systat(1): improve parsing of delay value

[Nick Gasson]

Hi,

I incorrectly ran "systat netstat -N" instead of "systat -N netstat" and
got confused why it wasn't resolving host names. The -N gets parsed with
atof to a 0s delay that is then clamped to 5s. The patch below instead
prints an error if the delay cannot be parsed. I think the <= 0 case
should also produce an error but I left the existing behaviour of
setting it to 5s.


Index: usr.bin/systat/main.c
===================================================================
RCS file: /cvs/src/usr.bin/systat/main.c,v
retrieving revision 1.72
diff -u -p -u -p -r1.72 main.c
--- usr.bin/systat/main.c       12 Jan 2020 20:51:08 -0000      1.72
+++ usr.bin/systat/main.c       25 Jan 2021 08:07:34 -0000
@@ -415,6 +415,22 @@ gethz(void)
 }
 
 int
+parse_delay(const char *str, double *delay)
+{
+       char *endptr = NULL;
+       double value;
+
+       value = strtod(str, &endptr);
+       if (*endptr == '\0') {
+               if (value <= 0)
+                       value = 5;
+               *delay = value;
+               return 0;
+       } else
+               return 1;
+}
+
+int
 main(int argc, char *argv[])
 {
        char errbuf[_POSIX2_LINE_MAX];
@@ -475,9 +491,8 @@ main(int argc, char *argv[])
                        nflag = 1;
                        break;
                case 's':
-                       delay = atof(optarg);
-                       if (delay <= 0)
-                               delay = 5;
+                       if (parse_delay(optarg, &delay))
+                               errx(1, "-s %s: invalid delay value", optarg);
                        break;
                case 'w':
                        rawwidth = strtonum(optarg, 1, MAX_LINE_BUF-1, &errstr);
@@ -497,16 +512,14 @@ main(int argc, char *argv[])
        argv += optind;
 
        if (argc == 1) {
-               double del = atof(argv[0]);
-               if (del == 0)
+               if (parse_delay(argv[0], &delay))
                        viewstr = argv[0];
-               else
-                       delay = del;
        } else if (argc == 2) {
                viewstr = argv[0];
-               delay = atof(argv[1]);
-               if (delay <= 0)
-                       delay = 5;
+               if (parse_delay(argv[1], &delay))
+                       errx(1, "invalid delay value: %s", argv[1]);
+       } else {
+               usage();
        }
 
        udelay = (useconds_t)(delay * 1000000.0);