1 files changed, 51 insertions, 0 deletions
diff --git a/libntp/atoint.c b/libntp/atoint.c
new file mode 100644
index 0000000..1064b36
--- /dev/null
+++ b/libntp/atoint.c
@@ -0,0 +1,51 @@
+/*
+ * atoint - convert an ascii string to a signed long, with error checking
+ */
+#include <config.h>
+#include <sys/types.h>
+#include <ctype.h>
+
+#include "ntp_types.h"
+#include "ntp_stdlib.h"
+
+int
+atoint(
+	const char *str,
+	long *ival
+	)
+{
+	register long u;
+	register const char *cp;
+	register int isneg;
+	register int oflow_digit;
+
+	cp = str;
+
+	if (*cp == '-') {
+		cp++;
+		isneg = 1;
+		oflow_digit = '8';
+	} else {
+		isneg = 0;
+		oflow_digit = '7';
+	}
+
+	if (*cp == '\0')
+	    return 0;
+
+	u = 0;
+	while (*cp != '\0') {
+		if (!isdigit((int)*cp))
+		    return 0;
+		if (u > 214748364 || (u == 214748364 && *cp > oflow_digit))
+		    return 0;	/* overflow */
+		u = (u << 3) + (u << 1);
+		u += *cp++ - '0';	/* ascii dependent */
+	}
+
+	if (isneg)
+	    *ival = -u;
+	else 
+	    *ival = u;
+	return 1;
+}