf, 8);
@@ -173,13 +200,13 @@
}
// Sanity check
- if (newpos + ctrl[0] > new_size) {
+ if (newpos + ctrl[0] > *new_size) {
fprintf(stderr, "corrupt patch (new file overrun)\n");
return 1;
}
// Read diff string
- len_read = BZ2_bzRead(&bzerr, dpfbz2, new_data + newpos, ctrl[0]);
+ len_read = BZ2_bzRead(&bzerr, dpfbz2, *new_data + newpos, ctrl[0]);
if (len_read < ctrl[0] || !(bzerr == BZ_OK || bzerr == BZ_STREAM_END)) {
fprintf(stderr, "corrupt patch (read diff)\n");
return 1;
@@ -188,7 +215,7 @@
// Add old data to diff string
for (i = 0; i < ctrl[0]; ++i) {
if ((oldpos+i >= 0) && (oldpos+i < old_size)) {
- new_data[newpos+i] += old_data[oldpos+i];
+ (*new_data)[newpos+i] += old_data[oldpos+i];
}
}
@@ -197,13 +224,13 @@
oldpos += ctrl[0];
// Sanity check
- if (newpos + ctrl[1] > new_size) {
+ if (newpos + ctrl[1] > *new_size) {
fprintf(stderr, "corrupt patch (new file overrun)\n");
return 1;
}
// Read extra string
- len_read = BZ2_bzRead(&bzerr, epfbz2, new_data + newpos, ctrl[1]);
+ len_read = BZ2_bzRead(&bzerr, epfbz2, *new_data + newpos, ctrl[1]);
if (len_read < ctrl[1] || !(bzerr == BZ_OK || bzerr == BZ_STREAM_END)) {
fprintf(stderr, "corrupt patch (read extra)\n");
return 1;
@@ -221,12 +248,5 @@
fclose(dpf);
fclose(epf);
- if (fwrite(new_data, 1, new_size, output) < new_size) {
- fprintf(stderr, "short write of output: %d (%s)\n", errno, strerror(errno));
- return 1;
- }
- SHA_update(ctx, new_data, new_size);
- free(new_data);
-
return 0;
}