m3core/src/runtime/LINUXLIBC6/RTHeapDepC.c

/* Copyright (C) 1992, Digital Equipment Corporation */
/* All rights reserved. */
/* See the file COPYRIGHT for a full description. */

/* Last modified on Fri Jun 21 12:45:49 PDT 1996 by heydon */
/*      modified on Thu Jun 29 09:42:09 PDT 1995 by kalsow */
/*      modified on Tue Feb  2 11:15:57 PST 1993 by jdd */

/* This is RTHeapDepC.c for Linux. */

/* This file implements wrappers for almost all Linux system calls
   that take pointers as arguments. These wrappers allow the system
   calls to take arguments that might point to the traced heap, which
   may be VM-protected in the Ultrix implementation of the collector.
   The wrappers read and write the referents of all pointers about to
   passed to the system call, which ensures that the pages are not
   protected when the call is made.

   Each wrapper is a critical section, with RT0u__inCritical non-zero,
   so that another thread cannot cause the pages to become reprotected
   before the system call is performed.
*/

/*
   (Copied from the SunOS version, some comments about unavailable information
   does not apply for Linux). 

   A few system calls are not handled here, or are handled only
   partially.  This restricts the system calls that can be made from
   Modula-3, or from libraries that are passed pointers into the
   Modula-3 traced heap.  These system calls are:

   1) sigvec.  Sigvec takes 3 arguments, but passes 4 to the kernel.
      The extra argument is the address of the sigtramp code, which is
      copyrighted.  The sigtramp code appears in the the standard .o
      file that also defines sigvec, so that sigvec cannot be
      redefined here without including sigtramp.  Rewriting sigtramp
      seemed too error-prone, so sigvec is not supported here, meaning
      that sigvec cannot be called with arguments on the heap.

   2) syscall.  Implementing syscall would require a huge case
      statement, with one case per system call.  This seemed too
      error-prone, so syscall cannot take arguments that point into
      the traced heap.

   3) ioctl.  Ioctl's third argument may be a pointer, and some device
      drivers might interpret the referent as containing more
      pointers.  These second-level pointers are not handled here, so
      they must not point into the traced heap if they exist.
      Handling this problem in general is impossible, since the set of
      device drivers is open-ended.

   4) profil.  The memory referenced by the "buff" argument is updated
      after the call returns, and there is no mechanism to permanently
      unprotect it.

   5) Undocumented system calls.  There are private system calls with
      no manual pages, so it was impossible to write wrappers.

   6) audgen, whose manpage is incomprehensible.

   7) clone, which (like profil) updates one of its arguments (the other
      thread's stack) after it has returned.

   (Some calls in Section 2 are already wrappers for other system
   calls; it is not necessary to reimplement them here.)

   Also, longjmp must not be used from a signal handler to abnormally
   exit from a system call.

   Finally, if a system call references an object on the heap, each
   pointer must reference only one object.  Therefore, it is not
   possible to write the heap contents with a single write. */

/* Added the following for glibc6 - rrw.
   
   umount
   munlock
   delete_module
   modify_ldt
   query_module
   clone (sort-of : we need a wrapper to make sure gc is finished before 
        fork())
   bdflush
   statfs


   */

/* Not added due to lack of docs :

   break

   */


#include <stdarg.h>
#include <sys/types.h>
#include <sys/time.h>
#include <errno.h>
#include <syscall.h>
#include <sys/file.h>
#include <sys/msg.h>
#include <sys/sem.h>
#include <sys/signal.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/ipc.h>
#include <dirent.h>
#include <sys/times.h>
#include <sys/resource.h>
#include <sys/wait.h>

#if __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1
#include <asm/ipc.h>
#endif

extern int RT0u__inCritical;
#define ENTER_CRITICAL RT0u__inCritical++
#define EXIT_CRITICAL  RT0u__inCritical--

void (*RTHeapRep_Fault)(char*);
void (*RTCSRC_FinishVM)();

static char RTHeapDepC__c;
#define MAKE_READABLE(x) if (x) { RTHeapDepC__c = *(char*)(x); }
#define MAKE_WRITABLE(x) if (x) { *(char*)(x) = RTHeapDepC__c = *(char*)(x); }
#define MAKE_WRITEABLE MAKE_WRITABLE

/* glibc has no socketcall() nor __ipc() */
#define socketcall(a,b) syscall(SYS_socketcall,a,b)
#define __ipc(a,b,c,d,e) syscall(SYS_ipc,a,b,c,d,e)

#define SYS_SOCKET	1
#define SYS_BIND	2
#define SYS_CONNECT	3
#define SYS_LISTEN	4
#define SYS_ACCEPT	5
#define SYS_GETSOCKNAME	6
#define SYS_GETPEERNAME	7
#define SYS_SOCKETPAIR	8
#define SYS_SEND	9
#define SYS_RECV	10
#define SYS_SENDTO	11
#define SYS_RECVFROM	12
#define SYS_SHUTDOWN	13
#define SYS_SETSOCKOPT	14
#define SYS_GETSOCKOPT	15
#define SYS_SENDMSG	16
#define SYS_RECVMSG	17

/* Unless otherwise noted, all the following wrappers have the same
   structure. */

int accept(int sockfd, struct sockaddr *peer, socklen_t *paddrlen)
{ int result;

  unsigned long args[3];

  ENTER_CRITICAL;
  MAKE_WRITABLE(peer);
  MAKE_WRITABLE(paddrlen);

  args[0] = sockfd;
  args[1] = (unsigned long)peer;
  args[2] = (unsigned long)paddrlen;
  result = socketcall(SYS_ACCEPT, args);

  EXIT_CRITICAL;
  return result;
}

int access(path, mode)
char *path;
int mode;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  result = syscall(SYS_access, path, mode);
  EXIT_CRITICAL;
  return result;
}

int acct(file)
char *file;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(file);
  result = syscall(SYS_acct, file);
  EXIT_CRITICAL;
  return result;
}

int __real_adjtime(const struct timeval *delta, struct timeval *olddelta);

int __wrap_adjtime(const struct timeval *delta, struct timeval *olddelta)
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(delta);
  MAKE_WRITABLE(olddelta);
  result = __real_adjtime(delta, olddelta);
  EXIT_CRITICAL;
  return result;
}

/*
int atomic_op(op, addr)
int op;
int *addr;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(addr);
  result = syscall(SYS_atomic_op, op, addr);
  EXIT_CRITICAL;
  return result;
}

int audcntl(request, argp, len, flag, audit_id)
int request;
char *argp;
int len;
int flag;
audit_ID_t audit_id;
{ int result;

  ENTER_CRITICAL;
  switch (request) {
  case GET_SYS_AMASK:
  case GET_TRUSTED_AMASK:
  case GET_PROC_AMASK:
    MAKE_WRITABLE(argp);
    break;
  case SET_SYS_AMASK:
  case SET_TRUSTED_AMASK:
  case SET_PROC_AMASK:
    MAKE_READABLE(argp);
    break;
  default:
    break;
  }
  result = syscall(SYS_audcntl, request, argp, len, flag, audit_id);
  EXIT_CRITICAL;
  return result;
}

int audgen(event, tokenp, argv)
int event;
char *tokenp, *argv[];
{ int result;

  ENTER_CRITICAL;
  
  { char *t, **a;

    for (t = tokenp, a = argv; t; t++, a++) {
      if (A_TOKEN_PTR(*t)) {
        MAKE_READABLE(*a);
      }
    }
  }
  result = syscall(SYS_audgen, tokenp, argv);
  EXIT_CRITICAL;
  return result;
}
*/

int bdflush(func, thing) 
  int func;
  void *thing;
{
  int ret;

  ENTER_CRITICAL;
  if (func >= 3 && (func%2)==1) {
    MAKE_WRITEABLE(thing);
  }
  ret = syscall(SYS_bdflush, func, thing);
  EXIT_CRITICAL;

  return ret;
}

int bind(int sockfd, const struct sockaddr *myaddr, socklen_t addrlen)
{ int result;

  unsigned long args[3];

  ENTER_CRITICAL;
  MAKE_READABLE(myaddr);

  args[0] = sockfd;
  args[1] = (unsigned long)myaddr;
  args[2] = addrlen;
  result = socketcall(SYS_BIND, args);

  EXIT_CRITICAL;
  return result;
}

/*
int cachectl(addr, nbytes, op)
char *addr;
int nbytes, op;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(addr);
  result = syscall(SYS_cachectl, addr, nbytes, op);
  EXIT_CRITICAL;
  return result;
}

int cacheflush(addr, nbytes, cache)
char *addr;
int nbytes, cache;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(addr);
  result = syscall(SYS_cacheflush, addr, nbytes, cache);
  EXIT_CRITICAL;
  return result;
}
*/

int chdir(path)
char *path;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  result = syscall(SYS_chdir, path);
  EXIT_CRITICAL;
  return result;
}

int chmod(path, mode)
char *path;
mode_t mode;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  result = syscall(SYS_chmod, path, mode);
  EXIT_CRITICAL;
  return result;
}

int chown(path, owner, group)
char *path;
uid_t owner;
gid_t group;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  result = syscall(SYS_chown, path, owner, group);
  EXIT_CRITICAL;
  return result;
}

int chroot(dirname)
char *dirname;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(dirname);
  result = syscall(SYS_chroot, dirname);
  EXIT_CRITICAL;
  return result;
}

int connect(int sockfd, const struct sockaddr *saddr, socklen_t addrlen)
{ int result;

  unsigned long args[3];

  ENTER_CRITICAL;
  MAKE_READABLE(saddr);

  args[0] = sockfd;
  args[1] = (unsigned long)saddr;
  args[2] = addrlen;
  result = socketcall(SYS_CONNECT, args);

  EXIT_CRITICAL;
  return result;
}

int creat(pathname, mode)
const char *pathname;
mode_t mode;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(pathname);
  result = syscall(SYS_creat, pathname, mode);
  EXIT_CRITICAL;
  return result;
}

int delete_module(const char *name) {
  int result;
  
  ENTER_CRITICAL;
  MAKE_READABLE(name);
  result = syscall(SYS_delete_module, name);
  EXIT_CRITICAL;
  return result;
  }

/* execve is implemented differently since it does not return, which
   would leave RT0u__inCritical set in the parent if called in the child
   of a vfork. Many calls leave the process in an undefined state in the
   case of EFAULT, but we assume that execve is not one of these. */

int execve(name, argv, envp)
char *name;
char *argv[];
char *envp[];
{ int result;

  for (;;) {
    result = syscall(SYS_execve, name, argv, envp);
    if (result == -1 && errno == EFAULT) {
      MAKE_READABLE(name);
      { char **a; for (a = argv; *a; a++) MAKE_READABLE(*a); }
      { char **e; for (e = envp; *e; e++) MAKE_READABLE(*e); }
    } else {
      return result;
    }
  }
}

/*
int exportfs(name, rootuid, exflags)
char *name;
int rootuid, exflags;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(name);
  result = syscall(SYS_exportfs, name, rootuid, exflags);
  EXIT_CRITICAL;
  return result;
}
*/

int fcntl(int fd, int cmd, ...)
{ int result;

  va_list ap;

  long arg;

  ENTER_CRITICAL;
  switch (cmd) {
  case F_GETLK:
    va_start(ap,cmd);
    arg = va_arg(ap,long);
    MAKE_WRITABLE(arg);
    result = syscall(SYS_fcntl, fd, cmd, arg);
    va_end(ap);
    break;
  case F_SETLK:
  case F_SETLKW:
    va_start(ap,cmd);
    arg = va_arg(ap,long);
    MAKE_READABLE(arg);
    result = syscall(SYS_fcntl, fd, cmd, arg);
    va_end(ap);
    break;
  case F_SETFD:
  case F_SETFL:
  case F_DUPFD:
    va_start(ap,cmd);
    arg = va_arg(ap,long);
    result = syscall(SYS_fcntl, fd, cmd, arg);
    va_end(ap);
    break;
  default:
    result = syscall(SYS_fcntl, fd, cmd);
    break;
  }

  EXIT_CRITICAL;
  return result;
}

int fstat(fd, buf)
int fd;
struct stat *buf;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(buf);
  result = __fstat(fd, buf);
  EXIT_CRITICAL;
  return result;
}

int getdents(unsigned int fd, struct dirent *dirp, unsigned int count)
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(dirp);
  result = syscall(SYS_getdents, fd, dirp, count);
  EXIT_CRITICAL;
  return result;
}

#if 0 /* FIXME: disabled, no easy way to call */
int __getdirentries(int fd, char *buf, size_t nbytes, long *basep);

int __wrap_getdirentries(int fd, char *buf, size_t nbytes, long *basep)
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(buf);
  MAKE_WRITABLE(basep);
  result = __getdirentries(fd, buf, nbytes, basep);
  EXIT_CRITICAL;
  return result;
}
#endif
/*
int getdomainname(name, namelen)
char *name;
int namelen;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(name);
  result = syscall(SYS_getdomainname, name, namelen);
  EXIT_CRITICAL;
  return result;
}

int gethostname(name, namelen)
char *name;
int namelen;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(name);
  result = syscall(SYS_gethostname, name, namelen);
  EXIT_CRITICAL;
  return result;
}
*/

int getgroups(gidsetsize, grouplist)
int gidsetsize;
int grouplist[];
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(grouplist);
  result = syscall(SYS_getgroups, gidsetsize, grouplist);
  EXIT_CRITICAL;
  return result;
}

#if __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 2
int getitimer(__itimer_which_t which, struct itimerval *value)
#else
int getitimer(enum __itimer_which which, struct itimerval *value)
#endif
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(value);
  result = syscall(SYS_getitimer, which, value);
  EXIT_CRITICAL;
  return result;
}

/*
int getmnt(start, buffer, nbytes, mode, path)
int *start;
struct fs_data *buffer;
int nbytes, mode;
char *path;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(start);
  MAKE_WRITABLE(buffer);
  MAKE_READABLE(path);
  result = syscall(SYS_getmnt, start, buffer, nbytes, mode, path);
  EXIT_CRITICAL;
  return result;
}
*/

int getpeername(int sockfd, struct sockaddr *addr, socklen_t *paddrlen)
{ int result;

  unsigned long args[3];

  ENTER_CRITICAL;
  MAKE_WRITABLE(addr);
  MAKE_WRITABLE(paddrlen);

  args[0] = sockfd;
  args[1] = (unsigned long)addr;
  args[2] = (unsigned long)paddrlen;
  result = socketcall(SYS_GETPEERNAME, args);

  EXIT_CRITICAL;
  return result;
}

#if __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 2
int getrlimit(__rlimit_resource_t resource, struct rlimit *rlp)
#else
int getrlimit(enum __rlimit_resource resource, struct rlimit *rlp)
#endif
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(rlp);
  result = syscall(SYS_getrlimit, resource, rlp);
  EXIT_CRITICAL;
  return result;
}

int getrusage(who, rusage)
int who;
struct rusage *rusage;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(rusage);
  result = syscall(SYS_getrusage, who, rusage);
  EXIT_CRITICAL;
  return result;
}

int getsockname(int sockfd, struct sockaddr *addr, socklen_t *paddrlen)
{ int result;

  unsigned long args[3];

  ENTER_CRITICAL;
  MAKE_WRITABLE(addr);
  MAKE_WRITABLE(paddrlen);

  args[0] = sockfd;
  args[1] = (unsigned long)addr;
  args[2] = (unsigned long)paddrlen;
  result = socketcall(SYS_GETSOCKNAME, args);

  EXIT_CRITICAL;
  return result;
}

int getsockopt(int fd, int level, int optname, void *optval, socklen_t *optlen)
{ int result;

  unsigned long args[5];

  ENTER_CRITICAL;
  MAKE_WRITABLE(optval);
  MAKE_WRITABLE(optlen);

  args[0]=fd;
  args[1]=level;
  args[2]=optname;
  args[3]=(unsigned long)optval;
  args[4]=(unsigned long)optlen;
  result = (socketcall (SYS_GETSOCKOPT, args));

  EXIT_CRITICAL;
  return result;
}

/*
int getsysinfo(op, buffer, nbytes, start, arg)
unsigned op;
char *buffer;
unsigned nbytes;
int *start;
char *arg;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(buffer);
  MAKE_WRITABLE(start);
  MAKE_WRITABLE(arg);
  result = syscall(SYS_getsysinfo, op, buffer, nbytes, start, arg);
  EXIT_CRITICAL;
  return result;
}
*/

int gettimeofday(tp, tzp)
struct timeval *tp;
struct timezone *tzp;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(tp);
  MAKE_WRITABLE(tzp);
  result = syscall(SYS_gettimeofday, tp, tzp);
  EXIT_CRITICAL;
  return result;
}

/* ioctl must test the argp argument carefully.  It may be a pointer,
   or maybe not.  At a slight expense, we call RTHeapRep.Fault to
   unprotect the page if it's in the traced heap, but do nothing
   otherwise. */

int ioctl(d, request, argp)
int d, request;
char *argp;
{ int result;

  ENTER_CRITICAL;
  if (RTHeapRep_Fault) RTHeapRep_Fault(argp); /* make it readable */
  if (RTHeapRep_Fault) RTHeapRep_Fault(argp); /* make it writable */
  result = syscall(SYS_ioctl, d, request, argp);
  EXIT_CRITICAL;
  return result;
}

int link(name1, name2)
char *name1;
char *name2;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(name1);
  MAKE_READABLE(name2);
  result = syscall(SYS_link, name1, name2);
  EXIT_CRITICAL;
  return result;
}

int lstat(path, buf)
const char *path;
struct stat *buf;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  MAKE_WRITABLE(buf);
  result = __lstat(path, buf);
  EXIT_CRITICAL;
  return result;
}

int mkdir(path, mode)
char *path;
mode_t mode;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  result = syscall(SYS_mkdir, path, mode);
  EXIT_CRITICAL;
  return result;
}

int mknod(path, mode, dev)
const char *path;
mode_t mode;
dev_t dev;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  result = __mknod(path, mode, dev);
  EXIT_CRITICAL;
  return result;
}

int modify_ldt(func, ptr, bytecount)
  int func;
  void *ptr;
  int bytecount;
{ int result;

 ENTER_CRITICAL;
 MAKE_WRITEABLE(ptr);
 result = syscall(SYS_modify_ldt, func, ptr, bytecount);
 EXIT_CRITICAL;
 return result;
}

int mount(special, name, rwflag, type, options)
char *special;
char *name;
int rwflag, type;
char *options;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(special);
  MAKE_READABLE(name);
  MAKE_READABLE(options);
  result = syscall(SYS_mount, special, name, rwflag, type, options);
  EXIT_CRITICAL;
  if (result != -1) {
    result = 0;
  }
  return result;
}

int munlock(addr, len) 
     const void *addr;
     size_t len;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(addr);
  result = syscall(SYS_munlock, addr, len);
  EXIT_CRITICAL;
  return result;
}

#define SEMOP           1
#define SEMGET          2
#define SEMCTL          3
#define MSGSND          11
#define MSGRCV          12
#define MSGGET          13
#define MSGCTL          14
#define SHMAT           21
#define SHMDT           22
#define SHMGET          23
#define SHMCTL          24


int msgctl(msqid, cmd, buf)
int msqid, cmd;
struct msqid_ds *buf;
{ int result;

  ENTER_CRITICAL;
  switch (cmd) {
  case IPC_SET:
    MAKE_READABLE(buf);
    break;
  case IPC_STAT:
    MAKE_WRITABLE(buf);
    break;
  default:
    break;
  }

  result = __ipc(MSGCTL, msqid, cmd, 0, buf);
  EXIT_CRITICAL;
  return result;
}

int msgrcv(int msqid, void *msgp, size_t msgsz, long int msgtyp, int msgflg)
{ int result;

  struct ipc_kludge tmp; 

  ENTER_CRITICAL;
  MAKE_WRITABLE(msgp);

  tmp.msgp = msgp;
  tmp.msgtyp = msgtyp; 
  result = __ipc (MSGRCV, msqid, msgsz, msgflg, &tmp);

  EXIT_CRITICAL;
  return result;
}

#if __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 2
int msgsnd(int msqid, __const void *msgp, size_t msgsz, int msgflg)
#else
int msgsnd(int msqid, void *msgp, size_t msgsz, int msgflg)
#endif
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(msgp);

  result = __ipc(MSGSND, msqid, msgsz, msgflg,  msgp);

  EXIT_CRITICAL;
  return result;
}

int open(const char *filename, int flags, ...)
{ int result;

  va_list ap;

  ENTER_CRITICAL;
  MAKE_READABLE(filename);
  if (flags & O_CREAT) {
    va_start(ap,flags);
    result = syscall(SYS_open, filename, flags, va_arg(ap,mode_t));
    va_end(ap);
  } else {
    result = syscall(SYS_open, filename, flags);
  }
  EXIT_CRITICAL;
  return result;
}

int query_module(name, which, buf, bufsize, ret)
  const char *name;
  int which;
  void *buf;
  size_t bufsize;
  size_t *ret;
{
  int result;
  
  ENTER_CRITICAL;
  MAKE_READABLE(name);
  MAKE_WRITEABLE(buf); MAKE_WRITEABLE(ret);
  result = query_module(name, which, buf, bufsize, ret);
  EXIT_CRITICAL;

  return result;
}

/*
int quota(cmd, uid, arg, addr)
int cmd, uid, arg;
caddr_t addr;
{ int result;

  ENTER_CRITICAL;
  switch (cmd) {
  case Q_SETDLIM:
  case Q_SETDUSE:
  case Q_SETWARN:
    MAKE_READABLE(addr);
    break;
  case Q_GETDLIM:
    MAKE_WRITABLE(addr);
    break;
  default:
    break;
  }
  result = syscall(SYS_quota, cmd, uid, arg, addr);
  EXIT_CRITICAL;
  return result;
}
*/

int read(d, buf, nbytes)
int d;
char *buf;
int nbytes;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(buf);
  result = syscall(SYS_read, d, buf, nbytes);
  EXIT_CRITICAL;
  return result;
}

int readlink(path, buf, bufsiz)
char *path;
char *buf;
int bufsiz;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  MAKE_WRITABLE(buf);
  result = syscall(SYS_readlink, path, buf, bufsiz);
  EXIT_CRITICAL;
  return result;
}

ssize_t __real_readv(int d, const struct iovec *iov, int count);

ssize_t __wrap_readv(int d, const struct iovec *iov, int count)
{ int result;

  ENTER_CRITICAL;
  { int i;
    for (i = 0; i < count; i++) {
      MAKE_WRITABLE(iov[i].iov_base);
    }
  }
  result = __real_readv(d, iov, count);
  /*****************
  result = syscall(SYS_readv, d, iov, count);
  *****************/
  EXIT_CRITICAL;
  return result;
}

int recv(int sockfd, void *buffer, size_t len, int flags)
{ int result;

  unsigned long args[4];

  ENTER_CRITICAL;
  MAKE_WRITABLE(buffer);

  args[0] = sockfd;
  args[1] = (unsigned long) buffer;
  args[2] = len;
  args[3] = flags;
  result = (socketcall (SYS_RECV, args));

  EXIT_CRITICAL;
  return result;
}

int recvfrom(int sockfd, void *buffer, size_t len, int flags, 
		struct sockaddr *to, socklen_t *tolen)
{ int result;

  unsigned long args[6];

  ENTER_CRITICAL;
  MAKE_WRITABLE(buffer);
  MAKE_WRITABLE(to);
  MAKE_WRITABLE(tolen);

  args[0] = sockfd;
  args[1] = (unsigned long) buffer;
  args[2] = len;
  args[3] = flags;
  args[4] = (unsigned long) to;
  args[5] = (unsigned long) tolen;
  result = (socketcall (SYS_RECVFROM, args));

  EXIT_CRITICAL;
  return result;
}

int recvmsg(sockfd, msg, flags)
int sockfd;
struct msghdr *msg;
int flags;
{ int result;

  unsigned long args[3];

  ENTER_CRITICAL;

/*
  MAKE_WRITABLE(msg->msg_name);
  { int i;
    for (i = 0; i < msg->msg_iovlen; i++) {
      if (msg->msg_iov[i].iov_len > 0) {
        MAKE_WRITABLE(msg->msg_iov[i].iov_base);
      }
    }
  }
  MAKE_WRITABLE(msg->msg_accrights);
*/

  MAKE_WRITABLE(msg);

  args[0] = sockfd;
  args[1] = (unsigned long) msg;
  args[2] = flags;
  result = (socketcall (SYS_RECVMSG, args));

  EXIT_CRITICAL;
  return result;
}

int rename(from, to)
char *from;
char *to;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(from);
  MAKE_READABLE(to);
  result = syscall(SYS_rename, from, to);
  EXIT_CRITICAL;
  return result;
}

int rmdir(path)
char *path;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  result = syscall(SYS_rmdir, path);
  EXIT_CRITICAL;
  return result;
}

int select(int n, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, 
    struct timeval *timeout)
{ int result;

  ENTER_CRITICAL;
  if (readfds != NULL) MAKE_WRITABLE(readfds);
  if (writefds != NULL) MAKE_WRITABLE(writefds);
  if (exceptfds != NULL) MAKE_WRITABLE(exceptfds);
  if (timeout != NULL) MAKE_WRITABLE(timeout);
  result = __select(n, readfds, writefds, exceptfds, timeout);
  EXIT_CRITICAL;
  return result;
}

#if __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1

union semun
{
  int val;
  struct semid_ds *buf;
  unsigned short int *array;
  struct seminfo *__buf;
};

int semctl(int semid, int semnum, int cmd, ...)
{ 
  va_list ap;
  union semun arg;
  int result;

  va_start(ap,cmd);
  arg = va_arg(ap,union semun);
  va_end(ap);

#else

int semctl(semid, semnum, cmd, arg)
int semid, cmd;
int semnum;
union semun arg;
{ 
  int result;

#endif

  ENTER_CRITICAL;
  switch (cmd) {
  case IPC_SET:
    MAKE_READABLE(arg.buf);
    break;
  case GETALL:
  case IPC_STAT:
    MAKE_WRITABLE(arg.buf);
    break;
  default:
    break;
  }

  result = __ipc (SEMCTL, semid, semnum, cmd, &arg);

  EXIT_CRITICAL;
  return result;
}

int semop(semid, sops, nsops)
int semid;
struct sembuf *sops;
unsigned nsops;
{ int result;

  ENTER_CRITICAL;
  { int i;
    for (i = 0; i < nsops; i++) {
      MAKE_READABLE(sops + i);
    }
  }

  result = __ipc (SEMOP, semid, (int) nsops, 0, sops);

  EXIT_CRITICAL;
  return result;
}

int send(int sockfd, const void *buffer, size_t len, int flags)
{ int result;

  unsigned long args[4];

  ENTER_CRITICAL;
  MAKE_READABLE(buffer);

  args[0] = sockfd;
  args[1] = (unsigned long) buffer;
  args[2] = len;
  args[3] = flags;
  result = (socketcall (SYS_SEND, args));

  EXIT_CRITICAL;
  return result;
}

int sendmsg(int sockfd, const struct msghdr *msg, int flags)
{ int result;

  unsigned long args[3];

  ENTER_CRITICAL;

/*
  MAKE_READABLE(msg->msg_name);
  { int i;
    for (i = 0; i < msg->msg_iovlen; i++) {
      if (msg->msg_iov[i].iov_len > 0) {
        MAKE_READABLE(msg->msg_iov[i].iov_base);
      }
    }
  }
  MAKE_WRITABLE(msg->msg_accrights);
*/

  MAKE_WRITABLE(msg);

  args[0] = sockfd;
  args[1] = (unsigned long) msg;
  args[2] = flags;
  result = (socketcall (SYS_SENDMSG, args));

  EXIT_CRITICAL;
  return result;
}

int sendto(int sockfd, const void *buffer, size_t len, int flags, 
           const struct sockaddr *to, socklen_t tolen)
{ int result;

  unsigned long args[6];

  ENTER_CRITICAL;
  MAKE_READABLE(buffer);
  MAKE_READABLE(to);

  args[0] = sockfd;
  args[1] = (unsigned long) buffer;
  args[2] = len;
  args[3] = flags;
  args[4] = (unsigned long) to;
  args[5] = tolen;
  result = (socketcall (SYS_SENDTO, args));

  EXIT_CRITICAL;
  return result;
}

int setdomainname(name, namelen)
char *name;
int namelen;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(name);
  result = syscall(SYS_setdomainname, name, namelen);
  EXIT_CRITICAL;
  return result;
}

int setgroups(ngroups, gidset)
int ngroups;
int *gidset;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(gidset);
  result = syscall(SYS_setgroups, ngroups, gidset);
  EXIT_CRITICAL;
  return result;
}

int sethostname(name, namelen)
char *name;
int namelen;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(name);
  result = syscall(SYS_sethostname, name, namelen);
  EXIT_CRITICAL;
  return result;
}

#if __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 2
int setitimer(__itimer_which_t which, __const struct itimerval *value,
              struct itimerval *ovalue)
#else
int setitimer(enum __itimer_which which, const struct itimerval *value, 
   struct itimerval *ovalue)
#endif
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(value);
  MAKE_WRITABLE(ovalue);
  result = syscall(SYS_setitimer, which, value, ovalue);
  EXIT_CRITICAL;
  return result;
}

/*
int setquota(special, file)
char *special;
char *file;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(special);
  MAKE_READABLE(file);
  result = syscall(SYS_setquota, special, file);
  EXIT_CRITICAL;
  return result;
}
*/

#if __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 2
int setrlimit(__rlimit_resource_t resource, __const struct rlimit *rlp)
#else
int setrlimit(enum __rlimit_resource resource, const struct rlimit *rlp)
#endif
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(rlp);
  result = syscall(SYS_setrlimit, resource, rlp);
  EXIT_CRITICAL;
  return result;
}

int setsockopt(fd, level, optname, optval, optlen)
int fd, level, optname;
const void *optval;
socklen_t optlen;
{ int result;

  unsigned long args[5];

  ENTER_CRITICAL;
  MAKE_READABLE(optval);

  args[0]=fd;
  args[1]=level;
  args[2]=optname;
  args[3]=(unsigned long)optval;
  args[4]=optlen;
  result = (socketcall (SYS_SETSOCKOPT, args));

  EXIT_CRITICAL;
  return result;
}

/*
int setsysinfo(op, buffer, nbytes, arg, flag)
unsigned op;
char *buffer;
unsigned nbytes;
unsigned arg;
unsigned flag;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(buffer);
  result = syscall(SYS_setsysinfo, op, buffer, nbytes, arg, flag);
  EXIT_CRITICAL;
  return result;
}
*/

int settimeofday(tp, tzp)
const struct timeval *tp;
const struct timezone *tzp;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(tp);
  MAKE_READABLE(tzp);
  result = syscall(SYS_settimeofday, tp, tzp);
  EXIT_CRITICAL;
  return result;
}

int sigaction(int signum, const struct sigaction *act, 
	      struct sigaction *oldact)
{ int result;

  ENTER_CRITICAL;
  if(oldact != NULL) MAKE_WRITABLE(oldact);
  MAKE_READABLE(act);
  result = syscall(SYS_sigaction, signum, act, oldact);
  EXIT_CRITICAL;
  return result;
}

int sigpending(set)
sigset_t *set;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(set);
  result = syscall(SYS_sigpending, set);
  EXIT_CRITICAL;
  return result;
}

int sigprocmask(int how, const sigset_t *set, sigset_t *oldset)
{ int result;

  ENTER_CRITICAL;
  if (oldset != NULL) MAKE_WRITABLE(oldset);
  MAKE_READABLE(set);
  result = syscall(SYS_sigprocmask, how, set, oldset);
  EXIT_CRITICAL;
  return result;
}

/*
int sigstack(ss, oss)
struct sigstack *ss;
struct sigstack *oss;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(ss);
  MAKE_WRITABLE(oss);
  result = syscall(SYS_sigstack, ss, oss);
  EXIT_CRITICAL;
  return result;
}
*/

int socketpair(family, type, protocol, sockvec)
int family, type, protocol;
int sockvec[2];
{ int result;

  unsigned long args[4];

  ENTER_CRITICAL;
  MAKE_WRITABLE(sockvec);

  args[0] = family;
  args[1] = type;
  args[2] = protocol;
  args[3] = (unsigned long)sockvec;
  result = socketcall(SYS_SOCKETPAIR, args);

  EXIT_CRITICAL;
  return result;
}

int stat(path, buf)
const char *path;
struct stat *buf;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  MAKE_WRITABLE(buf);
  result = __stat(path, buf);
  EXIT_CRITICAL;
  return result;
}

int swapon(special)
char *special;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(special);
  result = syscall(SYS_swapon, special);
  EXIT_CRITICAL;
  return result;
}

int symlink(name1, name2)
char *name1;
char *name2;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(name1);
  MAKE_READABLE(name2);
  result = syscall(SYS_symlink, name1, name2);
  EXIT_CRITICAL;
  return result;
}

time_t time(time_t *t)
{ int result;

  ENTER_CRITICAL;
  if (t != NULL) MAKE_WRITABLE(t);
  result = syscall(SYS_time, t);
  EXIT_CRITICAL;
  return result;
}

clock_t times(struct tms *buf) {
  clock_t result;
  
  ENTER_CRITICAL;
  MAKE_WRITEABLE(buf);
  result = syscall(SYS_times, buf);
  EXIT_CRITICAL;

  return result;
}

int truncate(path, length)
char *path;
int length;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  result = syscall(SYS_truncate, path, length);
  EXIT_CRITICAL;
  return result;
}

int umount(dir) 
  const char *dir;
  { int result;

    ENTER_CRITICAL;
    MAKE_READABLE(dir);
    result = syscall(SYS_umount, dir);
    EXIT_CRITICAL;
    return result;
  }

int uname(name)
struct utsname *name;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(name);
  result = syscall(SYS_uname, name);
  EXIT_CRITICAL;
  return result;
}

int unlink(path)
char *path;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(path);
  result = syscall(SYS_unlink, path);
  EXIT_CRITICAL;
  return result;
}

int ustat(dev, buf)
dev_t dev;
struct ustat *buf;
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(buf);
  result = syscall(SYS_ustat, dev, buf);
  EXIT_CRITICAL;
  return result;
}

int __real_utimes(const char *file, struct timeval *tvp);

int __wrap_utimes(const char *file, struct timeval *tvp)
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(file);
  MAKE_READABLE(tvp);
  result = __real_utimes(file, tvp);
  EXIT_CRITICAL;
  return result;
}

pid_t wait(union wait *status)
{
  return wait3(status, 0, 0);
}

pid_t __real_wait3(union wait *status, int options, struct rusage *rusage);

pid_t __wrap_wait3(union wait *status, int options, struct rusage *rusage)
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(status);
  MAKE_WRITABLE(rusage);
  result = __real_wait3(status, options, rusage);
  EXIT_CRITICAL;
  return result;
}

pid_t waitpid(pid_t pid, int *status, int options)
{ int result;

  ENTER_CRITICAL;
  MAKE_WRITABLE(status);
  result = syscall(SYS_waitpid, pid, status, options);
  EXIT_CRITICAL;
  return result;
}

int write(fd, buf, nbytes)
int fd;
char *buf;
int nbytes;
{ int result;

  ENTER_CRITICAL;
  MAKE_READABLE(buf);
  result = syscall(SYS_write, fd, buf, nbytes);
  EXIT_CRITICAL;
  return result;
}

static int kernel_writev = 0; /* 0=unknown, 1=yes, 2=no */

int writev(fd, iov, ioveclen)
int fd;
const struct iovec *iov;
int ioveclen;
{ int result;

  ENTER_CRITICAL;
  { int i;
    for (i = 0; i < ioveclen; i++) {
      if (iov[i].iov_len > 0) {
        MAKE_READABLE(iov[i].iov_base);
      }
    }
  }
  /****** NOT all versions of Linux have a writev kernel call...
  result = __writev(fd, iov, ioveclen);
  **********/
  if (kernel_writev == 2) {
    result = fake_writev(fd, iov, ioveclen);
  } else if (kernel_writev == 1) {
    result = syscall(SYS_writev, fd, iov, ioveclen);
  } else {
    result = first_writev(fd, iov, ioveclen);
  }
  EXIT_CRITICAL;
  return result;
}

/* We don't know if writev() is a supported kernel call or not.
   So, we'll try the kernel call once and remember whether it
   fails. */

int first_writev(fd, iov, ioveclen)
int fd;
const struct iovec *iov;
size_t ioveclen;
{ int result;

  result = syscall(SYS_writev, fd, iov, ioveclen);
  if ((result > 0) || (errno != ENOSYS)) {
    kernel_writev = 1;  /* we've got kernel support for writev() */
  } else {
    kernel_writev = 2;  /* nope, we need the user-level hack */
    result = fake_writev(fd, iov, ioveclen);
  }
  return result;
}

/* Early versions of Linux supported writev() as a user-level library
   routine, not a kernel call.  Those versions copied the entire
   contents of the output buffer onto the caller's stack.  The
   scheme "works" on the initial Unix stack, but is prone to overflowing
   the fixed size Modula-3 stacks.  Unfortunately, the X11 library
   passes large bitmaps to the server via writev().  So, we deal
   with it here.  Note that this implementation makes multiple
   write() calls, hence it's not exactly equivalent to writev()
   when the size of the write matters (eg. on some sockets).  */

int fake_writev(fd, iov, ioveclen)
int fd;
const struct iovec *iov;
size_t ioveclen;
{
  int i, k, n = 0;
  for(i = 0; i < ioveclen; i++)
  {
    k = write(fd, iov[i].iov_base, iov[i].iov_len);
    if (k < 0) return k;
    n += k;
  }
  return n;
}

/* fork also requires special treatment, although it takes no
   argument.  fork crashes Ultrix if some pages are unreadable, so we
   must unprotect the heap before calling fork */

pid_t fork()
{
  pid_t result;
  pid_t me = getpid();

  ENTER_CRITICAL;
  if (RTCSRC_FinishVM)  RTCSRC_FinishVM();
  result = syscall(SYS_fork);
  EXIT_CRITICAL;
  if (result == me) {
    result = 0;
  }
  return result;
}

/* Clone is nearly the same as fork. */
pid_t clone(sp, flags)
     void *sp;
     int flags;
{
  pid_t result;
  pid_t me = getpid();

  ENTER_CRITICAL;
  MAKE_WRITEABLE(sp);
  if (RTCSRC_FinishVM)  RTCSRC_FinishVM();
  result = syscall(SYS_clone, sp, flags);
  EXIT_CRITICAL;
  if (result == me) {
    result = 0;
  }
  return result;
}