Archipelago » qemu

/* Code for loading Linux executables.  Mostly linux kenrel code.  */

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <errno.h>

#include <unistd.h>

#include <stdio.h>

#include <stdlib.h>

#include "qemu.h"

#define NGROUPS 32

/* ??? This should really be somewhere else.  */

void memcpy_to_target(target_ulong dest, const void *src,

                      unsigned long len)

{

    void *host_ptr;

    host_ptr = lock_user(dest, len, 0);

    memcpy(host_ptr, src, len);

    unlock_user(host_ptr, dest, 1);

}

static int in_group_p(gid_t g)

{

    /* return TRUE if we're in the specified group, FALSE otherwise */

    int                ngroup;

    int                i;

    gid_t        grouplist[NGROUPS];

    ngroup = getgroups(NGROUPS, grouplist);

    for(i = 0; i < ngroup; i++) {

        if(grouplist[i] == g) {

            return 1;

        }

    }

    return 0;

}

static int count(char ** vec)

{

    int                i;

    for(i = 0; *vec; i++) {

        vec++;

    }

    return(i);

}

static int prepare_binprm(struct linux_binprm *bprm)

{

    struct stat                st;

    int mode;

    int retval, id_change;

    if(fstat(bprm->fd, &st) < 0) {

        return(-errno);

    }

    mode = st.st_mode;

    if(!S_ISREG(mode)) {        /* Must be regular file */

        return(-EACCES);

    }

    if(!(mode & 0111)) {        /* Must have at least one execute bit set */

        return(-EACCES);

    }

    bprm->e_uid = geteuid();

    bprm->e_gid = getegid();

    id_change = 0;

    /* Set-uid? */

    if(mode & S_ISUID) {

            bprm->e_uid = st.st_uid;

        if(bprm->e_uid != geteuid()) {

            id_change = 1;

        }

    }

    /* Set-gid? */

    /*

     * If setgid is set but no group execute bit then this

     * is a candidate for mandatory locking, not a setgid

     * executable.

     */

    if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {

        bprm->e_gid = st.st_gid;

        if (!in_group_p(bprm->e_gid)) {

                id_change = 1;

        }

    }

    memset(bprm->buf, 0, sizeof(bprm->buf));

    retval = lseek(bprm->fd, 0L, SEEK_SET);

    if(retval >= 0) {

        retval = read(bprm->fd, bprm->buf, 128);

    }

    if(retval < 0) {

        perror("prepare_binprm");

        exit(-1);

        /* return(-errno); */

    }

    else {

        return(retval);

    }

}

/* Construct the envp and argv tables on the target stack.  */

target_ulong loader_build_argptr(int envc, int argc, target_ulong sp,

                                 target_ulong stringp, int push_ptr)

{

    int n = sizeof(target_ulong);

    target_ulong envp;

    target_ulong argv;

    sp -= (envc + 1) * n;

    envp = sp;

    sp -= (argc + 1) * n;

    argv = sp;

    if (push_ptr) {

        sp -= n; tputl(sp, envp);

        sp -= n; tputl(sp, argv);

    }

    sp -= n; tputl(sp, argc);

    while (argc-- > 0) {

        tputl(argv, stringp); argv += n;

        stringp += target_strlen(stringp) + 1;

    }

    tputl(argv, 0);

    while (envc-- > 0) {

        tputl(envp, stringp); envp += n;

        stringp += target_strlen(stringp) + 1;

    }

    tputl(envp, 0);

    return sp;

}

int loader_exec(const char * filename, char ** argv, char ** envp, 

             struct target_pt_regs * regs, struct image_info *infop)

{

    struct linux_binprm bprm;

    int retval;

    int i;

    bprm.p = TARGET_PAGE_SIZE*MAX_ARG_PAGES-sizeof(unsigned int);

    for (i=0 ; i<MAX_ARG_PAGES ; i++)       /* clear page-table */

            bprm.page[i] = 0;

    retval = open(filename, O_RDONLY);

    if (retval < 0)

        return retval;

    bprm.fd = retval;

    bprm.filename = (char *)filename;

    bprm.argc = count(argv);

    bprm.argv = argv;

    bprm.envc = count(envp);

    bprm.envp = envp;

    retval = prepare_binprm(&bprm);

    if(retval>=0) {

        if (bprm.buf[0] == 0x7f

                && bprm.buf[1] == 'E'

                && bprm.buf[2] == 'L'

                && bprm.buf[3] == 'F') {

            retval = load_elf_binary(&bprm,regs,infop);

#if defined(TARGET_HAS_BFLT)

        } else if (bprm.buf[0] == 'b'

                && bprm.buf[1] == 'F'

                && bprm.buf[2] == 'L'

                && bprm.buf[3] == 'T') {

            retval = load_flt_binary(&bprm,regs,infop);

#endif

        } else {

            fprintf(stderr, "Unknown binary format\n");

            return -1;

        }

    }

    if(retval>=0) {

        /* success.  Initialize important registers */

        do_init_thread(regs, infop);

        return retval;

    }

    /* Something went wrong, return the inode and free the argument pages*/

    for (i=0 ; i<MAX_ARG_PAGES ; i++) {

        free(bprm.page[i]);

    }

    return(retval);

}