Rewrite logged NSData to UTF-8 text

data-to-str.m

//clang -framework Foundation -fobjc-arc data-to-str.m -o data-to-str
#import <Foundation/Foundation.h>
#import <sysexits.h>

void
usage(void) {
	fprintf(stderr, "usage: %s DATA\n"
		"  treats data as hex bytes, skips spaces,\n"
		"  writes UTF-8 text interpretation to stdout\n",
		getprogname());
}

int
main(void)
{
	@autoreleasepool {
		NSProcessInfo *info = [NSProcessInfo processInfo];
		NSArray *args = [info arguments];
		if ([args count] < 2) {
			fprintf(stderr, "error: no string argument supplied\n");
			usage();
			exit(EX_USAGE);
		}

		NSString *text = args[1];
		const char *s = [text UTF8String];
		char buf[3];
		buf[2] = '\0';
		size_t end = strlen(s);
		char *t = malloc(end / 2 + 1);
		size_t j = 0;
		for (size_t i = 0; i < end; i += 2, j += 1) {
			while (s[i] == ' ') i += 1;
			if (!s[i]) break;

			buf[0] = s[i];
			buf[1] = s[i + 1];
			long val = strtol(buf, NULL, 16);
			t[j] = (char)val;
		}
		t[j] = '\0';
		puts(t);
	}
}