fix write_fd_block

src/fs.c

@@ -107,7 +107,7 @@ static void mark_free(unsigned int block_no)
 	read_block(0, (void *) &fsh);
 
 	if (block_no > fsh.block_count) {
-		pr_err("block %d is out of fimesystem block range (%d)\n", block_no, fsh.block_count);
+		pr_err("block %d is out of filesystem block range (%d)\n", block_no, fsh.block_count);
 		return;
 	}
 
@@ -855,6 +855,11 @@ static void read_fd_block(unsigned int fd, unsigned int block_index, unsigned ch
 		else
 			memset(buf, 0, FS_BLOCK_SIZE);
 	} else {
+		/*
+		 * TODO: rewrite this potentially broken abomination normally
+		 *       it has not caused issues so far, but you can never be too sure
+		 */
+
 		int ext_no = (block_index - BLOCK_ADDRESSES_PER_INODE) / BLOCK_ADDRESSES_PER_INODE_EXTENSION;
 		int ext_offset = (block_index - BLOCK_ADDRESSES_PER_INODE) % BLOCK_ADDRESSES_PER_INODE_EXTENSION;
 
@@ -922,22 +927,20 @@ static int write_fd_block(unsigned int fd, unsigned int block_index, unsigned ch
 
 			struct fs_inode_extension ext;
 			memset(&ext, 0, sizeof(struct fs_inode_extension));
+			write_block(new_block, (void *) &ext);
 
 			f.next_extension = new_block;
 			write_block(fs_file_descriptions[fd].inode, (void *) &f);
 		}
 
-		unsigned int target_extension_address;
-		unsigned int previous_extension_address = f.next_extension;
-		unsigned int i;
+		unsigned int next_ext = f.next_extension;
+		unsigned int curr_ext = 0;
+
+		struct fs_inode_extension ext;
 
 		// seek to target extension address
-		for (
-			target_extension_address = previous_extension_address, i = 0;
-			(i < ext_no);
-			i++
-		) {
-			if (!target_extension_address) {
+		for (unsigned int i = 0; i < ext_no + 1; i++) {
+			if (!next_ext) {
 				int new_block = find_free_block();
 				if (!new_block) {
 					pr_err("failed to write to fd=%d block=%d: can't allocate block for inode extension\n",
@@ -946,76 +949,35 @@ static int write_fd_block(unsigned int fd, unsigned int block_index, unsigned ch
 				}
 				mark_used(new_block);
 
-				// updating previous inode extension
-				struct fs_inode_extension prev_ext;
-				read_block(previous_extension_address, (void *) &prev_ext);  // read
-				prev_ext.next_extension = new_block;                         // modify
-				write_block(previous_extension_address, (void *) &prev_ext); // write
+				ext.next_extension = new_block;
+				write_block(curr_ext, (void *) &ext);
 
-				// writing new inode extension
-				struct fs_inode_extension ext;
-				memset(&ext, 0, sizeof(struct fs_inode_extension));
-				write_block(target_extension_address, (void *) &ext);
+				struct fs_inode_extension new_ext;
+				memset(&new_ext, 0, sizeof(struct fs_inode_extension));
+				write_block(new_block, (void *) &new_ext);
 
-				target_extension_address = new_block;
+				next_ext = new_block;
 			}
 
-			struct fs_inode_extension ext;
-			read_block(target_extension_address, (void *) &ext);
-			previous_extension_address = target_extension_address;
-			target_extension_address = ext.next_extension;
+			curr_ext = next_ext;
+			read_block(curr_ext, (void *) &ext);
+			next_ext = ext.next_extension;
 		}
 
-		if (!target_extension_address) {
-			int new_block = find_free_block();
-			if (!new_block) {
-				pr_err("failed to write to fd=%d block=%d: can't allocate block for inode extension\n",
-						fd, block_index);
-				return -1;
-			}
-
-			struct fs_inode_extension prev_ext;
-			read_block(previous_extension_address, (void *) &prev_ext);  // read
-			prev_ext.next_extension = new_block;                         // modify
-			write_block(previous_extension_address, (void *) &prev_ext); // write
-
+		if (!ext.blocks[ext_offset]) {
 			int new_data_block = find_free_block();
 			if (!new_data_block) {
 				pr_err("failed to write to fd=%d block=%d: can't allocate block for data\n",
 						fd, block_index);
 				return -1;
 			}
-
-			mark_used(new_block);
 			mark_used(new_data_block);
 
-			// writing new inode extension
-			struct fs_inode_extension ext;
-			memset(&ext, 0, sizeof(struct fs_inode_extension));
 			ext.blocks[ext_offset] = new_data_block;
-			write_block(target_extension_address, (void *) &ext);
-
-			// writing new data block
-			write_block(new_data_block, (void *) buf);
-		} else {
-			struct fs_inode_extension ext;
-			read_block(target_extension_address, (void *) &ext);
-
-			if (!ext.blocks[ext_offset]) {
-				int new_data_block = find_free_block();
-				if (!new_data_block) {
-					pr_err("failed to write to fd=%d block=%d: can't allocate block for data\n",
-							fd, block_index);
-					return -1;
-				}
-				mark_used(new_data_block);
-
-				ext.blocks[ext_offset] = new_data_block;
-				write_block(target_extension_address, (void *) &ext);
-			}
-
-			write_block(ext.blocks[ext_offset], (void *) buf);
+			write_block(curr_ext, (void *) &ext);
 		}
+
+		write_block(ext.blocks[ext_offset], (void *) buf);
 	}
 }
 
@@ -1104,25 +1066,40 @@ int fs_write(void *d)
 	int block_index = fs_file_descriptions[fd].rw_offset / FS_BLOCK_SIZE;
 	int block_offset = fs_file_descriptions[fd].rw_offset % FS_BLOCK_SIZE;
 
+	unsigned int total_bytes_written = 0;
+
 	unsigned char data_buffer[FS_BLOCK_SIZE];
 
-	if (block_offset + str_len <= FS_BLOCK_SIZE) {
+	// first block
+	read_fd_block(fd, block_index, data_buffer);
+	{
+		unsigned int copy_amount = ((FS_BLOCK_SIZE - block_offset) <= str_len)
+			? FS_BLOCK_SIZE - block_offset
+			: str_len;
+		memcpy(&(data_buffer[block_offset]), str, copy_amount);
+		total_bytes_written += copy_amount;
+	}
+	write_fd_block(fd, block_index, data_buffer);
+	block_index++;
+
+	// full middle blocks
+	for ( ; str_len - total_bytes_written >= FS_BLOCK_SIZE; block_index++) {
+		write_fd_block(fd, block_index, (unsigned char *) &(str[total_bytes_written]));
+		total_bytes_written += FS_BLOCK_SIZE;
+	}
+
+	// last partial block
+	if (str_len - total_bytes_written) {
 		read_fd_block(fd, block_index, data_buffer);
-		memcpy(&(data_buffer[block_offset]), str, str_len);
-		write_fd_block(fd, block_index, data_buffer);
-	} else {
-		read_fd_block(fd, block_index, data_buffer);
-		memcpy(&(data_buffer[block_offset]), str, FS_BLOCK_SIZE - block_offset);
+		memcpy(data_buffer, &(str[total_bytes_written]), str_len - total_bytes_written);
 		write_fd_block(fd, block_index, data_buffer);
 
-		read_fd_block(fd, block_index+1, data_buffer);
-		memcpy(data_buffer, &(str[FS_BLOCK_SIZE - block_offset]), str_len - block_offset);
-		write_fd_block(fd, block_index+1, data_buffer);
+		total_bytes_written += (str_len - total_bytes_written);
 	}
 
 	pr("Moving fd %d offset: %d -> %d\n",
-			fd, fs_file_descriptions[fd].rw_offset, fs_file_descriptions[fd].rw_offset + str_len);
-	fs_file_descriptions[fd].rw_offset += str_len;
+			fd, fs_file_descriptions[fd].rw_offset, fs_file_descriptions[fd].rw_offset + total_bytes_written);
+	fs_file_descriptions[fd].rw_offset += total_bytes_written;
 
 	struct fs_inode f;
 	read_block(fs_file_descriptions[fd].inode, (void *) &f);