Accessing OS X keychain item from trusted application - objective-c

Question

I'm creating a keychain and then I'm adding an item with predefined trusted aplication list to it:
SecKeychainCreate([keychainPath UTF8String], (UInt32)strlen(keychainPass), keychainPass, FALSE, NULL, &someKeychain);
OSStatus someStatus = SecKeychainItemCreateFromContent(kSecGenericPasswordItemClass, &list, len, encryptedPass, someKeychain, accessRef, &someKeychainItem);
When I open the newly created keychain with Keychain Access application, I can see my application on the trusted app list:
The problem is, when I try to read the key from that keychain through one of the trusted applications
SecKeychainUnlock(someKeychain, (UInt32)strlen(keychainPass), keychainPass, TRUE);
UInt32 passwordLen = 0;
void *passData = nil;
const char *cUser_name = [NSUserName() cStringUsingEncoding:NSUTF8StringEncoding];
OSStatus genericPassErr = SecKeychainFindGenericPassword(someKeychain, 0, NULL, strlen(cUser_name), cUser_name, &passwordLen, &passData, NULL);
genericPassErr equals -25293, which means
Error: 0xFFFF9D33 -25293 The user name or passphrase you entered is not correct.
Earlier in the code, I run SecKeychainSetUserInteractionAllowed(0), and if I comment this line out, I get prompted by the system for my permission for the application to access the keychain, and if I grant it, everything runs fine. However, the whole point is that I need to be able to do that without prompting the user. And I expect it to work like this since I added the app to the ACL. Do you know what am I doing wrong?
Everything works without prompt as well when I tick the "all programs have access to this item" radio box in the attached screenshot. But I don't want everyone to be able to access it, just the listed apps.

Answer 1

I was able to make a similar test program work. However, I had to remove and re-add the tool to the always allowed list after each time I had rebuilt it. I did get the same error code when not doing that.
Here's the code:
#import <Foundation/Foundation.h>
#import <Security/Security.h>
int main()
{
#autoreleasepool
{
SecKeychainRef kc;
OSStatus status = SecKeychainSetUserInteractionAllowed(false);
printf("status: %d\n", status);
status = SecKeychainOpen("/Users/tsnorri/Library/Keychains/test.keychain", &kc);
printf("status: %d\n", status);
{
char const *keychainPass = "test123";
status = SecKeychainUnlock(kc, (UInt32) strlen(keychainPass), keychainPass, true);
CFStringRef err = SecCopyErrorMessageString(status, NULL);
printf("status: %d err: %s\n", status, [(id) err UTF8String]);
CFRelease(err);
}
UInt32 passwordLen = 0;
void *passData = NULL;
char const *userName = "tsnorri";
char const *serviceName = "test";
{
SecKeychainItemRef item = NULL;
status = SecKeychainFindGenericPassword(kc, strlen(serviceName), serviceName, strlen(userName), userName, &passwordLen, &passData, &item);
CFStringRef err = SecCopyErrorMessageString(status, NULL);
printf("status: %d err: %s\n", status, [(id) err UTF8String]);
CFRelease(err);
}
printf("pass: %s\n", passData);
}
return 0;
}