From: pavenis AT lanet DOT lv
To: "Eli Zaretskii" <eliz AT is DOT elta DOT co DOT il>, djgpp-workers AT delorie DOT com,
        acottrel AT ihug DOT com DOT au, djgpp-workers AT delorie DOT com, pavenis AT lanet DOT lv,
        sandmann AT clio DOT rice DOT edu
Date: Fri, 17 Aug 2001 15:58:14 +0300
MIME-Version: 1.0
Content-type: Multipart/Mixed; boundary=Message-Boundary-24862
Subject: Re: _open.c commit?  (was Re: Selector Exhaustion)
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In-reply-to: <2561-Fri17Aug2001115601+0300-eliz@is.elta.co.il>
References: <10108162209 DOT AA13700 AT clio DOT rice DOT edu> (sandmann AT clio DOT rice DOT edu)
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On 17 Aug 2001, at 11:56, Eli Zaretskii wrote:

> > From: sandmann AT clio DOT rice DOT edu (Charles Sandmann)
> > Date: Thu, 16 Aug 2001 17:09:40 -0500 (CDT)
> > 
> > Should we sit on the current selector cleanup patch or commit it also?
> 
> I think it should be committed and we should ask people to build
> applications (such as Make, RHIDE, and Bash) with it and test it in a
> variety of environments.
> 
> However, I'd like to see that patch changed so that plain DOS systems
> aren't affected at all.  Why slow down systems which don't need that?
> We already have the _windows_major variable that can be used to easily
> test for whether we are on Windows, and _get_dos_version(1) can be
> used for NT/W2K/XP.

What about this? I added test for CWSDPMI v5 (corresponding DPMI
call doesn't work with earlier versions). Also added possibility to
enable or disable workaround from environment:
	SET   WORKAROUND_LDT_DESCRIPTORS_LEAK={y|n}

y is default for all cases except when CWSDPMI is begin used. 
Perhaps we should think also about using some bit in 
_crt0_startup_flags
	
Andris



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   ---- File information -----------
     File:  dosexec.c.diff4
     Date:  17 Aug 2001, 15:57
     Size:  3566 bytes.
     Type:  Text

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*** djgpp/src/libc/dos/process/dosexec.c~1	Mon Jul 30 14:35:52 2001
--- djgpp/src/libc/dos/process/dosexec.c	Fri Aug 17 15:57:00 2001
*************** size_t __cmdline_str_len = sizeof(__cmdl
*** 157,163 ****
     if LFN is 2, there is a possiblity that the contents of the
     transfer buffer will be overrun!  */
  static int
! direct_exec_tail(const char *program, const char *args,
  		 char * const envp[], const char *proxy, int lfn,
  		 const char *cmdline_var)
  {
--- 157,163 ----
     if LFN is 2, there is a possiblity that the contents of the
     transfer buffer will be overrun!  */
  static int
! direct_exec_tail_1 (const char *program, const char *args,
  		 char * const envp[], const char *proxy, int lfn,
  		 const char *cmdline_var)
  {
*************** direct_exec_tail(const char *program, co
*** 413,418 ****
--- 413,505 ----
    return r.h.al;	/* AL holds the child exit code */
  }
  
+ 
+ 
+ static int direct_exec_tail (const char *program, const char *args,
+ 		 char * const envp[], const char *proxy, int lfn,
+ 		 const char *cmdline_var)
+ {
+   int   i, ret;
+   int   sel1=0, sel2=0;
+   char  desc_map[8192];
+   static int   workaround_descriptor_leaks = 1;
+   static int   first_call = 1;
+   static int   is_nt = 0;
+ 
+   if (first_call)
+   {
+      int flags;
+      char dpmi_vendor[128], *W;
+      is_nt = (_osmajor==5 && _osminor==0 && _get_dos_version(1)==0x0532) ? 1 : 0;
+ 
+      /* Disable descriptors leak workaround whenCWSDPMI v5 is begin    */
+      /* used (don't work with earlier versions as corresponding DPMI   */
+      /* call is supported beginning from v5)                           */
+ 
+      ret = __dpmi_get_capabilities (&flags,dpmi_vendor);
+      if (ret==0 && strcmp(dpmi_vendor+2,"CWSDPMI")==0)
+         workaround_descriptor_leaks = 0;
+ 
+      /* Added possibility to enable/disable LDT descriptors leak       */
+      /* workaround from environment (I think nice for testing or when  */
+      /* one have trouble)                                              */                                                        
+ 
+      W = getenv("WORKAROUND_LDT_DESCRIPTORS_LEAK");
+      if (W)
+      {
+ 	 if (*W=='y' || *W=='Y') workaround_descriptor_leaks = 1;
+ 	 if (*W=='n' || *W=='N') workaround_descriptor_leaks = 0;
+      }
+ 
+      first_call = 0;
+   }
+ 
+   if (workaround_descriptor_leaks)
+   {
+      if (is_nt)
+      {
+ 	 sel1 = __dpmi_allocate_ldt_descriptors (1);
+      }
+      else
+      {
+ 	 char * map = desc_map;
+ 	 for (i=_my_ds() % 7; i<0x00010000; i+=8)
+ 	 {  /* FIXME: Use __dpmi_get_selector_increment_value() instead of 8 ?  */
+ 		*map++ = (__dpmi_get_descriptor_access_rights(i) & 0x80) ? 0 : 1;
+ 	 }
+      }
+   }
+ 
+   ret = direct_exec_tail_1 ( program, args, envp, proxy, lfn, cmdline_var );
+ 
+   if (workaround_descriptor_leaks)
+   {
+      if (is_nt)
+      {
+         sel2 = __dpmi_allocate_ldt_descriptors (1);
+         if (sel1>_dos_ds && sel2>_dos_ds)
+         {
+            for (i=sel2; i>=sel1; i-=8)
+               __dpmi_free_ldt_descriptor (i);
+         }
+      }
+      else
+      {
+         char * map = desc_map;
+         for (i=_my_ds() % 7; i<0x00010000; i+=8)
+         {
+            if (*map++)
+            {
+                if (__dpmi_get_descriptor_access_rights(i) & 0x80)
+                    __dpmi_free_ldt_descriptor (i);
+            }
+         }
+      }
+   }
+   return ret;
+ }
+ 
+ 
  int
  _dos_exec(const char *program, const char *args, char * const envp[],
  	  const char *cmdline_var)

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