Lingering open files resulting in "Too many open files" - c++

Question

I have code using boost to list directory contents, iterate through each file, and do some data processing stuff. The results are being printed to an output file ('histFile').
After ~2555 files have been processed, I get the error:
boost::filesystem::directory_iterator::construct: Too many open files: "/Users/.../.../.../directory_with_files"
My code is:
for(int i = 0; i < 10000; i++) {
FILE *histFile;
string outputFileName = "somename";
bool ifRet = initFile(histFile, outputFileName.c_str(), "a"); // 1
fclose(histFile); // 2
}
If I comment out the last two lines above ('1' and '2'), the code finishes fine. Thus it seems copies of 'histFile' are being left open, but I don't understand how! This is the operative part of the method:
bool initFile(FILE *&ofFile, const char *fileName, const char *openType, int overwriteOption) {
if(overwriteOption < 0 || overwriteOption > 2) {
fprintf(stderr, "ERROR: ToolBox - initFile() : unknown 'overwriteOption' (%d), setting to (0)!\n", overwriteOption);
}
// Read-Only
if(openType == "r") {
if(ofFile = fopen(fileName, "r")) { return true; }
fprintf(stderr, "ERROR: Could not open file (%s)!\n", fileName);
return false;
}
// Appending:
if(openType == "a" || openType == "a+") {
// Check if file already exists
if(!fopen(fileName, "r")){
fprintf(stderr, "ERROR: (%s) File does not Exist, cannot append!\n", fileName);
return false;
}
if(ofFile = fopen(fileName, openType)) { return true; }
}
// Writing:
// if file already exists
if(FILE *temp = fopen(fileName, "r")){
if(overwriteOption == 2) {
fprintf(stderr, "ERROR: (%s) File Exists!\n", fileName);
return false;
}
if(overwriteOption == 1) {
}
if(overwriteOption == 0) {
char backupFileName[TB_CHARLIMIT], backupPrefix[TB_CHARLIMIT];
strcpy(backupFileName, fileName); // copy filename
// create a prefix w/ format '<YYYYMMDD>BACKUP_'
DateTime now;
sprintf(backupPrefix, "%s", now.getDateStr().c_str());
strcat(backupPrefix, "BACKUP_");
// add to copied filename, and move file
strcpy(backupFileName, prependFileName(backupFileName, backupPrefix));
moveFile(fileName, backupFileName);
}
fclose(temp);
}
if(ofFile = fopen(fileName, openType)) { return true; }
// Default: Return error and false
fprintf(stderr, "ERROR: Could not open file (%s)!\n", fileName);
return false;
}
Am I doing something wrong with pointers/references?
Any help greatly appreciated!

Answer 1

You're leaking a handle in this bit of code when you're testing if the file exists already:
// Appending:
if(openType == "a" || openType == "a+") {
// Check if file already exists
if(!fopen(fileName, "r")){ // <-- the FILE* opened here is leaked
fprintf(stderr, "ERROR: (%s) File does not Exist, cannot append!\n", fileName);
return false;
}
if(ofFile = fopen(fileName, openType)) { return true; }
}
Is there really a reason to make that check? Why not just let the file be created if it doesn't already exist?