The Linux Programming Interface

268 Chapter 14

Finally, we move the mount point to a new location within the directory hierarchy:

# mkdir /demo

# ./t_mount -f m /testfs /demo

# cat /proc/mounts | grep sda12 Verify change

/dev/sda12 /demo ext3 ro 0

Listing 14-1: Using mount()

–––––––––––––––––––––––––––––––––––––––––––––––––––––––––filesys/t_mount.c

#include <sys/mount.h>

#include "tlpi_hdr.h"

static void

usageError(const char *progName, const char *msg)

{

if (msg != NULL)

fprintf(stderr, "%s", msg);

fprintf(stderr, "Usage: %s [options] source target\n\n", progName);

fprintf(stderr, "Available options:\n");

#define fpe(str) fprintf(stderr, " " str) /* Shorter! */

fpe("-t fstype [e.g., 'ext2' or 'reiserfs']\n");

fpe("-o data [file system-dependent options,\n");

fpe(" e.g., 'bsdgroups' for ext2]\n");

fpe("-f mountflags can include any of:\n");

#define fpe2(str) fprintf(stderr, " " str)

fpe2("b - MS_BIND create a bind mount\n");

fpe2("d - MS_DIRSYNC synchronous directory updates\n");

fpe2("l - MS_MANDLOCK permit mandatory locking\n");

fpe2("m - MS_MOVE atomically move subtree\n");

fpe2("A - MS_NOATIME don't update atime (last access time)\n");

fpe2("V - MS_NODEV don't permit device access\n");

fpe2("D - MS_NODIRATIME don't update atime on directories\n");

fpe2("E - MS_NOEXEC don't allow executables\n");

fpe2("S - MS_NOSUID disable set-user/group-ID programs\n");

fpe2("r - MS_RDONLY read-only mount\n");

fpe2("c - MS_REC recursive mount\n");

fpe2("R - MS_REMOUNT remount\n");

fpe2("s - MS_SYNCHRONOUS make writes synchronous\n");

exit(EXIT_FAILURE);

}

int

main(int argc, char *argv[])

{

unsigned long flags;

char *data, *fstype;

int j, opt;

flags = 0;

data = NULL;

fstype = NULL;

while ((opt = getopt(argc, argv, "o:t:f:")) != -1) {

switch (opt) {