Properly check `strtol` for errors

We are now using a custom `strtol` implementation to make sure we're not
missing any overflow errors.

1 files changed, 79 insertions, 0 deletions

diff --git a/src/util.c b/src/util.c
index 995daf314..55a7ab2a9 100644
--- a/src/util.c
+++ b/src/util.c
@@ -2,6 +2,7 @@
 #include "common.h"
 #include <stdarg.h>
 #include <stdio.h>
+#include <ctype.h>
 
 void git_strarray_free(git_strarray *array)
 {
@@ -12,6 +13,84 @@ void git_strarray_free(git_strarray *array)
 	free(array->strings);
 }
 
+int git__strtol32(long *result, const char *nptr, const char **endptr, int base)
+{
+	const char *p;
+	long n, nn;
+	int c, ovfl, v, neg, ndig;
+
+	p = nptr;
+	neg = 0;
+	n = 0;
+	ndig = 0;
+	ovfl = 0;
+
+	/*
+	 * White space
+	 */
+	while (isspace(*p))
+		p++;
+
+	/*
+	 * Sign
+	 */
+	if (*p == '-' || *p == '+')
+		if (*p++ == '-')
+			neg = 1;
+
+	/*
+	 * Base
+	 */
+	if (base == 0) {
+		if (*p != '0')
+			base = 10;
+		else {
+			base = 8;
+			if (p[1] == 'x' || p[1] == 'X') {
+				p += 2;
+				base = 16;
+			}
+		}
+	} else if (base == 16 && *p == '0') {
+		if (p[1] == 'x' || p[1] == 'X')
+			p += 2;
+	} else if (base < 0 || 36 < base)
+		goto Return;
+
+	/*
+	 * Non-empty sequence of digits
+	 */
+	for (;; p++,ndig++) {
+		c = *p;
+		v = base;
+		if ('0'<=c && c<='9')
+			v = c - '0';
+		else if ('a'<=c && c<='z')
+			v = c - 'a' + 10;
+		else if ('A'<=c && c<='Z')
+			v = c - 'A' + 10;
+		if (v >= base)
+			break;
+		nn = n*base + v;
+		if (nn < n)
+			ovfl = 1;
+		n = nn;
+	}
+
+Return:
+	if (ndig == 0)
+		return GIT_ENOTNUM;
+
+	if (endptr)
+		*endptr = p;
+
+	if (ovfl)
+		return GIT_EOVERFLOW;
+
+	*result = neg ? -n : n;
+	return GIT_SUCCESS;
+}
+
 int git__fmt(char *buf, size_t buf_sz, const char *fmt, ...)
 {
 	va_list va;