commit 4649072b1b33d5e3f704badf76e5d7bf040d6f59
author Fabio Utzig <utzig@apache.org> Mon Sep 04 15:34:32 2017 -0300
committer David Brown <davidb@davidb.org> Wed Sep 06 16:16:58 2017 -0600
tree c5091e1e7fa4105bf291c7a6dfffe9311aa48ae0
parent 2eebf110ddef0ba0896d9c5584aff721b44d2f5d

Adds total size of a swap to the trailer

When starting a swap upgrade, the total size of data to be swapped is
calculated only at the beginning and saved to the trailer. This avoids
having to use complicated heuristics to find the total swap size, which
might depend on data that was already moved. When resuming a swap, the
size is found in the trailer and used.

Also includes some small comment fixes and refactors.

Signed-off-by: Fabio Utzig <utzig@apache.org>
Signed-off-by: David Brown <david.brown@linaro.org>

boot/bootutil/src/loader.c

diff --git a/boot/bootutil/src/loader.c b/boot/bootutil/src/loader.c
index 3a30bc8..b03b745 100644
--- a/boot/bootutil/src/loader.c
+++ b/boot/bootutil/src/loader.c
@@ -206,28 +206,6 @@
     return BOOT_SWAP_TYPE_FAIL;
 }
 
-#ifndef MCUBOOT_OVERWRITE_ONLY
-static int
-boot_read_header_from_scratch(struct image_header *out_hdr)
-{
-    const struct flash_area *fap;
-    int rc;
-
-    rc = flash_area_open(FLASH_AREA_IMAGE_SCRATCH, &fap);
-    if (rc != 0) {
-        return BOOT_EFLASH;
-    }
-
-    rc = flash_area_read(fap, 0, out_hdr, sizeof *out_hdr);
-    if (rc != 0) {
-        rc = BOOT_EFLASH;
-    }
-
-    flash_area_close(fap);
-    return rc;
-}
-#endif /* !MCUBOOT_OVERWRITE_ONLY */
-
 /*
  * Compute the total size of the given image.  Includes the size of
  * the TLVs.
@@ -477,7 +455,10 @@
         return BOOT_EFLASH;
     }
 
-    return boot_read_status_bytes(fap, bs);
+    rc = boot_read_status_bytes(fap, bs);
+
+    flash_area_close(fap);
+    return rc;
 }
 
 /**
@@ -797,7 +778,7 @@
 }
 
 static inline int
-boot_status_init_by_id(int flash_area_id)
+boot_status_init_by_id(int flash_area_id, const struct boot_status *bs)
 {
     const struct flash_area *fap;
     struct boot_swap_state swap_state;
@@ -814,6 +795,9 @@
         assert(rc == 0);
     }
 
+    rc = boot_write_swap_size(fap, bs->swap_size);
+    assert(rc == 0);
+
     rc = boot_write_magic(fap);
     assert(rc == 0);
 
@@ -907,7 +891,7 @@
 
         if (bs->idx == 0) {
             if (bs->use_scratch) {
-                boot_status_init_by_id(FLASH_AREA_IMAGE_SCRATCH);
+                boot_status_init_by_id(FLASH_AREA_IMAGE_SCRATCH, bs);
             } else {
                 /* Prepare the status area... here it is known that the
                  * last sector is not being used by the image data so it's
@@ -916,7 +900,7 @@
                 rc = boot_erase_last_sector_by_id(FLASH_AREA_IMAGE_0);
                 assert(rc == 0);
 
-                boot_status_init_by_id(FLASH_AREA_IMAGE_0);
+                boot_status_init_by_id(FLASH_AREA_IMAGE_0, bs);
             }
         }
 
@@ -982,6 +966,9 @@
                 assert(rc == 0);
             }
 
+            rc = boot_write_swap_size(fap, bs->swap_size);
+            assert(rc == 0);
+
             rc = boot_write_magic(fap);
             assert(rc == 0);
 
@@ -1057,42 +1044,43 @@
     struct image_header *hdr;
     uint32_t size;
     uint32_t copy_size;
-    struct image_header tmp_hdr;
     int rc;
 
     /* FIXME: just do this if asked by user? */
 
     size = copy_size = 0;
 
-    hdr = boot_img_hdr(&boot_data, 0);
-    if (hdr->ih_magic == IMAGE_MAGIC) {
-        rc = boot_read_image_size(0, hdr, &copy_size);
-        assert(rc == 0);
-    }
-
-    hdr = boot_img_hdr(&boot_data, 1);
-    if (hdr->ih_magic == IMAGE_MAGIC) {
-        rc = boot_read_image_size(1, hdr, &size);
-        assert(rc == 0);
-    }
-
-    if (!size || !copy_size || size == copy_size) {
-        rc = boot_read_header_from_scratch(&tmp_hdr);
-        assert(rc == 0);
-
-        hdr = &tmp_hdr;
+    if (bs->idx == 0 && bs->state == 0) {
+        /*
+         * No swap ever happened, so need to find the largest image which
+         * will be used to determine the amount of sectors to swap.
+         */
+        hdr = boot_img_hdr(&boot_data, 0);
         if (hdr->ih_magic == IMAGE_MAGIC) {
-            if (!size) {
-                rc = boot_read_image_size(2, hdr, &size);
-            } else {
-                rc = boot_read_image_size(2, hdr, &size);
-            }
+            rc = boot_read_image_size(0, hdr, &copy_size);
             assert(rc == 0);
         }
-    }
 
-    if (size > copy_size) {
-        copy_size = size;
+        hdr = boot_img_hdr(&boot_data, 1);
+        if (hdr->ih_magic == IMAGE_MAGIC) {
+            rc = boot_read_image_size(1, hdr, &size);
+            assert(rc == 0);
+        }
+
+        if (size > copy_size) {
+            copy_size = size;
+        }
+
+        bs->swap_size = copy_size;
+    } else {
+        /*
+         * If a swap was under way, the swap_size should already be present
+         * in the trailer...
+         */
+        rc = boot_read_swap_size(&bs->swap_size);
+        assert(rc == 0);
+
+        copy_size = bs->swap_size;
     }
 
     size = 0;