directory-url-unencoded.m

#import <Foundation/Foundation.h>

#include <sys/stat.h>

/*
clang -Wall -O2 -fobjc-arc directory-url-unencoded.m -o directory-url-unencoded -framework Foundation
*/

int main(int argc, char *argv[])
{
    NSString *tmpDir = NSTemporaryDirectory();
    NSLog(@"working in %@ ...", tmpDir);
    
    if (chdir([tmpDir UTF8String]) < 0) {
        perror([tmpDir UTF8String]);
        return 1;
    }
    
    // Rather than letting invalid UTF-8 make its way to the filesystem, this will actually create '%FF.ext' on the filesystem. Nice!
    const char directoryName[] = {(char)0xff, '.', 'e', 'x', 't', '\0'};
    if (mkdir(directoryName, 0700) < 0 && errno != EEXIST) {
        perror(directoryName);
        return 1;
    }
    
    // Sadly, this doesn't perform the same mapping, reporting nil instead of '%FF.ext'.
    NSString *directoryNameString = [[NSFileManager defaultManager] stringWithFileSystemRepresentation:directoryName length:strlen(directoryName)];
    NSLog(@"directoryNameString = %@", directoryNameString);

    // This properly escapes the % in the directory name.
    NSURL *parentDirectoryURL = [[NSURL fileURLWithPath:tmpDir] URLByAppendingPathComponent:@"%FF.ext" isDirectory:YES];
    NSLog(@"parentDirectoryURL = %@", parentDirectoryURL);
    assert([[parentDirectoryURL absoluteString] rangeOfString:@"%25FF"].location != NSNotFound);

    // We still have a properly escaped % in the directory name
    NSURL *fileURL = [parentDirectoryURL URLByAppendingPathComponent:@"file"];
    NSLog(@"fileURL = %@", fileURL);
    assert([[fileURL absoluteString] rangeOfString:@"%25FF"].location != NSNotFound);
    [[NSData data] writeToURL:fileURL options:0 error:NULL];

    // Now things start to go off the rails. NSFileManager or NSURL incorrectly decodes the %25FF into %FF in the URLs for the child URLs.
    NSArray *childrenURLs = [[NSFileManager defaultManager] contentsOfDirectoryAtURL:parentDirectoryURL includingPropertiesForKeys:nil options:0 error:NULL];
    assert([childrenURLs count] == 1);
    
    NSLog(@"childrenURLs = %@", childrenURLs);
    
    for (NSURL *childURL in childrenURLs) {
        NSLog(@"childURL = %@", childURL);

        // ... until finally we can't get the last path component (since the path is no longer a valid UTF-8 string).
        NSString *filename = [childURL lastPathComponent];
        NSLog(@"filename = %@", filename);
        assert([filename isEqual:@"file"]);
    }
    
    return 0;
}