gdb 8.2 can't recognized executable file on macOS Mojave 10.14

Question

I get gdb by brew install gdb.

The source file content is:

#include 
int main(){
    int a = 10;
    for(int i = 0; i<          


        

Answer 1

I published a temporary brew formula that seems to work, while awaiting for official brew formula to be updated:

brew install https://raw.githubusercontent.com/timotheecour/homebrew-timutil/master/gdb_tim.rb

Answer 2

I got gdb working on Mojave by:

a) getting the latest gdb source archive (at time of writing, ftp://sourceware.org/pub/gdb/snapshots/current/gdb-weekly-8.2.50.20190212.tar.xz) - amongst other things, it adds handling for recognizing executables on Mac.

b) build gdb. I got errors for variable shadowing in darwin-nat.c so I edited the file and rebuilt.

c) follow steps in https://forward-in-code.blogspot.com/2018/11/mojave-vs-gdb.html

Voila.

(source: GDB on Mac/Mojave: During startup program terminated with signal ?, Unknown signal)

Answer 3

I have got a good solution for me from stack overflow and I do not know why it works. Here is the link.

I am new to macOS, and I do the following:

1. Codesign gdb 8.0.1 in high Sierra
2. Update to Mojave
3. gdb 8.0.1 died with BFD: /Users/xxx/Codes/demo: unknown load command 0x32
4. Change to gdb 8.2.1 and come across Keychain error Unknown Error -2,147,414,007.

   Solve this by getting the certificate in Login then export it and import it into System(Delete it from Login if unable to import).

5. Finally, because of some kind of errors it still does not work and it comes with ERROR: Unable to start debugging. Unexpected GDB output from command "-exec-run". Unable to find Mach task port for process-id 1510: (os/kern) failure (0x5). (please check gdb is codesigned - see taskgated(8)), according to how to undo codesign, something wrong still exist and the answer tells me to brew reinstall gdb, but it still does not work, I called it a day yesterday.
6. Finally I come across that link, I AM HAPPYY, now I am able to debug!

Hope my solution can help.

Answer 4

gdb 8.2 installed from Homebrew is not compatible with Mac mojave. I have upgrade to 8.2.1. The issue should be resolved.

Answer 5

The problem is that clang-1000.11.45.2 distributed with Apple LLVM version 10.0.0 add a new load command to o-mach executables named LC_BUILD_VERSION.

$ otool -l test.o
...
Load command 1
       cmd LC_BUILD_VERSION
   cmdsize 24
  platform macos
       sdk n/a
     minos 10.14
    ntools 0
...

From the apple source:

/*
 * The build_version_command contains the min OS version on which this
 * binary was built to run for its platform.  The list of known platforms and
 * tool values following it.
 */

So currently bfd (program used by gdb to manipulate executables) is not able to interpret this command, and returns the error.

The temporary solution I found is directly edit bfd sources provide with gdb. I've only test with gdb-8.0.1.

First, download gdb-8.0.1 sources from mirrors. Then add to gdb-8.0.1/bfd/mach-o.c the following code at line 4649 :

case BFD_MACH_O_LC_BUILD_VERSION:
break;

And finally add int gdb-8.0.1/include/mach-o/loader.h :

  BFD_MACH_O_LC_BUILD_VERSION = 0x32

at line 189 (don't forget to add a , at the end of the line 188 after BFD_MACH_O_LC_VERSION_MIN_WATCHOS = 0x30).

After these instructions you can follow a classic gdb compilation as indicate inside the README :

run the ``configure'' script here, e.g.:

    ./configure 
    make

To install them (by default in /usr/local/bin, /usr/local/lib, etc),
then do:
    make install

Don't forget to sign gdb as explain here. If you still get the (os/kern) failure (0x5) error, just run sudo gdb.

This is a temporary solution waiting for the GNU team fix the problem directly on the repo.

EDIT

Binutils-gdb has been updated, these changes are now implemented in commit fc7b364.

Hope It will be helpfull.

Answer 6

I got past this issue on Mojave by thinning the app. GDB does not understand universal binaries. So if file myapp tells you myapp is a universal binary, try this:

lipo -thin x86_64 -output myapp-x86_64 myapp

And then

gdb myapp-x86_64