libreboot-utils: tidy up the rand code

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/libreboot-utils/Makefile

@@ -37,14 +37,16 @@ OBJS_NVMUTIL = \
 	obj/lib/io.o \
 	obj/lib/checksum.o \
 	obj/lib/word.o \
-	obj/lib/mkhtemp.o
+	obj/lib/mkhtemp.o \
+	obj/lib/rand.o
 
 OBJS_MKHTEMP = \
 	obj/mkhtemp.o \
 	obj/lib/file.o \
 	obj/lib/string.o \
 	obj/lib/num.o \
-	obj/lib/mkhtemp.o
+	obj/lib/mkhtemp.o \
+	obj/lib/rand.o
 
 # default mode
 CFLAGS_MODE = $(PORTABLE)
@@ -106,6 +108,9 @@ obj/lib/word.o: lib/word.c
 obj/lib/mkhtemp.o: lib/mkhtemp.c
 	$(CC_MODE) $(CFLAGS_MODE) -c lib/mkhtemp.c -o obj/lib/mkhtemp.o
 
+obj/lib/rand.o: lib/rand.c
+	$(CC_MODE) $(CFLAGS_MODE) -c lib/rand.c -o obj/lib/rand.o
+
 # install
 
 install: $(PROG) $(PROGMKH)

util/libreboot-utils/include/common.h

@@ -13,24 +13,13 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <limits.h>
+#include <errno.h>
 
 /* for linux getrandom
  */
 #if defined(__linux__)
-#include <errno.h>
-#if defined(__has_include)
-#if __has_include(<sys/random.h>)
 #include <sys/random.h>
-#define HAVE_GETRANDOM 1
-#endif
-#endif
-#if !defined(HAVE_GETRANDOM)
 #include <sys/syscall.h>
-#if defined(SYS_getrandom)
-#define HAVE_GETRANDOM_SYSCALL 1
-#endif
-#endif
-
 #endif
 
 #define items(x) (sizeof((x)) / sizeof((x)[0]))
@@ -384,24 +373,18 @@ int slen(const char *scmp, size_t maxlen,
     size_t *rval);
 int scmp(const char *a, const char *b,
     size_t maxlen, int *rval);
-
+int sdup(const char *s,
+    size_t n, char **dest);
+int scat(const char *s1, const char *s2,
+    size_t n, char **dest);
+int dcat(const char *s, size_t n,
+    size_t off, char **dest1,
+    char **dest2);
 /* numerical functions
  */
 
 unsigned short hextonum(char ch_s);
 size_t rlong(void);
-#if !(defined(FALLBACK_RAND_1989) && \
-    ((FALLBACK_RAND_1989) > 0))
-#if defined(__linux__)
-#if defined(HAVE_GETRANDOM) || \
-    defined(HAVE_GETRANDOM_SYSCALL)
-int fallback_rand_getrandom(void *buf, size_t len);
-#endif
-#endif
-#else
-size_t fallback_rand_1989(void);
-size_t entropy_jitter(void);
-#endif
 
 /* Helper functions for command: dump
  */

util/libreboot-utils/lib/mkhtemp.c

@@ -79,8 +79,8 @@ new_tmp_common(int *fd, char **path, int type,
 #endif
 	struct stat st;
 
-	const char *suffix;
+	const char *templatestr;
-	size_t suffix_len;
+	size_t templatestr_len;
 
 	size_t dirlen;
 	size_t destlen;
@@ -144,17 +144,17 @@ new_tmp_common(int *fd, char **path, int type,
 		goto err;
 
 	if (template != NULL)
-		suffix = template;
+		templatestr = template;
 	else
-		suffix = "tmp.XXXXXXXXXX";
+		templatestr = "tmp.XXXXXXXXXX";
 
-	if (slen(suffix, maxlen, &suffix_len) < 0)
+	if (slen(templatestr, maxlen, &templatestr_len) < 0)
 		goto err;
 
 	/* sizeof adds an extra byte, useful
 	 * because we also want '.' or '/'
 	 */
-	destlen = dirlen + 1 + suffix_len;
+	destlen = dirlen + 1 + templatestr_len;
 	if (destlen > maxlen - 1) {
 		errno = EOVERFLOW;
 		goto err;
@@ -168,7 +168,7 @@ new_tmp_common(int *fd, char **path, int type,
 
 	memcpy(dest, tmpdir, dirlen);
 	*(dest + dirlen) = '/';
-	memcpy(dest + dirlen + 1, suffix, suffix_len);
+	memcpy(dest + dirlen + 1, templatestr, templatestr_len);
 	*(dest + destlen) = '\0';
 
 	fname = dest + dirlen + 1;
@@ -603,7 +603,7 @@ mkhtemp(int *fd,
 	    if_err_sys(slen(template, max_len, &len) < 0) ||
 	    if_err(len >= max_len, EMSGSIZE)
 	      ||
-	    if_err_sys(slen(fname, max_len, &fname_len)) ||
+	    if_err_sys(slen(fname, max_len, &fname_len) < 0) ||
 	    if_err(fname == NULL, EINVAL) ||
 	    if_err(strrchr(fname, '/') != NULL, EINVAL))
 		return -1;
@@ -611,7 +611,7 @@ mkhtemp(int *fd,
 	for (end = template + len; /* count X */
 	    end > template && *--end == 'X'; xc++);
 
-	if (if_err(xc < 6 || xc > len, EINVAL) ||
+	if (if_err(xc < 3 || xc > len, EINVAL) ||
 	    if_err(fname_len > len, EOVERFLOW))
 		return -1;
 
@@ -622,7 +622,7 @@ mkhtemp(int *fd,
 	if((fname_copy = malloc(fname_len + 1)) == NULL)
 		goto err;
 
-	/* fname_copy = suffix region only; p points to trailing XXXXXX */
+	/* fname_copy = templatestr region only; p points to trailing XXXXXX */
 	memcpy(fname_copy,
 	    template + len - fname_len,
 	    fname_len + 1);
@@ -886,53 +886,30 @@ err:
 int
 mkhtemp_fill_random(char *p, size_t xc)
 {
-	size_t chx = 0;
-	int rand_failures = 0;
-
-	size_t r;
-
-	int saved_rand_error = 0;
 	static char ch[] =
 	    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 
+	size_t chx = 0;
+	size_t r;
+
 	/* clamp rand to prevent modulo bias
-	 * (reduced risk of entropy leak)
 	 */
 	size_t limit = ((size_t)-1) - (((size_t)-1) % (sizeof(ch) - 1));
-
 	int saved_errno = errno;
 
-	if (p == NULL) {
+	if (if_err(p == NULL, EFAULT))
-		errno = EFAULT;
+		return -1;
-		goto err_mkhtemp_fill_random;
-	}
 
 	for (chx = 0; chx < xc; chx++) {
 
-		do {
-			saved_rand_error = errno;
-			rand_failures = 0;
 retry_rand:
-			errno = 0;
+		/* on bsd: uses arc4random
-
+		   on linux: uses getrandom
-			/* on bsd: uses arc4random
+		   *never returns error*
-			   on linux: uses getrandom
+		 */
-			   on OLD linux: /dev/urandom
+		r = rlong(); /* always returns successful */
-			   on old/other unix: /dev/urandom
+		if (r >= limit)
-			 */
+			goto retry_rand;
-			r = rlong();
-
-			if (errno > 0) {
-				if (++rand_failures <= 8)
-					goto retry_rand;
-
-				goto err_mkhtemp_fill_random;
-			}
-
-			rand_failures = 0;
-			errno = saved_rand_error;
-
-		} while (r >= limit);
 
 		p[chx] = ch[r % (sizeof(ch) - 1)];
 	}
@@ -940,12 +917,6 @@ retry_rand:
 	errno = saved_errno;
 	return 0;
 
-err_mkhtemp_fill_random:
-
-	if (errno == saved_errno)
-		errno = ECANCELED;
-
-	return -1;
 }
 
 /* WARNING: **ONCE** per file.

util/libreboot-utils/lib/num.c

@@ -2,6 +2,7 @@
  * Copyright (c) 2026 Leah Rowe <leah@libreboot.org>
  *
  * Numerical functions.
+ * NOTE: randomness was moved to rand.c
  */
 
 /*
@@ -12,10 +13,6 @@ TODO: properly handle errno in this file
 #include <sys/param.h>
 #endif
 #include <sys/types.h>
-#if defined(FALLBACK_RAND_1989) && \
-    (FALLBACK_RAND_1989) > 0
-#include <sys/time.h>
-#endif
 
 #include <errno.h>
 #if !((defined(__OpenBSD__) && (OpenBSD) >= 201) || \
@@ -26,10 +23,6 @@ TODO: properly handle errno in this file
 #include <limits.h>
 #include <stddef.h>
 #include <string.h>
-#if defined(FALLBACK_RAND_1989) && \
-    (FALLBACK_RAND_1989) > 0
-#include <time.h>
-#endif
 #include <unistd.h>
 
 #include "../include/common.h"
@@ -117,321 +110,6 @@ err_hextonum:
 	/* caller just checks >15. */
 }
 
-/* Random numbers
- */
-
-/* when calling this: save errno
- * first, then set errno to zero.
- * on error, this function will
- * set errno and possibly return
- *
- * rlong also preserves errno
- * and leaves it unchanged on
- * success, so if you do it
- * right, you can detect error.
- * this is because it uses
- * /dev/urandom which can err.
- * ditto getrandom (EINTR),
- * theoretically.
- */
-
-size_t
-rlong(void)
-{
-#if !(defined(FALLBACK_RAND_1989) && \
-    ((FALLBACK_RAND_1989) > 0))
-#if (defined(__OpenBSD__) && (OpenBSD) >= 201) || \
-    defined(__FreeBSD__) || \
-    defined(__NetBSD__) || defined(__APPLE__)
-
-	int saved_errno = errno;
-	size_t rval;
-
-	arc4random_buf(&rval, sizeof(size_t));
-
-	errno = saved_errno;
-	return rval;
-#else
-	static int fd = -1;
-	static ssize_t nr = -1;
-	static size_t off = 0;
-#if defined (BUFSIZ)
-	static char rbuf[BUFSIZ];
-#else
-#ifndef PORTABLE
-	static char rbuf[4096];
-#elif ((PORTABLE) > 0)
-	static char rbuf[256]; /* scarce memory on old systems */
-#else
-	static char rbuf[4096]; /* typical 32-bit BUFSIZ */
-#endif
-#endif
-	size_t rval;
-	ssize_t new_nr;
-
-	int retries = 0;
-	int max_retries = 100;
-
-	int saved_errno = errno;
-
-#if defined(__linux__)
-#if defined(HAVE_GETRANDOM) || \
-    defined(HAVE_GETRANDOM_SYSCALL)
-
-	/* linux getrandom()
-	 *
-	 * we *can* use arc4random on
-	 * modern linux, but not on
-	 * every libc. better use the
-	 * official linux function
-	 */
-
-	if (fallback_rand_getrandom(&rval, sizeof(rval)) == 0) {
-		errno = saved_errno;
-		return rval;
-	}
-
-	/*
-	 * now fall back to urandom if getrandom failed:
-	 */
-#endif
-#endif
-
-	/* reading from urandom is inherently
-	 * unreliable on old systems, even if
-	 * newer systems make it more reliable
-	 *
-	 * modern linux/bsd make it safe, but
-	 * we have to assume that someone is
-	 * compiling this on linux from 1999
-	 *
-	 * this logic therefore applies various
-	 * tricks to mitigate possible os bugs
-	 */
-
-retry_urandom_read:
-
-	if (++retries > max_retries)
-		goto err_rlong;
-
-	if (nr < 0 || nr < (ssize_t)sizeof(size_t)) {
-
-		if (fd < 0) {
-
-			fd = open("/dev/urandom",
-			    O_RDONLY | O_BINARY | O_NOFOLLOW |
-			    O_CLOEXEC | O_NOCTTY);
-
-#ifdef USE_OLD_DEV_RANDOM
-#if (USE_OLD_DEV_RANDOM) > 0
-			/* WARNING:
-			 *   /dev/random may block
-			 *   forever and does **NOT**
-			 *   guarantee better entropy
-			 *   on old systems
-			 *
-			 *   only use it if needed
-			 */
-
-			if (fd < 0)
-				fd = open("/dev/random",
-				    O_RDONLY | O_BINARY | O_NOFOLLOW |
-				    O_CLOEXEC | O_NOCTTY);
-#endif
-#endif
-
-			if (fd < 0)
-				goto retry_urandom_read;
-
-			retries = 0;
-		}
-
-		new_nr = rw_file_exact(fd, (unsigned char *)rbuf,
-		    sizeof(rbuf), 0, IO_READ, LOOP_EAGAIN,
-		    LOOP_EINTR, MAX_ZERO_RW_RETRY, OFF_ERR);
-
-		if (new_nr < 0 || new_nr < (ssize_t)sizeof(rbuf))
-			goto retry_urandom_read;
-
-		/* only reset buffer after successful refill */
-		nr = new_nr;
-		off = 0;
-
-		/* don't re-use same fd, to mitaget
-		 * fd injection */
-		close_no_err(&fd);
-	}
-
-	fd = -1;
-	retries = 0;
-
-	memcpy(&rval, rbuf + off, sizeof(size_t));
-
-	nr -= (ssize_t)sizeof(size_t);
-	off += sizeof(size_t);
-
-	errno = saved_errno;
-
-	return rval;
-
-err_rlong:
-
-	if (errno == saved_errno)
-		errno = EIO;
-
-	return 0;
-
-#endif
-#else /* FALLBACK_RAND_1989 */
-	/* your computer is from a museum
-	 */
-	size_t mix = 0;
-	int nr = 0;
-	int saved_errno = errno;
-
-	/* 100 times, for entropy
-	 */
-	for (nr = 0; nr < 100; nr++)
-		mix ^= fallback_rand_1989();
-
-	errno = saved_errno;
-	return mix;
-#endif
-}
-
-#if !(defined(FALLBACK_RAND_1989) && \
-    ((FALLBACK_RAND_1989) > 0))
-#if defined(__linux__)
-#if defined(HAVE_GETRANDOM) || \
-    defined(HAVE_GETRANDOM_SYSCALL)
-int /* yes, linux is a fallback */
-fallback_rand_getrandom(void *buf, size_t len)
-{
-	size_t off = 0;
-	ssize_t rval = -1;
-	int saved_errno = errno;
-
-	if (!len) {
-		errno = EINVAL;
-		return -1;
-	}
-
-	if (buf == NULL) {
-		errno = EFAULT;
-		return -1;
-	}
-
-#if defined(HAVE_GETRANDOM) || \
-    defined(HAVE_GETRANDOM_SYSCALL)
-
-	while (off < len) {
-
-#if defined(HAVE_GETRANDOM)
-		rval = (ssize_t)getrandom((char *)buf + off, len - off, 0);
-#elif defined(HAVE_GETRANDOM_SYSCALL)
-		rval = (ssize_t)syscall(SYS_getrandom,
-		    (char *)buf + off, len - off, 0);
-#endif
-
-		if (rval < 0) {
-			if (errno == EINTR || errno == EAGAIN)
-				continue;
-
-			errno = EIO;
-			return -1; /* unsupported by kernel */
-		}
-
-		if (rval == 0) {
-			errno = EIO;
-			return -1;
-		}
-
-		off += (size_t)rval;
-	}
-
-	errno = saved_errno;
-	return 0;
-
-#else
-	(void)buf;
-	(void)len;
-
-	errno = EIO;
-	return -1;
-#endif
-}
-#endif
-#endif
-#else
-size_t
-fallback_rand_1989(void)
-{
-	static size_t mix = 0;
-	static size_t counter = 0;
-
-	struct timeval tv;
-
-	/* nobody should use this
-	 * (not crypto-safe)
-	 */
-
-	gettimeofday(&tv, NULL);
-
-	mix ^= (size_t)tv.tv_sec
-	    ^ (size_t)tv.tv_usec
-	    ^ (size_t)getpid()
-	    ^ (size_t)&mix
-	    ^ counter++
-	    ^ entropy_jitter();
-
-	/*
-	 * Stack addresses can vary between
-	 * calls, thus increasing entropy.
-	 */
-	mix ^= (size_t)&mix;
-	mix ^= (size_t)&tv;
-	mix ^= (size_t)&counter;
-
-	return mix;
-}
-
-size_t
-entropy_jitter(void)
-{
-	size_t mix;
-
-	struct timeval a, b;
-	ssize_t mix_diff;
-
-	int c;
-
-	mix = 0;
-
-	gettimeofday(&a, NULL);
-
-	for (c = 0; c < 32; c++) {
-
-		getpid();
-		gettimeofday(&b, NULL);
-
-		/*
-		 * prevent negative numbers to prevent overflow,
-		 * which would bias rand to large numbers
-		 */
-		mix_diff = (ssize_t)(b.tv_usec - a.tv_usec);
-		if (mix_diff < 0)
-			mix_diff = -mix_diff;
-
-		mix ^= (size_t)(mix_diff);
-
-		mix ^= (size_t)&mix;
-
-	}
-
-	return mix;
-}
-#endif
-
 void
 check_bin(size_t a, const char *a_name)
 {

util/libreboot-utils/lib/rand.c

@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: MIT
+ * Copyright (c) 2026 Leah Rowe <leah@libreboot.org>
+ *
+ * Random number generation
+ */
+
+#ifndef RAND_H
+#define RAND_H
+
+#ifdef __OpenBSD__
+#include <sys/param.h>
+#endif
+#include <sys/types.h>
+
+#include <errno.h>
+#if !((defined(__OpenBSD__) && (OpenBSD) >= 201) || \
+    defined(__FreeBSD__) || \
+    defined(__NetBSD__) || defined(__APPLE__))
+#include <fcntl.h> /* if not arc4random: /dev/urandom */
+#endif
+#include <limits.h>
+#include <stddef.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#include "../include/common.h"
+
+/* Random numbers
+ */
+
+/* when calling this: save errno
+ * first, then set errno to zero.
+ * on error, this function will
+ * set errno and possibly return
+ *
+ * rlong also preserves errno
+ * and leaves it unchanged on
+ * success, so if you do it
+ * right, you can detect error.
+ * this is because it uses
+ * /dev/urandom which can err.
+ * ditto getrandom (EINTR),
+ * theoretically.
+ */
+
+/* for the linux version: we use only the
+ * syscall, because we cannot trust /dev/urandom
+ * to be as robust, and some libc implementations
+ * may default to /dev/urandom under fault conditions.
+ *
+ * for general high reliability, we must abort on
+ * failure. in practise, it will likely never fail.
+ * the arc4random call on bsd never returns error.
+ */
+
+size_t
+rlong(void)
+{
+	size_t rval;
+	int saved_errno = errno;
+	errno = 0;
+
+#if (defined(__OpenBSD__) && (OpenBSD) >= 201) || \
+    defined(__FreeBSD__) || \
+    defined(__NetBSD__) || defined(__APPLE__)
+
+	arc4random_buf(&rval, sizeof(size_t));
+	goto out;
+
+#elif defined(__linux__)
+
+	size_t off = 0;
+	size_t len = sizeof(rval);
+	ssize_t rc;
+
+retry_rand:
+	rc = (ssize_t)syscall(SYS_getrandom,
+	    (char *)&rval + off, len - off, 0);
+
+	if (rc < 0) {
+		if (errno == EINTR || errno == EAGAIN)
+			goto retry_rand;
+
+		goto err; /* possibly unsupported by kernel */
+	}
+
+	if ((off += (size_t)rc) < len)
+		goto retry_rand;
+
+	goto out;
+err:
+	/*
+	 * getrandom can return with error, butt arc4random
+	 * doesn't. generally, getrandom will be reliably,
+	 * but we of course have to maintain parity with
+	 * BSD. So a rand failure is to be interpreted as
+	 * a major systems failure, and we act accordingly.
+	 */
+	err_no_cleanup(1, ECANCELED,
+	    "Randomisation failure, possibly unsupported in your kernel.");
+	exit(EXIT_FAILURE);
+
+#else
+#error Unsupported operating system (possibly unsecure randomisation)
+#endif
+
+out:
+	errno = saved_errno;
+	return rval;
+}
+#endif

util/libreboot-utils/lib/string.c

@@ -14,25 +14,12 @@
 #include <string.h>
 #include <stdlib.h>
 #include <unistd.h>
+#include <limits.h>
+#include <stdint.h>
 
 #include "../include/common.h"
 
-/* scmp() - strict string comparison
+/* strict strcmp */
- *
- * strict string comparison
- * similar to strncmp, but null and
- * unterminated inputs do not produce
- * a return value; on error, errno is
- * set and -1 is returned.
- *
- * the real return value is stored in
- * the 4th argument by pointer.
- *
- * the value at rval pointer is set,
- * only upon success. callers should
- * check the return value accordingly.
- */
-
 int
 scmp(const char *a,
     const char *b,
@@ -46,9 +33,8 @@ scmp(const char *a,
 	if (a == NULL ||
 	    b == NULL ||
 	    rval == NULL) {
-
 		errno = EFAULT;
-		return -1;
+		goto err;
 	}
 
 	for (ch = 0; ch < maxlen; ch++) {
@@ -67,27 +53,14 @@ scmp(const char *a,
 		}
 	}
 
-	/* block unterminated strings */
+err:
 	errno = EFAULT;
+	if (rval != NULL)
+		*rval = -1;
 	return -1;
 }
 
-/* slen() - strict strict length
+/* strict strlen */
- *
- * strict string length calculation
- * similar to strnlen, but null and
- * unterminated inputs do not produce
- * a return value; on error, errno is
- * set and -1 is returned.
- *
- * the real return value is stored in
- * the 3rd argument by pointer.
- *
- * the value at rval pointer is set,
- * only upon success. callers should
- * check the return value accordingly.
- */
-
 int
 slen(const char *s,
     size_t maxlen,
@@ -97,9 +70,8 @@ slen(const char *s,
 
 	if (s == NULL ||
 	    rval == NULL) {
-
 		errno = EFAULT;
-		return -1;
+		goto err;
 	}
 
 	for (ch = 0;
@@ -109,11 +81,114 @@ slen(const char *s,
 	if (ch == maxlen) {
 		/* unterminated */
 		errno = EFAULT;
-		return -1;
+		goto err;
 	}
 
 	*rval = ch;
 	return 0;
+err:
+	if (rval != NULL)
+		*rval = 0;
+	return -1;
+}
+
+/* strict strdup */
+int
+sdup(const char *s,
+    size_t n, char **dest)
+{
+	size_t size;
+	char *rval;
+
+	if (dest == NULL ||
+	    slen(s, n, &size) < 0 ||
+	    if_err(size == SIZE_MAX, EOVERFLOW) ||
+	    (rval = malloc(size + 1)) == NULL) {
+
+		if (dest != NULL)
+			*dest = NULL;
+		return -1;
+	}
+
+	memcpy(rval, s, size);
+	*(rval + size) = '\0';
+
+	*dest = rval;
+	return 0;
+}
+
+/* strict strcat */
+int
+scat(const char *s1, const char *s2,
+    size_t n, char **dest)
+{
+	size_t size1;
+	size_t size2;
+	char *rval;
+
+	if (dest == NULL ||
+	    slen(s1, n, &size1) < 0 ||
+	    slen(s2, n, &size2) < 0 ||
+	    if_err(size1 > SIZE_MAX - size2 - 1, EOVERFLOW) ||
+	    (rval = malloc(size1 + size2 + 1)) == NULL) {
+
+		if (dest != NULL)
+			*dest = NULL;
+		return -1;
+	}
+
+	memcpy(rval, s1, size1);
+	memcpy(rval + size1, s2, size2);
+	*(rval + size1 + size2) = '\0';
+
+	*dest = rval;
+	return 0;
+}
+
+/* strict split/de-cat - off is where
+   2nd buffer will start from */
+int
+dcat(const char *s, size_t n,
+    size_t off, char **dest1,
+    char **dest2)
+{
+	size_t size;
+	char *rval1 = NULL;
+	char *rval2 = NULL;
+
+	if (dest1 == NULL || dest2 == NULL ||
+	    slen(s, n, &size) < 0 ||
+	    if_err(size == SIZE_MAX, EOVERFLOW) ||
+	    if_err(off >= size, EOVERFLOW) ||
+	    (rval1 = malloc(off + 1)) == NULL ||
+	    (rval2 = malloc(size - off + 1)) == NULL) {
+
+		goto err;
+	}
+
+	memcpy(rval1, s, off);
+	*(rval1 + off) = '\0';
+
+	memcpy(rval2, s + off, size - off);
+	*(rval2 + size - off) = '\0';
+
+	*dest1 = rval1;
+	*dest2 = rval2;
+
+	return 0;
+
+err:
+	if (rval1 != NULL)
+		free(rval1);
+	if (rval2 != NULL)
+		free(rval2);
+
+	if (dest1 != NULL)
+		*dest1 = NULL;
+	if (dest2 != NULL)
+		*dest2 = NULL;
+
+	return -1;
 }
 
 /* the one for nvmutil state is in state.c */

util/libreboot-utils/mkhtemp.c

@@ -140,9 +140,9 @@ main(int argc, char *argv[])
 		for (p = template + tlen;
 		    p > template && *--p == 'X'; xc++);
 
-		if (xc < 6)
+		if (xc < 3) /* the gnu mktemp errs on less than 3 */
 			err_no_cleanup(stfu, EINVAL,
-			    "template must end in at least 6 X");
+			"template must have 3 X or more on end (12+ advised");
 	}
 
 	/* user supplied -p PATH - WARNING: