Thanks!

On Tue, Aug 27, 2024 at 11:22 AM Alejandro Colomar [off-list ref] wrote:

Hi Absee,

On Tue, Aug 27, 2024 at 06:09:33AM GMT, Absee Seeab wrote:

quoted

I'm not sure that's a good way to construct documentation examples
personally, but here is an example program demonstrating that my claim
is correct, as I agree that's useful for you to have.
Feel free to edit it as you see fit.

Thanks!

I've rewritten it to:


#define _GNU_SOURCE
#define _FILE_OFFSET_BITS 64
#include <err.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int
main(void)
{
        int         fd;
        int         pfd[2];
        off_t       off;
        const char  s[12] = "Hello, world";

        fd = open("out", O_WRONLY | O_CREAT | O_EXCL, 0666);
        if (fd == -1)
                err(EXIT_FAILURE, "open");

        if (pipe(pfd) == -1)
                err(EXIT_FAILURE, "pipe");

        if (write(pfd[1], s, sizeof(s)) != sizeof(s))
                err(EXIT_FAILURE, "write");
        if (close(pfd[1]) == -1)
                err(EXIT_FAILURE, "close");

        off = 10;
        if (splice(pfd[0], NULL, fd, &off, sizeof(s), 0) != sizeof(s))
                err(EXIT_FAILURE, "splice");
        if (close(pfd[0]) == -1)
                err(EXIT_FAILURE, "close");

        printf("New offset is %jd\n", (intmax_t) off);

        if (close(fd) == -1)
                err(EXIT_FAILURE, "close");
        exit(EXIT_SUCCESS);
}

And used it as

        $ gcc -Wall -Wextra splice.c
        $ ./a.out
        New offset is 22
        $ echo $?
        0
        $ hd out
        00000000  00 00 00 00 00 00 00 00  00 00 48 65 6c 6c 6f 2c  |..........Hello,|
        00000010  20 77 6f 72 6c 64                                 | world|
        00000016


I think this is interesting information to readers of the page.  (And we
didn't have an example, so this is better than nothing.)

I'll put it all together in a patch.

Have a lovely day!
Alex


--
<https://www.alejandro-colomar.es/>