Solved

getenv crashes

Posted on 2003-10-21
8
408 Views
Last Modified: 2012-06-27
Pro*C
getenv function in User exit crashes when an environment variable is not exported

if ((envdbg = getenv("somevar")) != NULL )

any idea of why this is happening?

Thanks!
0
Comment
Question by:Jkrish
  • 4
  • 3
8 Comments
 
LVL 45

Accepted Solution

by:
Kdo earned 40 total points
ID: 9592253

getenv() has been around a long time so I doubt that the problem is with this particular function.

How about "proving" if the function's failure is its own doing, or caused by something else clobbering part of the program by running the following:


main (int argc, char **argv)
{
  char *Var;
  int    idx;

  for (idx = 1; idx < argc; idx++)
  {
    Var = getenv (argv[idx]);
    printf (" %s = %s\n", argv[idx], Var == NULL ? "<none>" : Var);
  }
}

Test it by doing something like this:

runit path
runit path terminal test nothing etc


Kent




0
 
LVL 22

Expert Comment

by:grg99
ID: 9592894
Perhaps you've somehow scrozzled your local copy of the environment.

Try doing this crashy line first thing in your program. If it works there but doesnt later on,
yo may have stepped on the environment.

0
 
LVL 45

Expert Comment

by:Kdo
ID: 9593077

Hi grg99,

That's where my test code was going.  If it passes, then his program is scribbling where it aughtn't.

Kent
0
 

Author Comment

by:Jkrish
ID: 9599060
Problem is, the function is not a main function and it's an user exit
and it's more confusing because of the fact that other user exits (.pc files) are working fine.  
getenv is crashing even before it returns anything at all when the env variable is not exported.  

Thanks a lot guys!
0
PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

 
LVL 45

Expert Comment

by:Kdo
ID: 9599763

Hi Jkrish,

I'm not sure what your last comment meant.


Did you try the sample code that I provided to see if getenv() has a problem.  (I still don't think that getenv() is failing on its own.)

If you've got some really good debug tools (like Rational) you should be able to discover where your program is overflowing a buffer.

If not, link the program and generate a loadmap.  Find out what's loaded right above getenv().  Chances are that a buffer one or two items above getenv() is the culprit.


Kent
0
 

Author Comment

by:Jkrish
ID: 9602886
Many thanks Kent!

I am calling a user exit (Pro*C) from oracle forms (version 6)
and this piece of function is in a library archive and it's a .pc file.

It's interesting to see if I open a text file and insert a line of text
and close prior to running the above mentioned command,
( fp = fopen("testfile","w");
fprintf(fp,"testline\n");
fclose(fp);
)
everything works fine.  

Like you have pointed out, an item above the call to getenv must be a culprit. But this is the first line of code in the program (only oracle variables and host variables are declared above it).  

Thanks again
0
 
LVL 45

Expert Comment

by:Kdo
ID: 9605756

I wonder if the Oracle library includes its own getenv() function?

Kent
0
 

Author Comment

by:Jkrish
ID: 9606013
Resolved!

It was because of the following

FILE *fp;


if ((envdbg = getenv("somevar")) != NULL )
// open a file pointer fp if somevar exists
...
...
...

if (fp)
  fprintf(fp,"print message");  <-- it's crashing here because of this
as fp was not initialized.  

FILE *fp = NULL;  // solved the problem

Thanks a lot Kent!
0

Featured Post

Is Your AD Toolbox Looking More Like a Toybox?

Managing Active Directory can get complicated.  Often, the native tools for managing AD are just not up to the task.  The largest Active Directory installations in the world have relied on one tool to manage their day-to-day administration tasks: Hyena. Start your trial today.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
port mapped I/o query 10 163
Why this code doesn't work? 8 97
C programming help for beginner sort routine 5 261
Line meaning 9 81
This tutorial is posted by Aaron Wojnowski, administrator at SDKExpert.net.  To view more iPhone tutorials, visit www.sdkexpert.net. This is a very simple tutorial on finding the user's current location easily. In this tutorial, you will learn ho…
Summary: This tutorial covers some basics of pointer, pointer arithmetic and function pointer. What is a pointer: A pointer is a variable which holds an address. This address might be address of another variable/address of devices/address of fu…
The goal of this video is to provide viewers with basic examples to understand and use pointers in the C programming language.
The goal of this video is to provide viewers with basic examples to understand opening and writing to files in the C programming language.

930 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

14 Experts available now in Live!

Get 1:1 Help Now