ptrace/select/signal errno weirdness

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When sending a SIGINT to a ptraced process (run under gdb), an interrupted
select() call returns with errno==514. linux/include/linux/errno.h says:

/* Should never be seen by user programs */
#define ERESTARTSYS 512
#define ERESTARTNOINTR 513
#define ERESTARTNOHAND 514 /* restart if no handler.. */
#define ENOIOCTLCMD 515 /* No ioctl command */

As gdb is a user program, and the printf is printing it, there's something
wrong. This might be due to a problem in gdb, but the fact that the errno
is being seen in userspace seems bad.

A simple test program is included. To test, build and run it under gdb.
Hit ^C to get back to the gdb prompt, and enter 'signal SIGINT' to send a
SIGINT.

This has been reproduced on 2.4.18 (the Red Hat 7.3 errata kernel) and
2.4.19 (built from scratch).

Brian

----
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/select.h>
#include <sys/signal.h>
void
printsig(int sig) {
	fprintf(stderr, "got sig %d\n", sig);
}
int
main(int argc, char **argv) {
	int n;
	struct sigaction sa;
	memset(&sa, 0, sizeof sa);
	sa.sa_handler = printsig;
	n = sigaction(SIGINT, &sa, NULL);
	if (n < 0) {
		fprintf(stderr, "sigaction: %s\n", strerror(errno));
		exit(1);
	}
	n = select(0, NULL, NULL, NULL, NULL);
	if (n < 0) {
		fprintf(stderr, "select: %s\n", strerror(errno));
		exit(1);
	}
	exit(0);
}
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• Next message: Richard Zidlicky: "Re: Flush issues in boot phase"
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