mountblockd.c

// Mount Block Daemon
//
// (c) 2012 Adam Strzelecki nanoant.com
//
// Based on:
// http://superuser.com/questions/336455/mac-lion-fstab-is-deprecated-so-what-replaces-it-to-prevent-a-partition-from-m/336474#336474
//
// Compile with:
// cc mountblockd.c -g -o mountblockd -framework Foundation -framework DiskArbitration

#include <CoreFoundation/CoreFoundation.h>
#include <DiskArbitration/DiskArbitration.h>

CFStringRef *names = NULL;
int nameCount = 0;
bool run = true;
bool quiet = false;

DADissenterRef BlockMount(DADiskRef disk, void *context)
{
	CFDictionaryRef description = DADiskCopyDescription(disk);
	CFStringRef name = description ? CFDictionaryGetValue(description, kDADiskDescriptionVolumeNameKey) : NULL;
	DADissenterRef dissenter = NULL;
	bool block = false;
	char *str = NULL;
	if (name) {
		int i;
		CFIndex length = CFStringGetMaximumSizeForEncoding(CFStringGetLength(name), kCFStringEncodingUTF8);
		str = alloca(length + 1);
		CFStringGetCString(name, str, length, kCFStringEncodingUTF8);
		for (i = 0; i < nameCount; i++) {
			if (CFEqual(name, names[i])) {
				block = true;
				break;
			}
		}
	}
	if (block) {
		dissenter = DADissenterCreate(kCFAllocatorDefault, kDAReturnNotPermitted, NULL);
		if(!quiet) if(!quiet) fprintf(stderr, "BLOCKED volume `%s'\n", str);
	} else {
		if(!quiet) if(!quiet) fprintf(stderr, "allowed volume `%s'\n", str);
	}
	if (description) {
		CFRelease(description);
	}
	return dissenter;
}

void signal_handler(int sig) {
	switch(sig) {
	case SIGHUP:
		if(!quiet) fprintf(stderr, "received SIGHUP signal, not supported\n");
		CFRunLoopStop(CFRunLoopGetCurrent());
		break;
	case SIGTERM:
		if(!quiet) fprintf(stderr, "received SIGTERM signal, terminating\n");
		run = false; CFRunLoopStop(CFRunLoopGetCurrent());
		break;
	case SIGINT:
		if(!quiet) fprintf(stderr, "received SIGINT signal, terminating\n");
		run = false; CFRunLoopStop(CFRunLoopGetCurrent());
		break;
	case SIGQUIT:
		if(!quiet) fprintf(stderr, "received SIGQUIT signal, terminating\n");
		run = false; CFRunLoopStop(CFRunLoopGetCurrent());
		break;
	default:
		fprintf(stderr, "uhandled signal (%d) %s\n", sig, strsignal(sig));
		break;
	}
}

int main(int argc, const char *argv[])
{
	int argi;
	bool useConsole;

	for (argi = 1; argi < argc && argv[argi][0] == '-'; argi++) {
		if (!strcmp(argv[argi], "-quiet")) {
			quiet = true;
		} else {
			fprintf(stderr, "unknown parameter `%s'\n", argv[argi]);
		}
	}

	signal(SIGHUP,  signal_handler);
	signal(SIGTERM, signal_handler);
	signal(SIGINT,  signal_handler);
	signal(SIGQUIT, signal_handler);

	DAApprovalSessionRef session = DAApprovalSessionCreate(kCFAllocatorDefault);
	if (!session) {
		fprintf(stderr, "failed to create Disk Arbitration session\n");
	} else if (argc - argi <= 0) {
		fprintf(stderr, "usage: %s [-quiet] <name> ...\n", argv[0]);
	} else {
		CFStringRef cfStringNames[argc - argi];
		if(!quiet) fprintf(stderr, "blocking:\n");
		for(nameCount = 0; nameCount < argc - argi; nameCount++) {
			if(!quiet) fprintf(stderr, "(%d) `%s'\n", nameCount + 1, argv[nameCount + argi]);
			cfStringNames[nameCount] = CFStringCreateWithCStringNoCopy(NULL, 
						argv[nameCount + argi],
						kCFStringEncodingUTF8,
						kCFAllocatorNull);
		}
		names = cfStringNames;

		DARegisterDiskMountApprovalCallback(session, NULL, BlockMount, NULL);
		DAApprovalSessionScheduleWithRunLoop(session, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);

		while (run) {
			CFRunLoopRun();
		}

		DAApprovalSessionUnscheduleFromRunLoop(session, CFRunLoopGetCurrent(), kCFRunLoopDefaultMode);
		DAUnregisterApprovalCallback(session, BlockMount, NULL);
		CFRelease(session);
	}
	return 0;
}