/* dl_vms.xs
 * 
 * Platform:  OpenVMS, VAX or AXP or IA64
 * Author:    Charles Bailey  bailey@newman.upenn.edu
 * Revised:   See http://public.activestate.com/cgi-bin/perlbrowse
 *
 *                           Implementation Note
 *     This section is added as an aid to users and DynaLoader developers, in
 * order to clarify the process of dynamic linking under VMS.
 *     dl_vms.xs uses the supported VMS dynamic linking call, which allows
 * a running program to map an arbitrary file of executable code and call
 * routines within that file.  This is done via the VMS RTL routine
 * lib$find_image_symbol, whose calling sequence is as follows:
 *   status = lib$find_image_symbol(imgname,symname,symval,defspec);
 *   where
 *     status  = a standard VMS status value (unsigned long int)
 *     imgname = a fixed-length string descriptor, passed by
 *               reference, containing the NAME ONLY of the image
 *               file to be mapped.  An attempt will be made to
 *               translate this string as a logical name, so it may
 *               not contain any characters which are not allowed in
 *               logical names.  If no translation is found, imgname
 *               is used directly as the name of the image file.
 *     symname = a fixed-length string descriptor, passed by
 *               reference, containing the name of the routine
 *               to be located.
 *     symval  = an unsigned long int, passed by reference, into
 *               which is written the entry point address of the
 *               routine whose name is specified in symname.
 *     defspec = a fixed-length string descriptor, passed by
 *               reference, containing a default file specification
 *               whichis used to fill in any missing parts of the
 *               image file specification after the imgname argument
 *               is processed.
 * In order to accommodate the handling of the imgname argument, the routine
 * dl_expandspec() is provided for use by perl code (e.g. dl_findfile)
 * which wants to see what image file lib$find_image_symbol would use if
 * it were passed a given file specification.  The file specification passed
 * to dl_expandspec() and dl_load_file() can be partial or complete, and can
 * use VMS or Unix syntax; these routines perform the necessary conversions.
 *    In general, writers of perl extensions need only conform to the
 * procedures set out in the DynaLoader documentation, and let the details
 * be taken care of by the routines here and in DynaLoader.pm.  If anyone
 * comes across any incompatibilities, please let me know.  Thanks.
 *
 */

#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"

#include <descrip.h>
#include <fscndef.h>
#include <lib$routines.h>
#include <rms.h>
#include <ssdef.h>
#include <starlet.h>

#if defined(VMS_WE_ARE_CASE_SENSITIVE)
#define DL_CASE_SENSITIVE 1<<4
#else
#define DL_CASE_SENSITIVE 0
#endif

typedef unsigned long int vmssts;

struct libref {
  struct dsc$descriptor_s name;
  struct dsc$descriptor_s defspec;
};

typedef struct {
    AV *	x_require_symbols;
/* "Static" data for dl_expand_filespec() - This is static to save
 * initialization on each call; if you need context-independence,
 * just make these auto variables in dl_expandspec() and dl_load_file()
 */
    char	x_esa[NAM$C_MAXRSS];
    char	x_rsa[NAM$C_MAXRSS];
    struct FAB	x_fab;
    struct NAM	x_nam;
} my_cxtx_t;		/* this *must* be named my_cxtx_t */

#define DL_CXT_EXTRA	/* ask for dl_cxtx to be defined in dlutils.c */
#include "dlutils.c"    /* dl_debug, dl_last_error; SaveError not used  */

#define dl_require_symbols	(dl_cxtx.x_require_symbols)
#define dl_esa			(dl_cxtx.x_esa)
#define dl_rsa			(dl_cxtx.x_rsa)
#define dl_fab			(dl_cxtx.x_fab)
#define dl_nam			(dl_cxtx.x_nam)

/* $PutMsg action routine - records error message in dl_last_error */
static vmssts
copy_errmsg(struct dsc$descriptor_s *msg, vmssts unused)
{
    dTHX;
    dMY_CXT;
    if (*(msg->dsc$a_pointer) == '%') { /* first line */
        sv_setpvn(MY_CXT.x_dl_last_error, msg->dsc$a_pointer, (STRLEN)msg->dsc$w_length);
    }
    else { /* continuation line */
        sv_catpvn(MY_CXT.x_dl_last_error, msg->dsc$a_pointer, (STRLEN)msg->dsc$w_length);
    }
    DLDEBUG(2,PerlIO_printf(Perl_debug_log, "Saved error message: %s\n", dl_last_error));
    return 0;
}

/* Use $PutMsg to retrieve error message for failure status code */
static void
dl_set_error(vmssts sts, vmssts stv)
{
    vmssts vec[3];
    dTHX;

    vec[0] = stv ? 2 : 1;
    vec[1] = sts;  vec[2] = stv;
    _ckvmssts(sys$putmsg(vec,copy_errmsg,0,0));
}

/* wrapper for lib$find_image_symbol, so signalled errors can be saved
 * for dl_error and then returned */
static unsigned long int
my_find_image_symbol(struct dsc$descriptor_s *imgname,
                     struct dsc$descriptor_s *symname,
                     void (**entry)(),
                     struct dsc$descriptor_s *defspec)
{
  unsigned long int retsts;
  VAXC$ESTABLISH((__vms_handler)lib$sig_to_ret);
  retsts = lib$find_image_symbol(imgname,symname,entry,defspec,DL_CASE_SENSITIVE);
  return retsts;
}


static void
dl_private_init(pTHX)
{
    dl_generic_private_init(aTHX);
    {
	dMY_CXT;
	dl_require_symbols = get_av("DynaLoader::dl_require_symbols", GV_ADDMULTI);
	/* Set up the static control blocks for dl_expand_filespec() */
	dl_fab = cc$rms_fab;
	dl_nam = cc$rms_nam;
	dl_fab.fab$l_nam = &dl_nam;
	dl_nam.nam$l_esa = dl_esa;
	dl_nam.nam$b_ess = sizeof dl_esa;
	dl_nam.nam$l_rsa = dl_rsa;
	dl_nam.nam$b_rss = sizeof dl_rsa;
    }
}
MODULE = DynaLoader PACKAGE = DynaLoader

BOOT:
    (void)dl_private_init(aTHX);

void
dl_expandspec(filespec)
    char *	filespec
    CODE:
    char vmsspec[NAM$C_MAXRSS], defspec[NAM$C_MAXRSS];
    size_t deflen;
    vmssts sts;
    dMY_CXT;

    tovmsspec(filespec,vmsspec);
    dl_fab.fab$l_fna = vmsspec;
    dl_fab.fab$b_fns = strlen(vmsspec);
    dl_fab.fab$l_dna = 0;
    dl_fab.fab$b_dns = 0;
    DLDEBUG(1,PerlIO_printf(Perl_debug_log, "dl_expand_filespec(%s):\n",vmsspec));
    /* On the first pass, just parse the specification string */
    dl_nam.nam$b_nop = NAM$M_SYNCHK;
    sts = sys$parse(&dl_fab);
    DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\tSYNCHK sys$parse = %d\n",sts));
    if (!(sts & 1)) {
      dl_set_error(dl_fab.fab$l_sts,dl_fab.fab$l_stv);
      ST(0) = &PL_sv_undef;
    }
    else {
      /* Now set up a default spec - everything but the name */
      deflen = dl_nam.nam$l_name - dl_esa;
      memcpy(defspec,dl_esa,deflen);
      memcpy(defspec+deflen,dl_nam.nam$l_type,
             dl_nam.nam$b_type + dl_nam.nam$b_ver);
      deflen += dl_nam.nam$b_type + dl_nam.nam$b_ver;
      memcpy(vmsspec,dl_nam.nam$l_name,dl_nam.nam$b_name);
      DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\tsplit filespec: name = %.*s, default = %.*s\n",
                        dl_nam.nam$b_name,vmsspec,deflen,defspec));
      /* . . . and go back to expand it */
      dl_nam.nam$b_nop = 0;
      dl_fab.fab$l_dna = defspec;
      dl_fab.fab$b_dns = deflen;
      dl_fab.fab$b_fns = dl_nam.nam$b_name;
      sts = sys$parse(&dl_fab);
      DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\tname/default sys$parse = %d\n",sts));
      if (!(sts & 1)) {
        dl_set_error(dl_fab.fab$l_sts,dl_fab.fab$l_stv);
        ST(0) = &PL_sv_undef;
      }
      else {
        /* Now find the actual file */
        sts = sys$search(&dl_fab);
        DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\tsys$search = %d\n",sts));
        if (!(sts & 1)) {
          dl_set_error(dl_fab.fab$l_sts,dl_fab.fab$l_stv);
          ST(0) = &PL_sv_undef;
        }
        else {
          ST(0) = sv_2mortal(newSVpvn(dl_nam.nam$l_rsa,dl_nam.nam$b_rsl));
          DLDEBUG(1,PerlIO_printf(Perl_debug_log, "\tresult = \\%.*s\\\n",
                            dl_nam.nam$b_rsl,dl_nam.nam$l_rsa));
        }
      }
    }

void
dl_load_file(filename, flags=0)
    char *	filename
    int		flags
    PREINIT:
    dTHX;
    dMY_CXT;
    char vmsspec[NAM$C_MAXRSS];
    SV *reqSV, **reqSVhndl;
    STRLEN deflen;
    struct dsc$descriptor_s
      specdsc = {0, DSC$K_DTYPE_T, DSC$K_CLASS_S, 0},
      symdsc  = {0, DSC$K_DTYPE_T, DSC$K_CLASS_S, 0};
    struct fscnlst {
      unsigned short int len;
      unsigned short int code;
      char *string;
    }  namlst[2] = {{0,FSCN$_NAME,0},{0,0,0}};
    struct libref *dlptr;
    vmssts sts, failed = 0;
    void (*entry)();
    CODE:

    DLDEBUG(1,PerlIO_printf(Perl_debug_log, "dl_load_file(%s,%x):\n", filename,flags));
    specdsc.dsc$a_pointer = tovmsspec(filename,vmsspec);
    specdsc.dsc$w_length = strlen(specdsc.dsc$a_pointer);
    if (specdsc.dsc$w_length == 0) { /* undef in, empty out */
        XSRETURN_EMPTY;
    }
    DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\tVMS-ified filename is %s\n",
                      specdsc.dsc$a_pointer));
    Newx(dlptr,1,struct libref);
    dlptr->name.dsc$b_dtype = dlptr->defspec.dsc$b_dtype = DSC$K_DTYPE_T;
    dlptr->name.dsc$b_class = dlptr->defspec.dsc$b_class = DSC$K_CLASS_S;
    sts = sys$filescan(&specdsc,namlst,0);
    DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\tsys$filescan: returns %d, name is %.*s\n",
                      sts,namlst[0].len,namlst[0].string));
    if (!(sts & 1)) {
      failed = 1;
      dl_set_error(sts,0);
    }
    else {
      dlptr->name.dsc$w_length = namlst[0].len;
      dlptr->name.dsc$a_pointer = savepvn(namlst[0].string,namlst[0].len);
      dlptr->defspec.dsc$w_length = specdsc.dsc$w_length - namlst[0].len;
      Newx(dlptr->defspec.dsc$a_pointer, dlptr->defspec.dsc$w_length + 1, char);
      deflen = namlst[0].string - specdsc.dsc$a_pointer; 
      memcpy(dlptr->defspec.dsc$a_pointer,specdsc.dsc$a_pointer,deflen);
      memcpy(dlptr->defspec.dsc$a_pointer + deflen,
             namlst[0].string + namlst[0].len,
             dlptr->defspec.dsc$w_length - deflen);
      DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\tlibref = name: %s, defspec: %.*s\n",
                        dlptr->name.dsc$a_pointer,
                        dlptr->defspec.dsc$w_length,
                        dlptr->defspec.dsc$a_pointer));
      if (!(reqSVhndl = av_fetch(dl_require_symbols,0,FALSE)) || !(reqSV = *reqSVhndl)) {
        DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\t@dl_require_symbols empty, returning untested libref\n"));
      }
      else {
        symdsc.dsc$w_length = SvCUR(reqSV);
        symdsc.dsc$a_pointer = SvPVX(reqSV);
        DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\t$dl_require_symbols[0] = %.*s\n",
                          symdsc.dsc$w_length, symdsc.dsc$a_pointer));
        sts = my_find_image_symbol(&(dlptr->name),&symdsc,
                                    &entry,&(dlptr->defspec));
        DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\tlib$find_image_symbol returns %d\n",sts));
        if (!(sts&1)) {
          failed = 1;
          dl_set_error(sts,0);
        }
      }
    }

    if (failed) {
      Safefree(dlptr->name.dsc$a_pointer);
      Safefree(dlptr->defspec.dsc$a_pointer);
      Safefree(dlptr);
      ST(0) = &PL_sv_undef;
    }
    else {
      ST(0) = sv_2mortal(newSViv(PTR2IV(dlptr)));
    }


void
dl_find_symbol(librefptr,symname)
    void *	librefptr
    SV *	symname
    PREINIT:
    struct libref thislib = *((struct libref *)librefptr);
    struct dsc$descriptor_s
      symdsc = {SvCUR(symname),DSC$K_DTYPE_T,DSC$K_CLASS_S,SvPVX(symname)};
    void (*entry)();
    vmssts sts;
    CODE:

    DLDEBUG(1,PerlIO_printf(Perl_debug_log, "dl_find_symbol(%.*s,%.*s):\n",
                      thislib.name.dsc$w_length, thislib.name.dsc$a_pointer,
                      symdsc.dsc$w_length,symdsc.dsc$a_pointer));
    sts = my_find_image_symbol(&(thislib.name),&symdsc,
                               &entry,&(thislib.defspec));
    DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\tlib$find_image_symbol returns %d\n",sts));
    DLDEBUG(2,PerlIO_printf(Perl_debug_log, "\tentry point is %d\n",
                      (unsigned long int) entry));
    if (!(sts & 1)) {
      dl_set_error(sts,0);
      ST(0) = &PL_sv_undef;
    }
    else ST(0) = sv_2mortal(newSViv(PTR2IV(entry)));


void
dl_undef_symbols()
    PPCODE:


# These functions should not need changing on any platform:

void
dl_install_xsub(perl_name, symref, filename="$Package")
    char *	perl_name
    void *	symref 
    const char *	filename
    CODE:
    DLDEBUG(2,PerlIO_printf(Perl_debug_log, "dl_install_xsub(name=%s, symref=%x)\n",
        perl_name, symref));
    ST(0) = sv_2mortal(newRV((SV*)newXS_flags(perl_name,
					      (void(*)(pTHX_ CV *))symref,
					      filename, NULL,
					      XS_DYNAMIC_FILENAME)));


char *
dl_error()
    CODE:
    dMY_CXT;
    RETVAL = dl_last_error ;
    OUTPUT:
      RETVAL

#if defined(USE_ITHREADS)

void
CLONE(...)
    CODE:
    MY_CXT_CLONE;

    PERL_UNUSED_VAR(items);

    /* MY_CXT_CLONE just does a memcpy on the whole structure, so to avoid
     * using Perl variables that belong to another thread, we create our 
     * own for this thread.
     */
    MY_CXT.x_dl_last_error = newSVpvn("", 0);
    dl_require_symbols = get_av("DynaLoader::dl_require_symbols", GV_ADDMULTI);

#endif

# end.