Problem enumerating a directory
Problem enumerating a directory
- Subject: Problem enumerating a directory
- From: Mark Allan <email@hidden>
- Date: Fri, 27 Jul 2012 17:44:52 +0100
Hi all,
Apologies for asking a question which has been asked many times before, but I can't seem to find an answer to this particular one.
I'm trying to list a directory recursively to build up a snapshot of the contents and store them in a core data DB, but keep running into issues with the directory list. The core data part is working fine as far as I can tell!
I've tried writing a recursive method to call scandir() until the whole tree has been visited, but I'm coming unstuck converting NSStrings to const char* to char*. Unless I supply the path directly as a hard-coded C-string "/Users/mark", it works for a while, but then sometimes it forgets to add "/Users/mark" and starts scanning directories at the root of my HD! Hard coding the C string works perfectly but obviously isn't an option.
-(void) scan: (char *)theDir{
struct dirent **namelist;
int n;
size_t thisDirLength = strlen(theDir);
n = scandir(theDir, &namelist, 0, NULL);
if (n < 0){
perror("scandir");
}
else {
while(n--) {
theCounter++;
if (theCounter >= 1000) {
theCounter = 0;
[[self managedObjectContext] save:NULL];
[[self managedObjectContext] reset];
[thePool drain];
thePool = [[NSAutoreleasePool alloc] init];
}
if ((strcmp(namelist[n]->d_name,".") != 0) && (strcmp(namelist[n]->d_name,"..") != 0)) {
char* fullPath = malloc(thisDirLength + strlen(namelist[n]->d_name) + 2);
strcpy(fullPath, theDir);
strcat(fullPath, "/");
strcat(fullPath, namelist[n]->d_name);
[self addEntityWithPath:[NSString stringWithCString:fullPath encoding:NSUTF8StringEncoding]];
if (namelist[n]->d_type == DT_DIR) {
[self scan:fullPath];
}
free(fullPath);
}
free(namelist[n]);
}
free(namelist);
}
}
I then gave up on that approach and opted for the easier but slower cocoa solution (NSDirectoryEnumerator) but for some reason it gives up with neither an error nor a warning about half way through the tree. Could it be that modifications to the file system during the enumeration are causing it to fail?
-(void) startSnapshotForPath:(NSString *) thePath {
int theCounter = 0;
NSDirectoryEnumerator *dirEnumerator = [[NSFileManager defaultManager] enumeratorAtPath: thePath];
thePool = [[NSAutoreleasePool alloc] init];
for (NSString *theSubPath in dirEnumerator) {
[self addEntityWithPath:[thePath stringByAppendingPathComponent:theSubPath]];
theCounter++;
if (theCounter >= 1000) {
theCounter = 0;
[[self managedObjectContext] save:NULL];
[[self managedObjectContext] reset];
[thePool drain];
thePool = [[NSAutoreleasePool alloc] init];
}
}
[[self managedObjectContext] save:NULL];
[[self managedObjectContext] reset];
[thePool drain];
}
I've also tried Uli Kusterer's UKDirectoryEnumerator but that doesn't appear to be recursive! I suspect (although I haven't tried) that requesting the type of the path (i.e. file/directory) and creating a new UKDirectoryEnumerator for each subdirectory would be massively expensive.
Does anyone have any suggestions for where I can go from here please? How can I find out why NSDirectoryEnumerator is failing half-way through the process, and how can I stop it doing so? Failing that, does anyone have a better suggestion for how I can build the snapshot please?
Many thanks
Mark
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