root/fs/fcntl.c

/* */

DEFINITIONS

1. dupfd
2. sys_dup2
3. sys_dup
4. sys_fcntl
5. kill_fasync

   1 /*
   2  *  linux/fs/fcntl.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 #include <asm/segment.h>
   8 
   9 #include <linux/sched.h>
  10 #include <linux/kernel.h>
  11 #include <linux/errno.h>
  12 #include <linux/stat.h>
  13 #include <linux/fcntl.h>
  14 #include <linux/string.h>
  15 
  16 extern int fcntl_getlk(unsigned int, struct flock *);
  17 extern int fcntl_setlk(unsigned int, unsigned int, struct flock *);
  18 extern int sock_fcntl (struct file *, unsigned int cmd, unsigned long arg);
  19 
  20 static int dupfd(unsigned int fd, unsigned int arg)
     /*  */
  21 {
  22         if (fd >= NR_OPEN || !current->files->fd[fd])
  23                 return -EBADF;
  24         if (arg >= NR_OPEN)
  25                 return -EINVAL;
  26         while (arg < NR_OPEN)
  27                 if (current->files->fd[arg])
  28                         arg++;
  29                 else
  30                         break;
  31         if (arg >= NR_OPEN)
  32                 return -EMFILE;
  33         FD_CLR(arg, &current->files->close_on_exec);
  34         (current->files->fd[arg] = current->files->fd[fd])->f_count++;
  35         return arg;
  36 }
  37 
  38 asmlinkage int sys_dup2(unsigned int oldfd, unsigned int newfd)
     /*  */
  39 {
  40         if (oldfd >= NR_OPEN || !current->files->fd[oldfd])
  41                 return -EBADF;
  42         if (newfd == oldfd)
  43                 return newfd;
  44         /*
  45          * errno's for dup2() are slightly different than for fcntl(F_DUPFD)
  46          * for historical reasons.
  47          */
  48         if (newfd > NR_OPEN)    /* historical botch - should have been >= */
  49                 return -EBADF;  /* dupfd() would return -EINVAL */
  50 #if 1
  51         if (newfd == NR_OPEN)
  52                 return -EBADF;  /* dupfd() does return -EINVAL and that may
  53                                  * even be the standard!  But that is too
  54                                  * weird for now.
  55                                  */
  56 #endif
  57         sys_close(newfd);
  58         return dupfd(oldfd,newfd);
  59 }
  60 
  61 asmlinkage int sys_dup(unsigned int fildes)
     /*  */
  62 {
  63         return dupfd(fildes,0);
  64 }
  65 
  66 asmlinkage int sys_fcntl(unsigned int fd, unsigned int cmd, unsigned long arg)
     /*  */
  67 {       
  68         struct file * filp;
  69 
  70         if (fd >= NR_OPEN || !(filp = current->files->fd[fd]))
  71                 return -EBADF;
  72         switch (cmd) {
  73                 case F_DUPFD:
  74                         return dupfd(fd,arg);
  75                 case F_GETFD:
  76                         return FD_ISSET(fd, &current->files->close_on_exec);
  77                 case F_SETFD:
  78                         if (arg&1)
  79                                 FD_SET(fd, &current->files->close_on_exec);
  80                         else
  81                                 FD_CLR(fd, &current->files->close_on_exec);
  82                         return 0;
  83                 case F_GETFL:
  84                         return filp->f_flags;
  85                 case F_SETFL:
  86                         if ((arg & FASYNC) && !(filp->f_flags & FASYNC) &&
  87                             filp->f_op->fasync)
  88                                 filp->f_op->fasync(filp->f_inode, filp, 1);
  89                         if (!(arg & FASYNC) && (filp->f_flags & FASYNC) &&
  90                             filp->f_op->fasync)
  91                                 filp->f_op->fasync(filp->f_inode, filp, 0);
  92                         filp->f_flags &= ~(O_APPEND | O_NONBLOCK | FASYNC);
  93                         filp->f_flags |= arg & (O_APPEND | O_NONBLOCK |
  94                                                 FASYNC);
  95                         return 0;
  96                 case F_GETLK:
  97                         return fcntl_getlk(fd, (struct flock *) arg);
  98                 case F_SETLK:
  99                         return fcntl_setlk(fd, cmd, (struct flock *) arg);
 100                 case F_SETLKW:
 101                         return fcntl_setlk(fd, cmd, (struct flock *) arg);
 102                 case F_GETOWN:
 103                         /*
 104                          * XXX If f_owner is a process group, the
 105                          * negative return value will get converted
 106                          * into an error.  Oops.  If we keep the the
 107                          * current syscall conventions, the only way
 108                          * to fix this will be in libc.
 109                          */
 110                         return filp->f_owner;
 111                 case F_SETOWN:
 112                         filp->f_owner = arg; /* XXX security implications? */
 113                         if (S_ISSOCK (filp->f_inode->i_mode))
 114                                 sock_fcntl (filp, F_SETOWN, arg);
 115                         return 0;
 116                 default:
 117                         /* sockets need a few special fcntls. */
 118                         if (S_ISSOCK (filp->f_inode->i_mode))
 119                           {
 120                              return (sock_fcntl (filp, cmd, arg));
 121                           }
 122                         return -EINVAL;
 123         }
 124 }
 125 
 126 void kill_fasync(struct fasync_struct *fa, int sig)
     /*  */
 127 {
 128         while (fa) {
 129                 if (fa->magic != FASYNC_MAGIC) {
 130                         printk("kill_fasync: bad magic number in "
 131                                "fasync_struct!\n");
 132                         return;
 133                 }
 134                 if (fa->fa_file->f_owner > 0)
 135                         kill_proc(fa->fa_file->f_owner, sig, 1);
 136                 else
 137                         kill_pg(-fa->fa_file->f_owner, sig, 1);
 138                 fa = fa->fa_next;
 139         }
 140 }

/* */