init commit

3sem/cnts/contest5/03.c

@@ -0,0 +1,36 @@
+#include <stdlib.h>
+
+enum
+{
+    RWX_PERMISSIONS = 0777,
+};
+
+int
+parse_rwx_permissions(const char *str)
+{
+    if (str == NULL) {
+        return -1;
+    }
+
+    const char expected[] = "rwxrwxrwx";
+
+    unsigned res = 0;
+    int i = 0;
+    while (str[i]) {
+        res <<= 1;
+
+        if (str[i] == expected[i] && expected[i]) {
+            res |= 1;
+        } else if (str[i] != '-' || !expected[i]) {
+            return -1;
+        }
+
+        ++i;
+    }
+
+    if (res > RWX_PERMISSIONS || res < 0 || expected[i]) {
+        return -1;
+    }
+
+    return res;
+}