Example tries to clarify one should not refer to variables that are not in
on_exit() scope. Such variables include heap in main(). In short only
variables allocated from stack make is sense when calling on_exit().
Possible referal to global variables would technically work, but at the same
go makes function argument pointless and in such case one ought to prefer
atexit() instead.
Signed-off-by: Sami Kerola <kerolasa@xxxxxx>
---
man3/on_exit.3 | 40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)
diff --git a/man3/on_exit.3 b/man3/on_exit.3
index d2c2c3b17..c074cda76 100644
--- a/man3/on_exit.3
+++ b/man3/on_exit.3
@@ -100,6 +100,46 @@ It no longer occurs in Solaris (SunOS 5).
Portable application should avoid this function, and use the standard
.BR atexit (3)
instead.
+.SH EXAMPLE
+Following program uses
+.BR on_exit (3)
+to display data, that is allocated until processing is done.
+Notice that variables main() in heap are not in on_exit() scope.
+.PP
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+struct data {
+ int argc;
+ char *argv;
+};
+
+static void run_on_exit(int exit_val, void *arg)
+{
+ struct data *d = (struct data *)arg;
+
+ printf("argc: %d argv: %s\n", d->argc, d->argv);
+ free(d->argv);
+ free(d);
+ _exit(exit_val);
+}
+
+int main(int argc, char **argv)
+{
+ struct data *d;
+
+ if (1 < argc) {
+ d = malloc(sizeof(*d));
+ d->argc = argc;
+ d->argv = strdup(argv[1]);
+ on_exit(run_on_exit, d);
+ }
+ return 0;
+}
+.EE
.SH SEE ALSO
.BR _exit (2),
.BR atexit (3),
--
2.21.0
