fec: add --padding

[android-x86/system-extras.git] / verity / fec / image.cpp

diff --git a/verity/fec/image.cpp b/verity/fec/image.cpp
index 5c3eb8b..509b102 100644 (file)
--- a/verity/fec/image.cpp
+++ b/verity/fec/image.cpp
@@ -291,14 +291,11 @@ bool image_ecc_load(const std::string& filename, image *ctx)
 
 bool image_ecc_save(image *ctx)
 {
-    assert(sizeof(fec_header) <= FEC_BLOCKSIZE);
-
-    uint8_t header[FEC_BLOCKSIZE];
-    uint8_t *p = header;
+    assert(2 * sizeof(fec_header) <= FEC_BLOCKSIZE);
 
-    memset(p, 0, FEC_BLOCKSIZE);
+    uint8_t header[FEC_BLOCKSIZE] = {0};
 
-    fec_header *f = (fec_header *)p;
+    fec_header *f = (fec_header *)header;
 
     f->magic = FEC_MAGIC;
     f->version = FEC_VERSION;
@@ -310,7 +307,8 @@ bool image_ecc_save(image *ctx)
     SHA256(ctx->fec, ctx->fec_size, f->hash);
 
     /* store a copy of the fec_header at the end of the header block */
-    memcpy(&p[sizeof(header) - sizeof(fec_header)], p, sizeof(fec_header));
+    memcpy(&header[sizeof(header) - sizeof(fec_header)], header,
+        sizeof(fec_header));
 
     assert(ctx->fec_filename);
 
@@ -322,11 +320,24 @@ bool image_ecc_save(image *ctx)
             strerror(errno));
     }
 
-    if (!android::base::WriteFully(fd, ctx->fec, ctx->fec_size) ||
-        !android::base::WriteFully(fd, header, sizeof(header))) {
+    if (!android::base::WriteFully(fd, ctx->fec, ctx->fec_size)) {
         FATAL("failed to write to output: %s\n", strerror(errno));
     }
 
+    if (ctx->padding > 0) {
+        uint8_t padding[FEC_BLOCKSIZE] = {0};
+
+        for (uint32_t i = 0; i < ctx->padding; i += FEC_BLOCKSIZE) {
+            if (!android::base::WriteFully(fd, padding, FEC_BLOCKSIZE)) {
+                FATAL("failed to write padding: %s\n", strerror(errno));
+            }
+        }
+    }
+
+    if (!android::base::WriteFully(fd, header, sizeof(header))) {
+        FATAL("failed to write to header: %s\n", strerror(errno));
+    }
+
     close(fd);
 
     return true;