mkhtemp: generalised string concatenation

scatn in strings.c was buggy, so i replaced it; it
concatenates any number of things.

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

2 files changed, 30 insertions, 41 deletions

diff --git a/util/libreboot-utils/lib/mkhtemp.c b/util/libreboot-utils/lib/mkhtemp.c
index 72942868..743a59fd 100644
--- a/util/libreboot-utils/lib/mkhtemp.c
+++ b/util/libreboot-utils/lib/mkhtemp.c
@@ -135,19 +135,12 @@ new_tmp_common(int *fd, char **path, int type,
 	if (slen(templatestr, maxlen, &templatestr_len) < 0)
 		goto err;
 
-	/* sizeof adds an extra byte, useful
-	 * because we also want '.' or '/'
-	 */
+	/* may as well calculate in advance */
 	destlen = dirlen + 1 + templatestr_len;
-	if (destlen > maxlen - 1) {
-		errno = EOVERFLOW;
+	/* full path: */
+	if (scatn(3, (const char *[]) { tmpdir, "/", templatestr },
+	    maxlen, &dest) < 0)
 		goto err;
-	}
-
-	memcpy(smalloc(&dest, destlen + 1), tmpdir, dirlen);
-	*(dest + dirlen) = '/';
-	memcpy(dest + dirlen + 1, templatestr, templatestr_len);
-	*(dest + destlen) = '\0';
 
 	fname = dest + dirlen + 1;
 
diff --git a/util/libreboot-utils/lib/string.c b/util/libreboot-utils/lib/string.c
index c7f90f5d..9adbb120 100644
--- a/util/libreboot-utils/lib/string.c
+++ b/util/libreboot-utils/lib/string.c
@@ -174,49 +174,45 @@ sdup(const char *s,
 }
 
 /* concatenate N number of strings */
-/* slen already checks null/termination */
 int
 scatn(ssize_t sc, const char **sv,
     size_t max, char **rval)
 {
-	ssize_t i = 0;
-
-	size_t ts = 0;
-	size_t *size = NULL;
-
-	char *ct = NULL;
 	int saved_errno = errno;
 
-	if (if_err(sc <= 0, EINVAL) ||
-	    if_err(sc > SIZE_MAX / sizeof(size_t), EOVERFLOW) ||
-	    if_err(sv == NULL, EINVAL))
-		goto err;
+	char *final = NULL;
+	char *rcur = NULL;
+	char *rtmp = NULL;
+	size_t i;
 
-	vmalloc((void **)&size, sizeof(size_t) * sc);
+	if (if_err(sc < 2, EINVAL) ||
+	    if_err(sv == NULL, EFAULT) ||
+	    if_err(rval == NULL || *rval != NULL, EFAULT))
+		goto err;
 
-	for (i = 0; i < sc; i++, ts += size[i])
-		if (if_err(sv[i] == NULL, EINVAL) ||
-		    slen(sv[i], max, &size[i]) < 0 ||
-		    if_err(size[i] > max - 1, EOVERFLOW) ||
-		    if_err((size[i] + ts) < ts, EOVERFLOW))
-			goto err;
+	for (i = 0; i < sc; i++) {
 
-	if (if_err(ts > SIZE_MAX - 1, EOVERFLOW) ||
-	    if_err(ts > max - 1, EOVERFLOW))
-		goto err;
+		if (i == 0) {
+			if (sdup(sv[0], max, &final) < 0)
+				goto err;
+			continue;
+		}
 
-	smalloc(&ct, ts + 1);
-	for (ts = i = 0; i < sc; i++, ts += size[i])
-		memcpy(ct + ts, sv[i], size[i]);
+		rtmp = NULL;
+		if (scat(final, sv[i], max, &rtmp) < 0)
+			goto err;
 
-	*(ct + ts) = '\0';
-	*rval = ct;
+		free_and_set_null(&final);
+		final = rtmp;
+		rtmp = NULL;
+	}
 
-	errno = saved_errno;
+	*rval = final;
 	return 0;
 err:
-	free_and_set_null(&ct);
-	free_and_set_null((char **)&size);
+	free_and_set_null(&rcur);
+	free_and_set_null(&rtmp);
+	free_and_set_null(&final);
 
 	return set_errno(saved_errno, EFAULT);
 }
@@ -230,7 +226,7 @@ scat(const char *s1, const char *s2,
 	size_t size2;
 	char *rval = NULL;
 
-	if (dest == NULL ||
+	if (if_err(dest == NULL || *dest != NULL, EFAULT) ||
 	    slen(s1, n, &size1) < 0 ||
 	    slen(s2, n, &size2) < 0 ||
 	    if_err(size1 > SIZE_MAX - size2 - 1, EOVERFLOW)) {