File systems

Inputting 'j' can get file systems information:

File systems information is stored in /etc/mtab file (Please refer Wikipedia):

# cat /etc/mtab
proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0
sys /sys sysfs rw,nosuid,nodev,noexec,relatime 0 0
dev /dev devtmpfs rw,nosuid,relatime,size=1989392k,nr_inodes=497348,mode=755 0 0
run /run tmpfs rw,nosuid,nodev,relatime,mode=755 0 0
/dev/sda / ext4 rw,relatime 0 0
securityfs /sys/kernel/security securityfs rw,nosuid,nodev,noexec,relatime 0 0
tmpfs /dev/shm tmpfs rw,nosuid,nodev 0 0
devpts /dev/pts devpts rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000 0 0
......

This file is processed by jfs_load() function:

void jfs_load(int load)
{
    ......
    mfp = setmntent("/etc/mtab", "r");
    for (i = 0; i < JFSMAX && (mp = getmntent(mfp)) != NULL; i++) {
        strncpy(jfs[i].device, mp->mnt_fsname, JFSNAMELEN);
        strncpy(jfs[i].name, mp->mnt_dir, JFSNAMELEN);
        strncpy(jfs[i].type, mp->mnt_type, JFSTYPELEN);
        mp->mnt_fsname[JFSNAMELEN - 1] = 0;
        mp->mnt_dir[JFSNAMELEN - 1] = 0;
        mp->mnt_type[JFSTYPELEN - 1] = 0;
    }
    endmntent(mfp);
    ......
}

We should use dedicated functions: setmntent(), getmntent() and endmntent() to parse /etc/mtab file.