[Cryptech-Commits] [sw/libhal] 02/03: Reorder writing of new chunks in ks_set_attribute().

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sra at hactrn.net pushed a commit to branch ksng
in repository sw/libhal.

commit 1863db8fd34c582445238c30d32b9f7b282b2f1e
Author: Rob Austein <sra at hactrn.net>
AuthorDate: Thu Nov 3 18:17:13 2016 -0400

    Reorder writing of new chunks in ks_set_attribute().
    
    ks_set_attribute() was written before hal_ks_index_fsck(), and was
    violating the latter's assumptions for no particularly good reason.
    Writing out new chunks in the expected order is no more work, and
    simplifies the consistency checks, so do it that way.
---
 ks_flash.c | 66 ++++++++++++++++++++++++++++++++++++++------------------------
 1 file changed, 41 insertions(+), 25 deletions(-)

diff --git a/ks_flash.c b/ks_flash.c
index 952253e..2eda9e3 100644
--- a/ks_flash.c
+++ b/ks_flash.c
@@ -1327,6 +1327,10 @@ static  hal_error_t ks_set_attribute(hal_ks_t *ks,
   if (db.ksi.used + total_chunks + 1 > db.ksi.size)
     return HAL_ERROR_NO_KEY_INDEX_SLOTS;
 
+  /*
+   * Phase 1: Deprecate all the old chunks, remember where the were.
+   */
+
   for (chunk = 0; chunk < total_chunks; chunk++) {
     int hint = slot->hint + chunk;
     if ((err = hal_ks_index_find(&db.ksi, &slot->name, chunk, &blocks[chunk], &hint)) != HAL_OK ||
@@ -1334,31 +1338,9 @@ static  hal_error_t ks_set_attribute(hal_ks_t *ks,
       return err;
   }
 
-  {
-    block = cache_pick_lru();
-
-    memset(block, 0xFF, sizeof(*block));
-
-    block->header.block_type   = BLOCK_TYPE_ATTR;
-    block->header.block_status = BLOCK_STATUS_LIVE;
-    block->header.total_chunks = total_chunks + 1;
-    block->header.this_chunk   = total_chunks;
-    block->attr.name = slot->name;
-    block->attr.attributes_len = 0;
-
-    hal_rpc_pkey_attribute_t attrs[1];
-    size_t total = 0;
-
-    if ((err = hal_ks_attribute_insert(block->attr.attributes,
-                                       SIZEOF_FLASH_ATTRIBUTE_BLOCK_ATTRIBUTES,
-                                       attrs, &block->attr.attributes_len, &total,
-                                       type, value, value_len))                         != HAL_OK ||
-        (err = hal_ks_index_add(&db.ksi, &slot->name, total_chunks, &b, NULL))          != HAL_OK ||
-        (err = block_write(b, block))                                                   != HAL_OK)
-      return err;
-
-    cache_mark_used(block, b);
-  }
+  /*
+   * Phase 2: Rewrite all the existing chunks with the new total_chunks value.
+   */
 
   for (chunk = 0; chunk < total_chunks; chunk++) {
     int hint = slot->hint + chunk;
@@ -1391,6 +1373,40 @@ static  hal_error_t ks_set_attribute(hal_ks_t *ks,
       return err;
   }
 
+  /*
+   * Phase 3: Write the new chunk.
+   */
+
+  {
+    block = cache_pick_lru();
+
+    memset(block, 0xFF, sizeof(*block));
+
+    block->header.block_type   = BLOCK_TYPE_ATTR;
+    block->header.block_status = BLOCK_STATUS_LIVE;
+    block->header.total_chunks = total_chunks + 1;
+    block->header.this_chunk   = total_chunks;
+    block->attr.name = slot->name;
+    block->attr.attributes_len = 0;
+
+    hal_rpc_pkey_attribute_t attrs[1];
+    size_t total = 0;
+
+    if ((err = hal_ks_attribute_insert(block->attr.attributes,
+                                       SIZEOF_FLASH_ATTRIBUTE_BLOCK_ATTRIBUTES,
+                                       attrs, &block->attr.attributes_len, &total,
+                                       type, value, value_len))                         != HAL_OK ||
+        (err = hal_ks_index_add(&db.ksi, &slot->name, total_chunks, &b, NULL))          != HAL_OK ||
+        (err = block_write(b, block))                                                   != HAL_OK)
+      return err;
+
+    cache_mark_used(block, b);
+  }
+
+  /*
+   * Phase 4: Zero the old chunks we deprecated in phase 1.
+   */
+
   for (chunk = 0; chunk < total_chunks; chunk++)
     if ((err = block_zero(blocks[chunk])) != HAL_OK)
       return err;