Switch to refcounted strings for storing cached file blocks.

[bluesky.git] / inode.c

diff --git a/inode.c b/inode.c
index 154614d..7ea8dbf 100644 (file)
--- a/inode.c
+++ b/inode.c
@@ -37,6 +37,54 @@ void bluesky_inode_update_ctime(BlueSkyInode *inode, gboolean update_mtime)
         inode->mtime = now;
 }
 
+/* Compute the HMAC keyed-hash function using the given hash algorithm, data,
+ * and key. */
+void compute_hmac(GChecksumType algo,
+                  const guchar *data, gsize data_len,
+                  const guchar *key, gsize key_len,
+                  guint8 *buffer, gsize *digest_len)
+{
+    int block_size;
+
+    switch (algo) {
+    case G_CHECKSUM_MD5:
+    case G_CHECKSUM_SHA1:
+    case G_CHECKSUM_SHA256:
+        block_size = 64;
+        break;
+    default:
+        g_error("Unknown hash algorithm for HMAC: %d\n", algo);
+    }
+
+    gsize digest_size = g_checksum_type_get_length(algo);
+
+    guchar keybuf[block_size];
+    memset(keybuf, 0, block_size);
+    memcpy(keybuf, key, MIN(block_size, key_len));
+    for (int i = 0; i < block_size; i++)
+        keybuf[i] ^= 0x36;
+
+    GChecksum *csum1 = g_checksum_new(algo);
+    g_checksum_update(csum1, keybuf, block_size);
+    g_checksum_update(csum1, data, data_len);
+    guint8 digest[digest_size];
+    g_checksum_get_digest(csum1, digest, &digest_size);
+
+    memset(keybuf, 0, block_size);
+    memcpy(keybuf, key, MIN(block_size, key_len));
+    for (int i = 0; i < block_size; i++)
+        keybuf[i] ^= 0x5c;
+
+    GChecksum *csum2 = g_checksum_new(algo);
+    g_checksum_update(csum2, keybuf, block_size);
+    g_checksum_update(csum2, digest, digest_size);
+
+    g_checksum_get_digest(csum2, buffer, digest_len);
+
+    g_checksum_free(csum1);
+    g_checksum_free(csum2);
+}
+
 /* Unfortunately a glib hash table is only guaranteed to be able to store
  * 32-bit keys if we use the key directly.  If we want 64-bit inode numbers,
  * we'll have to allocate memory to store the 64-bit inumber, and use a pointer
@@ -66,6 +114,7 @@ BlueSkyFS *bluesky_new_fs(gchar *name)
     fs->inodes = g_hash_table_new(bluesky_fs_key_hash_func,
                                   bluesky_fs_key_equal_func);
     fs->next_inum = BLUESKY_ROOT_INUM + 1;
+    fs->store = s3store_new();
 
     return fs;
 }
@@ -84,12 +133,14 @@ uint64_t bluesky_fs_alloc_inode(BlueSkyFS *fs)
     return inum;
 }
 
-BlueSkyInode *bluesky_new_inode(uint64_t inum, BlueSkyFileType type)
+BlueSkyInode *bluesky_new_inode(uint64_t inum, BlueSkyFS *fs,
+                                BlueSkyFileType type)
 {
     BlueSkyInode *i = g_new0(BlueSkyInode, 1);
 
     i->lock = g_mutex_new();
     i->type = type;
+    i->fs = fs;
     i->inum = inum;
 
     switch (type) {
@@ -142,14 +193,16 @@ void bluesky_block_touch(BlueSkyInode *inode, uint64_t i)
 
     switch (block->type) {
     case BLUESKY_BLOCK_ZERO:
-        block->data = g_malloc0(BLUESKY_BLOCK_SIZE);
+        block->data = bluesky_string_new(g_malloc0(BLUESKY_BLOCK_SIZE),
+                                         BLUESKY_BLOCK_SIZE);
         break;
     case BLUESKY_BLOCK_REF:
-        /* TODO: Pull in data first */
-        block->data = g_malloc0(BLUESKY_BLOCK_SIZE);
-        break;
+        bluesky_block_fetch(inode->fs, block);
+        g_assert(block->type == BLUESKY_BLOCK_CACHED);
+        /* Fall through */
     case BLUESKY_BLOCK_CACHED:
     case BLUESKY_BLOCK_DIRTY:
+        block->data = bluesky_string_dup(block->data);
         break;
     }
 
@@ -177,7 +230,7 @@ void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size)
         for (guint i = inode->blocks->len; i < blocks; i++) {
             BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock, i);
             g_free(b->ref);
-            g_free(b->data);
+            bluesky_string_unref(b->data);
         }
         g_array_set_size(inode->blocks, blocks);
     }
@@ -191,7 +244,7 @@ void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size)
             bluesky_block_touch(inode, blocks - 1);
             int end_offset = size % BLUESKY_BLOCK_SIZE;
             if (end_offset > 0) {
-                memset(&b->data[end_offset], 0,
+                memset(&b->data->data[end_offset], 0,
                        BLUESKY_BLOCK_SIZE - end_offset);
             }
         }
@@ -219,7 +272,8 @@ void bluesky_file_write(BlueSkyInode *inode, uint64_t offset,
         bluesky_block_touch(inode, block_num);
         BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
                                          block_num);
-        memcpy(&b->data[block_offset], data, bytes);
+        memcpy(&b->data->data[block_offset], data, bytes);
+        bluesky_block_flush(inode->fs, b);
 
         offset += bytes;
         data += bytes;
@@ -248,12 +302,11 @@ void bluesky_file_read(BlueSkyInode *inode, uint64_t offset,
             memset(buf, 0, bytes);
             break;
         case BLUESKY_BLOCK_REF:
-            /* TODO: Pull in data first */
-            memset(buf, 0, bytes);
-            break;
+            bluesky_block_fetch(inode->fs, b);
+            /* Fall through */
         case BLUESKY_BLOCK_CACHED:
         case BLUESKY_BLOCK_DIRTY:
-            memcpy(buf, &b->data[block_offset], bytes);
+            memcpy(buf, &b->data->data[block_offset], bytes);
             break;
         }
 
@@ -262,3 +315,41 @@ void bluesky_file_read(BlueSkyInode *inode, uint64_t offset,
         len -= bytes;
     }
 }
+
+/* Read the given block from cloud-backed storage if the data is not already
+ * cached. */
+void bluesky_block_fetch(BlueSkyFS *fs, BlueSkyBlock *block)
+{
+    if (block->type != BLUESKY_BLOCK_REF)
+        return;
+
+    g_print("Fetching block from %s\n", block->ref);
+    BlueSkyRCStr *string = s3store_get(fs->store, block->ref);
+
+    bluesky_string_unref(block->data);
+    block->data = string;
+    block->type = BLUESKY_BLOCK_CACHED;
+}
+
+/* Write the given block to cloud-backed storage and mark it clean. */
+void bluesky_block_flush(BlueSkyFS *fs, BlueSkyBlock *block)
+{
+    if (block->type != BLUESKY_BLOCK_DIRTY)
+        return;
+
+    GChecksum *csum = g_checksum_new(G_CHECKSUM_SHA256);
+    g_checksum_update(csum, block->data->data, block->data->len);
+    gchar *name = g_strdup(g_checksum_get_string(csum));
+
+    g_print("Flushing block as %s\n", name);
+    s3store_put(fs->store, name, block->data);
+    g_free(block->ref);
+    block->ref = name;
+
+    /* block->type = BLUESKY_BLOCK_CACHED; */
+    bluesky_string_unref(block->data);
+    block->data = NULL;
+    block->type = BLUESKY_BLOCK_REF;
+
+    g_checksum_free(csum);
+}