quick & dirty read Macho-O binary headers

readmacho.c

// like: otool -h <binary>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>

#include <mach-o/loader.h>

int main(int argc, char *argv[]) {
    struct mach_header_64 *hdr;
    unsigned int hdr_size = sizeof( struct mach_header_64 );
    char *object;

    if (argc < 2)
        return 1;

    object = argv[1];
    int fd = open(object, O_RDONLY);

    hdr = (struct mach_header_64 *)calloc(1, hdr_size);
    if ((read(fd, (void *)hdr, hdr_size)) > 0) {
        printf(
            "magic: 0x%08x %s\n"
            "cpu type: %u\n"
            "cpu subtype: %d\n"
            "filetype: %x\n"
            "number of commands: %u\n"
            "size of commands: %u\n"
            "flags: 0x%x\n",
                hdr->magic, ((hdr->magic^0xfeedfa00) == 0xcf ? "(64-bit)" : "(32-bit)"),
                (cpu_type_t)hdr->cputype,
                (cpu_subtype_t)hdr->cpusubtype & 0x000000ff,
                hdr->filetype,
                hdr->ncmds,
                hdr->sizeofcmds,
                hdr->flags
            );
    } else {
        perror("error");
    }
    close(fd);

    return 0;
}