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/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/mount.h>
#include "mounts.h"
static MountsState g_mounts_state = {
NULL, // volumes
0, // volumes_allocd
0 // volume_count
};
static inline void
free_volume_internals(const MountedVolume *volume, int zero)
{
free((char *)volume->device);
free((char *)volume->mount_point);
free((char *)volume->filesystem);
free((char *)volume->flags);
if (zero) {
memset((void *)volume, 0, sizeof(*volume));
}
}
#define PROC_MOUNTS_FILENAME "/proc/mounts"
int
scan_mounted_volumes()
{
char buf[2048];
const char *bufp;
int fd;
ssize_t nbytes;
if (g_mounts_state.volumes == NULL) {
const int numv = 32;
MountedVolume *volumes = malloc(numv * sizeof(*volumes));
if (volumes == NULL) {
errno = ENOMEM;
return -1;
}
g_mounts_state.volumes = volumes;
g_mounts_state.volumes_allocd = numv;
memset(volumes, 0, numv * sizeof(*volumes));
} else {
/* Free the old volume strings.
*/
int i;
for (i = 0; i < g_mounts_state.volume_count; i++) {
free_volume_internals(&g_mounts_state.volumes[i], 1);
}
}
g_mounts_state.volume_count = 0;
/* Open and read the file contents.
*/
fd = open(PROC_MOUNTS_FILENAME, O_RDONLY);
if (fd < 0) {
goto bail;
}
nbytes = read(fd, buf, sizeof(buf) - 1);
close(fd);
if (nbytes < 0) {
goto bail;
}
buf[nbytes] = '\0';
/* Parse the contents of the file, which looks like:
*
* # cat /proc/mounts
* rootfs / rootfs rw 0 0
* /dev/pts /dev/pts devpts rw 0 0
* /proc /proc proc rw 0 0
* /sys /sys sysfs rw 0 0
* /dev/block/mtdblock4 /system yaffs2 rw,nodev,noatime,nodiratime 0 0
* /dev/block/mtdblock5 /data yaffs2 rw,nodev,noatime,nodiratime 0 0
* /dev/block/mmcblk0p1 /sdcard vfat rw,sync,dirsync,fmask=0000,dmask=0000,codepage=cp437,iocharset=iso8859-1,utf8 0 0
*
* The zeroes at the end are dummy placeholder fields to make the
* output match Linux's /etc/mtab, but don't represent anything here.
*/
bufp = buf;
while (nbytes > 0) {
char device[64];
char mount_point[64];
char filesystem[64];
char flags[128];
int matches;
/* %as is a gnu extension that malloc()s a string for each field.
*/
matches = sscanf(bufp, "%63s %63s %63s %127s",
device, mount_point, filesystem, flags);
if (matches == 4) {
device[sizeof(device)-1] = '\0';
mount_point[sizeof(mount_point)-1] = '\0';
filesystem[sizeof(filesystem)-1] = '\0';
flags[sizeof(flags)-1] = '\0';
MountedVolume *v =
&g_mounts_state.volumes[g_mounts_state.volume_count++];
v->device = strdup(device);
v->mount_point = strdup(mount_point);
v->filesystem = strdup(filesystem);
v->flags = strdup(flags);
} else {
printf("matches was %d on <<%.40s>>\n", matches, bufp);
}
/* Eat the line.
*/
while (nbytes > 0 && *bufp != '\n') {
bufp++;
nbytes--;
}
if (nbytes > 0) {
bufp++;
nbytes--;
}
}
return 0;
bail:
//TODO: free the strings we've allocated.
g_mounts_state.volume_count = 0;
return -1;
}
const MountedVolume *
find_mounted_volume_by_device(const char *device)
{
if (g_mounts_state.volumes != NULL) {
int i;
for (i = 0; i < g_mounts_state.volume_count; i++) {
MountedVolume *v = &g_mounts_state.volumes[i];
/* May be null if it was unmounted and we haven't rescanned.
*/
if (v->device != NULL) {
if (strcmp(v->device, device) == 0) {
return v;
}
}
}
}
return NULL;
}
const MountedVolume *
find_mounted_volume_by_mount_point(const char *mount_point)
{
if (g_mounts_state.volumes != NULL) {
int i;
for (i = 0; i < g_mounts_state.volume_count; i++) {
MountedVolume *v = &g_mounts_state.volumes[i];
/* May be null if it was unmounted and we haven't rescanned.
*/
if (v->mount_point != NULL) {
if (strcmp(v->mount_point, mount_point) == 0) {
return v;
}
}
}
}
return NULL;
}
int
unmount_mounted_volume(const MountedVolume *volume)
{
/* Intentionally pass NULL to umount if the caller tries
* to unmount a volume they already unmounted using this
* function.
*/
int ret = umount(volume->mount_point);
if (ret == 0) {
free_volume_internals(volume, 1);
return 0;
}
return ret;
}
int
remount_read_only(const MountedVolume* volume)
{
return mount(volume->device, volume->mount_point, volume->filesystem,
MS_NOATIME | MS_NODEV | MS_NODIRATIME |
MS_RDONLY | MS_REMOUNT, 0);
}