I am trying to create an application that sends commands to GDB via NSTask and directs the output to a UITextView. It works fine on Mac (iOS Simulator). However, when deployed to the device itself (iPhone), it does not display any registers after the "info registers" command. The code is:
- (void)viewDidLoad { self.title = @"GDB"; NSLog(@"Pid for GDB execution is :%@", pid); UIBarButtonItem *btnClicked = [[UIBarButtonItem alloc] initWithTitle:@"Commands" style:UIBarButtonItemStyleBordered target:self action:@selector(btnClicked:)]; self.navigationItem.rightBarButtonItem = btnClicked; [btnClicked release]; stringInput = @"info registers"; task = [[NSTask alloc] init]; [task setLaunchPath: @"/usr/bin/gdb"]; arguments; arguments = [NSArray arrayWithObjects:@"abc", pid, nil]; [task setArguments: arguments]; // dataInput = [stringInput dataUsingEncoding:NSUTF8StringEncoding]; outputPipe; outputPipe = [NSPipe pipe]; [task setStandardOutput: outputPipe]; // inputPipe; inputPipe = [NSPipe pipe]; [task setStandardInput:inputPipe]; taskOutput; taskOutput = [outputPipe fileHandleForReading]; // taskInput; taskInput = [inputPipe fileHandleForWriting]; [task launch]; [[[task standardInput] fileHandleForWriting] writeData:dataInput]; close([taskInput fileDescriptor]); dataOutput; dataOutput = [taskOutput readDataToEndOfFile]; NSString *stringOutput; stringOutput = [[NSString alloc] initWithData: dataOutput encoding: NSUTF8StringEncoding]; NSLog (@"GDB Output:\n%@", stringOutput); //NSLog(@"GDB Input:\ n@ ", stringInput); //[string release]; [task release]; [arguments release]; textView = [[UITextView alloc]initWithFrame:CGRectMake(8,17,330,440)]; textView.editable=NO; textView.scrollEnabled=YES; [self.view addSubview:textView]; textView.text = [textView.text stringByAppendingString:stringOutput]; [super viewDidLoad]; }
The output on the iOS simulator is as follows (x86 registers)
The output on a real device (iPhone) is as follows:
The build output on startup on the iPhone is as follows:
RE:Notice: Launching: com.apple.gdb abc: No such file or directory //420: No such file or directory Unable to access task for process-id 420: (os/kern) failure. The program has no registers now. 2011-08-29 09:10:05.923 TableViewController_09[421:507] GDB Output: GNU gdb 6.3.50.20050815-cvs (Fri May 20 08:08:42 UTC 2011) Copyright 2004 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "--host=arm-apple-darwin9 --target="... (gdb) (gdb)
As a side note, I even tried adding the -arch arguments to armv7 *. It still cannot connect to the specified process.
Edit: Perhaps I found the source of my problems. This appeared in the console when I tried to call gdb on my iPhone through the app:
Sep 8 11:13:26 unknown sandboxd[2138] <Notice>: gdb(2137) deny mach-priv-task-port Process: gdb [2137] Path: /usr/bin/gdb Load Address: 0x1000 Identifier: gdb Version: ??? (1.0) Code Type: ARM (Native) Parent Process: TableViewController_09 [2135] Date/Time: 2011-09-08 11:13:25.948 +0800 OS Version: iPhone OS 4.3.3 (8J2) Report Version: 104 Backtrace: 0 libsystem_kernel.dylib 0x36223c8c task_for_pid + 8 1 gdb 0x001e4428 macosx_child_attach + 44 (macosx-nat-inferior.c:1781) 2 gdb 0x00082f18 attach_command + 116 (infcmd.c:3089) 3 gdb 0x000a3788 catch_command_errors + 100 (exceptions.c:540) 4 gdb 0x000a53e4 captured_main + 2632 (main.c:888) 5 gdb 0x000a3838 catch_errors + 104 (exceptions.c:525) 6 gdb 0x000a4988 gdb_main + 56 (main.c:1033) 7 gdb 0x0000224c main + 40 (gdb.c:36) 8 gdb 0x0000217c _start + 312 9 gdb 0x00002018 start + 24 10 gdb 0x001e3dac macosx_lookup_task + 1596 (macosx-nat-inferior.c:1522) Binary Images: 0x1000 - 0x2fbf5b +gdb arm /usr/bin/gdb 0x36214000 - 0x3622bfff libsystem_kernel.dylib armv7 <a06ec84e53bf32098b63c0caebdb45b6> /usr/lib/system/libsystem_kernel.dylib
If anyone knows a solution to this problem, please report it. I searched for a solution for several weeks to no avail ...