mk_elfconfig.c

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <elf.h>

int
main(int argc, char **argv)
{
    unsigned char ei[EI_NIDENT];
    union { short s; char c[2]; } endian_test;

    if (fread(ei, 1, EI_NIDENT, stdin) != EI_NIDENT) {
        fprintf(stderr, "Error: input truncated\n");
        return 1;
    }
    if (memcmp(ei, ELFMAG, SELFMAG) != 0) {
        fprintf(stderr, "Error: not ELF\n");
        return 1;
    }
    switch (ei[EI_CLASS]) {
    case ELFCLASS32:
        printf("#define KERNEL_ELFCLASS ELFCLASS32\n");
        break;
    case ELFCLASS64:
        printf("#define KERNEL_ELFCLASS ELFCLASS64\n");
        break;
    default:
        exit(1);
    }
    switch (ei[EI_DATA]) {
    case ELFDATA2LSB:
        printf("#define KERNEL_ELFDATA ELFDATA2LSB\n");
        break;
    case ELFDATA2MSB:
        printf("#define KERNEL_ELFDATA ELFDATA2MSB\n");
        break;
    default:
        exit(1);
    }

    if (sizeof(unsigned long) == 4) {
        printf("#define HOST_ELFCLASS ELFCLASS32\n");
    } else if (sizeof(unsigned long) == 8) {
        printf("#define HOST_ELFCLASS ELFCLASS64\n");
    }

    endian_test.s = 0x0102;
    if (memcmp(endian_test.c, "\x01\x02", 2) == 0)
        printf("#define HOST_ELFDATA ELFDATA2MSB\n");
    else if (memcmp(endian_test.c, "\x02\x01", 2) == 0)
        printf("#define HOST_ELFDATA ELFDATA2LSB\n");
    else
        exit(1);

    return 0;
}