Date: Wed, 13 Nov 2002 10:07:22 -0800 (PST) From: Nate Lawson <nate@root.org> To: Sheldon Hearn <sheldonh@starjuice.net> Cc: current@freebsd.org Subject: Re: sleep(1) behavior Message-ID: <Pine.BSF.4.21.0211131003010.39871-200000@root.org> In-Reply-To: <20021113080425.GO1278@starjuice.net>
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[-- Attachment #1 --]
On Wed, 13 Nov 2002, Sheldon Hearn wrote:
> On (2002/11/12 16:37), Nate Lawson wrote:
>
> > I've found an interesting contradiction and was wondering what behavior
> > sleep should have. It checks for a command line flag with getopt(3) and
> > exits with usage() if it finds one. However, it then checks for a '-' or
> > '+' sign. If negative, it behaves like "sleep 0" and exits
> > immediately. This case can almost never be triggered since the
> > getopt(3) will catch the minus sign, even if a digit follows it.
> >
> > Current behavior:
> > sleep 0 = exits immediately
> > sleep -1 = exits with usage()
> > sleep -f = exits with usage()
> > sleep " -1" = exits immediately and is the only way I know to trigger
> > the negative case.
> >
> > What is the standard, desired behavior?
>
> IEEE Std 1003.2-1992 says:
>
> time A nonnegative decimal integer specifying the number of
> seconds for which to suspend execution.
>
> I think it's pretty clear that negative time arguments to sleep(1) are
> not portable.
Thanks, that's what I was expecting. The attached patch provides the
following behavior:
sleep 0 = exit 0 immediately
sleep [ \t]*1AAAA = sleep 1 second
sleep [ \t]*\.2zzz = sleep .2 seconds
sleep [ \t]*-.* = usage()
Please let me know if there are any problems with this patch.
-Nate
[-- Attachment #2 --]
Index: sleep.c
===================================================================
RCS file: /home/ncvs/src/bin/sleep/sleep.c,v
retrieving revision 1.12
diff -u -r1.12 sleep.c
--- sleep.c 30 Jun 2002 05:15:04 -0000 1.12
+++ sleep.c 13 Nov 2002 18:00:31 -0000
@@ -47,10 +47,10 @@
#include <ctype.h>
#include <limits.h>
-#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>
+#include <string.h>
void usage(void);
@@ -59,51 +59,43 @@
{
struct timespec time_to_sleep;
long l;
- int ch, neg;
char *p;
- while ((ch = getopt(argc, argv, "")) != -1)
- switch(ch) {
- case '?':
- default:
- usage();
- /* NOTREACHED */
- }
- argc -= optind;
- argv += optind;
-
- if (argc != 1) {
+ if (argc != 2) {
usage();
/* NOTREACHED */
}
- p = argv[0];
+ p = argv[1];
/* Skip over leading whitespaces. */
while (isspace((unsigned char)*p))
++p;
- /* Check for optional `+' or `-' sign. */
- neg = 0;
+ /* No arguments or negative values are allowed */
if (*p == '-') {
- neg = 1;
- ++p;
+ usage();
+ /* NOTREACHED */
}
- else if (*p == '+')
+
+ /* Check for optional `+' sign. */
+ if (*p == '+')
++p;
/* Calculate seconds. */
- if (isdigit((unsigned char)*p)) {
- l = strtol(p, &p, 10);
- if (l > INT_MAX) {
+ l = 0;
+ while (isdigit((unsigned char)*p)) {
+ l = (l * 10) + (*p - '0');
+ if (l > INT_MAX || l < 0) {
/*
* Avoid overflow when `seconds' is huge. This assumes
* that the maximum value for a time_t is >= INT_MAX.
*/
l = INT_MAX;
+ break;
}
- } else
- l = 0;
+ ++p;
+ }
time_to_sleep.tv_sec = (time_t)l;
/* Calculate nanoseconds. */
@@ -119,7 +111,7 @@
} while (l /= 10);
}
- if (!neg && (time_to_sleep.tv_sec > 0 || time_to_sleep.tv_nsec > 0))
+ if (time_to_sleep.tv_sec > 0 || time_to_sleep.tv_nsec > 0)
(void)nanosleep(&time_to_sleep, (struct timespec *)NULL);
exit(0);
@@ -128,7 +120,8 @@
void
usage(void)
{
+ const char *msg = "usage: sleep seconds\n";
- (void)fprintf(stderr, "usage: sleep seconds\n");
+ write(STDOUT_FILENO, msg, strlen(msg));
exit(1);
}
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