// SPDX-License-Identifier: GPL-2.0
/*
 * arch/alpha/boot/tools/objstrip.c
 *
 * Strip the object file headers/trailers from an executable (ELF or ECOFF).
 *
 * Copyright (C) 1996 David Mosberger-Tang.
 */
/*
 * Converts an ECOFF or ELF object file into a bootable file.  The
 * object file must be a OMAGIC file (i.e., data and bss follow immediately
 * behind the text).  See DEC "Assembly Language Programmer's Guide"
 * documentation for details.  The SRM boot process is documented in
 * the Alpha AXP Architecture Reference Manual, Second Edition by
 * Richard L. Sites and Richard T. Witek.
 */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

#include <sys/fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>

#include <linux/a.out.h>
#include <linux/coff.h>
#include <linux/param.h>
#ifdef __ELF__
# include <linux/elf.h>
# define elfhdr elf64_hdr
# define elf_phdr elf64_phdr
# define elf_check_arch(x) ((x)->e_machine == EM_ALPHA)
#endif

/* bootfile size must be multiple of BLOCK_SIZE: */
#define BLOCK_SIZE      512

const char * prog_name;


static void
usage (void)
{
    fprintf(stderr,
            "usage: %s [-v] -p file primary\n"
            "       %s [-vb] file [secondary]\n", prog_name, prog_name);
    exit(1);
}


int
main (int argc, char *argv[])
{
    size_t nwritten, tocopy, n, mem_size, fil_size, pad = 0;
    int fd, ofd, i, j, verbose = 0, primary = 0;
    char buf[8192], *inname;
    struct exec * aout;         /* includes file & aout header */
    long offset;
#ifdef __ELF__
    struct elfhdr *elf;
    struct elf_phdr *elf_phdr;  /* program header */
    unsigned long long e_entry;
#endif

    prog_name = argv[0];

    for (i = 1; i < argc && argv[i][0] == '-'; ++i) {
        for (j = 1; argv[i][j]; ++j) {
            switch (argv[i][j]) {
              case 'v':
                  verbose = ~verbose;
                  break;

              case 'b':
                  pad = BLOCK_SIZE;
                  break;

              case 'p':
                  primary = 1;          /* make primary bootblock */
                  break;
            }
        }
    }

    if (i >= argc) {
        usage();
    }
    inname = argv[i++];

    fd = open(inname, O_RDONLY);
    if (fd == -1) {
        perror("open");
        exit(1);
    }

    ofd = 1;
    if (i < argc) {
        ofd = open(argv[i++], O_WRONLY | O_CREAT | O_TRUNC, 0666);
        if (ofd == -1) {
            perror("open");
            exit(1);
        }
    }

    if (primary) {
        /* generate bootblock for primary loader */
        
        unsigned long bb[64], sum = 0;
        struct stat st;
        off_t size;
        int i;

        if (ofd == 1) {
            usage();
        }

        if (fstat(fd, &st) == -1) {
            perror("fstat");
            exit(1);
        }

        size = (st.st_size + BLOCK_SIZE - 1) & ~(BLOCK_SIZE - 1);
        memset(bb, 0, sizeof(bb));
        strcpy((char *) bb, "Linux SRM bootblock");
        bb[60] = size / BLOCK_SIZE;     /* count */
        bb[61] = 1;                     /* starting sector # */
        bb[62] = 0;                     /* flags---must be 0 */
        for (i = 0; i < 63; ++i) {
            sum += bb[i];
        }
        bb[63] = sum;
        if (write(ofd, bb, sizeof(bb)) != sizeof(bb)) {
            perror("boot-block write");
            exit(1);
        }
        printf("%lu\n", size);
        return 0;
    }

    /* read and inspect exec header: */

    if (read(fd, buf, sizeof(buf)) < 0) {
        perror("read");
        exit(1);
    }

#ifdef __ELF__
    elf = (struct elfhdr *) buf;

    if (elf->e_ident[0] == 0x7f && strncmp((char *)elf->e_ident + 1, "ELF", 3) == 0) {
        if (elf->e_type != ET_EXEC) {
            fprintf(stderr, "%s: %s is not an ELF executable\n",
                    prog_name, inname);
            exit(1);
        }
        if (!elf_check_arch(elf)) {
            fprintf(stderr, "%s: is not for this processor (e_machine=%d)\n",
                    prog_name, elf->e_machine);
            exit(1);
        }
        if (elf->e_phnum != 1) {
            fprintf(stderr,
                    "%s: %d program headers (forgot to link with -N?)\n",
                    prog_name, elf->e_phnum);
        }

        e_entry = elf->e_entry;

        lseek(fd, elf->e_phoff, SEEK_SET);
        if (read(fd, buf, sizeof(*elf_phdr)) != sizeof(*elf_phdr)) {
            perror("read");
            exit(1);
        }

        elf_phdr = (struct elf_phdr *) buf;
        offset   = elf_phdr->p_offset;
        mem_size = elf_phdr->p_memsz;
        fil_size = elf_phdr->p_filesz;

        /* work around ELF bug: */
        if (elf_phdr->p_vaddr < e_entry) {
            unsigned long delta = e_entry - elf_phdr->p_vaddr;
            offset   += delta;
            mem_size -= delta;
            fil_size -= delta;
            elf_phdr->p_vaddr += delta;
        }

        if (verbose) {
            fprintf(stderr, "%s: extracting %#016lx-%#016lx (at %lx)\n",
                    prog_name, (long) elf_phdr->p_vaddr,
                    elf_phdr->p_vaddr + fil_size, offset);
        }
    } else
#endif
    {
        aout = (struct exec *) buf;

        if (!(aout->fh.f_flags & COFF_F_EXEC)) {
            fprintf(stderr, "%s: %s is not in executable format\n",
                    prog_name, inname);
            exit(1);
        }

        if (aout->fh.f_opthdr != sizeof(aout->ah)) {
            fprintf(stderr, "%s: %s has unexpected optional header size\n",
                    prog_name, inname);
            exit(1);
        }

        if (N_MAGIC(*aout) != OMAGIC) {
            fprintf(stderr, "%s: %s is not an OMAGIC file\n",
                    prog_name, inname);
            exit(1);
        }
        offset = N_TXTOFF(*aout);
        fil_size = aout->ah.tsize + aout->ah.dsize;
        mem_size = fil_size + aout->ah.bsize;

        if (verbose) {
            fprintf(stderr, "%s: extracting %#016lx-%#016lx (at %lx)\n",
                    prog_name, aout->ah.text_start,
                    aout->ah.text_start + fil_size, offset);
        }
    }

    if (lseek(fd, offset, SEEK_SET) != offset) {
        perror("lseek");
        exit(1);
    }

    if (verbose) {
        fprintf(stderr, "%s: copying %lu byte from %s\n",
                prog_name, (unsigned long) fil_size, inname);
    }

    tocopy = fil_size;
    while (tocopy > 0) {
        n = tocopy;
        if (n > sizeof(buf)) {
            n = sizeof(buf);
        }
        tocopy -= n;
        if ((size_t) read(fd, buf, n) != n) {
            perror("read");
            exit(1);
        }
        do {
            nwritten = write(ofd, buf, n);
            if ((ssize_t) nwritten == -1) {
                perror("write");
                exit(1);
            }
            n -= nwritten;
        } while (n > 0);
    }

    if (pad) {
        mem_size = ((mem_size + pad - 1) / pad) * pad;
    }

    tocopy = mem_size - fil_size;
    if (tocopy > 0) {
        fprintf(stderr,
                "%s: zero-filling bss and aligning to %lu with %lu bytes\n",
                prog_name, pad, (unsigned long) tocopy);

        memset(buf, 0x00, sizeof(buf));
        do {
            n = tocopy;
            if (n > sizeof(buf)) {
                n = sizeof(buf);
            }
            nwritten = write(ofd, buf, n);
            if ((ssize_t) nwritten == -1) {
                perror("write");
                exit(1);
            }
            tocopy -= nwritten;
        } while (tocopy > 0);
    }
    return 0;
}