Message-Id:	<3.0.1.32.19980107133235.007d35a0@yacker.xiotech.com>
Date:	Wed, 07 Jan 1998 13:32:35 -0600
To:	djgpp-workers AT delorie DOT com
From:	Randy Maas <randym AT acm DOT org>
Subject:	patch for dup2
Mime-Version:	1.0

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This makes it so that a fsext can dup2() it's own file descriptor
Randy
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*** /local/src/libc/posix/unistd/dup2.c~1	Sun Sep 29 09:20:56 1996
--- /local/src/libc/posix/unistd/dup2.c	Wed Jan  7 13:09:44 1998
***************
*** 7,10 ****
--- 7,11 ----
  #include <io.h>
  #include <libc/dosio.h>
+ #include <sys/fsext.h>
  
  int
***************
*** 12,17 ****
--- 13,35 ----
  {
    __dpmi_regs r;
+   __FSEXT_Function *func, *newfunc;
+ 
    if (fd == newfd)
      return newfd;
+   func = __FSEXT_get_function(fd);
+   if (func)
+   {
+     int rv;
+     if (func(__FSEXT_dup2, &rv, &fd))
+       return rv;
+ 
+     /* We will have dup2 the fs extension's file descriptor ourselves.  To
+        prevent trouble, we make sure that extension using newfd (if any) is
+        closed off. */
+     newfunc = __FSEXT_get_function(newfd);
+     if (newfunc)
+       close(newfd);
+   }
+ 
    __file_handle_set(newfd, __file_handle_modes[fd] ^ (O_BINARY|O_TEXT));
    r.h.ah = 0x46;
***************
*** 25,28 ****
--- 43,60 ----
    }
    setmode(newfd, __file_handle_modes[fd]);
+ 
+   /* if the fd refers to a file extension, and it didn't handle the dup2()
+      command (eg, it is an older fsext), we can do this ourselves: just set
+      the handle for newfd to be the same as the handler for fd, and copy the
+      data part (this is a bug potential if the fsext is using a dynamically
+      alloced resource for the data and it does not manage this on its own)
+    */
+   if (func) close(newfd);
+   {
+      void* data = __FSEXT_get_data(fd);
+      __FSEXT_set_function(newfd, func);
+      __FSEXT_set_data(newfd, data);
+   }
+ 
    return newfd;
  }

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