From: dbe AT wgn DOT net ($Bill Luebkert)
Subject: Re: gcc and file reading HELP!!
26 Oct 1997 20:52:32 -0800
Message-ID: <345415EA.A32C0630.cygnus.gnu-win32@wgn.net>
References: <199710262046 DOT PAA17818 AT romeo DOT its DOT uwo DOT ca>
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To: "Steven I. Pollmann" <spollman AT julian DOT uwo DOT ca>
Cc: gnu-win32 AT cygnus DOT com

Steven I. Pollmann wrote:
> 
>         Sorry about the message, but I'm having a problem with my "c"
> program reading lines of text from a file with gnu-win32.  The file compiles
> fine, but when it executes,
> the lines are displayed, and then stack errors are reported to the screen at
> the end, terminating the program.  The program appears to work fine on the
> Unix operating system we have at school.  Please help, I'd like to get this
> working with windows.
> 
> here is the program:

More than likely you're overflowing a buffer.

> #include <stdio.h>
> #define maxFilename 40

40 is too small for long filenames.

> int main()
> {
> int OpenFile(FILE **filePoint, char fileName [maxFilename]);
> void CloseFile(FILE **filePoint);
> void PrintFileContents(FILE **filePoint);
> 
> char userFile[maxFilename];
> FILE *sourcefp;
> 
>    printf("Enter a file to open: \n");
>    scanf("%s",userFile);
>    printf("file \"%s\" is being opened...",userFile);
> 
>    if (OpenFile(&sourcefp, userFile) == 1)
>    {
>       printf("file \"%s\" opened.\n",userFile);
> 
>       PrintFileContents(&sourcefp);
> 
>       CloseFile(&sourcefp);
>       printf("file \"%s\" closed.\n",userFile);
>    }
> 
> return 0;
> }
> 
> /* open file for reading */
> 
> int OpenFile(FILE **filePoint, char fileName [maxFilename])
> {
>    if ((*filePoint = fopen(fileName,"r")) == NULL)
>    {
>       printf("Can't open %s for reading \n",fileName);
>       return 0;
>    }
>    else
>    {
>       *filePoint = fopen(fileName,"r");
>       return 1;
>    }
> }
> 
> /*close file */
> 
> void CloseFile(FILE **filePoint)
> {
>    fclose(*filePoint);
> }
> 
> /* Print File contents */
> 
> void PrintFileContents(FILE **filePoint)
> {
>    char info[20];

I would change this ridiculously small buffer from 20 to BUFSIZ.
fscanf is basically a terrible routine in that it can overwrite 
your buffer.

>    while ((fscanf(*filePoint,"%s",info)) != EOF)
>    {
>       printf("%s\n",info);
> 
>    }
> }

HTH,
-- 
  ,-/-  __      _  _         $Bill Luebkert
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