AnachronautandClaude Opus 5
78e9eef472
SBFS version two adds directories out of space each entry had already set aside: two of the four reserved bytes become a parent, and one of the seven spare flag bits says an entry is a directory. The entry is still thirty two bytes, so it still divides two hundred and fifty six and still never straddles a block, and nothing in the block layer knows anything happened. A directory is an entry with no blocks. That is what keeps the flat array of entries the whole allocation map, which is the property the format is built on: with files laid down contiguously, every block is inside some entry's range or it is not, and an entry with no range is in nobody's way. There is still no allocation table to consult and none to keep right. THE PARENT IS AN INDEX PLUS ONE, so zero means the root. A version one disk has zeroes in those bytes, and "in the root" is exactly where every file on a flat disk is - so a version one image is already a valid version two image, with nothing to convert and no tool to convert it with. A disk is at the lowest version that describes what is on it. format makes a version one disk and mkdir is what raises it, so everything built here stays readable by a reader that has never heard of a directory right up until it really does have one. That is what lets this land before the machine knows anything: the whole existing suite passes untouched. The tool gains mkdir and rmdir, and list, put, get and delete take paths. list also now reports entries used against entries available, because a disk has two ceilings and the entry one is the one nobody notices until it bites. rmdir refuses a directory with anything in it, and that is not politeness: parents are entry indices, a freed index gets handed out again, and the children of a removed directory would reappear inside whatever took its place. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01E2JrLzFvuFX9fgi1LDRjrW
1007 lines
37 KiB
C
1007 lines
37 KiB
C
// SplitDisk.c
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// Makes and edits SplitBit disk images from the host.
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//
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// Until SplitBit can write its own filesystem there has to be some way to get a program
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// onto a disk, and this is it. It is not a shortcut around the machine: it speaks exactly
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// the format SplitBit will speak, so an image this makes is one the machine can read and
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// an image the machine writes is one this can read back.
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//
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// Written by Anachronaut
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#include "sbfs.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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// Numbers on a SplitBit disk are most significant byte first, the same as everywhere
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// else on the machine.
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static uint16_t readWord(const uint8_t *at) {
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return (uint16_t)((at[0] << 8) | at[1]);
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}
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static void writeWord(uint8_t *at, uint16_t value) {
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at[0] = (uint8_t)(value >> 8);
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at[1] = (uint8_t)(value & 0xFF);
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}
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static FILE *openImage(const char *path, const char *mode) {
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FILE *image = fopen(path, mode);
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if (image == NULL) {
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fprintf(stderr, "Error: Couldn't open the disk image \"%s\".\n", path);
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}
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return image;
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}
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static int readBlock(FILE *image, uint16_t block, uint8_t *into) {
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if (fseek(image, (long)block * SBFS_BLOCK_BYTES, SEEK_SET) != 0
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|| fread(into, 1, SBFS_BLOCK_BYTES, image) != SBFS_BLOCK_BYTES) {
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fprintf(stderr, "Error: Couldn't read block %u.\n", block);
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return 1;
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}
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return 0;
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}
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static int writeBlock(FILE *image, uint16_t block, const uint8_t *from) {
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if (fseek(image, (long)block * SBFS_BLOCK_BYTES, SEEK_SET) != 0
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|| fwrite(from, 1, SBFS_BLOCK_BYTES, image) != SBFS_BLOCK_BYTES) {
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fprintf(stderr, "Error: Couldn't write block %u.\n", block);
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return 1;
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}
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return 0;
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}
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typedef struct {
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uint8_t version;
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uint16_t diskBlocks;
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uint16_t directoryStart;
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uint16_t directoryBlocks;
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uint16_t freeBlocks;
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} Superblock;
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// Reads block 0 and checks it really is one of ours. Without the magic a blank image and
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// a formatted one with no files would be the same thing.
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static int readSuperblock(FILE *image, Superblock *super) {
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uint8_t block[SBFS_BLOCK_BYTES];
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if (readBlock(image, 0, block)) {
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return 1;
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}
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if (memcmp(block, SBFS_MAGIC, SBFS_MAGIC_BYTES) != 0) {
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fprintf(stderr, "Error: That is not a SplitBit disk. Format it first.\n");
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return 1;
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}
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// Either version is read. A version one disk has zeroes in the bytes version two
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// uses for a parent, and zero is the root, so every file on it reads as a file in the
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// root - which is exactly where it is. Nothing is converted here.
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if (block[SBFS_SUPER_VERSION] != SBFS_VERSION_FLAT
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&& block[SBFS_SUPER_VERSION] != SBFS_VERSION_TREE) {
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fprintf(stderr, "Error: That disk is version %u, and this understands %u and %u.\n",
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block[SBFS_SUPER_VERSION], SBFS_VERSION_FLAT, SBFS_VERSION_TREE);
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return 1;
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}
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super->version = block[SBFS_SUPER_VERSION];
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super->diskBlocks = readWord(block + SBFS_SUPER_DISK);
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super->directoryStart = readWord(block + SBFS_SUPER_DIRSTART);
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super->directoryBlocks = readWord(block + SBFS_SUPER_DIRBLOCKS);
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super->freeBlocks = readWord(block + SBFS_SUPER_FREE);
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return 0;
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}
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static int writeSuperblock(FILE *image, const Superblock *super) {
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uint8_t block[SBFS_BLOCK_BYTES];
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memset(block, 0, sizeof(block));
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memcpy(block, SBFS_MAGIC, SBFS_MAGIC_BYTES);
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// Written back at the version it was read at. Putting a file on a flat disk leaves it
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// flat; only creating a directory on it makes the difference real, and only mkdir
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// raises the number.
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block[SBFS_SUPER_VERSION] = super->version;
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writeWord(block + SBFS_SUPER_DISK, super->diskBlocks);
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writeWord(block + SBFS_SUPER_DIRSTART, super->directoryStart);
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writeWord(block + SBFS_SUPER_DIRBLOCKS, super->directoryBlocks);
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writeWord(block + SBFS_SUPER_FREE, super->freeBlocks);
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return writeBlock(image, 0, block);
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}
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// The whole directory, held in memory while a command works on it. It is small enough
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// that reading it once and writing it back once is simpler than picking at blocks, and it
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// is what the machine will do too once it has the Data Memory to spare.
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typedef struct {
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uint8_t *bytes;
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int entries;
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} Directory;
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static int readDirectory(FILE *image, const Superblock *super, Directory *directory) {
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directory->entries = super->directoryBlocks * SBFS_ENTRIES_PER_BLOCK;
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directory->bytes = malloc((size_t)super->directoryBlocks * SBFS_BLOCK_BYTES);
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if (directory->bytes == NULL) {
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fprintf(stderr, "Error: Out of memory reading the directory.\n");
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return 1;
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}
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for (uint16_t i = 0; i < super->directoryBlocks; i++) {
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if (readBlock(image, (uint16_t)(super->directoryStart + i),
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directory->bytes + (size_t)i * SBFS_BLOCK_BYTES)) {
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free(directory->bytes);
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directory->bytes = NULL;
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return 1;
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}
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}
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return 0;
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}
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static int writeDirectory(FILE *image, const Superblock *super, const Directory *directory) {
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for (uint16_t i = 0; i < super->directoryBlocks; i++) {
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if (writeBlock(image, (uint16_t)(super->directoryStart + i),
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directory->bytes + (size_t)i * SBFS_BLOCK_BYTES)) {
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return 1;
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}
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}
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return 0;
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}
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static uint8_t *entryAt(const Directory *directory, int index) {
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return directory->bytes + (size_t)index * SBFS_ENTRY_BYTES;
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}
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static int entryInUse(const uint8_t *entry) {
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return (entry[SBFS_ENTRY_FLAGS] & SBFS_FLAG_IN_USE) != 0;
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}
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static int entryIsDirectory(const uint8_t *entry) {
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return (entry[SBFS_ENTRY_FLAGS] & SBFS_FLAG_DIRECTORY) != 0;
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}
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// The index of the entry this one lives in, or -1 for the root. Stored as index plus one
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// so that a zeroed field - which is what every version one entry has - means the root.
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static int entryParent(const uint8_t *entry) {
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return SBFS_PARENT_INDEX(readWord(entry + SBFS_ENTRY_PARENT));
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}
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static void entrySetParent(uint8_t *entry, int parent) {
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writeWord(entry + SBFS_ENTRY_PARENT,
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parent < 0 ? SBFS_PARENT_ROOT : SBFS_PARENT_OF(parent));
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}
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static uint32_t entrySize(const uint8_t *entry) {
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return (uint32_t)readWord(entry + SBFS_ENTRY_BLOCKS) * SBFS_BLOCK_BYTES
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+ entry[SBFS_ENTRY_TAIL];
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}
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static uint16_t entryBlocksUsed(const uint8_t *entry) {
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return (uint16_t)SBFS_BLOCKS_USED(readWord(entry + SBFS_ENTRY_BLOCKS),
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entry[SBFS_ENTRY_TAIL]);
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}
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// Names are compared as written, the way labels are, and are padded rather than
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// terminated, so a name that fills the field has no terminator to find.
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static void entryName(const uint8_t *entry, char *into) {
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memcpy(into, entry + SBFS_ENTRY_NAME, SBFS_NAME_BYTES);
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into[SBFS_NAME_BYTES] = '\0';
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}
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// ---- Paths ----
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//
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// A path is names separated by '/', and every path this tool is given is from the root:
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// there is no working directory on the host, and one would have nowhere to live between
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// two runs of a command line tool. The machine is the side that gets one of those.
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//
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// The root is not an entry. It is the absence of a parent, so -1 stands for it throughout
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// and is a perfectly good answer rather than a failure - which is why every function here
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// returns its outcome separately from the index it found.
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// How long a path this tool will carry. Nothing in the format says: a path is not stored
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// anywhere, it is only ever walked, and what is stored is one name and one parent.
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#define SBFS_PATH_BYTES 512
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// Copies the next name out of a path and returns where the path goes on, or NULL when
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// there are no more. Empty pieces - a leading separator, a doubled one, a trailing one -
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// are skipped rather than refused, so "/Apps/" and "Apps" walk the same way.
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static const char *nextComponent(const char *path, char *into, int *tooLong) {
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while (*path == SBFS_SEPARATOR) {
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path++;
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}
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if (*path == '\0') {
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return NULL;
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}
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size_t n = 0;
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while (*path != '\0' && *path != SBFS_SEPARATOR) {
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if (n < SBFS_NAME_BYTES) {
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into[n] = *path;
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}
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n++;
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path++;
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}
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*tooLong = (n > SBFS_NAME_BYTES);
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into[n > SBFS_NAME_BYTES ? SBFS_NAME_BYTES : n] = '\0';
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return path;
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}
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// One named child of one directory. `parent` is an entry index, or -1 for the root.
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//
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// This is the whole of what a directory is. There is no list of children anywhere: being
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// a child is a fact written in the child, so finding them means looking at all of them.
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// That is the same walk the flat version did, with one more thing compared.
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static int findIn(const Directory *directory, const char *name, int parent) {
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char held[SBFS_NAME_BYTES + 1];
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for (int i = 0; i < directory->entries; i++) {
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const uint8_t *entry = entryAt(directory, i);
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if (!entryInUse(entry)) {
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continue;
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}
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if (entryParent(entry) != parent) {
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continue;
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}
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entryName(entry, held);
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if (strcmp(held, name) == 0) {
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return i;
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}
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}
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return -1;
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}
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// Walks a whole path. Zero if it got there, and then *index is the entry it names or -1
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// for the root. Anything else leaves *why saying what stopped it.
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static int resolve(const Directory *directory, const char *path, int *index,
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const char **why) {
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int at = -1;
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char name[SBFS_NAME_BYTES + 1];
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int tooLong = 0;
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const char *rest = path;
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while ((rest = nextComponent(rest, name, &tooLong)) != NULL) {
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if (tooLong) {
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*why = "has a name longer than 22 characters in it";
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return 1;
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}
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if (strcmp(name, ".") == 0) {
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continue;
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}
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if (strcmp(name, "..") == 0) {
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if (at >= 0) {
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at = entryParent(entryAt(directory, at));
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}
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continue; // ".." from the root is the root.
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}
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// Only a directory can be walked through. The LAST thing on the path is not
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// checked here, because only the caller knows whether it wanted a file or a
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// directory, and it can say so far better than this can.
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if (at >= 0 && !entryIsDirectory(entryAt(directory, at))) {
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*why = "has something in it that is not a directory";
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return 1;
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}
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int found = findIn(directory, name, at);
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if (found < 0) {
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*why = "is not there";
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return 1;
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}
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at = found;
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}
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*index = at;
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return 0;
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}
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// Walks all but the last name, so that a caller can make the last one. *parent comes back
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// as the directory to make it in, and `leaf` as the name to make. `leaf` must have room
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// for SBFS_NAME_BYTES + 1.
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static int resolveParent(const Directory *directory, const char *path, char *leaf,
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int *parent, const char **why) {
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const char *cut = strrchr(path, SBFS_SEPARATOR);
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const char *last = cut ? cut + 1 : path;
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if (*last == '\0') {
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*why = "ends in a separator, so it does not name anything";
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return 1;
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}
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if (strlen(last) > SBFS_NAME_BYTES) {
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*why = "ends in a name longer than 22 characters";
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return 1;
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}
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if (strcmp(last, ".") == 0 || strcmp(last, "..") == 0) {
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*why = "ends in a name that is already taken by the filesystem";
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return 1;
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}
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strcpy(leaf, last);
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if (cut == NULL) {
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*parent = -1; // A bare name belongs in the root.
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return 0;
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}
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char head[SBFS_PATH_BYTES];
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size_t n = (size_t)(cut - path);
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if (n >= sizeof(head)) {
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*why = "is longer than this tool will carry";
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return 1;
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}
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memcpy(head, path, n);
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head[n] = '\0';
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return resolve(directory, head, parent, why); // "" is the root, which is correct.
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}
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// Whether something can be made inside *parent at all. The root always can.
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static int parentIsUsable(const Directory *directory, int parent, const char *path) {
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if (parent >= 0 && !entryIsDirectory(entryAt(directory, parent))) {
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fprintf(stderr, "Error: \"%s\" is inside something that is not a directory.\n", path);
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return 0;
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}
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return 1;
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}
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// Whether a directory has anything in it. Nothing points down, so this is the only way
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// to know: something is in it if something says it is.
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static int directoryHasChildren(const Directory *directory, int parent) {
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for (int i = 0; i < directory->entries; i++) {
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const uint8_t *entry = entryAt(directory, i);
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if (entryInUse(entry) && entryParent(entry) == parent) {
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return 1;
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}
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}
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return 0;
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}
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// Where the first free run of the wanted length begins, or -1 if there is not one.
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//
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// There is no allocation bitmap, and that is the design rather than an omission: with
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// files laid down contiguously, every block is either inside some entry's range or it is
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// not, so the directory already is the allocation map. A bitmap would be a second copy of
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// a fact that is already written down, and a second copy is a thing that can disagree.
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static long findFreeRun(const Directory *directory, const Superblock *super, uint16_t wanted) {
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if (wanted == 0) {
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// An empty file occupies nothing, so it has no start to speak of. Block 0 is the
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// superblock and can never hold file data, which makes it the honest way to say
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// "nowhere" without inventing a place that belongs to somebody else.
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(void)directory;
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return 0;
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}
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uint32_t firstData = (uint32_t)super->directoryStart + super->directoryBlocks;
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for (uint32_t candidate = firstData; candidate + wanted <= super->diskBlocks; candidate++) {
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uint32_t clash = 0;
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for (int i = 0; i < directory->entries && !clash; i++) {
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const uint8_t *entry = entryAt(directory, i);
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if (!entryInUse(entry)) {
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continue;
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}
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uint32_t start = readWord(entry + SBFS_ENTRY_START);
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uint32_t used = entryBlocksUsed(entry);
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if (used == 0) {
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continue;
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}
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if (candidate < start + used && start < candidate + wanted) {
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// Overlaps this file, so start looking again past the end of it.
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clash = start + used;
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}
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}
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if (clash) {
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candidate = clash - 1; // The loop's increment takes it to clash.
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continue;
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}
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return (long)candidate;
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}
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return -1;
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}
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static uint16_t countFree(const Directory *directory, const Superblock *super) {
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uint32_t used = 0;
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for (int i = 0; i < directory->entries; i++) {
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const uint8_t *entry = entryAt(directory, i);
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if (entryInUse(entry)) {
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used += entryBlocksUsed(entry);
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}
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}
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// Block 0 and everything up to the end of the directory is not available.
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uint32_t overhead = (uint32_t)super->directoryStart + super->directoryBlocks;
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return (uint16_t)(super->diskBlocks - overhead - used);
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}
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// ---- Commands ----
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static int commandFormat(const char *path, uint16_t blocks, uint16_t directoryBlocks) {
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if (blocks <= 1u + directoryBlocks) {
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fprintf(stderr, "Error: A disk of %u blocks has no room for a superblock and a"
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" directory of %u.\n", blocks, directoryBlocks);
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return 1;
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}
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// Quietly, because a disk that is not there yet is the ordinary case for format and
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// not something to complain about on the way past.
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FILE *image = fopen(path, "r+b");
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if (image == NULL) {
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image = openImage(path, "w+b");
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if (image == NULL) {
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return 1;
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}
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}
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uint8_t empty[SBFS_BLOCK_BYTES];
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memset(empty, 0, sizeof(empty));
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for (uint16_t i = 0; i < blocks; i++) {
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if (writeBlock(image, i, empty)) {
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fclose(image);
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return 1;
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}
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}
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Superblock super;
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// A DISK IS AT THE LOWEST VERSION THAT DESCRIBES WHAT IS ON IT, and a fresh one has
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// no directories on it, so it is flat and flat is version one. The number says what
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// the disk contains, not which tool made it - which is what lets everything built
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// here still be mounted by a reader that has never heard of a directory. mkdir is
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// what raises it, because mkdir is what makes the difference true.
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super.version = SBFS_VERSION_FLAT;
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super.diskBlocks = blocks;
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super.directoryStart = SBFS_FIRST_DIRECTORY_BLOCK;
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super.directoryBlocks = directoryBlocks;
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super.freeBlocks = (uint16_t)(blocks - 1 - directoryBlocks);
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if (writeSuperblock(image, &super)) {
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fclose(image);
|
|
return 1;
|
|
}
|
|
fclose(image);
|
|
printf("Formatted %s: %u blocks, %u of directory, %u free.\n",
|
|
path, blocks, directoryBlocks, super.freeBlocks);
|
|
return 0;
|
|
}
|
|
|
|
// The full path of an entry, built by walking up the parents and writing them out
|
|
// backwards. Nothing stores a path, so this is the only way to have one.
|
|
//
|
|
// The depth cap is what makes this safe on a disk whose parents form a loop: walking up
|
|
// would otherwise never reach the root. Running out of depth is reported as not fitting,
|
|
// which is what it is.
|
|
static int entryPath(const Directory *directory, int index, char *into, size_t room) {
|
|
int chain[64];
|
|
int depth = 0;
|
|
while (index >= 0 && depth < (int)(sizeof(chain) / sizeof(chain[0]))) {
|
|
chain[depth++] = index;
|
|
index = entryParent(entryAt(directory, index));
|
|
}
|
|
if (index >= 0) {
|
|
return -1; // Deeper than this will walk, or a loop.
|
|
}
|
|
size_t at = 0;
|
|
char name[SBFS_NAME_BYTES + 1];
|
|
for (int i = depth - 1; i >= 0; i--) {
|
|
entryName(entryAt(directory, chain[i]), name);
|
|
size_t n = strlen(name);
|
|
if (at + n + 2 > room) {
|
|
return -1;
|
|
}
|
|
into[at++] = SBFS_SEPARATOR;
|
|
memcpy(into + at, name, n);
|
|
at += n;
|
|
}
|
|
into[at] = '\0';
|
|
return (int)at;
|
|
}
|
|
|
|
// What a listing added up to. Kept together because the two numbers are only meaningful
|
|
// beside each other: a disk runs out of entries, not of files.
|
|
typedef struct {
|
|
int files;
|
|
int directories;
|
|
} Tally;
|
|
|
|
// Prints one directory and everything under it, depth first and in entry order, which is
|
|
// the order the machine will walk them in too.
|
|
//
|
|
// Recursing from the root can never loop, because it only ever descends into entries
|
|
// whose parent is where it already is. A cycle among entries is therefore not an infinite
|
|
// walk - it is a set of entries this never reaches, which is what the caller counts.
|
|
static void listTree(const Directory *directory, int parent, char *prefix, size_t at,
|
|
Tally *tally) {
|
|
char name[SBFS_NAME_BYTES + 1];
|
|
for (int i = 0; i < directory->entries; i++) {
|
|
const uint8_t *entry = entryAt(directory, i);
|
|
if (!entryInUse(entry) || entryParent(entry) != parent) {
|
|
continue;
|
|
}
|
|
entryName(entry, name);
|
|
size_t n = strlen(name);
|
|
if (at + n + 2 >= SBFS_PATH_BYTES) {
|
|
continue; // Deeper than this tool will print.
|
|
}
|
|
prefix[at] = SBFS_SEPARATOR;
|
|
memcpy(prefix + at + 1, name, n + 1);
|
|
if (entryIsDirectory(entry)) {
|
|
printf("%-34s %8s %7s %7s\n", prefix, "dir", "-", "-");
|
|
tally->directories++;
|
|
listTree(directory, i, prefix, at + 1 + n, tally);
|
|
} else {
|
|
printf("%-34s %8u %7u %7u\n", prefix, entrySize(entry),
|
|
readWord(entry + SBFS_ENTRY_START), entryBlocksUsed(entry));
|
|
tally->files++;
|
|
}
|
|
prefix[at] = '\0';
|
|
}
|
|
}
|
|
|
|
static int commandList(const char *path, const char *within) {
|
|
FILE *image = openImage(path, "rb");
|
|
if (image == NULL) {
|
|
return 1;
|
|
}
|
|
Superblock super;
|
|
Directory directory;
|
|
if (readSuperblock(image, &super) || readDirectory(image, &super, &directory)) {
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
printf("%s: %u blocks, %u of directory, %u entries, version %u.\n",
|
|
path, super.diskBlocks, super.directoryBlocks, directory.entries,
|
|
super.version);
|
|
printf("%-34s %8s %7s %7s\n", "NAME", "BYTES", "START", "BLOCKS");
|
|
char prefix[SBFS_PATH_BYTES];
|
|
Tally tally = { 0, 0 };
|
|
int start = -1;
|
|
if (within != NULL) {
|
|
const char *why = NULL;
|
|
if (resolve(&directory, within, &start, &why)) {
|
|
fprintf(stderr, "Error: \"%s\" %s.\n", within, why);
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
if (start >= 0 && !entryIsDirectory(entryAt(&directory, start))) {
|
|
fprintf(stderr, "Error: \"%s\" is not a directory.\n", within);
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
}
|
|
// Listing one directory still prints whole paths, because a path that is only true
|
|
// relative to an argument the reader cannot see is worse than no path at all.
|
|
size_t from = 0;
|
|
prefix[0] = '\0';
|
|
if (start >= 0) {
|
|
int n = entryPath(&directory, start, prefix, sizeof(prefix));
|
|
if (n < 0) {
|
|
fprintf(stderr, "Error: \"%s\" is nested too deep to print.\n", within);
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
from = (size_t)n;
|
|
}
|
|
listTree(&directory, start, prefix, from, &tally);
|
|
|
|
// The count in the superblock is a cache, so say what the directory actually adds up
|
|
// to as well. If the two ever disagree, the directory is the one to believe.
|
|
uint16_t counted = countFree(&directory, &super);
|
|
printf("%d file%s", tally.files, tally.files == 1 ? "" : "s");
|
|
if (tally.directories > 0) {
|
|
printf(", %d director%s", tally.directories,
|
|
tally.directories == 1 ? "y" : "ies");
|
|
}
|
|
// Entries are the ceiling nobody notices until they hit it, and on a disk of small
|
|
// files they run out long before the blocks do. Saying both means never having to
|
|
// work out which one is about to bite.
|
|
printf(", %d of %d entries used, %u blocks free",
|
|
tally.files + tally.directories, directory.entries, counted);
|
|
if (counted != super.freeBlocks) {
|
|
printf(" (the superblock says %u, which is stale)", super.freeBlocks);
|
|
}
|
|
printf(".\n");
|
|
|
|
// Everything in use should have been reached by walking down from the root. Anything
|
|
// that was not is pointing at a parent that is not there, or at itself, and that is
|
|
// worth saying out loud rather than quietly leaving off the listing.
|
|
if (within == NULL) {
|
|
int inUse = 0;
|
|
for (int i = 0; i < directory.entries; i++) {
|
|
if (entryInUse(entryAt(&directory, i))) {
|
|
inUse++;
|
|
}
|
|
}
|
|
if (inUse != tally.files + tally.directories) {
|
|
printf("%d entr%s in use but not reachable from the root.\n",
|
|
inUse - (tally.files + tally.directories),
|
|
inUse - (tally.files + tally.directories) == 1 ? "y is" : "ies are");
|
|
}
|
|
}
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return 0;
|
|
}
|
|
|
|
static int commandPut(const char *path, const char *hostFile, const char *asName) {
|
|
FILE *source = fopen(hostFile, "rb");
|
|
if (source == NULL) {
|
|
fprintf(stderr, "Error: Couldn't open \"%s\".\n", hostFile);
|
|
return 1;
|
|
}
|
|
fseek(source, 0, SEEK_END);
|
|
long size = ftell(source);
|
|
rewind(source);
|
|
if (size < 0) {
|
|
fprintf(stderr, "Error: Couldn't measure \"%s\".\n", hostFile);
|
|
fclose(source);
|
|
return 1;
|
|
}
|
|
|
|
FILE *image = openImage(path, "r+b");
|
|
if (image == NULL) {
|
|
fclose(source);
|
|
return 1;
|
|
}
|
|
Superblock super;
|
|
Directory directory;
|
|
if (readSuperblock(image, &super) || readDirectory(image, &super, &directory)) {
|
|
fclose(source);
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
// Where it goes and what it is called are one argument. A bare name still means the
|
|
// root, so every command line that worked before this still works.
|
|
char leaf[SBFS_NAME_BYTES + 1];
|
|
int parent = -1;
|
|
const char *why = NULL;
|
|
if (resolveParent(&directory, asName, leaf, &parent, &why)) {
|
|
fprintf(stderr, "Error: \"%s\" %s.\n", asName, why);
|
|
goto failed;
|
|
}
|
|
if (!parentIsUsable(&directory, parent, asName)) {
|
|
goto failed;
|
|
}
|
|
if (findIn(&directory, leaf, parent) >= 0) {
|
|
fprintf(stderr, "Error: \"%s\" is already there. Delete it first.\n", asName);
|
|
goto failed;
|
|
}
|
|
int slot = -1;
|
|
for (int i = 0; i < directory.entries && slot < 0; i++) {
|
|
if (!entryInUse(entryAt(&directory, i))) {
|
|
slot = i;
|
|
}
|
|
}
|
|
if (slot < 0) {
|
|
fprintf(stderr, "Error: The directory is full: %d entries, all taken.\n", directory.entries);
|
|
goto failed;
|
|
}
|
|
|
|
uint16_t whole = (uint16_t)SBFS_WHOLE_BLOCKS(size);
|
|
uint8_t tail = (uint8_t)SBFS_TAIL_BYTES(size);
|
|
uint16_t needed = (uint16_t)SBFS_BLOCKS_USED(whole, tail);
|
|
long start = findFreeRun(&directory, &super, needed);
|
|
if (start < 0) {
|
|
fprintf(stderr, "Error: No run of %u free blocks. There may be room on the disk"
|
|
" without there being room in one piece.\n", needed);
|
|
goto failed;
|
|
}
|
|
|
|
uint8_t block[SBFS_BLOCK_BYTES];
|
|
for (uint16_t i = 0; i < needed; i++) {
|
|
memset(block, 0, sizeof(block));
|
|
size_t got = fread(block, 1, SBFS_BLOCK_BYTES, source);
|
|
if (got == 0 && i < needed) {
|
|
fprintf(stderr, "Error: \"%s\" ended sooner than its size said.\n", hostFile);
|
|
goto failed;
|
|
}
|
|
if (writeBlock(image, (uint16_t)(start + i), block)) {
|
|
goto failed;
|
|
}
|
|
}
|
|
|
|
uint8_t *entry = entryAt(&directory, slot);
|
|
memset(entry, 0, SBFS_ENTRY_BYTES);
|
|
entry[SBFS_ENTRY_FLAGS] = SBFS_FLAG_IN_USE;
|
|
writeWord(entry + SBFS_ENTRY_START, (uint16_t)start);
|
|
writeWord(entry + SBFS_ENTRY_BLOCKS, whole);
|
|
entry[SBFS_ENTRY_TAIL] = tail;
|
|
memcpy(entry + SBFS_ENTRY_NAME, leaf, strlen(leaf));
|
|
entrySetParent(entry, parent);
|
|
|
|
super.freeBlocks = countFree(&directory, &super);
|
|
if (writeDirectory(image, &super, &directory) || writeSuperblock(image, &super)) {
|
|
goto failed;
|
|
}
|
|
printf("Put %s on as \"%s\": %ld bytes at block %ld.\n", hostFile, asName, size, start);
|
|
free(directory.bytes);
|
|
fclose(source);
|
|
fclose(image);
|
|
return 0;
|
|
|
|
failed:
|
|
free(directory.bytes);
|
|
fclose(source);
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
|
|
static int commandGet(const char *path, const char *name, const char *hostFile) {
|
|
FILE *image = openImage(path, "rb");
|
|
if (image == NULL) {
|
|
return 1;
|
|
}
|
|
Superblock super;
|
|
Directory directory;
|
|
if (readSuperblock(image, &super) || readDirectory(image, &super, &directory)) {
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
int slot = -1;
|
|
const char *why = NULL;
|
|
if (resolve(&directory, name, &slot, &why) || slot < 0) {
|
|
fprintf(stderr, "Error: \"%s\" %s.\n", name, why ? why : "is the root, which is not a file");
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
if (entryIsDirectory(entryAt(&directory, slot))) {
|
|
fprintf(stderr, "Error: \"%s\" is a directory. There is nothing to take off.\n", name);
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
const uint8_t *entry = entryAt(&directory, slot);
|
|
uint32_t size = entrySize(entry);
|
|
uint16_t start = readWord(entry + SBFS_ENTRY_START);
|
|
uint16_t used = entryBlocksUsed(entry);
|
|
|
|
FILE *out = fopen(hostFile, "wb");
|
|
if (out == NULL) {
|
|
fprintf(stderr, "Error: Couldn't write \"%s\".\n", hostFile);
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
uint8_t block[SBFS_BLOCK_BYTES];
|
|
uint32_t left = size;
|
|
for (uint16_t i = 0; i < used; i++) {
|
|
if (readBlock(image, (uint16_t)(start + i), block)) {
|
|
fclose(out);
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
uint32_t take = (left < SBFS_BLOCK_BYTES) ? left : SBFS_BLOCK_BYTES;
|
|
fwrite(block, 1, take, out);
|
|
left -= take;
|
|
}
|
|
fclose(out);
|
|
printf("Got \"%s\" off as %s: %u bytes.\n", name, hostFile, size);
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return 0;
|
|
}
|
|
|
|
static int commandDelete(const char *path, const char *name) {
|
|
FILE *image = openImage(path, "r+b");
|
|
if (image == NULL) {
|
|
return 1;
|
|
}
|
|
Superblock super;
|
|
Directory directory;
|
|
if (readSuperblock(image, &super) || readDirectory(image, &super, &directory)) {
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
int slot = -1;
|
|
const char *why = NULL;
|
|
if (resolve(&directory, name, &slot, &why) || slot < 0) {
|
|
fprintf(stderr, "Error: \"%s\" %s.\n", name, why ? why : "is the root, which cannot be deleted");
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
// delete is for files and rmdir is for directories, so that neither can be the one
|
|
// that took away more than was asked for.
|
|
if (entryIsDirectory(entryAt(&directory, slot))) {
|
|
fprintf(stderr, "Error: \"%s\" is a directory. Use rmdir.\n", name);
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
// A deleted entry and a never used one are the same thing: the in use bit goes down
|
|
// and its blocks are free again. The blocks themselves are left as they were, which
|
|
// is worth knowing if anything is ever meant to be private.
|
|
memset(entryAt(&directory, slot), 0, SBFS_ENTRY_BYTES);
|
|
super.freeBlocks = countFree(&directory, &super);
|
|
int failed = writeDirectory(image, &super, &directory) || writeSuperblock(image, &super);
|
|
if (!failed) {
|
|
printf("Deleted \"%s\". %u blocks free.\n", name, super.freeBlocks);
|
|
}
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return failed;
|
|
}
|
|
|
|
// ---- mkdir ----
|
|
//
|
|
// A directory costs one entry and no blocks at all. Its start, blocks and tail stay zero,
|
|
// which is what keeps it out of the allocator's way: with files laid down contiguously an
|
|
// entry with no range cannot overlap anything.
|
|
//
|
|
// This is also the only thing that raises a disk from version one to version two, because
|
|
// it is the only thing that makes the difference between them real.
|
|
static int commandMakeDirectory(const char *path, const char *name) {
|
|
FILE *image = openImage(path, "r+b");
|
|
if (image == NULL) {
|
|
return 1;
|
|
}
|
|
Superblock super;
|
|
Directory directory;
|
|
if (readSuperblock(image, &super) || readDirectory(image, &super, &directory)) {
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
char leaf[SBFS_NAME_BYTES + 1];
|
|
int parent = -1;
|
|
const char *why = NULL;
|
|
int failed = 1;
|
|
if (resolveParent(&directory, name, leaf, &parent, &why)) {
|
|
fprintf(stderr, "Error: \"%s\" %s.\n", name, why);
|
|
goto done;
|
|
}
|
|
if (!parentIsUsable(&directory, parent, name)) {
|
|
goto done;
|
|
}
|
|
if (findIn(&directory, leaf, parent) >= 0) {
|
|
fprintf(stderr, "Error: \"%s\" is already there.\n", name);
|
|
goto done;
|
|
}
|
|
int slot = -1;
|
|
for (int i = 0; i < directory.entries && slot < 0; i++) {
|
|
if (!entryInUse(entryAt(&directory, i))) {
|
|
slot = i;
|
|
}
|
|
}
|
|
if (slot < 0) {
|
|
fprintf(stderr, "Error: The directory is full: %d entries, all taken.\n",
|
|
directory.entries);
|
|
goto done;
|
|
}
|
|
uint8_t *entry = entryAt(&directory, slot);
|
|
memset(entry, 0, SBFS_ENTRY_BYTES);
|
|
entry[SBFS_ENTRY_FLAGS] = SBFS_FLAG_IN_USE | SBFS_FLAG_DIRECTORY;
|
|
memcpy(entry + SBFS_ENTRY_NAME, leaf, strlen(leaf));
|
|
entrySetParent(entry, parent);
|
|
|
|
int raised = (super.version < SBFS_VERSION_TREE);
|
|
super.version = SBFS_VERSION_TREE;
|
|
super.freeBlocks = countFree(&directory, &super);
|
|
if (writeDirectory(image, &super, &directory) || writeSuperblock(image, &super)) {
|
|
goto done;
|
|
}
|
|
printf("Made \"%s\" as entry %d.\n", name, slot);
|
|
if (raised) {
|
|
printf("The disk is now version %d, because it has a directory on it.\n",
|
|
SBFS_VERSION_TREE);
|
|
}
|
|
failed = 0;
|
|
done:
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return failed;
|
|
}
|
|
|
|
// ---- rmdir ----
|
|
//
|
|
// Refuses a directory with anything in it, and that refusal is not politeness. Parents
|
|
// are entry indices, and a freed index is handed out again to the next thing put on the
|
|
// disk - so the children of a deleted directory would reappear inside whatever took its
|
|
// place. Emptying it first is the only safe order, and making the caller do that is the
|
|
// smallest way to guarantee it.
|
|
static int commandRemoveDirectory(const char *path, const char *name) {
|
|
FILE *image = openImage(path, "r+b");
|
|
if (image == NULL) {
|
|
return 1;
|
|
}
|
|
Superblock super;
|
|
Directory directory;
|
|
if (readSuperblock(image, &super) || readDirectory(image, &super, &directory)) {
|
|
fclose(image);
|
|
return 1;
|
|
}
|
|
int slot = -1;
|
|
const char *why = NULL;
|
|
int failed = 1;
|
|
if (resolve(&directory, name, &slot, &why)) {
|
|
fprintf(stderr, "Error: \"%s\" %s.\n", name, why);
|
|
goto done;
|
|
}
|
|
if (slot < 0) {
|
|
fprintf(stderr, "Error: The root is not something that can be removed.\n");
|
|
goto done;
|
|
}
|
|
if (!entryIsDirectory(entryAt(&directory, slot))) {
|
|
fprintf(stderr, "Error: \"%s\" is a file. Use delete.\n", name);
|
|
goto done;
|
|
}
|
|
if (directoryHasChildren(&directory, slot)) {
|
|
fprintf(stderr, "Error: \"%s\" still has things in it. Empty it first.\n", name);
|
|
goto done;
|
|
}
|
|
memset(entryAt(&directory, slot), 0, SBFS_ENTRY_BYTES);
|
|
super.freeBlocks = countFree(&directory, &super);
|
|
if (writeDirectory(image, &super, &directory) || writeSuperblock(image, &super)) {
|
|
goto done;
|
|
}
|
|
printf("Removed \"%s\".\n", name);
|
|
failed = 0;
|
|
done:
|
|
free(directory.bytes);
|
|
fclose(image);
|
|
return failed;
|
|
}
|
|
|
|
static void printUsage(const char *program) {
|
|
printf("Usage: %s <command> <image> [arguments]\n", program);
|
|
printf("\n");
|
|
printf("Commands:\n");
|
|
printf(" format <image> [blocks] [dirblocks] Lay down a fresh filesystem.\n");
|
|
printf(" list <image> [path] Show the disk, or one directory of it.\n");
|
|
printf(" put <image> <file> [path] Put a host file onto it.\n");
|
|
printf(" get <image> <path> [file] Take one off it.\n");
|
|
printf(" delete <image> <path> Remove a file.\n");
|
|
printf(" mkdir <image> <path> Make a directory.\n");
|
|
printf(" rmdir <image> <path> Remove an empty one.\n");
|
|
printf("\n");
|
|
printf("Blocks are %d bytes. A name may be %d characters, and a path is names with\n",
|
|
SBFS_BLOCK_BYTES, SBFS_NAME_BYTES);
|
|
printf("'%c' between them, always from the root. Without a path, put uses the file's\n",
|
|
SBFS_SEPARATOR);
|
|
printf("own name, which is often too long, and it will say so.\n");
|
|
}
|
|
|
|
// The part of a path after the last separator, so that put can default to a file's own
|
|
// name rather than the whole path it was found at.
|
|
static const char *baseName(const char *path) {
|
|
const char *slash = strrchr(path, '/');
|
|
return slash ? slash + 1 : path;
|
|
}
|
|
|
|
int main(int argc, char *argv[]) {
|
|
if (argc < 2 || strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0) {
|
|
printUsage(argv[0]);
|
|
return argc < 2 ? 1 : 0;
|
|
}
|
|
const char *command = argv[1];
|
|
if (argc < 3) {
|
|
fprintf(stderr, "Error: %s needs a disk image.\n", command);
|
|
return 1;
|
|
}
|
|
const char *path = argv[2];
|
|
|
|
if (strcmp(command, "format") == 0) {
|
|
long blocks = (argc > 3) ? strtol(argv[3], NULL, 0) : 512;
|
|
long directoryBlocks = (argc > 4) ? strtol(argv[4], NULL, 0) : SBFS_DEFAULT_DIRECTORY_BLOCKS;
|
|
if (blocks < 2 || blocks > 0xFFFF || directoryBlocks < 1 || directoryBlocks > 0xFFFF) {
|
|
fprintf(stderr, "Error: A disk is between 2 and 65535 blocks, with at least"
|
|
" one of directory.\n");
|
|
return 1;
|
|
}
|
|
return commandFormat(path, (uint16_t)blocks, (uint16_t)directoryBlocks);
|
|
}
|
|
if (strcmp(command, "list") == 0) {
|
|
return commandList(path, (argc > 3) ? argv[3] : NULL);
|
|
}
|
|
if (strcmp(command, "mkdir") == 0) {
|
|
if (argc < 4) {
|
|
fprintf(stderr, "Error: mkdir needs a directory to make.\n");
|
|
return 1;
|
|
}
|
|
return commandMakeDirectory(path, argv[3]);
|
|
}
|
|
if (strcmp(command, "rmdir") == 0) {
|
|
if (argc < 4) {
|
|
fprintf(stderr, "Error: rmdir needs a directory to remove.\n");
|
|
return 1;
|
|
}
|
|
return commandRemoveDirectory(path, argv[3]);
|
|
}
|
|
if (strcmp(command, "put") == 0) {
|
|
if (argc < 4) {
|
|
fprintf(stderr, "Error: put needs a file to put on.\n");
|
|
return 1;
|
|
}
|
|
return commandPut(path, argv[3], (argc > 4) ? argv[4] : baseName(argv[3]));
|
|
}
|
|
if (strcmp(command, "get") == 0) {
|
|
if (argc < 4) {
|
|
fprintf(stderr, "Error: get needs the name of a file on the disk.\n");
|
|
return 1;
|
|
}
|
|
return commandGet(path, argv[3], (argc > 4) ? argv[4] : argv[3]);
|
|
}
|
|
if (strcmp(command, "delete") == 0) {
|
|
if (argc < 4) {
|
|
fprintf(stderr, "Error: delete needs the name of a file on the disk.\n");
|
|
return 1;
|
|
}
|
|
return commandDelete(path, argv[3]);
|
|
}
|
|
fprintf(stderr, "Error: There is no \"%s\" command.\n", command);
|
|
printUsage(argv[0]);
|
|
return 1;
|
|
}
|