platform_system_core/toolbox/umount.c
Ken Sumrall 940c81078e Add -o loop= option to mount, and fix error detection in mount and umount
This fixes bug http://b.android.com/18419, which complains about a bogus
error check in the mount command (it also was wrong in the umount command)
and also asks for the mount command to support more than one loopback
device, as mentioned in the FIXME comments in mount.c.  This required some
corresponding changes to umount.c

Change-Id: Ib796c70926395e61557e487bad64984d3295d5f3
2011-07-13 14:37:41 -07:00

90 lines
1.8 KiB
C

#include <sys/mount.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <linux/loop.h>
#define LOOPDEV_MAXLEN 64
#define LOOP_MAJOR 7
static int is_loop(char *dev)
{
struct stat st;
int ret = 0;
if (stat(dev, &st) == 0) {
if (S_ISBLK(st.st_mode) && (major(st.st_rdev) == LOOP_MAJOR)) {
ret = 1;
}
}
return ret;
}
static int is_loop_mount(const char* path, char *loopdev)
{
FILE* f;
int count;
char device[256];
char mount_path[256];
char rest[256];
int result = 0;
int path_length = strlen(path);
f = fopen("/proc/mounts", "r");
if (!f) {
fprintf(stdout, "could not open /proc/mounts\n");
return -1;
}
do {
count = fscanf(f, "%255s %255s %255s\n", device, mount_path, rest);
if (count == 3) {
if (is_loop(device) && strcmp(path, mount_path) == 0) {
strlcpy(loopdev, device, LOOPDEV_MAXLEN);
result = 1;
break;
}
}
} while (count == 3);
fclose(f);
return result;
}
int umount_main(int argc, char *argv[])
{
int loop, loop_fd;
char loopdev[LOOPDEV_MAXLEN];
if(argc != 2) {
fprintf(stderr,"umount <path>\n");
return 1;
}
loop = is_loop_mount(argv[1], loopdev);
if(umount(argv[1])){
fprintf(stderr,"failed.\n");
return 1;
}
if (loop) {
// free the loop device
loop_fd = open(loopdev, O_RDONLY);
if (loop_fd < 0) {
perror("open loop device failed");
return 1;
}
if (ioctl(loop_fd, LOOP_CLR_FD, 0) < 0) {
perror("ioctl LOOP_CLR_FD failed");
return 1;
}
close(loop_fd);
}
return 0;
}