Classic Mac file reading

MacReader.c

// Location of the application: volume & directory, or 0 if unknown.
static short gAppVolRefNum;
static long gAppParID;

// Get an FSSpec pointing to a file with the given name.
static OSErr GetDataFile(FSSpec *spec, const char *filename) {
	ProcessSerialNumber psn = {0, kCurrentProcess};
	ProcessInfoRec info = {0};
	FSSpec app_spec;
	Str255 pname;
	size_t len;

	// Get the volume & directory containing the application.
	if (gAppVolRefNum == 0) {
		info.processInfoLength = sizeof(info);
		info.processAppSpec = &app_spec;
		;
		err = GetProcessInformation(&psn, info);
		if (err != noErr) {
			return err;
		}
		gAppVolRefNum = app_spec.volRefNum;
		gAppParID = app_spec.parID;
	}

	// Convert filename to Pascal string.
	len = strlen(filename);
	assert(len <= 255);
	pname[0] = len;
	memcpy(pname + 1, filename, len);

	return FSMakeFSSpec(gAppVolRef, gAppParID, pname, spec);
}

// Takes a Pascal string as an argument.
FILE *OpenData(const char *filename) {
	FSSpec spec;
	OSErr err;

	err = GetDataFile(&spec, filename);
	if (err != noErr) {
		printf("FSMakeFSSpec: %d\n", err);
		return NULL;
	}
	return FSp_fopen(&spec, "rb");
}

// Read an entire file into memory.
uint8_t *readFully(const char *filename) {
	short refNum;
	FSSpec spec;
	OSErr err;
	long size, count;
	uint8_t *resultBuffer;

	err = GetDataFile(&spec, filename);
	if (err != noErr) {
		printf("GetDataFile: %d\n", err);
		return NULL;
	}
	err = FSpOpenDF(&spec, fsRdPerm, &refNum);
	if (err != noErr) {
		printf("FSpOpenDF: %d\n", err);
		return NULL;
	}
	err = GetEOF(refNum, &size);
	if (err != noErr) {
		printf("GetEOF: %d\n", err);
		FSClose(refNum);
		return NULL;
	}
	resultBuffer = calloc(1, size);
	assert(resultBuffer);
	count = size;
	err = FSRead(refNum, &count, resultBuffer);
	FSClose(refNum);
	if (err != noErr) {
		printf("FSRead: %d\n", err);
		free(resultBuffer);
		return NULL;
	}
	return resultBuffer;
}