Small macOS CLI program to list filesystem items

FSTraversal.m

//
//  main.m
//  FSTraversal
//
//  Created by Andrey Filipenkov on 03/03/17.
//  Copyright © 2017 Andrey Filipenkov. All rights reserved.
//

@import Foundation;

#include <libgen.h>

#define MEASURE_TIME 0

static NSString *const DepthArgument = @"depth";
static NSString *const HeightArgument = @"height";

static NSString *const DirSeparator = @"/";
static NSString *const RootRelativePath = @"/";


@interface FSItem : NSObject

@property (nonatomic, copy) NSString *relativePath;
@property (nonatomic, assign) NSUInteger depth;
@property (nonatomic, assign) NSUInteger height;
@property (nonatomic, weak) FSItem *parent;

+ (instancetype)itemWithRelativePath:(NSString *)relativePath depth:(NSUInteger)depth parent:(FSItem *)parent;

@end

@implementation FSItem

+ (instancetype)itemWithRelativePath:(NSString *)relativePath depth:(NSUInteger)depth parent:(FSItem *)parent
{
    FSItem *item = [self new];
    item.relativePath = relativePath;
    item.depth = depth;
    item.parent = parent;
    return item;
}

@end


int main(int argc, const char *argv[])
{
    @autoreleasepool
    {
        if (argc < 2)
        {
            printf("usage: %s <path> [-%s <depth> -%s <height>]\n", basename((char *)argv[0]), DepthArgument.UTF8String, HeightArgument.UTF8String);
            return 0;
        }

        NSString *rootPath = @(argv[1]).stringByStandardizingPath;
        if (![[NSFileManager defaultManager] fileExistsAtPath:rootPath])
        {
            fprintf(stderr, "filesystem item doesn't exist: %s\n", rootPath.UTF8String);
            return 1;
        }

#if MEASURE_TIME
        NSDate *startDate = [NSDate new];
#endif

        NSUInteger relativePathStartIndex = rootPath.length;
        if (relativePathStartIndex == 1) // we're searching in system volume root
            relativePathStartIndex = 0;
        NSString *(^relativePath)(NSString *path) = ^NSString *(NSString *path) {
            return [path substringFromIndex:relativePathStartIndex];
        };

        // TODO: parse with NSScanner to know if an arg can actually be converted into a number
        // TODO: don't use NSUserDefaults to read args as it doesn't work with negative numbers
        NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
        BOOL hasFilterArgs = [defaults objectForKey:DepthArgument] != nil && [defaults objectForKey:HeightArgument] != nil;
        NSInteger depthArg = [defaults integerForKey:DepthArgument], heightArg = [defaults integerForKey:HeightArgument];
        BOOL computingForRootPath = depthArg == 0;

        NSMutableArray<FSItem *> *__block fsItems = [NSMutableArray new];
        NSMutableDictionary<NSString *, FSItem *> *parentFSItemsDic;
        if (!hasFilterArgs || computingForRootPath)
        {
            FSItem *rootItem = [FSItem itemWithRelativePath:RootRelativePath depth:0 parent:nil];
            [fsItems addObject:rootItem];

            if (!hasFilterArgs)
                parentFSItemsDic = [NSMutableDictionary dictionaryWithObject:rootItem forKey:RootRelativePath];
        }

        FSItem *__block currentFilteredItem = fsItems.lastObject;
        void(^maybeRemoveLastItem)() = !hasFilterArgs ? nil : ^{
            if (currentFilteredItem && currentFilteredItem.height < heightArg)
                [fsItems removeLastObject];
        };

        NSUInteger lastDepth = 0;
        NSDirectoryEnumerator<NSURL *> *dirEnum = [[NSFileManager defaultManager] enumeratorAtURL:[NSURL fileURLWithPath:rootPath]
                                                                       includingPropertiesForKeys:hasFilterArgs ? nil : @[NSURLParentDirectoryURLKey]
                                                                                          options:kNilOptions errorHandler:nil];
        for (NSURL *url in dirEnum)
        {
            NSUInteger currentDepth = dirEnum.level;
            if (hasFilterArgs && currentDepth < depthArg)
                continue;

            @autoreleasepool
            {
                if (hasFilterArgs)
                {
                    if (currentDepth == depthArg)
                    {
                        maybeRemoveLastItem();
                        [fsItems addObject:[FSItem itemWithRelativePath:relativePath(url.path) depth:currentDepth parent:nil]];
                        currentFilteredItem = fsItems.lastObject;
                    }
                    else
                    {
                        if (currentFilteredItem)
                        {
                            NSUInteger height = currentDepth - depthArg;
                            if (height > heightArg)
                            {
                                currentFilteredItem = nil;
                                [fsItems removeLastObject];

                                if (computingForRootPath)
                                    break;
                                else
                                    [dirEnum skipDescendants];
                            }
                            else
                            {
                                if (currentFilteredItem.height < height)
                                    currentFilteredItem.height = height;
                            }
                        }
                        else
                            [dirEnum skipDescendants];
                    }
                    continue;
                }

                NSURL *parentUrl;
                [url getResourceValue:&parentUrl forKey:NSURLParentDirectoryURLKey error:NULL];

                NSString *relativeParentPath = relativePath(parentUrl.path);
                if (!relativeParentPath.length)
                    relativeParentPath = RootRelativePath;

                FSItem *parentItem = parentFSItemsDic[relativeParentPath];
                if (!parentItem)
                    parentItem = parentFSItemsDic[relativeParentPath] = fsItems.lastObject;
                [fsItems addObject:[FSItem itemWithRelativePath:relativePath(url.path) depth:currentDepth parent:parentItem]];

                if (lastDepth == currentDepth)
                    continue;
                lastDepth = currentDepth;

                for (NSUInteger height = 1; parentItem != nil; ++height, parentItem = parentItem.parent)
                {
                    if (parentItem.height < height)
                        parentItem.height = height;
                    else
                        break;
                }
            }
        }
        if (maybeRemoveLastItem)
            maybeRemoveLastItem();

#if MEASURE_TIME
        NSTimeInterval searchTime = -startDate.timeIntervalSinceNow;
#endif

        if (fsItems.count)
        {
            for (FSItem *item in fsItems)
            {
                printf("%s", item.relativePath.UTF8String);
                if (!hasFilterArgs)
                    printf(" %lu %lu", item.depth, item.height);
                printf("\n");
            }
        }
        else
            printf("no results matching given criteria have been found\n");

#if MEASURE_TIME
        printf("%lu filesystem items, traversal time %.2lfs, printing time %.2lfs\n", fsItems.count, searchTime, -startDate.timeIntervalSinceNow - searchTime);
#endif
    }
    return 0;
}