Re: Problem enumerating a directory
Re: Problem enumerating a directory
- Subject: Re: Problem enumerating a directory
- From: Kevin Perry <email@hidden>
- Date: Fri, 27 Jul 2012 10:10:00 -0700
You should probably try -[NSFileManager enumeratorAtURL:includingPropertiesForKeys:options:errorHandler:]. The errorHandler block will give you more detail about any errors that occur in the middle of the enumeration (and give you the ability to ignore them).
-KP
On Jul 27, 2012, at 9:44 AM, Mark Allan <email@hidden> wrote:
> 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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