Replace the placeholder with a suckless C rg.

rg prints n cryptographically random strings of length l, matching
rg.veltar.systems. Bytes come from getrandom(2) on Linux and rand_s
on Windows. make selects clang and .exe when OS=Windows_NT.

1 files changed, 185 insertions, 0 deletions

diff --git a/rg.c b/rg.c
new file mode 100644
index 0000000..9191956
--- /dev/null
+++ b/rg.c
@@ -0,0 +1,185 @@
+/* See LICENSE file for copyright and license details. */
+#ifdef __linux__
+#ifndef _DEFAULT_SOURCE
+#define _DEFAULT_SOURCE
+#endif
+#endif
+#ifdef _WIN32
+#ifndef _CRT_RAND_S
+#define _CRT_RAND_S
+#endif
+#endif
+
+#include <errno.h>
+#include <limits.h>
+#include <stdarg.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#ifndef _WIN32
+#include <unistd.h>
+#include <sys/random.h>
+#endif
+
+#include "arg.h"
+#include "config.h"
+
+char *argv0;
+
+static unsigned char rbuf[256];
+static size_t rpos = sizeof rbuf;
+
+static void
+die(const char *fmt, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmt);
+	vfprintf(stderr, fmt, ap);
+	va_end(ap);
+
+	if (fmt[0] && fmt[strlen(fmt)-1] == ':') {
+		fputc(' ', stderr);
+		perror(NULL);
+	} else {
+		fputc('\n', stderr);
+	}
+
+	exit(1);
+}
+
+static void
+usage(void)
+{
+	fprintf(stderr, "usage: %s [-v] [-n n] [-l l]\n", argv0 ? argv0 : "rg");
+	exit(1);
+}
+
+static int
+fillrand(unsigned char *buf, size_t n)
+{
+#ifdef _WIN32
+	size_t i;
+	unsigned int r;
+	int k;
+
+	for (i = 0; i < n; ) {
+		if (rand_s(&r) != 0)
+			return -1;
+		for (k = 0; k < 4 && i < n; k++)
+			buf[i++] = (unsigned char)(r >> (8 * k));
+	}
+	return 0;
+#else
+	size_t off;
+	ssize_t r;
+
+	off = 0;
+	while (off < n) {
+		r = getrandom(buf + off, n - off, 0);
+		if (r < 0) {
+			if (errno == EINTR)
+				continue;
+			return -1;
+		}
+		if (r == 0)
+			return -1;
+		off += (size_t)r;
+	}
+	return 0;
+#endif
+}
+
+static unsigned char
+randbyte(void)
+{
+	if (rpos >= sizeof rbuf) {
+		if (fillrand(rbuf, sizeof rbuf) < 0)
+			die("rg: rng:");
+		rpos = 0;
+	}
+	return rbuf[rpos++];
+}
+
+static uint32_t
+randu32(void)
+{
+	return ((uint32_t)randbyte() << 24) |
+	    ((uint32_t)randbyte() << 16) |
+	    ((uint32_t)randbyte() << 8) |
+	    (uint32_t)randbyte();
+}
+
+static uint32_t
+randbelow(uint32_t n)
+{
+	uint32_t x, min;
+
+	if (n <= 1)
+		return 0;
+	/* reject [0, 2^32 % n) so x % n is unbiased */
+	min = (uint32_t)(-n) % n;
+	do {
+		x = randu32();
+	} while (x < min);
+	return x % n;
+}
+
+static int
+eint(const char *s)
+{
+	char *end;
+	long v;
+
+	if (s == NULL || s[0] == '\0')
+		usage();
+	errno = 0;
+	v = strtol(s, &end, 10);
+	if (errno || end == s || *end != '\0' || v < INT_MIN || v > INT_MAX)
+		die("rg: invalid number '%s'", s);
+	return (int)v;
+}
+
+int
+main(int argc, char *argv[])
+{
+	int i, j, n, l, alen;
+
+	n = defn;
+	l = defl;
+
+	ARGBEGIN {
+	case 'n':
+		n = eint(EARGF(usage()));
+		break;
+	case 'l':
+		l = eint(EARGF(usage()));
+		break;
+	case 'v':
+		puts("rg-" VERSION);
+		return 0;
+	default:
+		usage();
+	} ARGEND
+
+	if (argc)
+		usage();
+	if (n < minn || n > maxn)
+		die("rg: n must be %d..%d", minn, maxn);
+	if (l < minl || l > maxl)
+		die("rg: l must be %d..%d", minl, maxl);
+
+	alen = (int)strlen(alphabet);
+	if (alen < 1)
+		die("rg: empty alphabet");
+
+	for (i = 0; i < n; i++) {
+		for (j = 0; j < l; j++)
+			putchar(alphabet[randbelow((uint32_t)alen)]);
+		putchar('\n');
+	}
+
+	return 0;
+}