Re: [PATCH] quickfetch(): Prevent overflow of the rev-list command line

Johan Herland [off-list ref] writes:

Maybe I need to do something to the close() call as well? What happens
on close() after EPIPE?

You should be OK (you could try this).

-- >8 --
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>

int main(int ac, char **av)
{
	int pipefd[2];
	int child;

	if (pipe(pipefd) < 0) {
		fprintf(stderr, "pipe failed: %s\n", strerror(errno));
		exit(1);
	}
	child = fork();
	if (child < 0) {
		fprintf(stderr, "fork failed: %s\n", strerror(errno));
		exit(1);
	} else if (child == 0) {
		char buf[1024];
		ssize_t sz;

		/* the child reads from the parent but does not talk back */
		close(pipefd[1]);

		/* emulate reading a bit, then dying without cleaning up */
		sz = read(pipefd[0], buf, sizeof(buf));
		fprintf(stderr, "read %lu bytes, and will die\n",
			(unsigned long) sz);
		exit(1);
	} else {
		const char data[] = "abcdefg";
		size_t len = sizeof(data);
		size_t written = 0;

		/* the parent writes to the child but does not listen */
		close(pipefd[0]);

		/* we will rite to the pipe even after the child is gone */
		signal(SIGPIPE, SIG_IGN);

		/* write, write, write, ... */
		while (1) {
			ssize_t sz = write(pipefd[1], data, len);
			if (sz < 0) {
				/* error */
				fprintf(stderr,
					"write failed (%s) after writing"
					" %lu bytes\n",
					strerror(errno),
					(unsigned long) written);
				break;
			}
			written += sz;
		}
		errno = 0;
		if (close(pipefd[1]))
			fprintf(stderr, "close failed: %s\n", strerror(errno));
		else
			fprintf(stderr, "close ok\n");
	}
	exit(0);
}