fix fs_truncate bugs

config.h

@@ -21,10 +21,11 @@
 
 /* FS config section */
 #define FS_MAX_DEVICE_FILE_NAME_LEN 512
-#define FS_BLOCK_SIZE 4096
+#define FS_BLOCK_SIZE 16
 #define FS_MAX_BITMAP_SIZE 64
 #define FS_MAX_PATH_LEN 512
 #define FS_MAX_OPEN_FD 32
+#define FS_MAX_FNAME_LEN 11
 
 
 #endif

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;
 	}
 
@@ -124,7 +124,7 @@ static void mark_free(unsigned int block_no)
 	write_block(bitmap_block_index+1, (void *) bitmap_block);
 
 	pr("Marked block_no=%d (block=%d, offset=%d, bit=%d) as free\n",
-			block_no, bitmap_block_index, bitmap_block_offset, bitmap_bit);
+			block_no, bitmap_block_index, bitmap_block_offset, block_no & 0x7);
 }
 
 static int identify_fs(void)
@@ -532,9 +532,86 @@ static int *find_filename_in_directory(unsigned int dir_inode_ptr, char *fname)
 		}
 	}
 
+	// list entries from inode extensions
+	struct fs_inode_extension ext;
+	unsigned int next_ext = dir.next_extension;
+
+	while (next_ext) {
+		read_block(next_ext, (void *) &ext);
+		next_ext = ext.next_extension;
+
+		for (int i = 0; i < BLOCK_ADDRESSES_PER_INODE_EXTENSION; i++) {
+			struct fs_directory_record recs[DIRECTORY_RECORDS_PER_BLOCK];
+
+			if (ext.blocks[i]) {
+				read_block(ext.blocks[i], (void *) &recs);
+
+				for (int k = 0; k < DIRECTORY_RECORDS_PER_BLOCK; k++) {
+					if (!recs[k].inode_no)
+						continue;
+
+					if (strcmp(fname, recs[k].fname))
+						continue;
+
+					// filename found
+					int *r = malloc(sizeof(int) * 3);
+					r[0] = i;
+					r[1] = k;
+					r[2] = recs[k].inode_no;
+					return r;
+				}
+			}
+		}
+	}
+
 	return NULL;
 }
 
+static int inode_is_referenced(unsigned int inode)
+{
+	struct fs_inode f;
+	read_block(inode, (void *) &f);
+
+	if (f.ref_count)
+		return 1;
+
+	for (int i = 0; i < FS_MAX_OPEN_FD; i++)
+		if (fs_file_descriptions[i].inode == inode)
+			return 1;
+
+	return 0;
+}
+
+static void clean_inode(unsigned int inode)
+{
+	pr("Removing all data related to inode=%d\n", inode);
+
+	struct fs_inode f;
+	read_block(inode, (void *) &f);
+
+	// clear blocks referenced in base inode
+	for (int i = 0; i < BLOCK_ADDRESSES_PER_INODE; i++) {
+		if (f.blocks[i])
+			mark_free(f.blocks[i]);
+	}
+	mark_free(inode);
+
+	// clear blocks referenced in inode extensions
+	struct fs_inode_extension ext;
+	unsigned int next_extension = f.next_extension;
+
+	while (next_extension) {
+		mark_free(next_extension);
+		read_block(next_extension, (void *) &ext);
+		next_extension = ext.next_extension;
+
+		for (int i = 0; i < BLOCK_ADDRESSES_PER_INODE_EXTENSION; i++) {
+			if (ext.blocks[i])
+				mark_free(ext.blocks[i]);
+		}
+	}
+}
+
 static int fs_add_fname_to_directory(unsigned int dir_inode_ptr, unsigned int target_inode_ptr, char *fname)
 {
 	{
@@ -689,6 +766,45 @@ static int fs_add_fname_to_directory(unsigned int dir_inode_ptr, unsigned int ta
 	return 0;
 }
 
+static void fs_remove_fname_from_directory_removal(struct fs_directory_record *recs, unsigned int k, unsigned int dir_block_addr)
+{
+	unsigned int inode_ptr_cache = recs[k].inode_no;
+	unsigned int inode_location_cache = read_inode_ptr(recs[k].inode_no);
+
+	// decrement ref_count
+	struct fs_inode f;
+	read_block(read_inode_ptr(recs[k].inode_no), (void *) &f);
+	f.ref_count--;
+	write_block(read_inode_ptr(recs[k].inode_no), (void *) &f);
+
+	// clear directory record inode_ptr
+	recs[k].inode_no = 0;
+	write_block(dir_block_addr, (void *) recs);
+
+	// if it drops to zero, nullify inode_ptr pointing to this inode
+	if (f.ref_count)
+		return;
+
+	pr("ref_count=0, clearing inode_ptr\n");
+	write_inode_ptr(inode_ptr_cache, 0);
+
+	// if no fd reference this inode, clean it up altogether
+	int i;
+	for (i = 0; i < FS_MAX_OPEN_FD; i++)
+		if (fs_file_descriptions[i].inode == inode_location_cache)
+			break;
+
+	if (i != FS_MAX_OPEN_FD) {
+		pr("Inode %d is still referenced by fd %d, not removing it\n",
+				inode_location_cache, i);
+		return;
+	}
+
+	pr("No open fd reference inode %d, cleaning up\n", inode_location_cache);
+
+	clean_inode(inode_location_cache);
+}
+
 static int fs_remove_fname_from_directory(unsigned int dir_inode_ptr, char *fname)
 {
 	// find directory record with this fname
@@ -715,68 +831,50 @@ static int fs_remove_fname_from_directory(unsigned int dir_inode_ptr, char *fnam
 
 			pr("Directory record for '%s' found in block=%d, record=%d, removing\n", fname, i, k);
 
-			unsigned int inode_ptr_cache = recs[k].inode_no;
+			fs_remove_fname_from_directory_removal(recs, k, dir.blocks[i]);
-			unsigned int inode_location_cache = read_inode_ptr(recs[k].inode_no);
-
-			// decrement ref_count
-			struct fs_inode f;
-			read_block(read_inode_ptr(recs[k].inode_no), (void *) &f);
-			f.ref_count--;
-			write_block(read_inode_ptr(recs[k].inode_no), (void *) &f);
-
-			// clear directory record inode_ptr
-			recs[k].inode_no = 0;
-			write_block(dir.blocks[i], (void *) &recs);
-
-			// if it drops to zero, nullify inode_ptr pointing to this inode
-			if (f.ref_count)
-				goto fs_remove_fname_from_directory_finish;
-
-			pr("ref_count=0, clearing inode_ptr\n");
-			write_inode_ptr(inode_ptr_cache, 0);
-
-			// if no fd reference this inode, clean it up altogether
-			int i;
-			for (i = 0; i < FS_MAX_OPEN_FD; i++)
-				if (fs_file_descriptions[i].inode == inode_location_cache)
-					break;
-
-			if (i != FS_MAX_OPEN_FD) {
-				pr("Inode %d is still referenced by fd %d, not removing it\n",
-						inode_location_cache, i);
-				goto fs_remove_fname_from_directory_finish;
-			}
-
-			pr("No open fd reference inode %d, cleaning up\n", inode_location_cache);
-
-			// clear blocks referenced in base inode
-			for (int i = 0; i < BLOCK_ADDRESSES_PER_INODE; i++) {
-				if (f.blocks[i])
-					mark_free(f.blocks[i]);
-			}
-			mark_free(inode_location_cache);
-
-			// clear blocks referenced in inode extensions
-			struct fs_inode_extension ext;
-			unsigned int next_extension = f.next_extension;
-
-			while (next_extension) {
-				mark_free(next_extension);
-				read_block(next_extension, (void *) &ext);
-				next_extension = ext.next_extension;
-
-				for (int i = 0; i < BLOCK_ADDRESSES_PER_INODE_EXTENSION; i++) {
-					if (ext.blocks[i])
-						mark_free(ext.blocks[i]);
-				}
-			}
 
 			goto fs_remove_fname_from_directory_finish;
 		}
 	}
 
 	// list entries from inode extension
-	// TODO
+	struct fs_inode_extension ext;
+
+	unsigned int next_ext = dir.next_extension;
+	unsigned int curr_ext = 0;
+
+	unsigned int ext_no = 0;
+
+	while (next_ext) {
+		ext_no++;
+		curr_ext = next_ext;
+		read_block(curr_ext, (void *) &ext);
+		next_ext = ext.next_extension;
+
+		for (int i = 0; i < BLOCK_ADDRESSES_PER_INODE_EXTENSION; i++) {
+			struct fs_directory_record recs[DIRECTORY_RECORDS_PER_BLOCK];
+
+			if (!ext.blocks[i])
+				continue;
+
+			read_block(ext.blocks[i], (void *) &recs);
+
+			for (int k = 0; k < DIRECTORY_RECORDS_PER_BLOCK; k++) {
+				if (!recs[k].inode_no)
+					continue;
+
+				if (strcmp(fname, recs[k].fname))
+					continue;
+
+				pr("Directory record for '%s' found in ext=%d, block=%d, record=%d, removing\n",
+						fname, ext_no, i, k);
+
+				fs_remove_fname_from_directory_removal(recs, k, ext.blocks[i]);
+
+				goto fs_remove_fname_from_directory_finish;
+			}
+		}
+	}
 
 	pr_err("no such file '%s'\n", fname);
 	return -1;
@@ -855,6 +953,11 @@ 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 +1025,20 @@ 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 next_ext = f.next_extension;
-		unsigned int previous_extension_address = f.next_extension;
+		unsigned int curr_ext = 0;
-		unsigned int i;
+
+		struct fs_inode_extension ext;
 
 		// seek to target extension address
-		for (
+		for (unsigned int i = 0; i < ext_no + 1; i++) {
-			target_extension_address = previous_extension_address, i = 0;
+			if (!next_ext) {
-			(i < ext_no);
-			i++
-		) {
-			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",
@@ -946,76 +1047,35 @@ static int write_fd_block(unsigned int fd, unsigned int block_index, unsigned ch
 				}
 				mark_used(new_block);
 
-				// updating previous inode extension
+				ext.next_extension = new_block;
-				struct fs_inode_extension prev_ext;
+				write_block(curr_ext, (void *) &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
 
-				// writing new inode extension
+				struct fs_inode_extension new_ext;
-				struct fs_inode_extension ext;
+				memset(&new_ext, 0, sizeof(struct fs_inode_extension));
-				memset(&ext, 0, sizeof(struct fs_inode_extension));
+				write_block(new_block, (void *) &new_ext);
-				write_block(target_extension_address, (void *) &ext);
 
-				target_extension_address = new_block;
+				next_ext = new_block;
 			}
 
-			struct fs_inode_extension ext;
+			curr_ext = next_ext;
-			read_block(target_extension_address, (void *) &ext);
+			read_block(curr_ext, (void *) &ext);
-			previous_extension_address = target_extension_address;
+			next_ext = ext.next_extension;
-			target_extension_address = ext.next_extension;
 		}
 
-		if (!target_extension_address) {
+		if (!ext.blocks[ext_offset]) {
-			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
-
 			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);
+			write_block(curr_ext, (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(ext.blocks[ext_offset], (void *) buf);
 	}
 }
 
@@ -1104,25 +1164,40 @@ 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);
+		memcpy(data_buffer, &(str[total_bytes_written]), str_len - total_bytes_written);
-		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);
 		write_fd_block(fd, block_index, data_buffer);
 
-		read_fd_block(fd, block_index+1, data_buffer);
+		total_bytes_written += (str_len - total_bytes_written);
-		memcpy(data_buffer, &(str[FS_BLOCK_SIZE - block_offset]), str_len - block_offset);
-		write_fd_block(fd, block_index+1, data_buffer);
 	}
 
 	pr("Moving fd %d offset: %d -> %d\n",
-			fd, fs_file_descriptions[fd].rw_offset, 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 += str_len;
+	fs_file_descriptions[fd].rw_offset += total_bytes_written;
 
 	struct fs_inode f;
 	read_block(fs_file_descriptions[fd].inode, (void *) &f);
@@ -1179,7 +1254,7 @@ int fs_truncate(void *d)
 
 		// look through base inode blocks
 		for (int i = 0; i < BLOCK_ADDRESSES_PER_INODE; i++, blocks_seen++) {
-			if ((blocks_seen > new_block_amount) && (f.blocks[i])) {
+			if ((blocks_seen >= new_block_amount) && (f.blocks[i])) {
 				mark_free(f.blocks[i]);
 				f.blocks[i] = 0;
 			}
@@ -1195,7 +1270,7 @@ int fs_truncate(void *d)
 			read_block(next_ext, (void *) &ext);
 
 			for (int i = 0; i < BLOCK_ADDRESSES_PER_INODE_EXTENSION; i++, blocks_seen++) {
-				if ((blocks_seen > new_block_amount) && (ext.blocks[i])) {
+				if ((blocks_seen >= new_block_amount) && (ext.blocks[i])) {
 					mark_free(ext.blocks[i]);
 					ext.blocks[i] = 0;
 				}
@@ -1206,7 +1281,11 @@ int fs_truncate(void *d)
 		}
 
 		// look through inode extensions themselves
-		int required_extensions = (f.size - BLOCK_ADDRESSES_PER_INODE) / BLOCK_ADDRESSES_PER_INODE_EXTENSION;
+		int required_blocks_after_base_inode = (int) f.size - (int) BLOCK_ADDRESSES_PER_INODE;
+		int required_extensions = required_blocks_after_base_inode >= 0
+			? required_blocks_after_base_inode / BLOCK_ADDRESSES_PER_INODE_EXTENSION
+			: 0;
+
 		if ((f.size - BLOCK_ADDRESSES_PER_INODE) % BLOCK_ADDRESSES_PER_INODE_EXTENSION)
 			required_extensions++;
 
@@ -1216,23 +1295,23 @@ int fs_truncate(void *d)
 			// zero base inode next_extension ptr
 			f.next_extension = 0;
 			write_block(read_inode_ptr(file_inode_ptr), (void *) &f);
+		} else {
+			// seek to last required extension
+			for (int i = 0; i < required_extensions; i++) {
+				if (!next_ext)
+					return 0;
+
+				curr_ext = next_ext;
+				read_block(curr_ext, (void *) &ext);
+				next_ext = ext.next_extension;
+			}
+
+			// remove next_extension ptr
+			ext.next_extension = 0;
+			write_block(curr_ext, (void *) &ext);
 		}
 
-		// seek to last required extension
+		// erase all remaining extensions
-		for (int i = 0; i < required_extensions; i++) {
-			if (!next_ext)
-				return 0;
-
-			curr_ext = next_ext;
-			read_block(next_ext, (void *) &ext);
-			next_ext = ext.next_extension;
-		}
-
-		// remove next_extension ptr
-		ext.next_extension = 0;
-		write_block(curr_ext, (void *) &ext);
-
-		// erase all extensions after this one
 		while (next_ext) {
 			mark_free(next_ext);
 			read_block(next_ext, (void *) &ext);
@@ -1258,42 +1337,12 @@ int fs_close(void *d)
 	fs_file_descriptions[fd].inode = 0;
 	pr("fd %d closed\n", fd);
 
-	// cleanup file data on disk if ref_count=0
+	if (inode_is_referenced(inode_location_cache))
-	// and no other open descriptor references it's inode
-
-	struct fs_inode f;
-	read_block(inode_location_cache, (void *) &f);
-	if (f.ref_count)
 		return 0;
 
-	for (int i = 0; i < FS_MAX_OPEN_FD; i++)
-		if (fs_file_descriptions[i].inode == inode_location_cache)
-			return 0;
-
-	// if ended up here, the inode is not referenced anywhere
 	pr("No open fd reference inode %d, cleaning up\n", inode_location_cache);
 
-	// clear blocks referenced in base inode
+	clean_inode(inode_location_cache);
-	for (int i = 0; i < BLOCK_ADDRESSES_PER_INODE; i++) {
-		if (f.blocks[i])
-			mark_free(f.blocks[i]);
-	}
-	mark_free(inode_location_cache);
-
-	// clear blocks referenced in inode extensions
-	struct fs_inode_extension ext;
-	unsigned int next_extension = f.next_extension;
-
-	while (next_extension) {
-		mark_free(next_extension);
-		read_block(next_extension, (void *) &ext);
-		next_extension = ext.next_extension;
-
-		for (int i = 0; i < BLOCK_ADDRESSES_PER_INODE_EXTENSION; i++) {
-			if (ext.blocks[i])
-				mark_free(ext.blocks[i]);
-		}
-	}
 }
 
 
@@ -1424,7 +1473,31 @@ int fs_ln(void *d)
 	}
 
 	// list entries from inode extensions
-	// TODO
+	struct fs_inode_extension ext;
+	unsigned int next_ext = dir.next_extension;
+
+	while (next_ext) {
+		read_block(next_ext, (void *) &ext);
+		next_ext = ext.next_extension;
+
+		for (int i = 0; i < BLOCK_ADDRESSES_PER_INODE_EXTENSION; i++) {
+			struct fs_directory_record recs[DIRECTORY_RECORDS_PER_BLOCK];
+
+			if (dir.blocks[i]) {
+				read_block(ext.blocks[i], (void *) &recs);
+
+				for (int k = 0; k < DIRECTORY_RECORDS_PER_BLOCK; k++) {
+					if (!recs[k].inode_no)
+						continue;
+
+					if (!strcmp(existing_fname, recs[k].fname)) {
+						original_inode_ptr = recs[k].inode_no;
+						goto original_inode_ptr_found;
+					}
+				}
+			}
+		}
+	}
 
 	pr_err("no such file '%s'\n", existing_fname);
 	return 0;