Program running in debug mode in C::B only - c

Question

I am currently writing a program which at some point needs to store the sizes of all the files in a specific folder in an array. My program crashes when running it on Code::Blocks in release mode, but does run in debug mode. It also runs without any problems on XCode on Mac OS. Here's the code:
#define MALLOC_ERROR -1
#define DIR_ACCESS_ERROR -2
#define FILE_ACCESS_ERROR -3
#define FILE_OPEN_ERROR -4
#define OUTPUT_FILE_OPEN_ERROR -5
#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <sys/stat.h>
#include <string.h>
#include <math.h>
int compare(const void*, const void*);
int getFileSizeMarginNumbers(char[], int, unsigned long int*);
int main(void){
FILE *out;
int n;
int i, count = 1;
unsigned long int *fileSizeMarginNumber;
char directoryName[] = "C:\\Users\\Борис\\Desktop\\new\\";
char outputFilePath[] = "C:\\Users\\Борис\\Desktop\\out.txt";
printf("Enter number of files in directory:");
scanf("%d", &n);
if (!(fileSizeMarginNumber = (unsigned long int*)malloc(n*sizeof(unsigned long int)))){
printf("Not enough memory");
return MALLOC_ERROR;
}
switch (getFileSizeMarginNumbers(directoryName, n, fileSizeMarginNumber)) {
case MALLOC_ERROR:
return MALLOC_ERROR;
break;
case DIR_ACCESS_ERROR:
return DIR_ACCESS_ERROR;
break;
case FILE_ACCESS_ERROR:
return FILE_ACCESS_ERROR;
break;
case FILE_OPEN_ERROR:
return FILE_OPEN_ERROR;
break;
}
qsort(fileSizeMarginNumber, n, sizeof(unsigned long int), compare);
if (!(out = fopen(outputFilePath, "w"))){
printf("Unable to open output file");
return OUTPUT_FILE_OPEN_ERROR;
}
for (i=1; i<n; ++i) {
if (fileSizeMarginNumber[i] == fileSizeMarginNumber[i - 1])
++count;
else{
fprintf(out, "%ldKB - %ldKB: %d file(s);\n", (fileSizeMarginNumber[i - 1] - 1)*16, fileSizeMarginNumber[i - 1]*16, count);
count = 1;
}
}
fprintf(out, "%ldKB - %ldKB: %d files;\n", (fileSizeMarginNumber[i - 1] - 1)*16, fileSizeMarginNumber[i - 1]*16, count);
return 0;
}
int getFileSizeMarginNumbers(char directoryName[], int n, unsigned long int *fileSizeMarginNumber){
int i, fileDescriptor;
struct dirent *file;
struct stat currentSize;
DIR *directory;
FILE *buf;
if (!(directory = opendir(directoryName))) {
printf("Unable to get access to the specified directory");
return DIR_ACCESS_ERROR;
}
for (i=0;i<2;++i){
if (!(file = readdir(directory))) {
printf("Unable to get access to a file in the specified directory");
return FILE_ACCESS_ERROR;
}
}
for (i=0; i<n; ++i) {
if (!(file = readdir(directory))) {
printf("Unable to get access to a file in the specified directory");
return FILE_ACCESS_ERROR;
}
printf("%s", strcat(strdup(directoryName), file->d_name));
if (!(buf = fopen(strcat(strdup(directoryName), file->d_name), "r"))){
printf("Unable to process a file in the specified directory");
return FILE_OPEN_ERROR;
}
fileDescriptor = fileno(buf);
fstat(fileDescriptor, &currentSize);
fileSizeMarginNumber[i] = (unsigned long int)truncl(currentSize.st_size/(1024*16)) + 1;
fclose(buf);
}
return 0;
}
int compare(const void *a, const void *b){
if ((*(long int*)a - *(long int*)b) < 0)
return -1;
else if ((*(long int*)a - *(long int*)b) == 0)
return 0;
else
return 1;
}
The problem seems to be located in the following block:
for (i=0; i<n; ++i) {
if (!(file = readdir(directory))) {
printf("Unable to get access to a file in the specified directory");
return FILE_ACCESS_ERROR;
}
printf("%s", strcat(strdup(directoryName), file->d_name));
if (!(buf = fopen(strcat(strdup(directoryName), file->d_name), "r"))){
printf("Unable to process a file in the specified directory");
return FILE_OPEN_ERROR;
}
fileDescriptor = fileno(buf);
fstat(fileDescriptor, &currentSize);
fileSizeMarginNumber[i] = (unsigned long int)truncl(currentSize.st_size/(1024*16)) + 1;
fclose(buf);
}
The program is supposed to open all files in a folder step-by-step. However, the second or third call to fopen sometimes triggers the following exception:
Program received signal SIGSEGV, Segmentation fault.
In ntdll!RtlLargeIntegerToChar () (C:\Windows\system32\ntdll.dll)
I do not understand this dependency on where I am running my program and I would've been very grateful for your help.
Thank you very much in advance.

Answer 1

That strcat() in fopen() is not correct:
strcat(strdup(directoryName), file->d_name)
First strdup() allocates strlen(directoryName)+1 bytes and copies directoryName then strcat() wants to append file->d_name to that copy. But as there is no extra space allocated a seg fault might occur. Do something like that instead:
char *pathname = MALLOC( strlen(directoryName) + strlen(file->d_name) + 1 );
strcpy( pathname, directoryName );
strcat( pathname, file->d_name );
And don't forget to free(pathname) when you don't need it any more