Attachment 246821 Details for Bug 275570 – deadlock.c

deadlock.c

file_275570.txt (text/plain), 2.12 KB, created by Alex S on 2023-12-06 13:48:25 UTC

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Creator: Alex S

Created: 2023-12-06 13:48:25 UTC

Size: 2.12 KB

patch

obsolete

>#include <assert.h>
>#include <err.h>
>#include <errno.h>
>#include <stdlib.h>
>#include <stdio.h>
>#include <string.h>
>#include <unistd.h>
>#include <sys/_iovec.h>
>#include <sys/file.h>
>#include <sys/mount.h>
>
>static void xmount(const char* fstype, const char* from, const char* to, int flags) {
>
>  char errmsg[255];
>  errmsg[0] = '\0';
>
>  int capacity = 8;
>
>  struct iovec* iov = malloc(sizeof(struct iovec) * capacity);
>
>  iov[0].iov_base = "fstype";
>  iov[0].iov_len  = sizeof("fstype");
>  iov[1].iov_base = __DECONST(char*, fstype);
>  iov[1].iov_len  = strlen(fstype) + 1;
>
>  iov[2].iov_base = "fspath";
>  iov[2].iov_len  = sizeof("fspath");
>  iov[3].iov_base = __DECONST(char*, to);
>  iov[3].iov_len  = strlen(to) + 1;
>
>  iov[4].iov_base = "from";
>  iov[4].iov_len  = sizeof("from");
>  iov[5].iov_base = __DECONST(char*, from);
>  iov[5].iov_len  = strlen(from) + 1;
>
>  iov[6].iov_base = "errmsg";
>  iov[6].iov_len  = sizeof("errmsg");
>  iov[7].iov_base = errmsg;
>  iov[7].iov_len  = sizeof(errmsg);
>
>  int len = 8;
>
>  if (flags & MNT_NOCOVER) {
>
>    assert(len + 2 <= capacity);
>
>    iov[len].iov_base = "nocover";
>    iov[len].iov_len  = sizeof("nocover");
>    len++;
>
>    iov[len].iov_base = NULL;
>    iov[len].iov_len  = 0;
>    len++;
>  }
>
>  assert(len == capacity);
>
>  if (nmount(iov, len, (int)flags) == -1) {
>    err(EXIT_FAILURE, "nmount %s -> %s: %s", from, to, errmsg);
>  }
>
>  free(iov);
>}
>
>static void xchdir(const char* path) {
>  if (chdir(path) == -1) {
>    err(EXIT_FAILURE, "chdir(\"%s\")", path);
>  }
>}
>
>static void xcreat(char* path, int mode) {
>  int fd = open(path, O_CREAT | O_WRONLY, mode);
>  if (fd == -1) {
>    err(EXIT_FAILURE, "can't create %s", path);
>  }
>  close(fd);
>}
>
>#define ROOT_DIR "/mnt"
>
>int main(int argc, char* argv[]) {
>
>  xchdir(ROOT_DIR);
>
>  xmount("tmpfs", "tmpfs", ".", MNT_NOEXEC);
>
>  xcreat(".setup-done", 0444);
>  xmount("nullfs", ".setup-done", ".setup-done", 0);
>
>  xmount("tmpfs", "tmpfs", ".", MNT_RDONLY | MNT_NOEXEC | MNT_UPDATE);
>
>  unmount(ROOT_DIR "/.setup-done", MNT_FORCE);
>  unmount(ROOT_DIR, MNT_FORCE);
>
>  return 0;
>}

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Attachments on bug 275570: 246821