WIP: hardened mktemp

i'm pretty much nearly there. still no dir support,
only files.

i won't keep amending now - will do more, then
squash later.

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

1 files changed, 74 insertions, 35 deletions

diff --git a/util/nvmutil/lib/string.c b/util/nvmutil/lib/string.c
index b1a5c3e2..ca58fb1c 100644
--- a/util/nvmutil/lib/string.c
+++ b/util/nvmutil/lib/string.c
@@ -9,67 +9,106 @@
 
 #include <errno.h>
 #include <stddef.h>
+#include <string.h>
 #include <unistd.h>
 
 #include "../include/common.h"
 
-/* Portable strncmp() that blocks
- * NULL/empty/unterminated strings
+/* scmp() - strict string comparison
+ *
+ * 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
-xstrxcmp(const char *a, const char *b, unsigned long maxlen)
+scmp(const char *a,
+    const char *b,
+    size_t maxlen,
+    int *rval)
 {
-	unsigned long i;
+	size_t ch;
+	unsigned char ac;
+	unsigned char bc;
 
-	if (a == NULL || b == NULL)
-		err(EINVAL, "NULL input to xstrxcmp");
+	if (a == NULL ||
+	    b == NULL ||
+	    rval == NULL) {
 
-	if (*a == '\0' || *b == '\0')
-		err(EINVAL, "Empty string in xstrxcmp");
+		errno = EFAULT;
+		return -1;
+	}
 
-	for (i = 0; i < maxlen; i++) {
+	for (ch = 0; ch < maxlen; ch++) {
 
-		unsigned char ac = (unsigned char)a[i];
-		unsigned char bc = (unsigned char)b[i];
+		ac = (unsigned char)a[ch];
+		bc = (unsigned char)b[ch];
 
-		if (ac == '\0' || bc == '\0') {
-			if (ac == bc)
-				return 0;
-			return ac - bc;
+		if (ac != bc) {
+			*rval = ac - bc;
+			return 0;
 		}
 
-		if (ac != bc)
-			return ac - bc;
+		if (ac == '\0') {
+			*rval = 0;
+			return 0;
+		}
 	}
 
-	err(EINVAL, "Unterminated string in xstrxcmp");
-
-	errno = EINVAL;
+	/* block unterminated strings */
+	errno = EFAULT;
 	return -1;
 }
 
-/* Portable strncmp() that blocks
- * NULL/empty/unterminated strings
+/* slen() - strict strict length
+ *
+ * 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.
  */
 
-unsigned long
-xstrxlen(const char *scmp, unsigned long maxlen)
+int
+slen(const char *s,
+    size_t maxlen,
+    size_t *rval)
 {
-	unsigned long xstr_index;
+	size_t ch;
 
-	if (scmp == NULL)
-		err(EINVAL, "NULL input to xstrxlen");
+	if (s == NULL ||
+	    rval == NULL) {
 
-	if (*scmp == '\0')
-		err(EINVAL, "Empty string in xstrxlen");
+		errno = EFAULT;
+		return -1;
+	}
 
-	for (xstr_index = 0;
-	    xstr_index < maxlen && scmp[xstr_index] != '\0';
-	    xstr_index++);
+	for (ch = 0;
+	    ch < maxlen && s[ch] != '\0';
+	    ch++);
 
-	if (xstr_index == maxlen)
-		err(EINVAL, "Unterminated string in xstrxlen");
+	if (ch == maxlen) {
+		/* unterminated */
+		errno = EFAULT;
+		return -1;
+	}
 
-	return xstr_index;
+	*rval = ch;
+	return 0;
 }