add misc/parse_number.h

misc/parse_number.h

@@ -0,0 +1,65 @@
+/**
+ * @file parse_number.h
+ * @author Ambroz Bizjak <ambrop7@gmail.com>
+ * 
+ * @section LICENSE
+ * 
+ * This file is part of BadVPN.
+ * 
+ * BadVPN is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ * 
+ * BadVPN is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ * 
+ * @section DESCRIPTION
+ * 
+ * Numeric string parsing.
+ */
+
+#ifndef BADVPN_MISC_PARSE_NUMBER_H
+#define BADVPN_MISC_PARSE_NUMBER_H
+
+#include <inttypes.h>
+
+static int parse_unsigned_integer (const char *str, uintmax_t *out);
+
+int parse_unsigned_integer (const char *str, uintmax_t *out)
+{
+    uintmax_t n = 0;
+    
+    if (!*str) {
+        return 0;
+    }
+    
+    while (*str) {
+        if (*str < '0' || *str > '9') {
+            return 0;
+        }
+        int digit = *str - '0';
+        
+        if (n > UINTMAX_MAX / 10) {
+            return 0;
+        }
+        n *= 10;
+        
+        if (digit > UINTMAX_MAX - n) {
+            return 0;
+        }
+        n += digit;
+        
+        str++;
+    }
+    
+    *out = n;
+    return 1;
+}
+
+#endif