convert an x86 bin to an arm through oahd-helper

oahd-wrapper.c

#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>

void help(char* curbin) {
    fprintf(stderr, "%s x86_bin arm64_output\n", curbin);
}

int main(int argc, char** argv) {
    printf("this will sigbus but the bin might be valid\n");
    if (argc < 3) {
        help(argv[0]);
        return 1;
    }

    int x86fd = open(argv[1], O_RDONLY);
    if (x86fd < 0) {
        perror("x86fd");
        return 2;
    }

    int armfd = open(argv[2], O_CREAT | O_WRONLY, 0755);
    if (armfd < 0) {
        perror("armfd");
        return 2;
    }

    char* x86fdstr = calloc(2048, 1);
    char* armfdstr = calloc(2048, 1);

    sprintf(x86fdstr, "%d", x86fd);
    sprintf(armfdstr, "%d", armfd);
    
    char* args[] = {
        "oahd-helper",
        x86fdstr,
        armfdstr,
        NULL,
    };

    execv("/usr/libexec/rosetta/oahd-helper", args);
    perror("execve");
}

Bash version because why not:

#!/bin/bash

exec 3< "$1"
exec 4> "$2"

/usr/libexec/rosetta/oahd-helper 3 4

Oh wow, that's really concise haha. Definitely a better solution IMO if you don't need/want to deal with C

Version that runs it natively instead of just transpiling it because why not:

#!/bin/bash

exec 3< "$1"
binary="$(mktemp)"

/usr/libexec/rosetta/oahd-helper 3 $binary; chmod +x $binary; exec $binary; rm -rf $binary

Hi, I'm late with this, but I can't get it to work. I tried to build the c code, as well as using bash:

./oahd-wrapper /Users/plugn/Downloads/mybinary /Users/plugn/Downloads/mybinary-arm

exec 3< "/Users/plugn/Downloads/mybinary"
exec 4> "/Users/plugn/Downloads/mybinary-arm" 
/usr/libexec/rosetta/oahd-helper 3 4

mybinary is about 13.6MB, and the newly created mybinary-arm contains exactly Zero bytes in both cases. Am I missing something? Note that mybinary is a binary containing both x86_64 and i386 architectures.

Nevermind, turns out my binary needed to be inside MyApp.app/Contents/MacOS/mybinary, not elsewhere.

My next question would be, can this converted binary be run in any way? Opening it will kill it immediately due to it having no signature, and trying to give it a signature results into the following error:

codesign -s "-" --verbose --force Downloads/MyApp.app/Contents/MacOS/mybinary-arm Downloads/MyApp.app/Contents/MacOS/mybinary-arm: main executable failed strict validation