I had a requirement, to use NSInvocation's
(void)getArgument:(void *)argumentLocation atIndex:(NSInteger)idx;
to get the argument. The argument is primarily NSString, So, in my function:
- (void)forwardInvocation:(NSInvocation *)invocation {
[invocation retainArguments];
NSString *biz;
[invocation getArgument:&biz atIndex:2];
NSString *statKey;
[invocation getArgument:&statKey atIndex:3];
getOriginalSelectorName:rawSelName blockArgCount:blockArgCount];
allowed = [self allowPerformSensitiveSelector:rawSelector biz:[biz copy] statKey:[statKey copy]];
...
}
However I met a double free crash. After debugging, I found the issue is that,
because invocation is actually holding a __CFString object, which is malloced on heap, and the length is >= 10, e.g. '1234567890', so when I call [invocation getArgument:&statKey atIndex:3];, the statKey is written with the pointer to 1234567890:
for example,
(lldb) p statKey // set by `getArgument:&statKey`
(__NSCFString *) $0 = 0x00000002839492e0 #"1234567890"
(lldb) mem read 0x00000002839492e0
0x2839492e0: 01 e9 be d8 a1 21 00 00 8c 07 00 00 04 00 00 00 .....!..........
0x2839492f0: 0a 31 32 33 34 35 36 37 38 39 30 00 00 00 00 00 .1234567890.....
(lldb) p statKey // outer one, passed from method parameters, resided in invocation
(__NSCFString *) $1 = 0x000000028372f780 #"1234567890"
(lldb) mem read 0x000000028372f780
0x28372f780: 01 e9 be d8 a1 21 00 00 ad 07 00 00 04 00 00 00 .....!..........
0x28372f790: e0 fd 97 83 02 00 00 00 0a 00 00 00 00 00 00 00 ................
So the newly NSString *statKey is actually is a pointer.
When the invocation is finished, I will met a crash, like a double free, because they both point to 0x21a1d8bee901
if the string is like [[NSMutableString alloc] initWithString:#'123456789'], even though this is a CFString, but when calling [invocation getArgument:&statKey atIndex:3], it will be
NSTaggedPointerString * #"123456789" 0x9c98d935e3d914c6.
So I assuem length of 10 of the string is the boundary.
So I want to ask, how do I fix this? I tried [statKey copy], or [invocation retainArguments];, not working. Thanks!
It's most likely very similar problem to NSInvocation returns value but makes app crash with EXC_BAD_ACCESS but for [invocation getArgument:...] and not a return value.
What happens is NSInvocation method is unaware of the value-fit-in-pointer optimised underlying type (NSTaggedPointerString *) and as a result ARC attempts to release it.
Fix should be:
NSString __unsafe_unretained *statKey;
[invocation getArgument:&statKey atIndex:3];
or:
void *statKey;
[invocation getArgument:&statKey atIndex:3];
Similar problem also described here: https://stackoverflow.com/a/56604328/5329717
Related
PROBLEM:
The problem I am trying to solve is the following. I have audio data recorded by AVAudioRecorder. I can get the NSData by:
NSData *data = [NSData dataWithContentsOfURL: self.audioRecorder.url];
But then I need to convert/reinterpret this NSData to a const char* form which would essentially look like
00 01 00 ff
which are bytes in hex or at least the equivalent string. They don't have to be actually in hex but just needs to be convertible to hex.
QUESTION:
My question is that the NSData has "\0" in them. So if I do something like this:
NSUInteger len = [data length];
Byte *byteData = (Byte*)malloc(len);
memcpy(byteData, [data bytes], len);
It would not work as the data will be cutoff when it meets the first "\0". I am super new to audio files, but I think it is because of the x00 values in the header. So basically, I don't want to them to be interpreted as "\0" but as "00". Is there a way to do this?
Not sure I understand the question or what you are trying to do. Your memcpy will copy all the bytes to the byteData buffer, it is only when you try to use the byteData buffer as a string (char*) and pass them into a format function (NSLog(%"%s", val)) will it cut off. If you want a string representation of the data as hex:
NSString* bytesToHex(Byte* bytes, NSUInteger count) {
NSMutableString *hex = [NSMutableString string];
for(int i = 0; i < count; i++) [hex appendFormat:#"%.2x " , *(bytes+i)];
return hex;
}
NSString* dataToHex(NSData* data) {
return bytesToHex((Byte*)data.bytes, data.length);
}
will do it, ie:
Byte* bytes = (Byte*)"t\0h\0i\0s\0 i\0s\0 a\0 t\0e\0st";
NSData* data = [NSData dataWithBytes:bytes length:24];
NSLog(#"%#",NSLog(#"%#", dataToHex(data));
will print:
74 00 68 00 69 00 73 00 20 69 00 73 00 20 61 00 20 74 00 65 00 73 74 00
or
Byte* bytes = (Byte*)"t\0h\0i\0s\0 i\0s\0 a\0 t\0e\0st";
NSData* data = [NSData dataWithBytes:bytes length:24];
NSUInteger len = [data length];
Byte *byteData = (Byte*)malloc(len);
memcpy(byteData, [data bytes], len);
NSLog(#"%#", bytesToHex(byteData, len));
will print:
74 00 68 00 69 00 73 00 20 69 00 73 00 20 61 00 20 74 00 65 00 73 74 00
Just remembered something
Even easier, if you use the NSData description property, it gives you the data in hex already!
Byte* bytes = (Byte*)"t\0h\0i\0s\0 i\0s\0 a\0 t\0e\0st";
NSData* data = [NSData dataWithBytes:bytes length:24];
NSLog(#"%#", data.description);
Will print
<74006800 69007300 20690073 00206100 20740065 00737400>
Not as pretty, but the same thing...
How to configure TAO corba server so that IOR string of this server generated from object_to_string is constant?
Each time the IOR string generated from object_to_string changes once server restarts. This is inconvenient since client has to update its cached server IOR string via reloading IOR file or namingservice accessing. As a result, it would be useful if server can generate a constant IOR string, no matter how many times it restarts.
My corba server is based on ACE+TAO and i do remember TAO supports constant IOR string: the IOR string each time it generates are same, and the solution is add some configurations for server. But i could not remember these configurations now.
=============================================
UPDATE:
In ACE_wrappers/TAO/tests/POA/Persistent_ID/server.cpp, i added a new function named testUniqe() which is similiar to creatPOA method. And the update file content is:
void testUniqu(CORBA::ORB_ptr orb_, PortableServer::POA_ptr poa_){
CORBA::PolicyList policies (2);
policies.length (2);
//IOR is the same even it is SYSTEM_ID
policies[0] = poa_->create_id_assignment_policy (PortableServer::USER_ID);
policies[1] = poa_->create_lifespan_policy (PortableServer::PERSISTENT);
PortableServer::POAManager_var poa_manager = poa_->the_POAManager ();
PortableServer::POA_ptr child_poa_ = poa_->create_POA ("childPOA", poa_manager.in (), policies);
// Destroy the policies
for (CORBA::ULong i = 0; i < policies.length (); ++i) {
policies[i]->destroy ();
}
test_i *servant = new test_i (orb_, child_poa_);
PortableServer::ObjectId_var oid = PortableServer::string_to_ObjectId("xushijie");
child_poa_->activate_object_with_id (oid, servant);
PortableServer::ObjectId_var id = poa_->activate_object (servant);
CORBA::Object_var object = poa_->id_to_reference (id.in ());
test_var test = test::_narrow (object.in ());
CORBA::String_var ior = orb_->object_to_string(test.in());
std::cout<<ior.in()<<std::endl;
poa_->the_POAManager()->activate();
orb_->run();
}
int
ACE_TMAIN (int argc, ACE_TCHAR *argv[])
{
try
{
CORBA::ORB_var orb =
CORBA::ORB_init (argc, argv);
int result = parse_args (argc, argv);
CORBA::Object_var obj =
orb->resolve_initial_references ("RootPOA");
PortableServer::POA_var root_poa =
PortableServer::POA::_narrow (obj.in ());
PortableServer::POAManager_var poa_manager =
root_poa->the_POAManager ();
testUniqu(orb.in(), root_poa.in());
orb->destroy ();
}
catch (const CORBA::Exception& ex)
{
ex._tao_print_exception ("Exception caught");
return -1;
}
return 0;
}
The problem is that the output server IORs are still different once restart. I also compared this code to the one in Page 412(Advance Corba Programming), but still fail..
///////////////////////////////////
UPDATE:
With "server -ORBListenEndpoints iiop://:1234 > /tmp/ior1", the generated two IORs are:
IOR:010000000d00000049444c3a746573743a312e300000000001000000000000007400000001010200150000007368696a69652d5468696e6b5061642d543431300000d2041b00000014010f0052535453f60054c6f80c000000000001000000010000000002000000000000000800000001000000004f41540100000018000000010000000100010001000000010001050901010000000000
IOR:010000000d00000049444c3a746573743a312e300000000001000000000000007400000001010200150000007368696a69652d5468696e6b5061642d543431300000d2041b00000014010f0052535468f60054da280a000000000001000000010000000002000000000000000800000001000000004f41540100000018000000010000000100010001000000010001050901010000000000
The result for tao_catior for ior1 and ior2:
ior1:
The Byte Order: Little Endian
The Type Id: "IDL:test:1.0"
Number of Profiles in IOR: 1
Profile number: 1
IIOP Version: 1.2
Host Name: **
Port Number: 1234
Object Key len: 27
Object Key as hex:
14 01 0f 00 52 53 54 53 f6 00 54 c6 f8 0c 00 00
00 00 00 01 00 00 00 01 00 00 00
The Object Key as string:
....RSTS..T................
The component <1> ID is 00 (TAG_ORB_TYPE)
ORB Type: 0x54414f00 (TAO)
The component <2> ID is 11 (TAG_CODE_SETS)
Component length: 24
Component byte order: Little Endian
Native CodeSet for char: Hex - 10001 Description - ISO8859_1
Number of CCS for char 1
Conversion Codesets for char are:
1) Hex - 5010001 Description - UTF-8
Native CodeSet for wchar: Hex - 10109 Description - UTF-16
Number of CCS for wchar 0
ecoding an IOR:
//ior2
The Byte Order: Little Endian
The Type Id: "IDL:test:1.0"
Number of Profiles in IOR: 1
Profile number: 1
IIOP Version: 1.2
Host Name: **
Port Number: 1234
Object Key len: 27
Object Key as hex:
14 01 0f 00 52 53 54 68 f6 00 54 da 28 0a 00 00
00 00 00 01 00 00 00 01 00 00 00
The Object Key as string:
....RSTh..T.(..............
The component <1> ID is 00 (TAG_ORB_TYPE)
ORB Type: 0x54414f00 (TAO)
The component <2> ID is 11 (TAG_CODE_SETS)
Component length: 24
Component byte order: Little Endian
Native CodeSet for char: Hex - 10001 Description - ISO8859_1
Number of CCS for char 1
Conversion Codesets for char are:
1) Hex - 5010001 Description - UTF-8
Native CodeSet for wchar: Hex - 10109 Description - UTF-16
Number of CCS for wchar 0
The diff result is:
< 14 01 0f 00 52 53 54 53 f6 00 54 c6 f8 0c 00 00
---
> 14 01 0f 00 52 53 54 68 f6 00 54 da 28 0a 00 00
19c19
< ....RSTS..T................
---
> ....RSTh..T.(..............
Similar diff result is:
< 14 01 0f 00 52 53 54 62 fd 00 54 2c 9a 0e 00 00
---
> 14 01 0f 00 52 53 54 02 fd 00 54 f9 a9 09 00 00
19c19
< ....RSTb..T,...............
---
> ....RST...T................
The difference is in ObjectKey.
============================================
update:
Instead of using above code, i find a better solution with helper TAO_ORB_Manager which is used NamingService and TAO/examples/Simple. TAO_ORB_Manager encapsulates API and generate persistent IORs, as example code in Simple.cpp:
if (this->orb_manager_.init_child_poa (argc, argv, "child_poa") == -1){
CORBA::String_var str =
this->orb_manager_.activate_under_child_poa (servant_name,
this->servant_.in ());
}
This is some description for TAO_ORB_Manager:
class TAO_UTILS_Export TAO_ORB_Manager
{
/**
* Creates a child poa under the root poa with PERSISTENT and
* USER_ID policies. Call this if you want a #a child_poa with the
* above policies, otherwise call init.
*
* #retval -1 Failure
* #retval 0 Success
*/
int init_child_poa (int &argc,
ACE_TCHAR *argv[],
const char *poa_name,
const char *orb_name = 0);
/**
* Precondition: init_child_poa has been called. Activate <servant>
* using the POA <activate_object_with_id> created from the string
* <object_name>. Users should call this to activate objects under
* the child_poa.
*
* #param object_name String name which will be used to create
* an Object ID for the servant.
* #param servant The servant to activate under the child POA.
*
* #return 0 on failure, a string representation of the object ID if
* successful. Caller of this method is responsible for
* memory deallocation of the string.
*/
char *activate_under_child_poa (const char *object_name,
PortableServer::Servant servant);
...................
}
After build, I can get what i want with -ORBListenEndpoints iiop://localhost:2809 option. Thanks #Johnny Willemsen help
You have to create the POA with a persistent lifespan policy, see ACE_wrappers/TAO/tests/POA/Persistent_ID as part of the TAO distribution.
I'm writing a program in Objective C to generate a MIDI file. As a test, I'm asking it to write a file which plays one note and stops it a delta tick afterwards.
But I'm trying to open it with Logic and Sibelius, and they both say that the file is corrupted.
Here's the hex readout of the file..
4D 54 68 64 00 00 00 06 00 01 00 01 00 40 - MThd header
4D 54 72 6B 00 00 00 0D - MTrk - with length of 13 as 32bit hex [00 00 00 0D]
81 00 90 48 64 82 00 80 48 64 - the track
delta noteOn delta noteOff
FF 2F 00 - end of file
And here's my routines to write the delta time, and write the note -
- (void) appendNote:(int)note state:(BOOL)on isMelody:(BOOL)melodyNote{ // generate a MIDI note and add it to the 'track' NSData object
char c[3];
if( on ){
c[0] = 0x90;
c[2] = volume;
} else {
c[0] = 0x80;
c[2] = lastVolume;
}
c[1] = note;
[track appendBytes:&c length:3];
}
- (void) writeVarTime:(int)value{ // generate a MIDI delta time and add it to the 'track' NSData object
char c[2];
if( value < 128 ){
c[0] = value;
[track appendBytes:&c length:1];
} else {
c[0] = value/128 | 0x80;
c[1] = value % 128;
[track appendBytes:&c length:2];
}
}
are there any clever MIDI gurus out there who can tell what's wrong with this MIDI file?
The delta time of the EOF event is missing.
I currently use.
Here is a few outputs I formatted them they were all together like this.
E14802000003FA00014C0000031501A8
currentAttackCount := StrToInt('$' + Copy(CurHex, 17, 4));
Log('Packet = ' + CurHex + ' Count = ' + IntToStr(currentAttackCount) + ' STR = ' + '$' + Copy(CurHex, 17, 4));
Formatted outputs
Packet = E1 48 02 00 00 03 FA 00 [01 4C] 00 00 03 15 01 A8 [Count = 76] [STR = $014C]
Packet = E1 48 02 00 00 03 FA 00 [01 4D] 00 00 03 15 02 26 [Count = 77] [STR = $014D]
Packet = E1 48 02 00 00 03 FA 00 [01 4F] 00 00 03 15 02 26 [Count = 79] [STR = $014F]
As you can see the STR
output which is STR = $014C
code: 'STR = ' + '$' + Copy(CurHex, 17, 4));
Now if you look at the StrToInt
currentAttackCount := StrToInt('$' + Copy(CurHex, 17, 4));
It's pretty much the same as STR so shouldn't $014C aka 0x014C be represented as 332 instead of 76
The 76 seems to come from the $4C aka 0x4C of the $014C why does it ignore the first 2 Hex Characters
Ah I think I figured it out.
`currentAttackCount: Byte;`
I increased it to
currentAttackCount: Word;
hopefully that would solve the problem.. missed it because it's a global variable and there is soo much code.
Friends,
It might look like familiar question but i really need help to convert NSData to any other understandable form. Basically i am using CoreWLAN framework and CWNetwork has properly called informationElement and it's data type is NSData. I have tried to convert it to any other readable format but not working. I have tried with all available string encoding. Below is sample code:
- (void) printNSData:(NSData *) dataToPrint forKey:(NSString *) key{
for(int i = 1 ; i < 16 ; i++){
size_t length = [dataToPrint length]+1;
unsigned char aBuffer[length];
[dataToPrint getBytes:aBuffer length:length];
aBuffer[length] = 0;
NSString *content = [[NSString alloc] initWithBytes:aBuffer
length:[dataToPrint length] encoding: i];
NSLog(#"%# : %# ", key,content);
}
/*
NSUTF16BigEndianStringEncoding = 0x90000100,
NSUTF16LittleEndianStringEncoding = 0x94000100,
NSUTF32StringEncoding = 0x8c000100,
NSUTF32BigEndianStringEncoding = 0x98000100,
NSUTF32LittleEndianStringEncoding = 0x9c000100,
NSProprietaryStringEncoding = 65536
*/
NSString *content = [[NSString alloc] initWithBytes:[dataToPrint bytes]
length:[dataToPrint length] encoding: NSUTF16BigEndianStringEncoding];
NSLog(#"%# : %# ",key, content);
content = [[NSString alloc] initWithBytes:[dataToPrint bytes]
length:[dataToPrint length] encoding: NSUTF16LittleEndianStringEncoding];
NSLog(#"%# : %# ",key, content);
content = [[NSString alloc] initWithBytes:[dataToPrint bytes]
length:[dataToPrint length] encoding: NSUTF32StringEncoding];
NSLog(#"%# : %# ", key,content);
content = [[NSString alloc] initWithBytes:[dataToPrint bytes]
length:[dataToPrint length] encoding: NSUTF32BigEndianStringEncoding];
NSLog(#"%# : %# ", key,content);
content = [[NSString alloc] initWithBytes:[dataToPrint bytes]
length:[dataToPrint length] encoding: NSUTF32LittleEndianStringEncoding];
NSLog(#"%# : %# ", key,content);
content = [[NSString alloc] initWithBytes:[dataToPrint bytes]
length:[dataToPrint length] encoding: NSProprietaryStringEncoding];
NSLog(#"%# : %#", key,content);
}
But i am getting either Null or empty response. Please please help.
Regards,
MP
You can't convert arbitrary data into a string. That only works for data that actually represents a string. Which is usually not the case if an API exposes a NSData object.
To get some meaning into the data you have to know what the data represents.
You might be able to get some structure into it by simply looking at it.
If I look at the first few bytes you have posted it looks like the data is well structured and not arbitrary.
The data seams to be split into packets. Each packet starts with a type identifier, which is followed by a $length byte. And then there will be $length bytes of data
The first packet contains the string "SYmantak"
00 08 53 79 6d 61 6e 74 61 6b
^^ Type Identifier
^^ Length
^^^^^^^^^^^^^^^^^^^^^^^ Data. In this case the ASCII string "SYmantak"
If you find a bunch of bytes that all lay between 0x20 and 0x7E you are probably looking at ASCII. That's basically how I figured out the payload of this packet. And because we have 8 bytes that are ASCII the 0x08 in front of the ASCII most likely means 8 bytes of data.
The next packets look like this:
01 08 82 84 0b 16 24 30 48 6c
^^ Type Identifier
^^ Length
^^^^^^^^^^^^^^^^^^^^^^^ Data. But not a ASCII string
03 01 06
2a 01 00
2f 01 00
30 14 01 00 00 0f ac 04 01 00 00 0f ac 04 01 00 00 0f ac 02 0c 00
32 04 0c 12 18 60
2d 1a 6e 18 1b ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
and so on. The general packet structure is quite easy to parse.
Though it will be very hard to turn these bytes into meaningful data. As you can see from the other packets, it's not always as easy as with the first packet that contained ASCII.
But please don't take this quickly reverse engineered structure for granted. I might be completely wrong about the meaning of these fields.
You should try to find the specification of this data. It should be somewhere in the IEEE 802.11 documents.