soundsmith/extract/2mg.c

231 lines
5.5 KiB
C
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2017-08-21 18:12:33 +00:00
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <ctype.h>
#include <unistd.h>
#include <sys/stat.h>
#define fourcc(x) (x[0] | (x[1] << 8) | (x[2] << 16) | (x[3] << 24))
static void handleDirectory(uint16_t key, uint8_t *disk, uint32_t diskLen);
static void handleEntry(uint8_t *entry, uint8_t *disk, uint32_t diskLen);
static void handleFile(uint16_t key, uint32_t len, char *name, uint8_t *disk,
uint32_t diskLen, int type);
static inline uint32_t r32(uint8_t *data) {
uint32_t r = *data++;
r |= *data++ << 8;
r |= *data++ << 16;
r |= *data << 24;
return r;
}
static inline uint16_t r16(uint8_t *data) {
uint16_t r = *data++;
r |= *data << 8;
return r;
}
int main(int argc, char *argv[]) {
if (argc != 2) {
fprintf(stderr, "Usage: %s <filename.2mg>\n", argv[0]);
fprintf(stderr, "This will extract all files in the 2mg into the current folder.\n");
fprintf(stderr, "It will create directories as needed.\n");
return -1;
}
FILE *f = fopen(argv[1], "rb");
if (!f) {
fprintf(stderr, "Couldn't open '%s'\n", argv[1]);
return -1;
}
fseek(f, 0, SEEK_END);
size_t len = ftell(f);
fseek(f, 0, SEEK_SET);
if (len < 64) {
fprintf(stderr, "%s is not a valid 2mg file\n", argv[1]);
fclose(f);
return -1;
}
uint8_t *header = malloc(64);
fread(header, 64, 1, f);
if (r32(header) != fourcc("2IMG")) {
fprintf(stderr, "%s is not a valid 2mg file\n", argv[1]);
fclose(f);
return -1;
}
if (r32(header + 0xc) != 1) {
fprintf(stderr, "Not in ProDOS format\n");
fclose(f);
return -1;
}
uint32_t diskLen = r32(header + 0x14) * 512;
uint32_t diskOfs = r32(header + 0x18);
free(header);
fseek(f, diskOfs, SEEK_SET);
uint8_t *disk = malloc(diskLen);
fread(disk, diskLen, 1, f);
fclose(f);
handleDirectory(2, disk, diskLen);
free(disk);
return 0;
}
static void readFilename(uint8_t *filename, uint8_t length, char *outname) {
for (int i = 0; i < length; i++) {
char ch = filename[i];
if (isalnum(ch) || ch == '_' || ch == '.' || ch ==' ') {
*outname++ = ch;
} else {
*outname++ = 'x';
char hi = ch >> 4;
char lo = ch & 0xf;
if (hi > 9)
*outname++ = 'a' + (hi - 10);
else
*outname++ = '0' + hi;
if (lo > 9)
*outname++ = 'a' + (lo - 10);
else
*outname++ = '0' + lo;
}
}
*outname = 0;
}
static void handleDirectory(uint16_t key, uint8_t *disk, uint32_t diskLen) {
uint8_t *block = disk + key * 512;
if ((block[4] & 0xf0) != 0xf0 && (block[4] & 0xf0) != 0xe0) {
fprintf(stderr, "Corrupted directory header\n");
return;
}
char dirname[50];
readFilename(block + 5, block[4] & 0xf, dirname);
mkdir(dirname, 0777);
chdir(dirname);
uint8_t entryLength = block[0x23];
uint8_t entriesPerBlock= block[0x24];
uint16_t fileCount = r16(block + 0x25);
uint8_t *entry = block + entryLength + 4;
uint8_t curEntry = 1;
uint16_t curFile = 0;
while (curFile < fileCount) {
if (entry[0] != 0) {
handleEntry(entry, disk, diskLen);
curFile++;
}
curEntry++;
entry += entryLength;
if (curEntry == entriesPerBlock) {
curEntry = 0;
block = disk + r16(block + 2) * 512;
entry = block + 4;
}
}
chdir("..");
}
static void handleEntry(uint8_t *entry, uint8_t *disk, uint32_t diskLen) {
uint16_t key = r16(entry + 0x11);
uint32_t eof = r32(entry + 0x15) & 0xffffff;
char filename[50];
readFilename(entry + 1, entry[0] & 0xf, filename);
switch (entry[0] & 0xf0) {
case 0x10:
handleFile(key, eof, filename, disk, diskLen, 1); // seedling
break;
case 0x20:
handleFile(key, eof, filename, disk, diskLen, 2); // sapling
break;
case 0x30:
handleFile(key, eof, filename, disk, diskLen, 3); // tree
break;
case 0xd0:
handleDirectory(key, disk, diskLen);
break;
default:
fprintf(stderr, "Unknown file type: %x\n", entry[0] >> 4);
return;
}
}
static void dumpSeedling(uint8_t *block, uint32_t len, FILE *f) {
if (block == NULL)
fseek(f, len, SEEK_CUR);
else
fwrite(block, len, 1, f);
}
static void dumpSapling(uint8_t *index, uint32_t len, FILE *f, uint8_t *disk,
uint32_t diskLen) {
if (index == NULL) {
fseek(f, len, SEEK_CUR);
return;
}
while (len > 0) {
uint16_t blockid = index[0] | (index[256] << 8);
uint8_t *block = NULL;
if (blockid && (blockid + 1) * 512 <= diskLen)
block = disk + blockid * 512;
uint32_t blen = len > 512 ? 512 : len;
dumpSeedling(block, blen, f);
len -= blen;
index++;
}
}
static void dumpTree(uint8_t *index, uint32_t len, FILE *f, uint8_t *disk,
uint32_t diskLen) {
if (index == NULL) {
fseek(f, len, SEEK_CUR);
return;
}
while (len > 0) {
uint16_t blockid = index[0] | (index[256] << 8);
uint8_t *block = NULL;
if (blockid && (blockid + 1) * 512 <= diskLen)
block = disk + blockid * 512;
uint32_t blen = len > 256 * 512 ? 256 * 512 : len;
dumpSapling(block, blen, f, disk, diskLen);
len -= blen;
index++;
}
}
static void handleFile(uint16_t key, uint32_t len, char *name, uint8_t *disk,
uint32_t diskLen, int type) {
uint8_t *block = disk + key * 512;
FILE *f = fopen(name, "wb");
if (!f) {
fprintf(stderr, "Failed to create '%s'\n", name);
return;
}
switch (type) {
case 1:
dumpSeedling(block, len, f);
break;
case 2:
dumpSapling(block, len, f, disk, diskLen);
break;
case 3:
dumpTree(block, len, f, disk, diskLen);
break;
}
fclose(f);
}