File read and write operations.

[bluesky.git] / inode.c

diff --git a/inode.c b/inode.c
index 1c6a083..154614d 100644 (file)
--- a/inode.c
+++ b/inode.c
@@ -8,6 +8,7 @@
 
 #include <stdint.h>
 #include <glib.h>
+#include <string.h>
 
 #include "bluesky.h"
 
@@ -132,6 +133,29 @@ void bluesky_insert_inode(BlueSkyFS *fs, BlueSkyInode *inode)
     g_mutex_unlock(fs->lock);
 }
 
+/* Mark a given block dirty and make sure that data is faulted in so that it
+ * can be written to. */
+void bluesky_block_touch(BlueSkyInode *inode, uint64_t i)
+{
+    g_return_if_fail(i < inode->blocks->len);
+    BlueSkyBlock *block = &g_array_index(inode->blocks, BlueSkyBlock, i);
+
+    switch (block->type) {
+    case BLUESKY_BLOCK_ZERO:
+        block->data = g_malloc0(BLUESKY_BLOCK_SIZE);
+        break;
+    case BLUESKY_BLOCK_REF:
+        /* TODO: Pull in data first */
+        block->data = g_malloc0(BLUESKY_BLOCK_SIZE);
+        break;
+    case BLUESKY_BLOCK_CACHED:
+    case BLUESKY_BLOCK_DIRTY:
+        break;
+    }
+
+    block->type = BLUESKY_BLOCK_DIRTY;
+}
+
 /* Set the size of a file.  This will truncate or extend the file as needed.
  * Newly-allocated bytes are zeroed. */
 void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size)
@@ -141,7 +165,7 @@ void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size)
     if (size == inode->size)
         return;
 
-    uint64_t blocks = (size + BLUESKY_BLOCK_SIZE - 1) / BLUESKY_MAX_FILE_SIZE;
+    uint64_t blocks = (size + BLUESKY_BLOCK_SIZE - 1) / BLUESKY_BLOCK_SIZE;
 
     if (blocks > inode->blocks->len) {
         /* Need to add new blocks to the end of a file.  New block structures
@@ -158,8 +182,83 @@ void bluesky_file_truncate(BlueSkyInode *inode, uint64_t size)
         g_array_set_size(inode->blocks, blocks);
     }
 
-    /* TODO: Zero out partial blocks if needed? */
+    /* If the file size is being decreased, ensure that any trailing data in
+     * the last block is zeroed. */
+    if (size < inode->size) {
+        BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
+                                         blocks - 1);
+        if (b->type != BLUESKY_BLOCK_ZERO) {
+            bluesky_block_touch(inode, blocks - 1);
+            int end_offset = size % BLUESKY_BLOCK_SIZE;
+            if (end_offset > 0) {
+                memset(&b->data[end_offset], 0,
+                       BLUESKY_BLOCK_SIZE - end_offset);
+            }
+        }
+    }
 
     inode->size = size;
     bluesky_inode_update_ctime(inode, 1);
 }
+
+void bluesky_file_write(BlueSkyInode *inode, uint64_t offset,
+                        const char *data, gint len)
+{
+    g_return_if_fail(inode->type == BLUESKY_REGULAR);
+    g_return_if_fail(offset < inode->size);
+    g_return_if_fail(len <= inode->size - offset);
+
+    if (len == 0)
+        return;
+
+    while (len > 0) {
+        uint64_t block_num = offset / BLUESKY_BLOCK_SIZE;
+        gint block_offset = offset % BLUESKY_BLOCK_SIZE;
+        gint bytes = MIN(BLUESKY_BLOCK_SIZE - block_offset, len);
+
+        bluesky_block_touch(inode, block_num);
+        BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
+                                         block_num);
+        memcpy(&b->data[block_offset], data, bytes);
+
+        offset += bytes;
+        data += bytes;
+        len -= bytes;
+    }
+
+    bluesky_inode_update_ctime(inode, 1);
+}
+
+void bluesky_file_read(BlueSkyInode *inode, uint64_t offset,
+                       char *buf, gint len)
+{
+    g_return_if_fail(inode->type == BLUESKY_REGULAR);
+    g_return_if_fail(offset < inode->size);
+    g_return_if_fail(len <= inode->size - offset);
+
+    while (len > 0) {
+        uint64_t block_num = offset / BLUESKY_BLOCK_SIZE;
+        gint block_offset = offset % BLUESKY_BLOCK_SIZE;
+        gint bytes = MIN(BLUESKY_BLOCK_SIZE - block_offset, len);
+
+        BlueSkyBlock *b = &g_array_index(inode->blocks, BlueSkyBlock,
+                                         block_num);
+        switch (b->type) {
+        case BLUESKY_BLOCK_ZERO:
+            memset(buf, 0, bytes);
+            break;
+        case BLUESKY_BLOCK_REF:
+            /* TODO: Pull in data first */
+            memset(buf, 0, bytes);
+            break;
+        case BLUESKY_BLOCK_CACHED:
+        case BLUESKY_BLOCK_DIRTY:
+            memcpy(buf, &b->data[block_offset], bytes);
+            break;
+        }
+
+        offset += bytes;
+        buf += bytes;
+        len -= bytes;
+    }
+}