lib/csu.i386/crt0.c

/*
 * Copyright (c) 1993 Paul Kranenburg
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Paul Kranenburg.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 *      $Id: crt0.c,v 1.12 1994/01/29 01:58:44 jtc Exp $
 */


#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "%W% (Erasmus) %G%";
#endif /* LIBC_SCCS and not lint */

extern void exit();
int _callmain();

#include <sys/param.h>

#ifdef DYNAMIC
#include <sys/types.h>
#include <sys/syscall.h>
#include <a.out.h>
#ifndef N_GETMAGIC
#define N_GETMAGIC(x)   ((x).a_magic)
#endif
#ifndef N_BSSADDR
#define N_BSSADDR(x)    (N_DATADDR(x)+(x).a_data)
#endif
#include <sys/mman.h>
#ifdef sun
#define MAP_COPY        MAP_PRIVATE
#define MAP_FILE        0
#define MAP_ANON        0
#endif
#include <link.h>

extern struct _dynamic _DYNAMIC;
static struct ld_entry  *ld_entry;
static void     __do_dynamic_link ();
static char     *_getenv();
static int      _strncmp();

#ifdef sun
#define LDSO    "/usr/lib/ld.so"
#endif
#ifdef BSD
#define LDSO    "/usr/libexec/ld.so"
#endif

#endif /* DYNAMIC */

static char             *_strrchr();

char                    **environ;

#ifdef BSD
extern  unsigned char   etext;
extern  unsigned char   eprol asm ("eprol");
extern                  start() asm("start");
extern                  mcount() asm ("mcount");

int                     errno;
static char             empty[1];
char                    *__progname = empty;
#endif

/*
 * We need these system calls, but can't use library stubs
 */
#define _exit(v)                __syscall(SYS_exit, (v))
#define open(name, f, m)        __syscall(SYS_open, (name), (f), (m))
#define close(fd)               __syscall(SYS_close, (fd))
#define read(fd, s, n)          __syscall(SYS_read, (fd), (s), (n))
#define write(fd, s, n)         __syscall(SYS_write, (fd), (s), (n))
#define dup(fd)                 __syscall(SYS_dup, (fd))
#define dup2(fd, fdnew)         __syscall(SYS_dup2, (fd), (fdnew))
#ifdef sun
#define mmap(addr, len, prot, flags, fd, off)   \
    __syscall(SYS_mmap, (addr), (len), (prot), _MAP_NEW|(flags), (fd), (off))
#else
#define mmap(addr, len, prot, flags, fd, off)   \
    __syscall(SYS_mmap, (addr), (len), (prot), (flags), (fd), (off))
#endif

#define _FATAL(str) \
        write(2, str, sizeof(str)), \
        _exit(1);


start()
{
        struct kframe {
                int     kargc;
                char    *kargv[1];      /* size depends on kargc */
                char    kargstr[1];     /* size varies */
                char    kenvstr[1];     /* size varies */
        };
        /*
         *      ALL REGISTER VARIABLES!!!
         */
        register struct kframe *kfp;
        register char **targv;
        register char **argv;
        extern void _mcleanup();
#ifdef DYNAMIC
        volatile caddr_t x;
#endif

#ifdef lint
        kfp = 0;
        initcode = initcode = 0;
#else /* not lint */
        /* just above the saved frame pointer */
        asm ("lea 4(%%ebp), %0" : "=r" (kfp) );
#endif /* not lint */
        for (argv = targv = &kfp->kargv[0]; *targv++; /* void */)
                /* void */ ;
        if (targv >= (char **)(*argv))
                --targv;
        environ = targv;

        if (argv[0])
                if ((__progname = _strrchr(argv[0], '/')) == NULL)
                        __progname = argv[0];
                else
                        ++__progname;

#ifdef DYNAMIC
        /* ld(1) convention: if DYNAMIC = 0 then statically linked */
#ifdef stupid_gcc
        if (&_DYNAMIC)
                __do_dynamic_link();
#else
        x = (caddr_t)&_DYNAMIC;
        if (x)
                __do_dynamic_link();
#endif
#endif /* DYNAMIC */

asm("eprol:");

#ifdef MCRT0
        atexit(_mcleanup);
        monstartup(&eprol, &etext);
#endif MCRT0

asm ("__callmain:");            /* Defined for the benefit of debuggers */
        exit(main(kfp->kargc, argv, environ));
}

#ifdef DYNAMIC
static void
__do_dynamic_link ()
{
        struct crt_ldso crt;
        struct exec     hdr;
        char            *ldso;
        int             dupzfd;
        int             (*entry)();

#ifdef DEBUG
        /* Provision for alternate ld.so - security risk! */
        if (!(ldso = _getenv("LDSO")))
#endif
                ldso = LDSO;

        crt.crt_ldfd = open(ldso, 0, 0);
        if (crt.crt_ldfd == -1) {
                _FATAL("No ld.so\n");
        }

        /* Read LDSO exec header */
        if (read(crt.crt_ldfd, &hdr, sizeof hdr) < sizeof hdr) {
                _FATAL("Failure reading ld.so\n");
        }
        if (N_GETMAGIC(hdr) != ZMAGIC && N_GETMAGIC(hdr) != QMAGIC) {
                _FATAL("Bad magic: ld.so\n");
        }

        /* We use MAP_ANON */
        crt.crt_dzfd = -1;

        /* Map in ld.so */
        crt.crt_ba = mmap(0, hdr.a_text,
                        PROT_READ|PROT_EXEC,
                        MAP_FILE|MAP_COPY,
                        crt.crt_ldfd, N_TXTOFF(hdr));
        if (crt.crt_ba == -1) {
                _FATAL("Cannot map ld.so\n");
        }

#ifdef BSD
/* !!!
 * This is gross, ld.so is a ZMAGIC a.out, but has `sizeof(hdr)' for
 * an entry point and not at PAGSIZ as the N_*ADDR macros assume.
 */
#undef N_DATADDR
#undef N_BSSADDR
#define N_DATADDR(x)    ((x).a_text)
#define N_BSSADDR(x)    ((x).a_text + (x).a_data)
#endif

        /* Map in data segment of ld.so writable */
        if (mmap(crt.crt_ba+N_DATADDR(hdr), hdr.a_data,
                        PROT_READ|PROT_WRITE,
                        MAP_FIXED|MAP_FILE|MAP_COPY,
                        crt.crt_ldfd, N_DATOFF(hdr)) == -1) {
                _FATAL("Cannot map ld.so\n");
        }

        /* Map bss segment of ld.so zero */
        if (hdr.a_bss && mmap(crt.crt_ba+N_BSSADDR(hdr), hdr.a_bss,
                        PROT_READ|PROT_WRITE,
                        MAP_FIXED|MAP_ANON|MAP_COPY,
                        crt.crt_dzfd, 0) == -1) {
                _FATAL("Cannot map ld.so\n");
        }

        crt.crt_dp = &_DYNAMIC;
        crt.crt_ep = environ;
        crt.crt_bp = (caddr_t)_callmain;
        crt.crt_prog = __progname;

        entry = (int (*)())(crt.crt_ba + sizeof hdr);
        if ((*entry)(CRT_VERSION_BSD_3, &crt) == -1) {
                _FATAL("ld.so failed\n");
        }

        ld_entry = _DYNAMIC.d_entry;
        return;
}

/*
 * DL stubs
 */

void *
dlopen(name, mode)
char    *name;
int     mode;
{
        if (ld_entry == NULL)
                return NULL;

        return (ld_entry->dlopen)(name, mode);
}

int
dlclose(fd)
void    *fd;
{
        if (ld_entry == NULL)
                return -1;

        return (ld_entry->dlclose)(fd);
}

void *
dlsym(fd, name)
void    *fd;
char    *name;
{
        if (ld_entry == NULL)
                return NULL;

        return (ld_entry->dlsym)(fd, name);
}

int
dlctl(fd, cmd, arg)
void    *fd, *arg;
int     cmd;
{
        if (ld_entry == NULL)
                return -1;

        return (ld_entry->dlctl)(fd, cmd, arg);
}

/*
 * Support routines
 */

static int
_strncmp(s1, s2, n)
        register char *s1, *s2;
        register n;
{

        if (n == 0)
                return (0);
        do {
                if (*s1 != *s2++)
                        return (*(unsigned char *)s1 - *(unsigned char *)--s2);
                if (*s1++ == 0)
                        break;
        } while (--n != 0);
        return (0);
}

static char *
_getenv(name)
        register char *name;
{
        extern char **environ;
        register int len;
        register char **P, *C;

        for (C = name, len = 0; *C && *C != '='; ++C, ++len);
        for (P = environ; *P; ++P)
                if (!_strncmp(*P, name, len))
                        if (*(C = *P + len) == '=') {
                                return(++C);
                        }
        return (char *)0;
}

        asm("   ___syscall:");
        asm("           popl %ecx");
        asm("           popl %eax");
        asm("           pushl %ecx");
        asm("           .byte 0x9a");
        asm("           .long 0");
        asm("           .word 7");
        asm("           pushl %ecx");
        asm("           jc 1f");
        asm("           ret");
        asm("   1:");
        asm("           movl    $-1,%eax");
        asm("           ret");

#endif /* DYNAMIC */

static char *
_strrchr(p, ch)
register char *p, ch;
{
        register char *save;

        for (save = NULL;; ++p) {
                if (*p == ch)
                        save = (char *)p;
                if (!*p)
                        return(save);
        }
/* NOTREACHED */
}

#ifdef MCRT0
asm ("  .text");
asm ("_eprol:");
#endif