CODEWITHSUNDEEP
objective-cfile-permissionschmod
TCB13
TCB13

Reputation: 3155

Objective-C: Enable/Disable File Reading (chmod a-r)

Using Objective-C, how can I give/take the permissions for all user to read a file?

I need something that has the same effects as chmod a-r and chmod a+r.

Thank you!

Upvotes: 1

Views: 1427

Answers (2)

James Webster
James Webster

Reputation: 32066

Are you also familiar with the chmod 755 file method of changing permissions? using octal numbers?

NSMutableDictionary *dict = [[NSMutableDictionary alloc] init]; 

//Prefixing zero is octal.
int readPermission = 04;
int writePermission = 02;
int executePermission = 01;

//End multiplication is to shift digits left.
int owner = (readPermission | writePermission | executePermission) * (8 * 8);   //7
int group = (readPermission)                                       * (8);       //4 
int other = (executePermission);                                                //1

int permissions = owner + group + other;  //0741

[dict setObject:[NSNumber numberWithInt:permissions] forKey:NSFilePosixPermissions]; 

NSError *error = nil;
[[NSFileManager defaultManager] setAttributes:dict ofItemAtPath:[file path] error:&error];

Upvotes: 6

abarnert
abarnert

Reputation: 365697

To do this in Objective C:

NSFileManager *fm = [NSFileManager defaultManager];
NSError *error = nil;
NSDict *attribs = [fm attributesOfItemAtPath:[file path] error:&error];
int permissions = [[attribs objectForKey:@"NSFilePosixPermissions"] intValue];
permissions |= (S_IRSUR | S_IRGRP | S_IROTH);
NSDict *newattribs = [NSDict dictionaryWithObject:[NSNumber numberWithInt:permissions]
                                           forKey:NSFilePosixPermissions];
[fm setAttributes:dict ofItemAtPath:[file path] error:&error];

Or, just get a POSIX path (with -[NSFileManager fileSystemRepresentationForPath]) and do it in C, using the chmod function—which is what the chmod command-line tool uses, and is portable to any POSIX platform.

Upvotes: 3

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