open_issues/alarm_setitimer: New.

2 files changed, 55 insertions, 0 deletions

diff --git a/open_issues/alarm_setitimer.mdwn b/open_issues/alarm_setitimer.mdwn
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+++ b/open_issues/alarm_setitimer.mdwn
@@ -0,0 +1,23 @@
+[[!meta copyright="Copyright © 2012 Free Software Foundation, Inc."]]
+
+[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable
+id="license" text="Permission is granted to copy, distribute and/or modify this
+document under the terms of the GNU Free Documentation License, Version 1.2 or
+any later version published by the Free Software Foundation; with no Invariant
+Sections, no Front-Cover Texts, and no Back-Cover Texts.  A copy of the license
+is included in the section entitled [[GNU Free Documentation
+License|/fdl]]."]]"""]]
+
+[[!meta title="alarm/setitimer"]]
+
+[[!tag open_issue_glibc open_issue_hurd]]
+
+`setitimer()`, called by `alarm()` when setting a new alarm, it is not able
+to disable on its own the timer when the alarm is fired the first time.
+On the other hand, manually invoking `alarm(0)` can cancel the running timer
+for `SIGALRM`.
+
+See also the attached file: on other OSes (e.g. Linux) it blocks waiting
+for a signal, while on GNU/Hurd it gets a new alarm and exits.
+
+[[alrm.c]]
diff --git a/open_issues/alarm_setitimer/alrm.c b/open_issues/alarm_setitimer/alrm.c
new file mode 100644
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+++ b/open_issues/alarm_setitimer/alrm.c
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+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static const char msg[] = "< got alarm\n";
+
+static void sighandler(int signo __attribute__((unused)))
+{
+  write(STDOUT_FILENO, msg, sizeof(msg) - 1);
+}
+
+int main()
+{
+  struct sigaction sa;
+  sa.sa_handler = sighandler;
+  sigemptyset(&sa.sa_mask);
+  sa.sa_flags = 0;
+  if (sigaction(SIGALRM, &sa, NULL) == -1)
+    return 1;
+
+  printf("> alarm in 2 secs...\n");
+  alarm(2);
+  pause();
+
+  printf("> alarm!\n");
+
+  pause();
+  printf("> got a signal...\n");
+
+  return 0;
+}