diff --git a/applypatch/applypatch.c b/applypatch/applypatch.c
index daf3729..99d3661 100644
--- a/applypatch/applypatch.c
+++ b/applypatch/applypatch.c
@@ -28,6 +28,7 @@
 #include "mincrypt/sha.h"
 #include "applypatch.h"
 #include "mtdutils/mtdutils.h"
+#include "edify/expr.h"
 
 int SaveFileContents(const char* filename, FileContents file);
 int LoadMTDContents(const char* filename, FileContents* file);
@@ -39,57 +40,57 @@
 // 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) {
-    printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
-    return -1;
-  }
-
-  file->size = file->st.st_size;
-  file->data = malloc(file->size);
-
-  FILE* f = fopen(filename, "rb");
-  if (f == NULL) {
-    printf("failed to open \"%s\": %s\n", filename, strerror(errno));
-    free(file->data);
     file->data = NULL;
-    return -1;
-  }
 
-  size_t bytes_read = fread(file->data, 1, file->size, f);
-  if (bytes_read != file->size) {
-    printf("short read of \"%s\" (%d bytes of %d)\n",
-            filename, bytes_read, file->size);
-    free(file->data);
-    file->data = NULL;
-    return -1;
-  }
-  fclose(f);
+    // 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);
+    }
 
-  SHA(file->data, file->size, file->sha1);
-  return 0;
+    if (stat(filename, &file->st) != 0) {
+        printf("failed to stat \"%s\": %s\n", filename, strerror(errno));
+        return -1;
+    }
+
+    file->size = file->st.st_size;
+    file->data = malloc(file->size);
+
+    FILE* f = fopen(filename, "rb");
+    if (f == NULL) {
+        printf("failed to open \"%s\": %s\n", filename, strerror(errno));
+        free(file->data);
+        file->data = NULL;
+        return -1;
+    }
+
+    ssize_t bytes_read = fread(file->data, 1, file->size, f);
+    if (bytes_read != file->size) {
+        printf("short read of \"%s\" (%ld bytes of %ld)\n",
+               filename, (long)bytes_read, (long)file->size);
+        free(file->data);
+        file->data = NULL;
+        return -1;
+    }
+    fclose(f);
+
+    SHA(file->data, file->size, file->sha1);
+    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;
-  }
+    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;
+    }
 }
 
 void FreeFileContents(FileContents* file) {
@@ -113,239 +114,240 @@
 // 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) {
-    printf("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;
+    char* copy = strdup(filename);
+    const char* magic = strtok(copy, ":");
+    if (strcmp(magic, "MTD") != 0) {
+        printf("LoadMTDContents called with bad filename (%s)\n",
+               filename);
+        return -1;
     }
-  }
-  if (colons < 3 || colons%2 == 0) {
-    printf("LoadMTDContents called with bad filename (%s)\n",
-            filename);
-  }
+    const char* partition = strtok(NULL, ":");
 
-  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) {
-      printf("LoadMTDContents called with bad size (%s)\n", filename);
-      return -1;
+    int i;
+    int colons = 0;
+    for (i = 0; filename[i] != '\0'; ++i) {
+        if (filename[i] == ':') {
+            ++colons;
+        }
     }
-    sha1sum[i] = strtok(NULL, ":");
-    index[i] = i;
-  }
+    if (colons < 3 || colons%2 == 0) {
+        printf("LoadMTDContents called with bad filename (%s)\n",
+               filename);
+    }
 
-  // sort the index[] array so it indexes the pairs in order of
-  // increasing size.
-  size_array = size;
-  qsort(index, pairs, sizeof(int), compare_size_indices);
+    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*));
 
-  if (!mtd_partitions_scanned) {
-    mtd_scan_partitions();
-    mtd_partitions_scanned = 1;
-  }
+    for (i = 0; i < pairs; ++i) {
+        const char* size_str = strtok(NULL, ":");
+        size[i] = strtol(size_str, NULL, 10);
+        if (size[i] == 0) {
+            printf("LoadMTDContents called with bad size (%s)\n", filename);
+            return -1;
+        }
+        sha1sum[i] = strtok(NULL, ":");
+        index[i] = i;
+    }
 
-  const MtdPartition* mtd = mtd_find_partition_by_name(partition);
-  if (mtd == NULL) {
-    printf("mtd partition \"%s\" not found (loading %s)\n",
-            partition, filename);
-    return -1;
-  }
+    // sort the index[] array so it indexes the pairs in order of
+    // increasing size.
+    size_array = size;
+    qsort(index, pairs, sizeof(int), compare_size_indices);
 
-  MtdReadContext* ctx = mtd_read_partition(mtd);
-  if (ctx == NULL) {
-    printf("failed to initialize read of mtd partition \"%s\"\n",
-            partition);
-    return -1;
-  }
+    if (!mtd_partitions_scanned) {
+        mtd_scan_partitions();
+        mtd_partitions_scanned = 1;
+    }
 
-  SHA_CTX sha_ctx;
-  SHA_init(&sha_ctx);
-  uint8_t parsed_sha[SHA_DIGEST_SIZE];
+    const MtdPartition* mtd = mtd_find_partition_by_name(partition);
+    if (mtd == NULL) {
+        printf("mtd partition \"%s\" not found (loading %s)\n",
+               partition, filename);
+        return -1;
+    }
 
-  // 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
+    MtdReadContext* ctx = mtd_read_partition(mtd);
+    if (ctx == NULL) {
+        printf("failed to initialize read of mtd partition \"%s\"\n",
+               partition);
+        return -1;
+    }
 
-  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) {
-        printf("short read (%d bytes of %d) for partition \"%s\"\n",
-                read, next, partition);
+    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) {
+                printf("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) {
+            printf("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.
+        printf("contents of MTD partition \"%s\" didn't match %s\n",
+               partition, filename);
         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) {
-      printf("failed to parse sha1 %s in %s\n",
-              sha1sum[index[i]], 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];
     }
 
-    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;
-    }
+    // Fake some stat() info.
+    file->st.st_mode = 0644;
+    file->st.st_uid = 0;
+    file->st.st_gid = 0;
 
-    p += read;
-  }
+    free(copy);
+    free(index);
+    free(size);
+    free(sha1sum);
 
-  mtd_read_close(ctx);
-
-  if (i == pairs) {
-    // Ran off the end of the list of (size,sha1) pairs without
-    // finding a match.
-    printf("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];
-  }
-
-  // Fake some stat() info.
-  file->st.st_mode = 0644;
-  file->st.st_uid = 0;
-  file->st.st_gid = 0;
-
-  free(copy);
-  free(index);
-  free(size);
-  free(sha1sum);
-
-  return 0;
+    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) {
-  int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC);
-  if (fd < 0) {
-    printf("failed to open \"%s\" for write: %s\n",
-            filename, strerror(errno));
-    return -1;
-  }
+    int fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC);
+    if (fd < 0) {
+        printf("failed to open \"%s\" for write: %s\n",
+               filename, strerror(errno));
+        return -1;
+    }
 
-  size_t bytes_written = FileSink(file.data, file.size, &fd);
-  if (bytes_written != file.size) {
-    printf("short write of \"%s\" (%d bytes of %d) (%s)\n",
-           filename, bytes_written, file.size, strerror(errno));
+    ssize_t bytes_written = FileSink(file.data, file.size, &fd);
+    if (bytes_written != file.size) {
+        printf("short write of \"%s\" (%ld bytes of %ld) (%s)\n",
+               filename, (long)bytes_written, (long)file.size,
+               strerror(errno));
+        close(fd);
+        return -1;
+    }
+    fsync(fd);
     close(fd);
-    return -1;
-  }
-  fsync(fd);
-  close(fd);
 
-  if (chmod(filename, file.st.st_mode) != 0) {
-    printf("chmod of \"%s\" failed: %s\n", filename, strerror(errno));
-    return -1;
-  }
-  if (chown(filename, file.st.st_uid, file.st.st_gid) != 0) {
-    printf("chown of \"%s\" failed: %s\n", filename, strerror(errno));
-    return -1;
-  }
+    if (chmod(filename, file.st.st_mode) != 0) {
+        printf("chmod of \"%s\" failed: %s\n", filename, strerror(errno));
+        return -1;
+    }
+    if (chown(filename, file.st.st_uid, file.st.st_gid) != 0) {
+        printf("chown of \"%s\" failed: %s\n", filename, strerror(errno));
+        return -1;
+    }
 
-  return 0;
+    return 0;
 }
 
 // Write a memory buffer to target_mtd partition, a string of the form
 // "MTD:<partition>[:...]".  Return 0 on success.
 int WriteToMTDPartition(unsigned char* data, size_t len,
                         const char* target_mtd) {
-  char* partition = strchr(target_mtd, ':');
-  if (partition == NULL) {
-    printf("bad MTD target name \"%s\"\n", target_mtd);
-    return -1;
-  }
-  ++partition;
-  // Trim off anything after a colon, eg "MTD:boot:blah:blah:blah...".
-  // We want just the partition name "boot".
-  partition = strdup(partition);
-  char* end = strchr(partition, ':');
-  if (end != NULL)
-    *end = '\0';
+    char* partition = strchr(target_mtd, ':');
+    if (partition == NULL) {
+        printf("bad MTD target name \"%s\"\n", target_mtd);
+        return -1;
+    }
+    ++partition;
+    // Trim off anything after a colon, eg "MTD:boot:blah:blah:blah...".
+    // We want just the partition name "boot".
+    partition = strdup(partition);
+    char* end = strchr(partition, ':');
+    if (end != NULL)
+        *end = '\0';
 
-  if (!mtd_partitions_scanned) {
-    mtd_scan_partitions();
-    mtd_partitions_scanned = 1;
-  }
+    if (!mtd_partitions_scanned) {
+        mtd_scan_partitions();
+        mtd_partitions_scanned = 1;
+    }
 
-  const MtdPartition* mtd = mtd_find_partition_by_name(partition);
-  if (mtd == NULL) {
-    printf("mtd partition \"%s\" not found for writing\n", partition);
-    return -1;
-  }
+    const MtdPartition* mtd = mtd_find_partition_by_name(partition);
+    if (mtd == NULL) {
+        printf("mtd partition \"%s\" not found for writing\n", partition);
+        return -1;
+    }
 
-  MtdWriteContext* ctx = mtd_write_partition(mtd);
-  if (ctx == NULL) {
-    printf("failed to init mtd partition \"%s\" for writing\n",
-            partition);
-    return -1;
-  }
+    MtdWriteContext* ctx = mtd_write_partition(mtd);
+    if (ctx == NULL) {
+        printf("failed to init mtd partition \"%s\" for writing\n",
+               partition);
+        return -1;
+    }
 
-  size_t written = mtd_write_data(ctx, (char*)data, len);
-  if (written != len) {
-    printf("only wrote %d of %d bytes to MTD %s\n",
-            written, len, partition);
-    mtd_write_close(ctx);
-    return -1;
-  }
+    size_t written = mtd_write_data(ctx, (char*)data, len);
+    if (written != len) {
+        printf("only wrote %d of %d bytes to MTD %s\n",
+               written, len, partition);
+        mtd_write_close(ctx);
+        return -1;
+    }
 
-  if (mtd_erase_blocks(ctx, -1) < 0) {
-    printf("error finishing mtd write of %s\n", partition);
-    mtd_write_close(ctx);
-    return -1;
-  }
+    if (mtd_erase_blocks(ctx, -1) < 0) {
+        printf("error finishing mtd write of %s\n", partition);
+        mtd_write_close(ctx);
+        return -1;
+    }
 
-  if (mtd_write_close(ctx)) {
-    printf("error closing mtd write of %s\n", partition);
-    return -1;
-  }
+    if (mtd_write_close(ctx)) {
+        printf("error closing mtd write of %s\n", partition);
+        return -1;
+    }
 
-  free(partition);
-  return 0;
+    free(partition);
+    return 0;
 }
 
 
@@ -354,547 +356,460 @@
 // the form "<digest>:<anything>".  Return 0 on success, -1 on any
 // error.
 int ParseSha1(const char* str, uint8_t* digest) {
-  int i;
-  const char* ps = str;
-  uint8_t* pd = digest;
-  for (i = 0; i < SHA_DIGEST_SIZE * 2; ++i, ++ps) {
-    int digit;
-    if (*ps >= '0' && *ps <= '9') {
-      digit = *ps - '0';
-    } else if (*ps >= 'a' && *ps <= 'f') {
-      digit = *ps - 'a' + 10;
-    } else if (*ps >= 'A' && *ps <= 'F') {
-      digit = *ps - 'A' + 10;
-    } else {
-      return -1;
+    int i;
+    const char* ps = str;
+    uint8_t* pd = digest;
+    for (i = 0; i < SHA_DIGEST_SIZE * 2; ++i, ++ps) {
+        int digit;
+        if (*ps >= '0' && *ps <= '9') {
+            digit = *ps - '0';
+        } else if (*ps >= 'a' && *ps <= 'f') {
+            digit = *ps - 'a' + 10;
+        } else if (*ps >= 'A' && *ps <= 'F') {
+            digit = *ps - 'A' + 10;
+        } else {
+            return -1;
+        }
+        if (i % 2 == 0) {
+            *pd = digit << 4;
+        } else {
+            *pd |= digit;
+            ++pd;
+        }
     }
-    if (i % 2 == 0) {
-      *pd = digit << 4;
-    } else {
-      *pd |= digit;
-      ++pd;
-    }
-  }
-  if (*ps != '\0' && *ps != ':') return -1;
-  return 0;
+    if (*ps != '\0') return -1;
+    return 0;
 }
 
-// Parse arguments (which should be of the form "<sha1>" or
-// "<sha1>:<filename>" into the array *patches, returning the number
-// of Patch objects in *num_patches.  Return 0 on success.
-int ParseShaArgs(int argc, char** argv, Patch** patches, int* num_patches) {
-  *num_patches = argc;
-  *patches = malloc(*num_patches * sizeof(Patch));
-
-  int i;
-  for (i = 0; i < *num_patches; ++i) {
-    if (ParseSha1(argv[i], (*patches)[i].sha1) != 0) {
-      printf("failed to parse sha1 \"%s\"\n", argv[i]);
-      return -1;
+// Search an array of sha1 strings for one matching the given sha1.
+// Return the index of the match on success, or -1 if no match is
+// found.
+int FindMatchingPatch(uint8_t* sha1, char** const patch_sha1_str,
+                      int num_patches) {
+    int i;
+    uint8_t patch_sha1[SHA_DIGEST_SIZE];
+    for (i = 0; i < num_patches; ++i) {
+        if (ParseSha1(patch_sha1_str[i], patch_sha1) == 0 &&
+            memcmp(patch_sha1, sha1, SHA_DIGEST_SIZE) == 0) {
+            return i;
+        }
     }
-    if (argv[i][SHA_DIGEST_SIZE*2] == '\0') {
-      (*patches)[i].patch_filename = NULL;
-    } else if (argv[i][SHA_DIGEST_SIZE*2] == ':') {
-      (*patches)[i].patch_filename = argv[i] + (SHA_DIGEST_SIZE*2+1);
-    } else {
-      printf("failed to parse filename \"%s\"\n", argv[i]);
-      return -1;
-    }
-  }
-
-  return 0;
-}
-
-// Search an array of Patch objects for one matching the given sha1.
-// Return the Patch object on success, or NULL if no match is found.
-const Patch* FindMatchingPatch(uint8_t* sha1, Patch* patches, int num_patches) {
-  int i;
-  for (i = 0; i < num_patches; ++i) {
-    if (memcmp(patches[i].sha1, sha1, SHA_DIGEST_SIZE) == 0) {
-      return patches+i;
-    }
-  }
-  return NULL;
+    return -1;
 }
 
 // Returns 0 if the contents of the file (argv[2]) or the cached file
 // match any of the sha1's on the command line (argv[3:]).  Returns
 // nonzero otherwise.
-int CheckMode(int argc, char** argv) {
-  if (argc < 3) {
-    printf("no filename given\n");
-    return 2;
-  }
+int applypatch_check(const char* filename,
+                     int num_patches, char** const patch_sha1_str) {
+    FileContents file;
+    file.data = NULL;
 
-  int num_patches;
-  Patch* patches;
-  if (ParseShaArgs(argc-3, argv+3, &patches, &num_patches) != 0) { return 1; }
+    // 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(filename, &file) != 0 ||
+        (num_patches > 0 &&
+         FindMatchingPatch(file.sha1, patch_sha1_str, num_patches) < 0)) {
+        printf("file \"%s\" doesn't have any of expected "
+               "sha1 sums; checking cache\n", filename);
 
-  FileContents file;
-  file.data = NULL;
+        free(file.data);
 
-  // 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 ||
-      (num_patches > 0 &&
-       FindMatchingPatch(file.sha1, patches, num_patches) == NULL)) {
-    printf("file \"%s\" doesn't have any of expected "
-            "sha1 sums; checking cache\n", argv[2]);
+        // If the source file is missing or corrupted, it might be because
+        // we were killed in the middle of patching it.  A copy of it
+        // should have been made in CACHE_TEMP_SOURCE.  If that file
+        // exists and matches the sha1 we're looking for, the check still
+        // passes.
+
+        if (LoadFileContents(CACHE_TEMP_SOURCE, &file) != 0) {
+            printf("failed to load cache file\n");
+            return 1;
+        }
+
+        if (FindMatchingPatch(file.sha1, patch_sha1_str, num_patches) < 0) {
+            printf("cache bits don't match any sha1 for \"%s\"\n", filename);
+            free(file.data);
+            return 1;
+        }
+    }
 
     free(file.data);
-
-    // If the source file is missing or corrupted, it might be because
-    // we were killed in the middle of patching it.  A copy of it
-    // should have been made in CACHE_TEMP_SOURCE.  If that file
-    // exists and matches the sha1 we're looking for, the check still
-    // passes.
-
-    if (LoadFileContents(CACHE_TEMP_SOURCE, &file) != 0) {
-      printf("failed to load cache file\n");
-      return 1;
-    }
-
-    if (FindMatchingPatch(file.sha1, patches, num_patches) == NULL) {
-      printf("cache bits don't match any sha1 for \"%s\"\n",
-              argv[2]);
-      return 1;
-    }
-  }
-
-  free(file.data);
-  return 0;
+    return 0;
 }
 
 int ShowLicenses() {
-  ShowBSDiffLicense();
-  return 0;
+    ShowBSDiffLicense();
+    return 0;
 }
 
 ssize_t FileSink(unsigned char* data, ssize_t len, void* token) {
-  int fd = *(int *)token;
-  ssize_t done = 0;
-  ssize_t wrote;
-  while (done < (ssize_t) len) {
-    wrote = write(fd, data+done, len-done);
-    if (wrote <= 0) {
-      printf("error writing %d bytes: %s\n", (int)(len-done), strerror(errno));
-      return done;
+    int fd = *(int *)token;
+    ssize_t done = 0;
+    ssize_t wrote;
+    while (done < (ssize_t) len) {
+        wrote = write(fd, data+done, len-done);
+        if (wrote <= 0) {
+            printf("error writing %d bytes: %s\n", (int)(len-done), strerror(errno));
+            return done;
+        }
+        done += wrote;
     }
-    done += wrote;
-  }
-  printf("wrote %d bytes to output\n", (int)done);
-  return done;
+    return done;
 }
 
 typedef struct {
-  unsigned char* buffer;
-  ssize_t size;
-  ssize_t pos;
+    unsigned char* buffer;
+    ssize_t size;
+    ssize_t pos;
 } MemorySinkInfo;
 
 ssize_t MemorySink(unsigned char* data, ssize_t len, void* token) {
-  MemorySinkInfo* msi = (MemorySinkInfo*)token;
-  if (msi->size - msi->pos < len) {
-    return -1;
-  }
-  memcpy(msi->buffer + msi->pos, data, len);
-  msi->pos += len;
-  return len;
+    MemorySinkInfo* msi = (MemorySinkInfo*)token;
+    if (msi->size - msi->pos < len) {
+        return -1;
+    }
+    memcpy(msi->buffer + msi->pos, data, len);
+    msi->pos += len;
+    return len;
 }
 
 // Return the amount of free space (in bytes) on the filesystem
 // containing filename.  filename must exist.  Return -1 on error.
 size_t FreeSpaceForFile(const char* filename) {
-  struct statfs sf;
-  if (statfs(filename, &sf) != 0) {
-    printf("failed to statfs %s: %s\n", filename, strerror(errno));
-    return -1;
-  }
-  return sf.f_bsize * sf.f_bfree;
+    struct statfs sf;
+    if (statfs(filename, &sf) != 0) {
+        printf("failed to statfs %s: %s\n", filename, strerror(errno));
+        return -1;
+    }
+    return sf.f_bsize * sf.f_bfree;
 }
 
-// This program applies binary patches to files in a way that is safe
+int CacheSizeCheck(size_t bytes) {
+    if (MakeFreeSpaceOnCache(bytes) < 0) {
+        printf("unable to make %ld bytes available on /cache\n", (long)bytes);
+        return 1;
+    } else {
+        return 0;
+    }
+}
+
+
+// This function applies binary patches to files in a way that is safe
 // (the original file is not touched until we have the desired
 // replacement for it) and idempotent (it's okay to run this program
 // multiple times).
 //
-// - if the sha1 hash of <tgt-file> is <tgt-sha1>, does nothing and exits
-//   successfully.
+// - if the sha1 hash of <target_filename> is <target_sha1_string>,
+//   does nothing and exits successfully.
 //
-// - otherwise, if the sha1 hash of <src-file> is <src-sha1>, applies the
-//   bsdiff <patch> to <src-file> to produce a new file (the type of patch
-//   is automatically detected from the file header).  If that new
-//   file has sha1 hash <tgt-sha1>, moves it to replace <tgt-file>, and
-//   exits successfully.  Note that if <src-file> and <tgt-file> are
-//   not the same, <src-file> is NOT deleted on success.  <tgt-file>
-//   may be the string "-" to mean "the same as src-file".
+// - otherwise, if the sha1 hash of <source_filename> is one of the
+//   entries in <patch_sha1_str>, the corresponding patch from
+//   <patch_data> (which must be a VAL_BLOB) is applied to produce a
+//   new file (the type of patch is automatically detected from the
+//   blob daat).  If that new file has sha1 hash <target_sha1_str>,
+//   moves it to replace <target_filename>, and exits successfully.
+//   Note that if <source_filename> and <target_filename> are not the
+//   same, <source_filename> is NOT deleted on success.
+//   <target_filename> may be the string "-" to mean "the same as
+//   source_filename".
 //
 // - 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.
-//
-//
-// As you might guess from the arguments, this function used to be
-// main(); it was split out this way so applypatch could be built as a
-// static library and linked into other executables as well.  In the
-// future only the library form will exist; we will not need to build
-// this as a standalone executable.
-//
-// The arguments to this function are just the command-line of the
-// standalone executable:
-//
-// <src-file> <tgt-file> <tgt-sha1> <tgt-size> [<src-sha1>:<patch> ...]
-//    to apply a patch.  Returns 0 on success, 1 on failure.
-//
-// "-c" <file> [<sha1> ...]
-//    to check a file's contents against zero or more sha1s.  Returns
-//    0 if it matches any of them, 1 if it doesn't.
-//
-// "-s" <bytes>
-//    returns 0 if enough free space is available on /cache; 1 if it
-//    does not.
-//
-// "-l"
-//    shows open-source license information and returns 0.
-//
-// This function returns 2 if the arguments are not understood (in the
-// standalone executable, this causes the usage message to be
-// printed).
-//
-// TODO: make the interface more sensible for use as a library.
+// <source_filename> 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 applypatch(int argc, char** argv) {
-  if (argc < 2) {
-    return 2;
-  }
+int applypatch(const char* source_filename,
+               const char* target_filename,
+               const char* target_sha1_str,
+               size_t target_size,
+               int num_patches,
+               char** const patch_sha1_str,
+               Value** patch_data) {
+    printf("\napplying patch to %s\n", source_filename);
 
-  if (strncmp(argv[1], "-l", 3) == 0) {
-    return ShowLicenses();
-  }
-
-  if (strncmp(argv[1], "-c", 3) == 0) {
-    return CheckMode(argc, argv);
-  }
-
-  if (strncmp(argv[1], "-s", 3) == 0) {
-    if (argc != 3) {
-      return 2;
-    }
-    size_t bytes = strtol(argv[2], NULL, 10);
-    if (MakeFreeSpaceOnCache(bytes) < 0) {
-      printf("unable to make %ld bytes available on /cache\n", (long)bytes);
-      return 1;
-    } else {
-      return 0;
-    }
-  }
-
-  uint8_t target_sha1[SHA_DIGEST_SIZE];
-
-  const char* source_filename = argv[1];
-  const char* target_filename = argv[2];
-  if (target_filename[0] == '-' &&
-      target_filename[1] == '\0') {
-    target_filename = source_filename;
-  }
-
-  printf("\napplying patch to %s\n", source_filename);
-
-  if (ParseSha1(argv[3], target_sha1) != 0) {
-    printf("failed to parse tgt-sha1 \"%s\"\n", argv[3]);
-    return 1;
-  }
-
-  unsigned long target_size = strtoul(argv[4], NULL, 0);
-
-  int num_patches;
-  Patch* patches;
-  if (ParseShaArgs(argc-5, argv+5, &patches, &num_patches) < 0) { return 1; }
-
-  FileContents copy_file;
-  FileContents source_file;
-  const char* source_patch_filename = NULL;
-  const char* copy_patch_filename = NULL;
-  int made_copy = 0;
-
-  // We try to load the target file into the source_file object.
-  if (LoadFileContents(target_filename, &source_file) == 0) {
-    if (memcmp(source_file.sha1, target_sha1, SHA_DIGEST_SIZE) == 0) {
-      // The early-exit case:  the patch was already applied, this file
-      // has the desired hash, nothing for us to do.
-      printf("\"%s\" is already target; no patch needed\n",
-              target_filename);
-      return 0;
-    }
-  }
-
-  if (source_file.data == NULL ||
-      (target_filename != source_filename &&
-       strcmp(target_filename, source_filename) != 0)) {
-    // Need to load the source file:  either we failed to load the
-    // target file, or we did but it's different from the source file.
-    free(source_file.data);
-    LoadFileContents(source_filename, &source_file);
-  }
-
-  if (source_file.data != NULL) {
-    const Patch* to_use =
-        FindMatchingPatch(source_file.sha1, patches, num_patches);
-    if (to_use != NULL) {
-      source_patch_filename = to_use->patch_filename;
-    }
-  }
-
-  if (source_patch_filename == NULL) {
-    free(source_file.data);
-    printf("source file is bad; trying copy\n");
-
-    if (LoadFileContents(CACHE_TEMP_SOURCE, &copy_file) < 0) {
-      // fail.
-      printf("failed to read copy file\n");
-      return 1;
+    if (target_filename[0] == '-' &&
+        target_filename[1] == '\0') {
+        target_filename = source_filename;
     }
 
-    const Patch* to_use =
-        FindMatchingPatch(copy_file.sha1, patches, num_patches);
-    if (to_use != NULL) {
-      copy_patch_filename = to_use->patch_filename;
-    }
-
-    if (copy_patch_filename == NULL) {
-      // fail.
-      printf("copy file doesn't match source SHA-1s either\n");
-      return 1;
-    }
-  }
-
-  int retry = 1;
-  SHA_CTX ctx;
-  int output;
-  MemorySinkInfo msi;
-  FileContents* source_to_use;
-  char* outname;
-
-  // assume that target_filename (eg "/system/app/Foo.apk") is located
-  // on the same filesystem as its top-level directory ("/system").
-  // We need something that exists for calling statfs().
-  char target_fs[strlen(target_filename)+1];
-  char* slash = strchr(target_filename+1, '/');
-  if (slash != NULL) {
-    int count = slash - target_filename;
-    strncpy(target_fs, target_filename, count);
-    target_fs[count] = '\0';
-  } else {
-    strcpy(target_fs, target_filename);
-  }
-
-  do {
-    // Is there enough room in the target filesystem to hold the patched
-    // file?
-
-    if (strncmp(target_filename, "MTD:", 4) == 0) {
-      // If the target is an MTD partition, we're actually going to
-      // write the output to /tmp and then copy it to the partition.
-      // statfs() always returns 0 blocks free for /tmp, so instead
-      // we'll just assume that /tmp has enough space to hold the file.
-
-      // We still write the original source to cache, in case the MTD
-      // write is interrupted.
-      if (MakeFreeSpaceOnCache(source_file.size) < 0) {
-        printf("not enough free space on /cache\n");
+    uint8_t target_sha1[SHA_DIGEST_SIZE];
+    if (ParseSha1(target_sha1_str, target_sha1) != 0) {
+        printf("failed to parse tgt-sha1 \"%s\"\n", target_sha1_str);
         return 1;
-      }
-      if (SaveFileContents(CACHE_TEMP_SOURCE, source_file) < 0) {
-        printf("failed to back up source file\n");
-        return 1;
-      }
-      made_copy = 1;
-      retry = 0;
-    } else {
-      int enough_space = 0;
-      if (retry > 0) {
-        size_t free_space = FreeSpaceForFile(target_fs);
-        int enough_space =
-          (free_space > (target_size * 3 / 2));  // 50% margin of error
-        printf("target %ld bytes; free space %ld bytes; retry %d; enough %d\n",
-               (long)target_size, (long)free_space, retry, enough_space);
-      }
+    }
 
-      if (!enough_space) {
-        retry = 0;
-      }
+    FileContents copy_file;
+    FileContents source_file;
+    const Value* source_patch_value = NULL;
+    const Value* copy_patch_value = NULL;
+    int made_copy = 0;
 
-      if (!enough_space && source_patch_filename != NULL) {
-        // Using the original source, but not enough free space.  First
-        // copy the source file to cache, then delete it from the original
-        // location.
+    // We try to load the target file into the source_file object.
+    if (LoadFileContents(target_filename, &source_file) == 0) {
+        if (memcmp(source_file.sha1, target_sha1, SHA_DIGEST_SIZE) == 0) {
+            // The early-exit case:  the patch was already applied, this file
+            // has the desired hash, nothing for us to do.
+            printf("\"%s\" is already target; no patch needed\n",
+                   target_filename);
+            return 0;
+        }
+    }
 
-        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.
-          printf("not enough free space for target but source is MTD\n");
-          return 1;
+    if (source_file.data == NULL ||
+        (target_filename != source_filename &&
+         strcmp(target_filename, source_filename) != 0)) {
+        // Need to load the source file:  either we failed to load the
+        // target file, or we did but it's different from the source file.
+        free(source_file.data);
+        LoadFileContents(source_filename, &source_file);
+    }
+
+    if (source_file.data != NULL) {
+        int to_use = FindMatchingPatch(source_file.sha1,
+                                       patch_sha1_str, num_patches);
+        if (to_use >= 0) {
+            source_patch_value = patch_data[to_use];
+        }
+    }
+
+    if (source_patch_value == NULL) {
+        free(source_file.data);
+        printf("source file is bad; trying copy\n");
+
+        if (LoadFileContents(CACHE_TEMP_SOURCE, &copy_file) < 0) {
+            // fail.
+            printf("failed to read copy file\n");
+            return 1;
         }
 
-        if (MakeFreeSpaceOnCache(source_file.size) < 0) {
-          printf("not enough free space on /cache\n");
-          return 1;
+        int to_use = FindMatchingPatch(copy_file.sha1,
+                                       patch_sha1_str, num_patches);
+        if (to_use > 0) {
+            copy_patch_value = patch_data[to_use];
         }
 
-        if (SaveFileContents(CACHE_TEMP_SOURCE, source_file) < 0) {
-          printf("failed to back up source file\n");
-          return 1;
+        if (copy_patch_value == NULL) {
+            // fail.
+            printf("copy file doesn't match source SHA-1s either\n");
+            return 1;
         }
-        made_copy = 1;
-        unlink(source_filename);
-
-        size_t free_space = FreeSpaceForFile(target_fs);
-        printf("(now %ld bytes free for target)\n", (long)free_space);
-      }
     }
 
-    const char* patch_filename;
-    if (source_patch_filename != NULL) {
-      source_to_use = &source_file;
-      patch_filename = source_patch_filename;
+    int retry = 1;
+    SHA_CTX ctx;
+    int output;
+    MemorySinkInfo msi;
+    FileContents* source_to_use;
+    char* outname;
+
+    // assume that target_filename (eg "/system/app/Foo.apk") is located
+    // on the same filesystem as its top-level directory ("/system").
+    // We need something that exists for calling statfs().
+    char target_fs[strlen(target_filename)+1];
+    char* slash = strchr(target_filename+1, '/');
+    if (slash != NULL) {
+        int count = slash - target_filename;
+        strncpy(target_fs, target_filename, count);
+        target_fs[count] = '\0';
     } else {
-      source_to_use = &copy_file;
-      patch_filename = copy_patch_filename;
+        strcpy(target_fs, target_filename);
     }
 
-    SinkFn sink = NULL;
-    void* token = NULL;
-    output = -1;
-    outname = NULL;
-    if (strncmp(target_filename, "MTD:", 4) == 0) {
-      // We store the decoded output in memory.
-      msi.buffer = malloc(target_size);
-      if (msi.buffer == NULL) {
-        printf("failed to alloc %ld bytes for output\n",
-               (long)target_size);
+    do {
+        // Is there enough room in the target filesystem to hold the patched
+        // file?
+
+        if (strncmp(target_filename, "MTD:", 4) == 0) {
+            // If the target is an MTD partition, we're actually going to
+            // write the output to /tmp and then copy it to the partition.
+            // statfs() always returns 0 blocks free for /tmp, so instead
+            // we'll just assume that /tmp has enough space to hold the file.
+
+            // We still write the original source to cache, in case the MTD
+            // write is interrupted.
+            if (MakeFreeSpaceOnCache(source_file.size) < 0) {
+                printf("not enough free space on /cache\n");
+                return 1;
+            }
+            if (SaveFileContents(CACHE_TEMP_SOURCE, source_file) < 0) {
+                printf("failed to back up source file\n");
+                return 1;
+            }
+            made_copy = 1;
+            retry = 0;
+        } else {
+            int enough_space = 0;
+            if (retry > 0) {
+                size_t free_space = FreeSpaceForFile(target_fs);
+                int enough_space =
+                    (free_space > (target_size * 3 / 2));  // 50% margin of error
+                printf("target %ld bytes; free space %ld bytes; retry %d; enough %d\n",
+                       (long)target_size, (long)free_space, retry, enough_space);
+            }
+
+            if (!enough_space) {
+                retry = 0;
+            }
+
+            if (!enough_space && source_patch_value != NULL) {
+                // 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.
+                    printf("not enough free space for target but source is MTD\n");
+                    return 1;
+                }
+
+                if (MakeFreeSpaceOnCache(source_file.size) < 0) {
+                    printf("not enough free space on /cache\n");
+                    return 1;
+                }
+
+                if (SaveFileContents(CACHE_TEMP_SOURCE, source_file) < 0) {
+                    printf("failed to back up source file\n");
+                    return 1;
+                }
+                made_copy = 1;
+                unlink(source_filename);
+
+                size_t free_space = FreeSpaceForFile(target_fs);
+                printf("(now %ld bytes free for target)\n", (long)free_space);
+            }
+        }
+
+        const Value* patch;
+        if (source_patch_value != NULL) {
+            source_to_use = &source_file;
+            patch = source_patch_value;
+        } else {
+            source_to_use = &copy_file;
+            patch = copy_patch_value;
+        }
+
+        if (patch->type != VAL_BLOB) {
+            printf("patch is not a blob\n");
+            return 1;
+        }
+
+        SinkFn sink = NULL;
+        void* token = NULL;
+        output = -1;
+        outname = NULL;
+        if (strncmp(target_filename, "MTD:", 4) == 0) {
+            // We store the decoded output in memory.
+            msi.buffer = malloc(target_size);
+            if (msi.buffer == NULL) {
+                printf("failed to alloc %ld bytes for output\n",
+                       (long)target_size);
+                return 1;
+            }
+            msi.pos = 0;
+            msi.size = target_size;
+            sink = MemorySink;
+            token = &msi;
+        } else {
+            // We write the decoded output to "<tgt-file>.patch".
+            outname = (char*)malloc(strlen(target_filename) + 10);
+            strcpy(outname, target_filename);
+            strcat(outname, ".patch");
+
+            output = open(outname, O_WRONLY | O_CREAT | O_TRUNC);
+            if (output < 0) {
+                printf("failed to open output file %s: %s\n",
+                       outname, strerror(errno));
+                return 1;
+            }
+            sink = FileSink;
+            token = &output;
+        }
+
+        char* header = patch->data;
+        ssize_t header_bytes_read = patch->size;
+
+        SHA_init(&ctx);
+
+        int result;
+
+        if (header_bytes_read >= 8 &&
+            memcmp(header, "BSDIFF40", 8) == 0) {
+            result = ApplyBSDiffPatch(source_to_use->data, source_to_use->size,
+                                      patch, 0, sink, token, &ctx);
+        } else if (header_bytes_read >= 8 &&
+                   memcmp(header, "IMGDIFF2", 8) == 0) {
+            result = ApplyImagePatch(source_to_use->data, source_to_use->size,
+                                     patch, sink, token, &ctx);
+        } else {
+            printf("Unknown patch file format\n");
+            return 1;
+        }
+
+        if (output >= 0) {
+            fsync(output);
+            close(output);
+        }
+
+        if (result != 0) {
+            if (retry == 0) {
+                printf("applying patch failed\n");
+                return result != 0;
+            } else {
+                printf("applying patch failed; retrying\n");
+            }
+            if (outname != NULL) {
+                unlink(outname);
+            }
+        } else {
+            // succeeded; no need to retry
+            break;
+        }
+    } while (retry-- > 0);
+
+    const uint8_t* current_target_sha1 = SHA_final(&ctx);
+    if (memcmp(current_target_sha1, target_sha1, SHA_DIGEST_SIZE) != 0) {
+        printf("patch did not produce expected sha1\n");
         return 1;
-      }
-      msi.pos = 0;
-      msi.size = target_size;
-      sink = MemorySink;
-      token = &msi;
+    }
+
+    if (output < 0) {
+        // Copy the temp file to the MTD partition.
+        if (WriteToMTDPartition(msi.buffer, msi.pos, target_filename) != 0) {
+            printf("write of patched data to %s failed\n", target_filename);
+            return 1;
+        }
+        free(msi.buffer);
     } else {
-      // We write the decoded output to "<tgt-file>.patch".
-      outname = (char*)malloc(strlen(target_filename) + 10);
-      strcpy(outname, target_filename);
-      strcat(outname, ".patch");
+        // Give the .patch file the same owner, group, and mode of the
+        // original source file.
+        if (chmod(outname, source_to_use->st.st_mode) != 0) {
+            printf("chmod of \"%s\" failed: %s\n", outname, strerror(errno));
+            return 1;
+        }
+        if (chown(outname, source_to_use->st.st_uid,
+                  source_to_use->st.st_gid) != 0) {
+            printf("chown of \"%s\" failed: %s\n", outname, strerror(errno));
+            return 1;
+        }
 
-      output = open(outname, O_WRONLY | O_CREAT | O_TRUNC);
-      if (output < 0) {
-        printf("failed to open output file %s: %s\n",
-               outname, strerror(errno));
-        return 1;
-      }
-      sink = FileSink;
-      token = &output;
+        // Finally, rename the .patch file to replace the target file.
+        if (rename(outname, target_filename) != 0) {
+            printf("rename of .patch to \"%s\" failed: %s\n",
+                   target_filename, strerror(errno));
+            return 1;
+        }
     }
 
-#define MAX_HEADER_LENGTH 8
-    unsigned char header[MAX_HEADER_LENGTH];
-    FILE* patchf = fopen(patch_filename, "rb");
-    if (patchf == NULL) {
-      printf("failed to open patch file %s: %s\n",
-             patch_filename, strerror(errno));
-      return 1;
-    }
-    int header_bytes_read = fread(header, 1, MAX_HEADER_LENGTH, patchf);
-    fclose(patchf);
+    // If this run of applypatch created the copy, and we're here, we
+    // can delete it.
+    if (made_copy) unlink(CACHE_TEMP_SOURCE);
 
-    SHA_init(&ctx);
-
-    int result;
-
-    if (header_bytes_read >= 4 &&
-        header[0] == 0xd6 && header[1] == 0xc3 &&
-        header[2] == 0xc4 && header[3] == 0) {
-      // xdelta3 patches begin "VCD" (with the high bits set) followed
-      // by a zero byte (the version number).
-      printf("error:  xdelta3 patches no longer supported\n");
-      return 1;
-    } else if (header_bytes_read >= 8 &&
-               memcmp(header, "BSDIFF40", 8) == 0) {
-      result = ApplyBSDiffPatch(source_to_use->data, source_to_use->size,
-                                    patch_filename, 0, sink, token, &ctx);
-    } else if (header_bytes_read >= 8 &&
-               memcmp(header, "IMGDIFF", 7) == 0 &&
-               (header[7] == '1' || header[7] == '2')) {
-      result = ApplyImagePatch(source_to_use->data, source_to_use->size,
-                                   patch_filename, sink, token, &ctx);
-    } else {
-      printf("Unknown patch file format\n");
-      return 1;
-    }
-
-    if (output >= 0) {
-      fsync(output);
-      close(output);
-    }
-
-    if (result != 0) {
-      if (retry == 0) {
-        printf("applying patch failed\n");
-        return result != 0;
-      } else {
-        printf("applying patch failed; retrying\n");
-      }
-      if (outname != NULL) {
-        unlink(outname);
-      }
-    } else {
-      // succeeded; no need to retry
-      break;
-    }
-  } while (retry-- > 0);
-
-  const uint8_t* current_target_sha1 = SHA_final(&ctx);
-  if (memcmp(current_target_sha1, target_sha1, SHA_DIGEST_SIZE) != 0) {
-    printf("patch did not produce expected sha1\n");
-    return 1;
-  }
-
-  if (output < 0) {
-    // Copy the temp file to the MTD partition.
-    if (WriteToMTDPartition(msi.buffer, msi.pos, target_filename) != 0) {
-      printf("write of patched data to %s failed\n", target_filename);
-      return 1;
-    }
-    free(msi.buffer);
-  } else {
-    // Give the .patch file the same owner, group, and mode of the
-    // original source file.
-    if (chmod(outname, source_to_use->st.st_mode) != 0) {
-      printf("chmod of \"%s\" failed: %s\n", outname, strerror(errno));
-      return 1;
-    }
-    if (chown(outname, source_to_use->st.st_uid,
-              source_to_use->st.st_gid) != 0) {
-      printf("chown of \"%s\" failed: %s\n", outname, strerror(errno));
-      return 1;
-    }
-
-    // Finally, rename the .patch file to replace the target file.
-    if (rename(outname, target_filename) != 0) {
-      printf("rename of .patch to \"%s\" failed: %s\n",
-              target_filename, strerror(errno));
-      return 1;
-    }
-  }
-
-  // If this run of applypatch created the copy, and we're here, we
-  // can delete it.
-  if (made_copy) unlink(CACHE_TEMP_SOURCE);
-
-  // Success!
-  return 0;
+    // Success!
+    return 0;
 }