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From: curtin@cbnewse.ATT.COM (C.S.Curtin)
Newsgroups: alt.msdos.programmer,comp.sys.ibm.pc
Subject: ms-dos FILES=fd in config.sys parameter
Keywords: config FILES MS4.01
Message-ID: <13340@cbnewse.ATT.COM>
Date: 3 Mar 90 16:23:56 GMT
Organization: AT&T Bell Laboratories, Naperville, IL.
Lines: 62


i am having a problem using MS-DOS 4.01 with the number of file
descriptors available. i changed config.sys to files=100 but cannot
get ms-dos to exceed 20 (the pre-dos3.3 maximum).  i wrote a small
test program in msc5.1 to see the difference of changing my
config.sys and still cannot exceed the 20 open files.

is there a way for dos to tell me the current maximum number of
file descriptors available? (while ms-dos is running?)
(i know that you can "type c:\config.sys", but is there any other
way to dump the max_index_length of the fd table?)

in the example program the file being opened is the same one, i had a
version that in each loop created a unique file name. this version
obtained the same results.

please reply via e-mail, i will summarize if enough interest.

any help is greatly appreciated, thanks!

craig curtin
/\/\/\/\/\/\/\/\/\/\/\ fd.c /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
#include <stdio.h>
#include <fcntl.h>    	/* for open flags */
#include <sys/types.h>	/* needed for  stat.h */
#include <sys/stat.h>	/* needed for  S_IREAD/S_IWRITE */
void main()
{
int i,fd;
   for (i=0;i<300;i++)
   {
        /* create any old junk file */
	if((fd=open("xx",(int)(O_CREAT|O_TRUNC|O_WRONLY|O_BINARY),
		                                      S_IREAD|S_IWRITE)) < 0)
	{
             /* wow, something caused an error*/
             perror("failed on open");
	     exit();
        }     
        fprintf(stdout,"successfully opened %d\n",fd);
   }
}
/\/\/\/\/\/\/\/\/\/\/\ fd.exe output /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
successfully opened 5
successfully opened 6
successfully opened 7
successfully opened 8
successfully opened 9
successfully opened 10
successfully opened 11
successfully opened 12
successfully opened 13
successfully opened 14
successfully opened 15
successfully opened 16
successfully opened 17
successfully opened 18
successfully opened 19
failed on open:  Too many open files
/\/\/\/\/\/\/\/\/\/\/\ fd.exe output /\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
i understand that msc opens fd 0-4 making the first available #5.
(btw: perror() sends output to stderr)