How to get mach-o uuid of a running process?

Question

to get UUID on mac i can use

dwarfdump -u path/to/compile/executable

also i can get UUID with simple crash in 'Binary Images' section

Is the way to get UUID without crash on ios device?

Answer 1

An executable's (mach-o file) UUID is created by the linker ld and is stored in a load command named LC_UUID. You can see all load commands of a mach-o file using otool:

otool -l path_to_executable

> ...
> Load command 8
>      cmd LC_UUID
>  cmdsize 24
>     uuid 3AB82BF6-8F53-39A0-BE2D-D5AEA84D8BA6
> ...

Any process can access its mach-o header using a global symbol named _mh_execute_header. Using this symbol you can iterate over the load commands to search LC_UUID. The payload of the command is the UUID:

#import <mach-o/ldsyms.h>

NSString *executableUUID()
{
    const uint8_t *command = (const uint8_t *)(&_mh_execute_header + 1);
    for (uint32_t idx = 0; idx < _mh_execute_header.ncmds; ++idx) {
        if (((const struct load_command *)command)->cmd == LC_UUID) {
            command += sizeof(struct load_command);
            return [NSString stringWithFormat:@"%02X%02X%02X%02X-%02X%02X-%02X%02X-%02X%02X-%02X%02X%02X%02X%02X%02X",
                    command[0], command[1], command[2], command[3],
                    command[4], command[5],
                    command[6], command[7],
                    command[8], command[9],
                    command[10], command[11], command[12], command[13], command[14], command[15]];
        } else {
            command += ((const struct load_command *)command)->cmdsize;
        }
    }
    return nil;
}