dupfdopen extended to allow file stealing in addition to dup function.

SCCS-vsn: sys/kern/kern_descrip.c 7.34

diff --git a/usr/src/sys/kern/kern_descrip.c b/usr/src/sys/kern/kern_descrip.c
index c065b1f..7b9c9cb 100644 (file)
--- a/usr/src/sys/kern/kern_descrip.c
+++ b/usr/src/sys/kern/kern_descrip.c
@@ -4,7 +4,7 @@
  *
  * %sccs.include.redist.c%
  *
  *
  * %sccs.include.redist.c%
  *

- *     @(#)kern_descrip.c      7.33 (Berkeley) %G%
+ *     @(#)kern_descrip.c      7.34 (Berkeley) %G%

  */
 
 #include "param.h"
  */
 
 #include "param.h"


@@ -735,7 +735,6 @@ fdopen(dev, mode, type, p)
        int mode, type;
        struct proc *p;
 {
        int mode, type;
        struct proc *p;
 {

-       USES_VOP_OPEN;

 
        /*
         * XXX Kludge: set curproc->p_dupfd to contain the value of the
 
        /*
         * XXX Kludge: set curproc->p_dupfd to contain the value of the


@@ -752,10 +751,11 @@ fdopen(dev, mode, type, p)
 /*
  * Duplicate the specified descriptor to a free descriptor.
  */
 /*
  * Duplicate the specified descriptor to a free descriptor.
  */

-dupfdopen(fdp, indx, dfd, mode)
+dupfdopen(fdp, indx, dfd, mode, error)

        register struct filedesc *fdp;
        register int indx, dfd;
        int mode;
        register struct filedesc *fdp;
        register int indx, dfd;
        int mode;

+       int error;

 {
        register struct file *wfp;
        struct file *fp;
 {
        register struct file *wfp;
        struct file *fp;


@@ -773,15 +773,56 @@ dupfdopen(fdp, indx, dfd, mode)
                return (EBADF);
 
        /*
                return (EBADF);
 
        /*

-        * Check that the mode the file is being opened for is a subset 
-        * of the mode of the existing descriptor.
+        * There are two cases of interest here.
+        *
+        * For ENODEV simply dup (dfd) to file descriptor
+        * (indx) and return.
+        *
+        * For ENXIO steal away the file structure from (dfd) and
+        * store it in (indx).  (dfd) is effectively closed by
+        * this operation.
+        *
+        * Any other error code is just returned.

         */
         */

-       if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag)
-               return (EACCES);
-       fdp->fd_ofiles[indx] = wfp;
-       fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
-       wfp->f_count++;
-       if (indx > fdp->fd_lastfile)
-               fdp->fd_lastfile = indx;
-       return (0);
+       switch (error) {
+       case ENODEV:
+               /*
+                * Check that the mode the file is being opened for is a
+                * subset of the mode of the existing descriptor.
+                */
+               if (((mode & (FREAD|FWRITE)) | wfp->f_flag) != wfp->f_flag)
+                       return (EACCES);
+               fdp->fd_ofiles[indx] = wfp;
+               fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
+               wfp->f_count++;
+               if (indx > fdp->fd_lastfile)
+                       fdp->fd_lastfile = indx;
+               return (0);
+
+       case ENXIO:
+               /*
+                * Steal away the file pointer from dfd, and stuff it into indx.
+                */
+               fdp->fd_ofiles[indx] = fdp->fd_ofiles[dfd];
+               fdp->fd_ofiles[dfd] = NULL;
+               fdp->fd_ofileflags[indx] = fdp->fd_ofileflags[dfd];
+               fdp->fd_ofileflags[dfd] = 0;
+               /*
+                * Complete the clean up of the filedesc structure by
+                * recomputing the various hints.
+                */
+               if (indx > fdp->fd_lastfile)
+                       fdp->fd_lastfile = indx;
+               else
+                       while (fdp->fd_lastfile > 0 &&
+                              fdp->fd_ofiles[fdp->fd_lastfile] == NULL)
+                               fdp->fd_lastfile--;
+                       if (dfd < fdp->fd_freefile)
+                               fdp->fd_freefile = dfd;
+               return (0);
+
+       default:
+               return (error);
+       }
+       /* NOTREACHED */

 }
 }