Thread-topic: Program crashes when executed normally, but runs w/o trouble in the Debugger
I apologize in advance if this is one of those stupid simple things, but I am teaching myself to program in C for the Mac by porting an old curve fitting program I use from time to time. I was defeated in my attempt to use the built-in Menu:Open... function in XCode, so I fell back on using fopen after acquiring the filename from a textbox in the user interface. This worked splendidly all through development (when I was running the program in the Debugger), but neither the "development" or "deployment" builds can do any file access w/o crashing.
The error in both cases occurred while interacting with libSystem.B.dylib, and both instances are Bad Access exceptions (Exception: EXC_BAD_ACCESS (0x0001); Codes: KERN_PROTECTION_FAILURE (0x0002) at 0x00000000). One of the performance tools (which also all crashed, while the Debugger doesn't seem to notice the problem) returned the following message: "/Programming/XCode_Projects/Grapher/Exponential Fitter.app/Contents/MacOS/Exponential Fitter accessed memory at 0x00000000 illegally. It probably tried to dereference a NULL pointer."
I am sure I am trying to do something stupid, and I could probably figure it out myself if it failed the same way in the Debugger that it does normally.
Any assistance would be appreciated; I have a fair amount of programming experience, but I am a chemist, not a programmer, and I fear it shows.
Thanks,
Dr. Ted Lorance
The offending code is as follows (the other file access routine is similar):
OSStatus fgetLaserData (WindowRef window)
{
const ControlID kFileName = { kCommandSignature, kFileNameFieldID };
ControlRef cr_FileName;
CFStringRef FileName_text;
OSStatus err = noErr;
char * buffer;
int flag;
char temp[20];
char localBuffer[60];
int i=0;
FILE * in_file;
Boolean success;
buffer = getenv ("PWD");
err = GetControlByID (window, &kFileName, &cr_FileName);
require_noerr_quiet (err, CantGetControl);
err = GetControlData (cr_FileName, 0, kControlEditTextCFStringTag, sizeof(CFStringRef), &FileName_text, NULL);
require_noerr (err, CantGetControlData);
success = CFStringGetCString(FileName_text, localBuffer, 40, kCFStringEncodingMacRoman);
printf("%s\n",localBuffer);
strcat(buffer,"/\0");
printf("%s\n",buffer);
strcat(buffer,localBuffer);
printf("%s\n",buffer);
in_file = fopen(buffer,"rt");
if (in_file==NULL)
{
printf("File not found.\n");
return err;
}
else
{
printf("File found. All is well. Nothing to see here.\n");
}
do {
flag=0;
fscanf (in_file, "%s", &temp);
etc.
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