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c++.dos.32-bits - _spawnl general protection fault error

reply E. Trelmar <E._member pathlink.com> writes:
I'm probably just coding something wrong, but every time I try to _spawnl a
certain program, I get an 0Dh (Hard Disk) general protection fault, possible
illegal memory address. I use the _P_WAIT style (spawn and wait till
termination) rather than the overlay and terminate parent process. I'm assuming
that the program (developed third-party) is 16-bit, and doesn't run in protected
mode from a direct spawn, I'm not sure though.
How does one spawn a 16 bit real-mode program from a 32-bit protected mode
program?

The program in question is tiffcp.exe, a free tool for collating .tif images.
Jul 10 2002
parent reply "Walter" <walter digitalmars.com> writes:
Try building a simple hello world program and see if that can be
successfully spawned. -Walter

"E. Trelmar" <E._member pathlink.com> wrote in message
news:aghoa0$1j84$1 digitaldaemon.com...

 I'm probably just coding something wrong, but every time I try to _spawnl


a

 certain program, I get an 0Dh (Hard Disk) general protection fault,


possible

 illegal memory address. I use the _P_WAIT style (spawn and wait till
 termination) rather than the overlay and terminate parent process. I'm


assuming

 that the program (developed third-party) is 16-bit, and doesn't run in


protected

 mode from a direct spawn, I'm not sure though.
 How does one spawn a 16 bit real-mode program from a 32-bit protected mode
 program?

 The program in question is tiffcp.exe, a free tool for collating .tif


images.





 Jul 10 2002



  parent reply E. Trelmar <E._member pathlink.com>  writes:


In article <aghpm8$1kt7$2 digitaldaemon.com>, Walter says...

Try building a simple hello world program and see if that can be
successfully spawned. -Walter


I should have specified, it doesn't spawn any 16 bit programs. I just tried
32-bit programs though, going off a tangent on your suggestion, and those
generate the same error. So I tried generating a 32-bit program with nothing but
a _spawnl command. It won't spawn either 32-bit or 16-bit programs (Again, the
same error). Is this simply my machine? Can anyone else get _spawnl to work in
32-bit dos?



 Jul 10 2002



  parent reply "Walter" <walter digitalmars.com>  writes:


"E. Trelmar" <E._member pathlink.com> wrote in message
news:aghqk5$1lht$1 digitaldaemon.com...

 I should have specified, it doesn't spawn any 16 bit programs. I just


tried

 32-bit programs though, going off a tangent on your suggestion, and those
 generate the same error. So I tried generating a 32-bit program with


nothing but

 a _spawnl command. It won't spawn either 32-bit or 16-bit programs (Again,


the

 same error). Is this simply my machine? Can anyone else get _spawnl to


work in

 32-bit dos?


I use this program all the time and it spawns successfully.
---------------------------------------------------------
/*_ timer.c   Mon Feb 29 1988   Modified by: Walter Bright */
/* Written by Walter Bright   */

#include <stdio.h>
#include <stdlib.h>
#if _WIN32
#include <windows.h>
typedef long long timer_t;
#else
#include <time.h>
#endif

#if __SC__ && !_WIN32
int _okbigbuf = 0; /* Use as little memory as possible */
#endif

int main(argc,argv)
int argc;
char *argv[];
{
 int status;
#if _WIN32
 timer_t starttime;
 timer_t freq;
 timer_t endtime;
 timer_t secs;
 timer_t fraction;

 if (argc < 2)
 { printf("Time execution of a command.\nUse:\n\ttimer command\n");
  exit(EXIT_FAILURE);
 }
 argv[argc] = 0;  /* terminate with a 0 (unportable method) */
 QueryPerformanceFrequency((LARGE_INTEGER *)&freq);
 QueryPerformanceCounter((LARGE_INTEGER *)&starttime);
 status = spawnvp(0,argv[1],argv + 1);
 QueryPerformanceCounter((LARGE_INTEGER *)&endtime);
 if (status == -1)
 { printf("'%s' failed to execute\n",argv[1]);
  exit(EXIT_FAILURE);
 }

 starttime = endtime - starttime;
 secs = starttime / freq;
 starttime -= secs * freq;
 fraction = (starttime * 10000) / freq;
 printf("Elapsed time = %lld.%04lld seconds\n",secs,fraction);
#else
 clock_t clock(),starttime;

 if (argc < 2)
 { printf("Time execution of a command.\nUse:\n\ttimer command\n");
  exit(1);
 }
 argv[argc] = 0;  /* terminate with a 0 (unportable method) */
 starttime = clock();
 status = spawnvp(0,argv[1],argv + 1);
 starttime = clock() - starttime;
 if (status == -1)
 { printf("'%s' failed to execute\n",argv[1]);
  exit(1);
 }
 printf("Elapsed time = %d.%02d seconds\n",(int) (starttime/CLK_TCK),
  (int) (starttime%CLK_TCK));
#endif
 if (status != 0)
  printf("--- errorlevel %d\n",status);
 return status;
}

#if __SC__ && !_WIN32

/* Prevent exit() and fclose() from being linked in from library */
/* (to conserve the size of the output file).    */

void exit(exitstatus)
int exitstatus;
{
 _exit(exitstatus);
}
#endif



 Jul 10 2002



  parent  E. Trelmar <E._member pathlink.com>  writes:


Both your program Walter (With process.h #included so it compiles for me) and
the example programs work successfully. Luckily, I just found out the problem
was that I wasn't passing a final NULL pointer to the spawnl series. Thank you
for the replies, I appreciate the help.



 Jul 11 2002