file.cpp

/*
    Fakeroot Next Generation - run command with fake root privileges
    This program is copyrighted. Copyright information is available at the
    AUTHORS file at the root of the source tree for the fakeroot-ng project

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/
#include "config.h"

#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/ptrace.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>

#include <assert.h>
#include <limits.h>

#include <string.h>

#include "syscalls.h"
#include "file_lie.h"
#include "chroot.h"
#include "arch/platform.h"

// Helper function - fill in an override structure from a stat structure
static void stat_override_copy( const ptlib_stat *stat, stat_override *override )
{
    override->dev=stat->dev;
    override->inode=stat->ino;
    override->uid=stat->uid;
    override->gid=stat->gid;
    override->dev_id=stat->rdev;
    override->mode=stat->mode;
}

// Same function for stat, lstat and fstat
bool sys_stat( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        // Entering the syscall
        state->state=pid_state::RETURN;
        state->context_state[0]=ptlib_get_argument( pid, 2 ); // Store the pointer to the stat struct
        dlog("stat64: " PID_F " stored pointer at %p\n", pid, (void*)state->context_state[0] );

        // If the process is chrooted, we need to translate the file name
        int real_sc=ptlib_get_syscall( pid );
        if( ( real_sc==PREF_STAT || real_sc==PREF_LSTAT ) ) {
            chroot_translate_param( pid, state, 1, real_sc!=PREF_LSTAT );
        }
    } else if( state->state==pid_state::RETURN ) {
        // Returning from the syscall
        int returncode=ptlib_get_retval( pid );
        dlog("stat64: " PID_F " returned %x\n", pid, returncode);

        try {
            if( ptlib_success( pid, sc_num ) ) {
                struct ptlib_stat ret;
                struct stat_override override;

                if( !ptlib_get_mem( pid, state->context_state[0], &ret, sizeof(ret) ) )
                    // Probably page fault - report the error
                    throw (int)errno;

                if( get_map( ret.dev, ret.ino, &override ) ) {
                    bool ok=true;

                    ret.uid=override.uid;
                    ret.gid=override.gid;
                    if( S_ISBLK(override.mode) || S_ISCHR(override.mode) ) {
                        // Only turn regular files into devices
                        if( !S_ISREG( ret.mode ) )
                            ok=false;
                        ret.rdev=override.dev_id;
                    } else {
                        // If the override is not a device, and the types do not match, this is not a valid entry
                        ok=(S_IFMT&ret.mode)==(S_IFMT&override.mode);
                    }
                    // Override the u=x flag for directories, but not files
                    if( S_ISDIR(ret.mode) ) {
                        ret.mode=(ret.mode&(~(07700|S_IFMT))) | (override.mode&(07700|S_IFMT));
                    } else {
                        ret.mode=(ret.mode&(~(07600|S_IFMT))) | (override.mode&(07600|S_IFMT));
                    }

                    if( ok ) {
                        dlog("stat64: " PID_F " override dev=" DEV_F " inode=" INODE_F " mode=%o uid=" UID_F " gid=" GID_F "\n",
                                pid, ret.dev, ret.ino, ret.mode, ret.uid, ret.gid );
                        if( !ptlib_set_mem( pid, &ret, state->context_state[0], sizeof(struct stat) ) ) {
                            // Probably page fault - report the error
                            throw (int)errno;
                            // No need to remove the map - it is legitimate
                        }

                    } else {
                        dlog("stat64: " PID_F " dev=" DEV_F " inode=" INODE_F " override entry corrupt - removed\n", pid, ret.dev, ret.ino );
                        remove_map( ret.dev, ret.ino );
                    }
                }
            }
        } catch( int error ) {
            ptlib_set_error( pid, state->orig_sc, error );
        }

        state->state=pid_state::NONE;
    }

    return true;
}

#if HAVE_OPENAT
bool sys_fstatat64( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        // Entering the syscall
        state->state=pid_state::RETURN;
        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 1 ), 2, (ptlib_get_argument(pid, 4)&AT_SYMLINK_NOFOLLOW)!=0 );

        state->context_state[0]=ptlib_get_argument( pid, 3 ); // Store the pointer to the stat struct
        dlog("statat64: " PID_F " stored pointer at %p\n", pid, (void*)state->context_state[0] );

        return true;
    } else {
        return sys_stat( sc_num, pid, state ); // Return code handling is the same as for the regular stat
    }
}
#endif

static bool real_chmod( int sc_num, pid_t pid, pid_state *state, int mode_offset, int stat_function, int extra_flags=-1 )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        // First we stat the file to find out what we are up against (dev/inode etc.)
        state->state=pid_state::REDIRECT2;
        state->orig_sc=sc_num;

        state->context_state[1]=ptlib_get_argument( pid, mode_offset+1 ); // Store the requested mode
        state->context_state[0]=0; // syscall parts progress

        ptlib_set_argument( pid, mode_offset+1, state->mem->get_mem() ); // where to store the stat result
        // one anomaly handled with special case. ugly, but not worth the interface complication
        if( extra_flags!=-1 ) {
            // some of the functions require an extra flag after the usual parameters
            dlog("real_chmod: set arg2 to %d\n", extra_flags);
            ptlib_set_argument( pid, mode_offset+2, extra_flags );
        }

        ptlib_set_syscall( pid, stat_function );

    } else if( state->state==pid_state::REDIRECT2 && state->context_state[0]==0 ) {
        if( ptlib_success( pid, sc_num ) ) {
            // Our stat succeeded
            struct stat_override override;
            struct ptlib_stat stat;

            if( !ptlib_get_mem( pid, state->mem->get_mem(), &stat, sizeof( stat ) ) ) {
                // This should never happen. We passed a buffer we are in charge of!
                assert(0);
            }

            ptlib_save_state( pid, state->saved_state );

            // Restore the original parameters to restart the actual chmod call
            for( int i=1; i<=mode_offset; ++i )
                ptlib_set_argument( pid, i, state->context_state[i+1] );

            // one anomaly handled with special case. ugly, but not worth the interface complication
            if( extra_flags!=-1 ) {
                // some of the functions require an extra flag after the usual parameters
                ptlib_set_argument( pid, mode_offset+2, extra_flags );
            }

            state->state=pid_state::REDIRECT1;

            // Modify the chmod mode
            mode_t mode=(mode_t)state->context_state[1];

            mode&=~07000; // Clear the SUID etc. bits
            if( S_ISDIR( stat.mode ) ) {
                // The node in question is a directory
                mode|=00700; // Make sure we have read, write and execute permission
            } else {
                // Node is not a directory
                mode|=00600; // Set read and write for owner
            }
            ptlib_set_argument( pid, mode_offset+1, mode );

            // Save the stuff we'll need in order to update the lies database
            state->context_state[2]=stat.dev;
            state->context_state[3]=stat.ino;

            state->context_state[0]=1; // Mark this as the actual chmod call

            // If we don't already have an entry for this file in the lies database, we will not have
            // the complete stat struct later on to create it.
            if( !get_map( stat.dev, stat.ino, &override ) ) {
                // Create a lie that is identical to the actual file
                stat_override_copy( &stat, &override );
                set_map( &override );
            }

            return ptlib_generate_syscall( pid, state->orig_sc, state->mem->get_shared() );
        } else {
            // stat failed - return that failure to the caller as is
            state->state=pid_state::NONE;
        }
    } else if( state->state==pid_state::REDIRECT2 && state->context_state[0]==1 ) {
        if( ptlib_success( pid, sc_num ) ) {
            // The chmod call succeeded - update the lies database
            struct stat_override override;

            if( !get_map( state->context_state[2], state->context_state[3], &override ) ) {
                // We explicitly created this map not so long ago - something is wrong
                // XXX What can we do except hope these are reasonable values
                override.dev=state->context_state[2];
                override.inode=state->context_state[3];
                override.uid=0;
                override.gid=0;
                override.dev_id=0;
                override.transient=true;

                dlog("chmod: " PID_F " error (race?) getting override info for dev " DEV_F " inode " INODE_F "\n",
                        pid, (dev_t)state->context_state[2], (ptlib_inode_t)state->context_state[3] );
            }
            override.mode=(override.mode&~07777)|(((mode_t)state->context_state[1])&07777);
            dlog("chmod: " PID_F " Setting override mode %o dev " DEV_F " inode " INODE_F "\n", pid, override.mode, override.dev,
                    override.inode );
            set_map( &override );

            ptlib_restore_state( pid, state->saved_state );
            ptlib_set_retval( pid, 0 );
        } else {
            // We just need to restore the saved state but keep the chmod error code
            int err=ptlib_get_error( pid, sc_num );

            ptlib_restore_state( pid, state->saved_state );
            ptlib_set_error( pid, sc_num, err );
        }

        state->state=pid_state::NONE;
    } else {
        dlog("chmod: " PID_F " unknown state %d\n", pid, state->state );
    }

    return true;
}

// The actual work is done by "real_chmod".
bool sys_chmod( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        chroot_translate_param( pid, state, 1, true );

        state->context_state[2]=ptlib_get_argument( pid, 1 ); // Store the file name
    }

    return real_chmod( sc_num, pid, state, 1, PREF_STAT );
}

bool sys_fchmod( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        state->context_state[2]=ptlib_get_argument( pid, 1 ); // Store the file descriptor
    }

    return real_chmod( sc_num, pid, state, 1, PREF_FSTAT );
}

#if HAVE_OPENAT
bool sys_fchmodat( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        // XXX At some potential future date, Linux may implement AT_SYMLINK_NOFOLLOW, at which point
        // this chroot translation will need to be reconsidered
        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 1), 2, true ); 

        state->context_state[2]=ptlib_get_argument( pid, 1 ); // Store the base dir fd
        state->context_state[3]=ptlib_get_argument( pid, 2 ); // Store the file name
        state->context_state[4]=ptlib_get_argument( pid, 4 ); // Store the flags
    }

    return real_chmod( sc_num, pid, state, 2, PREF_FSTATAT, 0 );
}
#endif

// context_state[0] and 1 should contain the desired uid and gid respectively
static bool real_chown( int sc_num, pid_t pid, pid_state *state, int own_offset, int stat_function, int extra_flags=-1 )
{
    // XXX Do we handle the mode change following a chown (file and directory) correctly?
    if( state->state==pid_state::NONE ) {
        // Map this to a stat operation
        ptlib_set_argument( pid, own_offset+1, state->mem->get_mem() );

        if( extra_flags!=-1 ) {
            ptlib_set_argument( pid, own_offset+2, extra_flags );
        }

        ptlib_set_syscall( pid, stat_function );
        dlog("chown: " PID_F " redirected chown call to stat\n", pid );

        state->state=pid_state::REDIRECT2;
    } else if( state->state==pid_state::REDIRECT2 ) {
        if( ptlib_success( pid, sc_num ) ) {
            struct ptlib_stat stat;
            struct stat_override override;

            if( !ptlib_get_mem( pid, state->mem->get_mem(), &stat, sizeof( stat ) ) ) {
                // This is a syscall we initiated, to a memory buffer we own. It should not have failed.
                assert(0);
            }

            if( !get_map( stat.dev, stat.ino, &override ) ) {
                dlog("chown: " PID_F " no override for file - create a new one\n", pid );
                stat_override_copy( &stat, &override );
            }

            if( ((int)state->context_state[0])!=-1 )
                override.uid=state->context_state[0];
            if( ((int)state->context_state[1])!=-1 )
                override.gid=state->context_state[1];

            dlog("chown: " PID_F " changing owner of dev " DEV_F " inode " INODE_F "\n", pid, override.dev, override.inode );
            set_map( &override );
        } else {
            dlog("chown: " PID_F " stat call failed with error %s\n", pid, strerror(ptlib_get_error(pid, sc_num)) );
        }

        state->state=pid_state::NONE;
    }

    return true;
}

bool sys_chown( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->context_state[0]=ptlib_get_argument(pid, 2);
        state->context_state[1]=ptlib_get_argument(pid, 3);

        chroot_translate_param( pid, state, 1, true );
    }
    
    return real_chown( sc_num, pid, state, 1, PREF_STAT );
}

bool sys_fchown( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->context_state[0]=ptlib_get_argument(pid, 2);
        state->context_state[1]=ptlib_get_argument(pid, 3);
    }
    
    return real_chown( sc_num, pid, state, 1, PREF_FSTAT );
}

bool sys_lchown( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->context_state[0]=ptlib_get_argument(pid, 2);
        state->context_state[1]=ptlib_get_argument(pid, 3);

        chroot_translate_param( pid, state, 1, false );
    }
    
    return real_chown( sc_num, pid, state, 1, PREF_LSTAT );
}

#if HAVE_OPENAT
bool sys_fchownat( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->context_state[0]=ptlib_get_argument(pid, 3);
        state->context_state[1]=ptlib_get_argument(pid, 4);
        state->context_state[2]=ptlib_get_argument(pid, 5);

        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 1 ), 2, (state->context_state[2]&AT_SYMLINK_NOFOLLOW)!=0 );
    }
    
    return real_chown( sc_num, pid, state, 2, PREF_FSTATAT, state->context_state[2] );
}
#endif

static bool real_mknod( int sc_num, pid_t pid, pid_state *state, int mode_offset, int stat_function, int extra_flags=-1 )
{
    if( state->state==pid_state::NONE ) {
        mode_t mode=(mode_t)state->context_state[0];

        // Remove SUID and add user read and write
        mode&=~07000;
        mode|= 00600;

        if( S_ISCHR(mode) || S_ISBLK(mode) ) {
            dlog("mknod: " PID_F " tried to create %s device, turn to regular file\n", pid, S_ISCHR(mode) ? "character" : "block" );
            mode=(mode&~S_IFMT) | S_IFREG;
        }
        ptlib_set_argument( pid, mode_offset+1, mode );

        dlog("mknod: %d mode %o\n", pid, (unsigned int)state->context_state[1] );
        state->state=pid_state::RETURN;
    } else if( state->state==pid_state::RETURN ) {
        if( ptlib_success( pid, sc_num ) ) {
            // Need to call "stat" on the file to see what inode number it got
            ptlib_save_state( pid, state->saved_state );

            for( int i=0; i<mode_offset; ++i ) {
                ptlib_set_argument( pid, i+1, state->context_state[2+i] ); // File name etc.
            }
            ptlib_set_argument( pid, mode_offset+1, state->mem->get_mem() ); // Struct stat

            if( extra_flags!=-1 ) {
                ptlib_set_argument( pid, mode_offset+2, extra_flags );
            }

            state->state=pid_state::REDIRECT1;

            dlog("mknod: " PID_F " Actual node creation successful. Calling stat\n", pid );
            return ptlib_generate_syscall( pid, stat_function, state->mem->get_shared() );
        } else {
            // Nothing to do if the call failed
            dlog("mknod: " PID_F " call failed with error %s\n", pid, strerror(ptlib_get_error(pid, sc_num) ) );
        }
    } else if( state->state==pid_state::REDIRECT2 ) {
        if( ptlib_success( pid, sc_num ) ) {
            ptlib_stat stat;
            stat_override override;

            if( !ptlib_get_mem( pid, state->mem->get_mem(), &stat, sizeof(stat) ) ) {
                // This should never happen. We passed a buffer we are in charge of!
                assert(0);
            }

            // This file was, supposedly, just created. Even if it has an entry in the override DB, that entry is obsolete
            stat_override_copy( &stat, &override );

            // We created the file, it should have our uid/gid
            override.uid=state->fsuid;
            override.gid=state->fsgid;

            dlog("mknod: " PID_F " registering the new device in the override DB dev " DEV_F " inode " INODE_F "\n", pid,
                stat.dev, stat.ino );

            mode_t mode=(mode_t)state->context_state[0];
            if( S_ISCHR(mode) || S_ISBLK(mode) || (mode&07000)!=0) {
                dlog("mknod: " PID_F " overriding the file type and/or mode\n", pid );
                override.mode=(override.mode&~(S_IFMT|07000)) | (mode&(S_IFMT|07000));
                override.dev_id=(dev_t)state->context_state[1];
            }
            // use the user read+write from the original, not the actual file
            // XXX This code disregards the umask
            override.mode&=~00600;
            override.mode|= mode&00600;

            set_map( &override );
        } else {
            // mknod succeeded, but stat failed?
            dlog("mknod: " PID_F " stat failed. Leave override DB non-updated\n", pid );
        }

        ptlib_restore_state( pid, state->saved_state );
        state->state=pid_state::NONE;
    }

    return true;
}

bool sys_mknod( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        chroot_translate_param( pid, state, 1, false );

        state->context_state[0]=ptlib_get_argument( pid, 2 ); // Mode
        state->context_state[1]=ptlib_get_argument( pid, 3 ); // Device ID
        state->context_state[2]=ptlib_get_argument( pid, 1 ); // File name
    }

    return real_mknod( sc_num, pid, state, 1, PREF_STAT );
}

#if HAVE_OPENAT
bool sys_mknodat( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 1 ), 2, false );

        state->context_state[0]=ptlib_get_argument( pid, 3 ); // Mode
        state->context_state[1]=ptlib_get_argument( pid, 4 ); // Device ID
        state->context_state[2]=ptlib_get_argument( pid, 1 ); // Base fd
        state->context_state[3]=ptlib_get_argument( pid, 2 ); // File name
    }

    return real_mknod( sc_num, pid, state, 1, PREF_FSTATAT, 0 );
}
#endif

static bool real_open( int sc_num, pid_t pid, pid_state *state, int mode_argnum )
{
    if( state->state==pid_state::NONE ) {
        if( (state->context_state[0]&O_CREAT)!=0 ) {
            // We are asking to create the file - make sure we give user read and write permission
            state->context_state[1]=ptlib_get_argument( pid, mode_argnum );
            mode_t mode=state->context_state[1];
            
            // Remove SUID and add user read and write permission
            mode&=~07000;
            mode|= 00600;

            if( mode!=state->context_state[1] ) {
                ptlib_set_argument( pid, mode_argnum, mode );
            }
        }

        state->state=pid_state::RETURN;
    } else if( state->state==pid_state::RETURN ) {
        // Did we request to create a new file?
        if( (state->context_state[0]&O_CREAT)!=0 && ptlib_success(pid, sc_num) ) {
            int fd=(long)ptlib_get_retval(pid);
            dlog("open: " PID_F " opened fd %d, assume we actually created it\n", pid, fd );

            ptlib_save_state( pid, state->saved_state );
            state->state=pid_state::REDIRECT1;

            // Call fstat to find out what we have
            ptlib_set_argument( pid, 1, fd );
            ptlib_set_argument( pid, 2, state->mem->get_mem() );
            return ptlib_generate_syscall( pid, PREF_FSTAT, state->mem->get_shared() );
        } else
            state->state=pid_state::NONE;
    } else if( state->state==pid_state::REDIRECT2 ) {
        if( ptlib_success( pid, sc_num ) ) {
            ptlib_stat stat;
            stat_override override;

            if( !ptlib_get_mem( pid, state->mem->get_mem(), &stat, sizeof( stat ) ) ) {
                // This should never happen. We passed a buffer we are in charge of!
                assert(0);
            }

            // XXX The test whether we just created a new file is not the most accurate in the world
            // In particular, if the previous instance was deleted, this will misbehave
            // Fixed: if the previous instance was deleted BY US, this should now be ok
            // Still, /dev/null is routinely found in the map for no good reason due to this code
            if( !get_map( stat.dev, stat.ino, &override ) || override.transient ) {
                // If the map already exists, assume we did not create a new file and don't touch the owners
                stat_override_copy( &stat, &override );

                override.uid=state->fsuid;
                override.gid=state->fsgid;
                override.mode&=~07600;
                override.mode|= state->context_state[1]&07600;
                // XXX We are ignoring the umask here!

                set_map( &override );
                dlog("open: " PID_F " creating override for dev " DEV_F " inode " INODE_F "\n", pid, override.dev, override.inode);
            } else {
                dlog("open: " PID_F " map for dev " DEV_F " inode " INODE_F " already exists - doing nothing\n", pid, stat.dev, stat.ino );
            }
        } else {
            dlog("open: " PID_F " fstat failed %s\n", pid, strerror( ptlib_get_error( pid, sc_num ) ) );
        }

        state->state=pid_state::NONE;
        ptlib_restore_state( pid, state->saved_state );
    }

    return true;
}

bool sys_open( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        chroot_translate_param( pid, state, 1, true );

        state->context_state[0]=ptlib_get_argument( pid, 2 ); //flags
    }

    return real_open( sc_num, pid, state, 3 );
}

#if HAVE_OPENAT
bool sys_openat( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 1 ), 2, true );

        state->context_state[0]=ptlib_get_argument( pid, 3 ); //flags
    }

    return real_open( sc_num, pid, state, 4 );
}
#endif

static bool real_mkdir( int sc_num, pid_t pid, pid_state *state, int mode_offset, int stat_function, int extra_flags=-1 )
{
    if( state->state==pid_state::NONE ) {
        // Make sure user has rwx on the created directory
        state->context_state[0]=ptlib_get_argument( pid, mode_offset+1 );

        mode_t mode=state->context_state[0];
        mode|= 00700;

        if( mode!=state->context_state[0] ) {
            // We did change the mode
            ptlib_set_argument( pid, mode_offset+1, mode );
        }

        state->state=pid_state::RETURN;
    } else if( state->state==pid_state::RETURN ) {
        state->state=pid_state::NONE;

        if( ptlib_success( pid, sc_num ) ) {
            dlog("mkdir: " PID_F " succeeded. Call stat\n", pid );
            ptlib_save_state( pid, state->saved_state );

            // Perform a stat operation so we can know the directory's dev and inode
            for( int i=1; i<=mode_offset; ++i )
                ptlib_set_argument( pid, i, state->context_state[i] ); // The original mkdir arguments
            ptlib_set_argument( pid, mode_offset+1, state->mem->get_mem() ); // stat structure

            if( extra_flags!=-1 ) {
                ptlib_set_argument( pid, mode_offset+2, extra_flags );
            }

            state->orig_sc=sc_num;
            state->state=pid_state::REDIRECT1;

            return ptlib_generate_syscall( pid, stat_function, state->mem->get_shared() );
        } else {
            // If mkdir failed, we don't have anything else to do.
            dlog("mkdir: " PID_F " failed with error %s\n", pid, strerror(ptlib_get_error( pid, sc_num ) ) );
        }
    } else if( state->state==pid_state::REDIRECT2 ) {
        if( ptlib_success( pid, sc_num ) ) {
            ptlib_stat stat;
            stat_override override;

            if( !ptlib_get_mem( pid, state->mem->get_mem(), &stat, sizeof( stat ) ) ) {
                // This should never happen. We passed a buffer we are in charge of!
                assert(0);
            }

            // Since mkdir fails if the directory already exists, there is no point to check whether the override already exists
            stat_override_copy( &stat, &override );
            override.uid=state->fsuid;
            override.gid=state->fsgid;

            override.mode&=~00700;
            override.mode|= state->context_state[0]&00700;
            // XXX This code does not take the umask into account

            dlog("mkdir: " PID_F " storing override for dev " DEV_F " inode " INODE_F "\n", pid, override.dev, override.inode);
            set_map( &override );
        } else {
            dlog("mkdir: " PID_F " stat failed with error %s\n", pid, strerror(ptlib_get_error(pid, sc_num)));
        }

        ptlib_restore_state( pid, state->saved_state );
        state->state=pid_state::NONE;
    }

    return true;
}

bool sys_mkdir( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        chroot_translate_param( pid, state, 1, true );

        state->context_state[1]=ptlib_get_argument( pid, 1 ); // Directory name

        if( log_level>0  ) {
            char name[PATH_MAX];

            ptlib_get_string( pid, state->context_state[0], name, sizeof(name) );

            dlog("mkdir: %d creates %s\n", pid, name );
        }
    }

    return real_mkdir( sc_num, pid, state, 1, PREF_STAT );
}

#if HAVE_OPENAT
bool sys_mkdirat( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 1 ), 2, true );

        state->context_state[1]=ptlib_get_argument( pid, 1 ); // File descriptor
        state->context_state[2]=ptlib_get_argument( pid, 2 ); // Directory name

        if( log_level>0  ) {
            char name[PATH_MAX];

            ptlib_get_string( pid, state->context_state[2], name, sizeof(name) );
            int fd=(int)state->context_state[1];

            dlog("mkdirat: %d creates %s at %x\n", pid, name, fd );
        }
    }

    return real_mkdir( sc_num, pid, state, 2, PREF_FSTATAT, 0 );
}
#endif

static bool real_symlink( int sc_num, pid_t pid, pid_state *state, int mode_offset, int stat_function, int extra_flags=-1 )
{
    if( state->state==pid_state::NONE ) {
        state->state=pid_state::RETURN;
    } else if( state->state==pid_state::RETURN ) {
        if( ptlib_success( pid, sc_num ) ) {
            dlog("symlink: " PID_F " success. Call stat to mark uid/gid override\n", pid );
            ptlib_save_state( pid, state->saved_state );

            for( int i=0; i<mode_offset; ++i ) {
                ptlib_set_argument( pid, i+1, state->context_state[i] ); // File name
            }
            ptlib_set_argument( pid, mode_offset+1, state->mem->get_mem() ); // stat structure

            if( extra_flags!=-1 ) {
                ptlib_set_argument( pid, mode_offset+2, extra_flags );
            }

            state->state=pid_state::REDIRECT1;

            return ptlib_generate_syscall( pid, stat_function, state->mem->get_shared() );
        } else {
            dlog("symlink: " PID_F " failed with error %s\n", pid, strerror( ptlib_get_error(pid, sc_num) ) );
            state->state=pid_state::NONE;
        }
    } else if( state->state==pid_state::REDIRECT2 ) {
        if( ptlib_success( pid, sc_num ) ) {
            ptlib_stat stat;
            stat_override override;

            if( !ptlib_get_mem( pid, state->mem->get_mem(), &stat, sizeof( stat ) ) ) {
                // This should never happen. We passed a buffer we are in charge of!
                assert(0);
            }

            // Make sure we got the right file
            if( S_ISLNK(stat.mode) ) {
                // No need to check the DB as we just created the file
                stat_override_copy( &stat, &override );

                override.uid=state->fsuid;
                override.gid=state->fsgid;

                dlog("symlink: " PID_F " set uid/gid override for dev " DEV_F " inode " INODE_F "\n", pid, override.dev, override.inode );
                set_map( &override );
            } else {
                dlog("symlink: " PID_F " acutal file on disk is not a symlink. Type %o dev " DEV_F " inode " INODE_F "\n", pid, stat.mode, stat.dev,
                    stat.ino );
            }
        } else {
            dlog("symlink: " PID_F " symlink succeeded, but stat failed with %s\n", pid, strerror(ptlib_get_error(pid, sc_num)));
        }

        ptlib_restore_state( pid, state->saved_state );
        state->state=pid_state::NONE;
    }

    return true;
}

bool sys_symlink( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        chroot_translate_param( pid, state, 2, false );

        state->context_state[0]=ptlib_get_argument( pid, 2 ); // new path
    }

    return real_symlink( sc_num, pid, state, 1, PREF_LSTAT );
}

#if HAVE_OPENAT
bool sys_symlinkat( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 2 ), 3, false );

        state->context_state[0]=ptlib_get_argument( pid, 2 ); // dirfd
        state->context_state[1]=ptlib_get_argument( pid, 3 ); // new path
    }

    return real_symlink( sc_num, pid, state, 2, PREF_FSTATAT, AT_SYMLINK_NOFOLLOW );
}
#endif

bool sys_getcwd( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->state=pid_state::RETURN;

        // If the process is chrooted, we need to translate the directory name
        if( chroot_is_chrooted(state) ) {
            // We don't want to report the real current directory, of course!
            state->context_state[0]=ptlib_get_argument( pid, 1 ); // Buffer
            state->context_state[1]=ptlib_get_argument( pid, 2 ); // Buffer len

            // Perform the actual call into our buffer
            ptlib_set_argument( pid, 1, state->mem->get_mem() );
            ptlib_set_argument( pid, 2, PATH_MAX );
        }
    } else if( state->state==pid_state::RETURN ) {
        state->state=pid_state::NONE;

        if( ptlib_success( pid, sc_num ) && chroot_is_chrooted(state) ) {
            // We are inside a chroot, and the call was successful
            char buffer[PATH_MAX];
            ptlib_get_string( pid, state->mem->get_mem(), buffer, sizeof(buffer) );
            char tmp=buffer[state->root->length()];
            buffer[state->root->length()]='\0';
            char *ptr=buffer;

            if( ( tmp=='/' || tmp=='\0' ) && *state->root==buffer ) {
                // Current directory is inside the chroot jail - need to truncate the prefix
                if( tmp=='/' ) {
                    ptr+=state->root->length();
                    *ptr=tmp;
                } else {
                    // The current directory is the new root
                    strcpy( buffer, "/" );
                }
            } else {
                // Current directory is outside of the jail - pass it to the program as is
                buffer[state->root->length()]=tmp;
            }

            // Emulate the actual call
            size_t len=strlen(ptr);

            if( len<state->context_state[1] ) {
                // Buffer is large enough
                ptlib_set_string( pid, ptr, state->context_state[0] );
                ptlib_set_retval( pid, len+1 );
            } else {
                // The buffer is not large enough
                ptlib_set_error( pid, sc_num, ERANGE );
            }
        }
    }

    return true;
}

bool sys_munmap( int sc_num, pid_t pid, pid_state *state )
{
    // XXX Does this work? We should never be called with REDIRECT1
    if( state->state==pid_state::NONE || state->state==pid_state::REDIRECT1 ) {
        if( state->state==pid_state::NONE ) {
            // This is our first time entering this munmap
            state->context_state[2]=0; // No state to restore
        }

        state->state=pid_state::RETURN;
        state->context_state[0]=0; // 0 is the next start address to unmap, 1 is the new length
        state->context_state[1]=0; // len=0 means we have no more mmaps to perform

        // Is this an attempt to release one of the memory areas we own?
        int_ptr start=ptlib_get_argument( pid, 1 );
        int_ptr end=start+ptlib_get_argument( pid, 2 );

        // If end wraps around then the kernel will fail this anyways
        // Same goes if the page size is not aligned or the length is zero
        if( start>end || (start%sysconf(_SC_PAGESIZE))!=0 || start==end )
            // XXX We still need to fail this ourselves, just to make sure
            return true;

        // Put the lower of the two addreses in addr1
        int_ptr addr1=state->mem->get_shared(), addr2=state->mem->get_mem();
        size_t len1=static_mem_size, len2=shared_mem_size-ptlib_prepare_memory_len();
        const char *name1="static", *name2="shared";

        if( addr1>addr2 ) {
            int_ptr tmp=addr1;
            addr1=addr2;
            addr2=tmp;

            size_t tmplen=len1;
            len1=len2;
            len2=tmplen;

            const char *tmpname=name1;
            name1=name2;
            name2=tmpname;
        }

        state->state=pid_state::REDIRECT2;
        if( start<addr1 && end>addr1 ) {
            // The unmap range covers the lower range
            dlog("sys_munmap: " PID_F " tried to unmap range %p-%p, which conflicts with our %s range %p-%p\n",
                pid, (void*)start, (void*)end, name1, (void*)addr1, (void*)(addr1+len1) );

            if( end>addr1+len1 ) {
                // There is an area to unmap above the lower range - mark it for a second syscall
                state->context_state[0]=addr1+len1;
                state->context_state[1]=end-state->context_state[0];
            }

            end=addr1;
        } else if( start>=addr1 && start<addr1+len1 ) {
            // The start pointer is inside the lower memory range
            dlog("sys_munmap: " PID_F " tried to unmap range %p-%p, which conflicts with our %s range %p-%p\n",
                pid, (void*)start, (void*)end, name1, (void*)addr1, (void*)(addr1+len1) );

            start=addr1+len1;
        } else if( start<addr2 && end>addr2 ) {
            // The unmap area covers the upper memory range
            dlog("sys_munmap: " PID_F " tried to unmap range %p-%p, which conflicts with our %s range %p-%p\n",
                pid, (void*)start, (void*)end, name2, (void*)addr2, (void*)(addr2+len2) );

            if( end>addr2+len2 ) {
                // There is an area to unmap above the upper range - mark it for a second (third?) syscall
                state->context_state[0]=addr2+len2;
                state->context_state[1]=end-state->context_state[0];
            }
            
            end=addr2;
        } else if( start>=addr2 && start<addr2+len2 ) {
            // The start pointer is inside the upper memory range
            dlog("sys_munmap: " PID_F " tried to unmap range %p-%p, which conflicts with our %s range %p-%p\n",
                pid, (void*)start, (void*)end, name2, (void*)addr2, (void*)(addr2+len2) );

            start=addr2+len2;
        } else {
            // The unmap range was a-ok. No need to touch the syscall at all
            state->state=pid_state::RETURN;
            return true;
        }

        // We had to change the parameters because of an overlap
        ptlib_set_argument( pid, 1, start );
        ptlib_set_argument( pid, 2, end-start );
    } else if( state->state==pid_state::RETURN || state->state==pid_state::REDIRECT2 ) {
        state->state=pid_state::NONE;

        if( ptlib_success( pid, sc_num ) ) {
            bool last=(state->context_state[1]==0);

            // If we are not done yet, we will need to store this position and come back to it
            if( state->context_state[2]==0 && !last ) {
                ptlib_save_state( pid, state->saved_state );
                state->context_state[2]=1;
            }

            if( !last ) {
                // We split the munmap into several calls - there are more calls to perform
                // Use REDIRECT3 rather than NONE so that strace won't see the extra call
                state->state=pid_state::REDIRECT3;

                ptlib_set_argument( pid, 1, state->context_state[0] );
                ptlib_set_argument( pid, 2, state->context_state[1] );
                return ptlib_generate_syscall( pid, sc_num, state->mem->get_shared() );
            }
        } else {
            // The syscall failed - we will end it here even if we thought we had something more to do
            dlog("sys_munmap: " PID_F " failed: %s\n", pid, strerror(ptlib_get_error(pid, sc_num)));
        }

        if( state->context_state[2]==1 ) {
            ptlib_restore_state( pid, state->saved_state );
        }
    }

    return true;
}

bool sys_link( int sc_num, pid_t pid, pid_state *state )
{
    // XXX lock memory
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->state=pid_state::RETURN;

        // Translate the "oldpath"
        chroot_translate_param( pid, state, 1, false, false, 0 );

        // Translate the "newpath"
        chroot_translate_param( pid, state, 2, false, false, PATH_MAX );
    } else if( state->state==pid_state::RETURN ) {
        state->state=pid_state::NONE;
    }

    return true;
}

#if HAVE_OPENAT
bool sys_linkat( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->state=pid_state::RETURN;

        // Translate the "oldpath"
        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 1), 2,
            (ptlib_get_argument( pid, 5)&AT_SYMLINK_FOLLOW)==0, false, 0 );

        // Translate the "newpath"
        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 3), 4, false, false, PATH_MAX );
    } else if( state->state==pid_state::RETURN ) {
        state->state=pid_state::NONE;
    }

    return true;
}
#endif

// In this function, context_state holds:
// 0 - state machine for redirected syscalls
// 1 - forced error number
// 2 - pointer to file name
// 
// after the lstat stage:
// 2 - 0: just delete. 1: need to mark for deletion from the override db as well
bool sys_unlink( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->context_state[0]=0; // Beginning of syscall
        state->context_state[1]=0; // No forced error

        if( chroot_is_chrooted( state ) ) {
            // Translate the filename. If the last path component is a symlink, that is what we want deleted
            if( !chroot_translate_param( pid, state, 1, false, true ) ) {
                // We had an error translating the file name - pass the error on
                state->state=pid_state::REDIRECT2;
                state->context_state[1]=errno;
                ptlib_set_syscall(pid, PREF_NOP);

                return true;
            }
        }

        // Keep a copy of the file name
        state->context_state[2]=ptlib_get_argument( pid, 1 );

        // We need to know whether the file was, indeed, deleted. One method goes like this
        // First, open the file. Next, unlink the file. Then, fstat the file.
        // Problem - cannot do that for symbolic links.
        //
        // Second method - lstat the file before, unlink. If link count before was 1, inode
        // is no more.
        // Problem - someone else may have linked it while between the lstat and the unlink.
        //
        // Third method - link the file to a temporary name, unlink the original, check link
        // count on temporary name.
        // Problem - not easy to translate relative name to one that can be used from another
        // process. On Linux, we do that using "linkat"

        // We now implement the second method
        ptlib_set_syscall( pid, PREF_LSTAT );
        ptlib_set_argument( pid, 2, state->mem->get_mem() );

        state->state=pid_state::REDIRECT2;

    } else if( state->state==pid_state::REDIRECT2 ) {
        state->state=pid_state::NONE;

        if( state->context_state[1]!=0 ) {
            // We need to force an error
            ptlib_set_error( pid, state->orig_sc, state->context_state[1] );
            state->state=pid_state::NONE;

            return true;
        }

        // Handle the actual state machine
        switch( state->context_state[0] ) {
        case 0:
            // lstat returned
            {
                if( ptlib_success( pid, sc_num ) ) {
                    ptlib_stat stat;

                    if( !ptlib_get_mem( pid, state->mem->get_mem(), &stat, sizeof( stat ) ) ) {
                        // This should never happen. We passed a buffer we are in charge of!
                        assert(0);
                    }

                    if( stat.nlink==1 ) {
                        // Store the relevant data in the shared memory
                        struct override_key *key=reinterpret_cast<override_key *>(state->mem->get_loc_c()+PATH_MAX);
                        key->dev=stat.dev;
                        key->inode=stat.ino;

                        state->context_state[2]=1;
                    } else {
                        state->context_state[2]=0;
                    }

                    // Perform the actual unlink operation
                    ptlib_save_state( pid, state->saved_state );
                    ptlib_generate_syscall( pid, state->orig_sc, state->mem->get_shared() );
                    state->state=pid_state::REDIRECT1;
                    state->context_state[0]=1;
                } else {
                    // lstat syscall failed - pass the error along
                    state->state=pid_state::NONE;
                    dlog("%s: " PID_F " lstat failed with error: %s\n", __FUNCTION__, pid, strerror(ptlib_get_error(pid, sc_num)));
                }
            }
            break;
        case 1:
            // unlink returned
            {
                bool success=ptlib_success( pid, sc_num );
                int error=success?0:ptlib_get_error( pid, sc_num );

                ptlib_restore_state( pid, state->saved_state );

                if( success ) {
                    if( state->context_state[2]==1 ) {
                        // Need to erase the override from our database
                        struct override_key *key=reinterpret_cast<override_key *>(state->mem->get_loc_c()+PATH_MAX);
                        stat_override map;

                        if( get_map( key->dev, key->inode, &map ) ) {
                            map.transient=true;
                            set_map( &map );
                            dlog("sys_unlink: " PID_F " inode " INODE_F " in override mapping marked transient\n", pid, key->inode );
                        }
                    }
                } else {
                    // The "restore state" command overwrote the error
                    ptlib_set_error( pid, sc_num, error );
                    dlog("%s: " PID_F " unlink failed with error: %s\n", __FUNCTION__, pid, strerror(error));
                }
            }
            break;
        }
    }

    return true;
}

#if HAVE_OPENAT
// In this function, context_state holds:
// 0 - state machine for redirected syscalls
// 1 - forced error number
// 2 - pointer to file name
// 
// after the lstat stage:
// 2 - 0: just delete. 1: need to mark for deletion from the override db as well
// 
// XXX Some code duplication with above function
bool sys_unlinkat( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->context_state[0]=(ptlib_get_argument(pid, 3)&AT_REMOVEDIR)==0 ? 0 : 10; // Beginning of syscall
        state->context_state[1]=0; // No forced error

        if( chroot_is_chrooted( state ) ) {
            // Translate the filename. If the last path component is a symlink, that is what we want deleted
            if( !chroot_translate_paramat( pid, state, ptlib_get_argument(pid, 1), 2, false, true ) ) {
                // We had an error translating the file name - pass the error on
                state->state=pid_state::REDIRECT2;
                state->context_state[1]=errno;
                ptlib_set_syscall(pid, PREF_NOP);

                return true;
            }
        }

        // Keep a copy of the file name
        state->context_state[2]=ptlib_get_argument( pid, 1 );
        state->context_state[3]=ptlib_get_argument( pid, 2 );

        // We need to know whether the file was, indeed, deleted. One method goes like this
        // First, open the file. Next, unlink the file. Then, fstat the file.
        // Problem - cannot do that for symbolic links.
        //
        // Second method - lstat the file before, unlink. If link count before was 1, inode
        // is no more.
        // Problem - someone else may have linked it while between the lstat and the unlink.
        //
        // Third method - link the file to a temporary name, unlink the original, check link
        // count on temporary name.
        // Problem - not easy to translate relative name to one that can be used from another
        // process. On Linux, we do that using "linkat"

        // We now implement the second method
        ptlib_set_syscall( pid, PREF_FSTATAT );
        ptlib_set_argument( pid, 3, state->mem->get_mem() );
        ptlib_set_argument( pid, 4, AT_SYMLINK_NOFOLLOW );

        state->state=pid_state::REDIRECT2;

    } else if( state->state==pid_state::REDIRECT2 ) {
        state->state=pid_state::NONE;

        if( state->context_state[1]!=0 ) {
            // We need to force an error
            ptlib_set_error( pid, state->orig_sc, state->context_state[1] );
            state->state=pid_state::NONE;

            return true;
        }

        // Handle the actual state machine
        switch( state->context_state[0] ) {
        case 0:
        case 10:
            // lstat returned
            {
                if( ptlib_success( pid, sc_num ) ) {
                    ptlib_stat stat;

                    // We are tight on context memory - first set up the args for the continuation syscall,
                    // only then handle the current call return
                    ptlib_save_state( pid, state->saved_state );
                    ptlib_set_argument( pid, 1, state->context_state[2] );
                    ptlib_set_argument( pid, 2, state->context_state[3] );
                    ptlib_set_argument( pid, 3, state->context_state[0]==10 ? AT_REMOVEDIR : 0 );

                    // Will the file be actually deleted?
                    if( !ptlib_get_mem( pid, state->mem->get_mem(), &stat, sizeof( stat ) ) ) {
                        // This should never happen. We passed a buffer we are in charge of!
                        assert(0);
                    }

                    if( stat.nlink==1 || state->context_state[0]==10 ) {
                        // Store the relevant data in the shared memory
                        struct override_key *key=reinterpret_cast<override_key *>(state->mem->get_loc_c()+PATH_MAX);
                        key->dev=stat.dev;
                        key->inode=stat.ino;

                        state->context_state[2]=1;
                    } else {
                        state->context_state[2]=0;
                    }

                    // Complete the continuation call
                    ptlib_generate_syscall( pid, state->orig_sc, state->mem->get_shared() );
                    state->state=pid_state::REDIRECT1;
                    state->context_state[0]=1;
                } else {
                    // lstat syscall failed - pass the error along
                    state->state=pid_state::NONE;
                    dlog("%s: " PID_F " fstatat failed with error: %s\n", __FUNCTION__, pid, strerror(ptlib_get_error(pid, sc_num)));
                }
            }
            break;
        case 1:
            // unlink returned
            {
                bool success=ptlib_success( pid, sc_num );
                int error=success?0:ptlib_get_error( pid, sc_num );

                ptlib_restore_state( pid, state->saved_state );

                if( success ) {
                    if( state->context_state[2]==1 ) {
                        // Need to erase the override from our database
                        struct override_key *key=reinterpret_cast<override_key *>(state->mem->get_loc_c()+PATH_MAX);
                        stat_override map;

                        if( get_map( key->dev, key->inode, &map ) ) {
                            map.transient=true;
                            set_map( &map );
                            dlog("%s: " PID_F " inode " INODE_F " in override mapping marked transient\n", __FUNCTION__,
                                    pid, key->inode );
                        }
                    }
                } else {
                    // The "restore state" command overwrote the error
                    ptlib_set_error( pid, sc_num, error );
                    dlog("%s: " PID_F " unlinkat failed with error: %s\n", __FUNCTION__, pid, strerror(error));
                }
            }
            break;
        }
    }

    return true;
}
#endif // HAVE_OPENAT

bool sys_rename( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->state=pid_state::RETURN;

        chroot_translate_param( pid, state, 1, false, false, 0 );
        chroot_translate_param( pid, state, 2, false, false, PATH_MAX );
    } else if( state->state==pid_state::RETURN ) {
        state->state=pid_state::NONE;
    }

    return true;
}

#if HAVE_OPENAT
bool sys_renameat( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->state=pid_state::RETURN;

        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 1), 2, false, false, 0 );
        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 3), 4, false, false, PATH_MAX );
    } else if( state->state==pid_state::RETURN ) {
        state->state=pid_state::NONE;
    }

    return true;
}
#endif

bool sys_rmdir( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        chroot_translate_param( pid, state, 1, false );

        // Keep a copy of the directory name to erase
        state->context_state[0]=0; // Internal state
        state->context_state[1]=ptlib_get_argument( pid, 1 );

        // We need to stat the directory before we erase it
        ptlib_set_argument( pid, 2, state->mem->get_mem() );
        ptlib_set_syscall( pid, PREF_LSTAT );

        state->state=pid_state::REDIRECT2;
    } else if( state->state==pid_state::REDIRECT2 ) {
        if( state->context_state[0]==0 ) {
            // lstat returned
            if( ptlib_success( pid, sc_num ) ) {
                ptlib_stat stat;

                if( !ptlib_get_mem( pid, state->mem->get_mem(), &stat, sizeof( stat ) ) ) {
                    // This should never happen. We passed a buffer we are in charge of!
                    assert(0);
                }

                struct override_key *key=reinterpret_cast<override_key *>(state->mem->get_loc_c()+PATH_MAX);
                key->dev=stat.dev;
                key->inode=stat.ino;

                state->context_state[0]=1;

                // Run the original syscall
                ptlib_save_state( pid, state->saved_state );
                ptlib_generate_syscall( pid, state->orig_sc, state->mem->get_shared() );
                state->state=pid_state::REDIRECT1;
            } else {
                // Pass the lstat error as if it were the rmdir error
                state->state=pid_state::NONE;
            }
        } else if( state->context_state[0]==1 ) {
            bool success=ptlib_success( pid, sc_num );
            int error=success?0:ptlib_get_error( pid, sc_num );

            ptlib_restore_state( pid, state->saved_state );

            if( success ) {
                // Need to erase the override from our database
                struct override_key *key=reinterpret_cast<override_key *>(state->mem->get_loc_c()+PATH_MAX);
                stat_override map;

                if( get_map( key->dev, key->inode, &map ) ) {
                    map.transient=true;
                    set_map( &map );
                    dlog("sys_rmdir: " PID_F " inode " INODE_F " in override mapping marked transient\n", pid, key->inode );
                }
            } else {
                // Need to copy the error number (overwritten by the state restore)
                ptlib_set_error( pid, sc_num, error );
            }

            state->state=pid_state::NONE;
        }
    }

    return true;
}

#if HAVE_OPENAT
bool sys_generic_chroot_at( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->state=pid_state::RETURN;

        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 1 ), 2, true );
    } else if( state->state==pid_state::RETURN ) {
        state->state=pid_state::NONE;
    }

    return true;
}

bool sys_generic_chroot_link_at( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->state=pid_state::RETURN;

        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 1 ), 2, false );
    } else if( state->state==pid_state::RETURN ) {
        state->state=pid_state::NONE;
    }

    return true;
}

// Generic chroot where follow or no follow is determined by AT_SYMLINK_NOFOLLOW in parameter 4
bool sys_generic_chroot_at_link4( int sc_num, pid_t pid, pid_state *state )
{
    if( state->state==pid_state::NONE ) {
        PROC_MEM_LOCK();

        state->state=pid_state::RETURN;

        chroot_translate_paramat( pid, state, ptlib_get_argument( pid, 1 ), 2, (ptlib_get_argument( pid, 4)&AT_SYMLINK_NOFOLLOW)==0 );
    } else if( state->state==pid_state::RETURN ) {
        state->state=pid_state::NONE;
    }

    return true;
}
#endif // HAVE_OPENAT