strEQ/strNE of 1 character strings seems better hand inlined,

[perl5.git] / doio.c

/*    doio.c
 *
 *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
 *    2000, 2001, 2002, 2003, 2004, 2005, by Larry Wall and others
 *
 *    You may distribute under the terms of either the GNU General Public
 *    License or the Artistic License, as specified in the README file.
 *
 */

/*
 * "Far below them they saw the white waters pour into a foaming bowl, and
 * then swirl darkly about a deep oval basin in the rocks, until they found
 * their way out again through a narrow gate, and flowed away, fuming and
 * chattering, into calmer and more level reaches."
 */

/* This file contains functions that do the actual I/O on behalf of ops.
 * For example, pp_print() calls the do_print() function in this file for
 * each argument needing printing.
 */

#include "EXTERN.h"
#define PERL_IN_DOIO_C
#include "perl.h"

#if defined(HAS_MSG) || defined(HAS_SEM) || defined(HAS_SHM)
#ifndef HAS_SEM
#include <sys/ipc.h>
#endif
#ifdef HAS_MSG
#include <sys/msg.h>
#endif
#ifdef HAS_SHM
#include <sys/shm.h>
# ifndef HAS_SHMAT_PROTOTYPE
    extern Shmat_t shmat (int, char *, int);
# endif
#endif
#endif

#ifdef I_UTIME
#  if defined(_MSC_VER) || defined(__MINGW32__)
#    include <sys/utime.h>
#  else
#    include <utime.h>
#  endif
#endif

#ifdef O_EXCL
#  define OPEN_EXCL O_EXCL
#else
#  define OPEN_EXCL 0
#endif

#include <signal.h>

bool
Perl_do_open(pTHX_ GV *gv, register char *name, I32 len, int as_raw,
	     int rawmode, int rawperm, PerlIO *supplied_fp)
{
    return do_openn(gv, name, len, as_raw, rawmode, rawperm,
		    supplied_fp, (SV **) NULL, 0);
}

bool
Perl_do_open9(pTHX_ GV *gv, register char *name, I32 len, int as_raw,
	      int rawmode, int rawperm, PerlIO *supplied_fp, SV *svs,
	      I32 num_svs)
{
    return do_openn(gv, name, len, as_raw, rawmode, rawperm,
		    supplied_fp, &svs, 1);
}

bool
Perl_do_openn(pTHX_ GV *gv, register char *name, I32 len, int as_raw,
	      int rawmode, int rawperm, PerlIO *supplied_fp, SV **svp,
	      I32 num_svs)
{
    register IO *io = GvIOn(gv);
    PerlIO *saveifp = Nullfp;
    PerlIO *saveofp = Nullfp;
    int savefd = -1;
    char savetype = IoTYPE_CLOSED;
    int writing = 0;
    PerlIO *fp;
    int fd;
    int result;
    bool was_fdopen = FALSE;
    bool in_raw = 0, in_crlf = 0, out_raw = 0, out_crlf = 0;
    char *type  = NULL;
    char mode[8];		/* stdio file mode ("r\0", "rb\0", "r+b\0" etc.) */
    SV *namesv;

    Zero(mode,sizeof(mode),char);
    PL_forkprocess = 1;		/* assume true if no fork */

    /* Collect default raw/crlf info from the op */
    if (PL_op && PL_op->op_type == OP_OPEN) {
	/* set up IO layers */
	U8 flags = PL_op->op_private;
	in_raw = (flags & OPpOPEN_IN_RAW);
	in_crlf = (flags & OPpOPEN_IN_CRLF);
	out_raw = (flags & OPpOPEN_OUT_RAW);
	out_crlf = (flags & OPpOPEN_OUT_CRLF);
    }

    /* If currently open - close before we re-open */
    if (IoIFP(io)) {
	fd = PerlIO_fileno(IoIFP(io));
	if (IoTYPE(io) == IoTYPE_STD) {
	    /* This is a clone of one of STD* handles */
	    result = 0;
	}
	else if (fd >= 0 && fd <= PL_maxsysfd) {
	    /* This is one of the original STD* handles */
	    saveifp  = IoIFP(io);
	    saveofp  = IoOFP(io);
	    savetype = IoTYPE(io);
	    savefd   = fd;
	    result   = 0;
	}
	else if (IoTYPE(io) == IoTYPE_PIPE)
	    result = PerlProc_pclose(IoIFP(io));
	else if (IoIFP(io) != IoOFP(io)) {
	    if (IoOFP(io)) {
		result = PerlIO_close(IoOFP(io));
		PerlIO_close(IoIFP(io)); /* clear stdio, fd already closed */
	    }
	    else
		result = PerlIO_close(IoIFP(io));
	}
	else
	    result = PerlIO_close(IoIFP(io));
	if (result == EOF && fd > PL_maxsysfd) {
	    /* Why is this not Perl_warn*() call ? */
	    PerlIO_printf(Perl_error_log,
			  "Warning: unable to close filehandle %s properly.\n",
			  GvENAME(gv));
	}
	IoOFP(io) = IoIFP(io) = Nullfp;
    }

    if (as_raw) {
        /* sysopen style args, i.e. integer mode and permissions */
	STRLEN ix = 0;
	int appendtrunc =
	     0
#ifdef O_APPEND	/* Not fully portable. */
	     |O_APPEND
#endif
#ifdef O_TRUNC	/* Not fully portable. */
	     |O_TRUNC
#endif
	     ;
	int modifyingmode =
	     O_WRONLY|O_RDWR|O_CREAT|appendtrunc;
	int ismodifying;

	if (num_svs != 0) {
	     Perl_croak(aTHX_ "panic: sysopen with multiple args");
	}
	/* It's not always

	   O_RDONLY 0
	   O_WRONLY 1
	   O_RDWR   2

	   It might be (in OS/390 and Mac OS Classic it is)

	   O_WRONLY 1
	   O_RDONLY 2
	   O_RDWR   3

	   This means that simple & with O_RDWR would look
	   like O_RDONLY is present.  Therefore we have to
	   be more careful.
	*/
	if ((ismodifying = (rawmode & modifyingmode))) {
	     if ((ismodifying & O_WRONLY) == O_WRONLY ||
		 (ismodifying & O_RDWR)   == O_RDWR   ||
		 (ismodifying & (O_CREAT|appendtrunc)))
		  TAINT_PROPER("sysopen");
	}
	mode[ix++] = IoTYPE_NUMERIC; /* Marker to openn to use numeric "sysopen" */

#if defined(USE_64_BIT_RAWIO) && defined(O_LARGEFILE)
	rawmode |= O_LARGEFILE;	/* Transparently largefiley. */
#endif

        IoTYPE(io) = PerlIO_intmode2str(rawmode, &mode[ix], &writing);

	namesv = sv_2mortal(newSVpvn(name,strlen(name)));
	num_svs = 1;
	svp = &namesv;
        type = Nullch;
	fp = PerlIO_openn(aTHX_ type, mode, -1, rawmode, rawperm, NULL, num_svs, svp);
    }
    else {
	/* Regular (non-sys) open */
	char *oname = name;
	STRLEN olen = len;
	char *tend;
	int dodup = 0;
	PerlIO *that_fp = NULL;

	type = savepvn(name, len);
	tend = type+len;
	SAVEFREEPV(type);

        /* Lose leading and trailing white space */
        /*SUPPRESS 530*/
        for (; isSPACE(*type); type++) ;
        while (tend > type && isSPACE(tend[-1]))
	    *--tend = '\0';

	if (num_svs) {
	    /* New style explicit name, type is just mode and layer info */
	    STRLEN l = 0;
#ifdef USE_STDIO
	    if (SvROK(*svp) && !strchr(name,'&')) {
		if (ckWARN(WARN_IO))
		    Perl_warner(aTHX_ packWARN(WARN_IO),
			    "Can't open a reference");
		SETERRNO(EINVAL, LIB_INVARG);
		goto say_false;
	    }
#endif /* USE_STDIO */
	    name = SvOK(*svp) ? SvPV(*svp, l) : "";
	    len = (I32)l;
	    name = savepvn(name, len);
	    SAVEFREEPV(name);
	}
	else {
	    name = type;
	    len  = tend-type;
	}
	IoTYPE(io) = *type;
	if ((*type == IoTYPE_RDWR) && /* scary */
           (*(type+1) == IoTYPE_RDONLY || *(type+1) == IoTYPE_WRONLY) &&
	    ((!num_svs || (tend > type+1 && tend[-1] != IoTYPE_PIPE)))) {
	    TAINT_PROPER("open");
	    mode[1] = *type++;
	    writing = 1;
	}

	if (*type == IoTYPE_PIPE) {
	    if (num_svs) {
		if (type[1] != IoTYPE_STD) {
	          unknown_open_mode:
		    Perl_croak(aTHX_ "Unknown open() mode '%.*s'", (int)olen, oname);
		}
		type++;
	    }
	    /*SUPPRESS 530*/
	    for (type++; isSPACE(*type); type++) ;
	    if (!num_svs) {
		name = type;
		len = tend-type;
	    }
	    if (*name == '\0') {
		/* command is missing 19990114 */
		if (ckWARN(WARN_PIPE))
		    Perl_warner(aTHX_ packWARN(WARN_PIPE), "Missing command in piped open");
		errno = EPIPE;
		goto say_false;
	    }
	    if ((*name == '-' && name[1] == '\0') || num_svs)
		TAINT_ENV();
	    TAINT_PROPER("piped open");
	    if (!num_svs && name[len-1] == '|') {
		name[--len] = '\0' ;
		if (ckWARN(WARN_PIPE))
		    Perl_warner(aTHX_ packWARN(WARN_PIPE), "Can't open bidirectional pipe");
	    }
	    mode[0] = 'w';
	    writing = 1;
	    if (out_raw)
		strcat(mode, "b");
	    else if (out_crlf)
		strcat(mode, "t");
	    if (num_svs > 1) {
		fp = PerlProc_popen_list(mode, num_svs, svp);
	    }
	    else {
		fp = PerlProc_popen(name,mode);
	    }
	    if (num_svs) {
		if (*type) {
		    if (PerlIO_apply_layers(aTHX_ fp, mode, type) != 0) {
			goto say_false;
		    }
		}
	    }
	} /* IoTYPE_PIPE */
	else if (*type == IoTYPE_WRONLY) {
	    TAINT_PROPER("open");
	    type++;
	    if (*type == IoTYPE_WRONLY) {
		/* Two IoTYPE_WRONLYs in a row make for an IoTYPE_APPEND. */
		mode[0] = IoTYPE(io) = IoTYPE_APPEND;
		type++;
	    }
	    else {
		mode[0] = 'w';
	    }
	    writing = 1;

	    if (out_raw)
		strcat(mode, "b");
	    else if (out_crlf)
		strcat(mode, "t");

	    if (*type == '&') {
	      duplicity:
		dodup = PERLIO_DUP_FD;
		type++;
		if (*type == '=') {
		    dodup = 0;
		    type++;
		}
		if (!num_svs && !*type && supplied_fp) {
		    /* "<+&" etc. is used by typemaps */
		    fp = supplied_fp;
		}
		else {
		    if (num_svs > 1) {
			Perl_croak(aTHX_ "More than one argument to '%c&' open",IoTYPE(io));
		    }
		    /*SUPPRESS 530*/
		    for (; isSPACE(*type); type++) ;
		    if (num_svs && (SvIOK(*svp) || (SvPOK(*svp) && looks_like_number(*svp)))) {
			fd = SvUV(*svp);
			num_svs = 0;
		    }
		    else if (isDIGIT(*type)) {
			fd = atoi(type);
		    }
		    else {
			IO* thatio;
			if (num_svs) {
			    thatio = sv_2io(*svp);
			}
			else {
			    GV *thatgv;
			    thatgv = gv_fetchpv(type,FALSE,SVt_PVIO);
			    thatio = GvIO(thatgv);
			}
			if (!thatio) {
#ifdef EINVAL
			    SETERRNO(EINVAL,SS_IVCHAN);
#endif
			    goto say_false;
			}
			if ((that_fp = IoIFP(thatio))) {
			    /* Flush stdio buffer before dup. --mjd
			     * Unfortunately SEEK_CURing 0 seems to
			     * be optimized away on most platforms;
			     * only Solaris and Linux seem to flush
			     * on that. --jhi */
#ifdef USE_SFIO
			    /* sfio fails to clear error on next
			       sfwrite, contrary to documentation.
			       -- Nick Clark */
			    if (PerlIO_seek(that_fp, 0, SEEK_CUR) == -1)
				PerlIO_clearerr(that_fp);
#endif
			    /* On the other hand, do all platforms
			     * take gracefully to flushing a read-only
			     * filehandle?  Perhaps we should do
			     * fsetpos(src)+fgetpos(dst)?  --nik */
			    PerlIO_flush(that_fp);
			    fd = PerlIO_fileno(that_fp);
			    /* When dup()ing STDIN, STDOUT or STDERR
			     * explicitly set appropriate access mode */
			    if (that_fp == PerlIO_stdout()
				|| that_fp == PerlIO_stderr())
			        IoTYPE(io) = IoTYPE_WRONLY;
			    else if (that_fp == PerlIO_stdin())
                                IoTYPE(io) = IoTYPE_RDONLY;
			    /* When dup()ing a socket, say result is
			     * one as well */
			    else if (IoTYPE(thatio) == IoTYPE_SOCKET)
				IoTYPE(io) = IoTYPE_SOCKET;
			}
			else
			    fd = -1;
		    }
		    if (!num_svs)
			type = Nullch;
		    if (that_fp) {
			fp = PerlIO_fdupopen(aTHX_ that_fp, NULL, dodup);
		    }
		    else {
			if (dodup)
			    fd = PerlLIO_dup(fd);
			else
			    was_fdopen = TRUE;
			if (!(fp = PerlIO_openn(aTHX_ type,mode,fd,0,0,NULL,num_svs,svp))) {
			    if (dodup)
				PerlLIO_close(fd);
			}
		    }
		}
	    } /* & */
	    else {
		/*SUPPRESS 530*/
		for (; isSPACE(*type); type++) ;
		if (*type == IoTYPE_STD && (!type[1] || isSPACE(type[1]) || type[1] == ':')) {
		    /*SUPPRESS 530*/
		    type++;
		    fp = PerlIO_stdout();
		    IoTYPE(io) = IoTYPE_STD;
		    if (num_svs > 1) {
			Perl_croak(aTHX_ "More than one argument to '>%c' open",IoTYPE_STD);
		    }
		}
		else  {
		    if (!num_svs) {
			namesv = sv_2mortal(newSVpvn(type,strlen(type)));
			num_svs = 1;
			svp = &namesv;
		        type = Nullch;
		    }
		    fp = PerlIO_openn(aTHX_ type,mode,-1,0,0,NULL,num_svs,svp);
		}
	    } /* !& */
	    if (!fp && type && *type && *type != ':' && !isIDFIRST(*type))
	       goto unknown_open_mode;
	} /* IoTYPE_WRONLY */
	else if (*type == IoTYPE_RDONLY) {
	    /*SUPPRESS 530*/
	    for (type++; isSPACE(*type); type++) ;
	    mode[0] = 'r';
	    if (in_raw)
		strcat(mode, "b");
	    else if (in_crlf)
		strcat(mode, "t");

	    if (*type == '&') {
		goto duplicity;
	    }
	    if (*type == IoTYPE_STD && (!type[1] || isSPACE(type[1]) || type[1] == ':')) {
		/*SUPPRESS 530*/
		type++;
		fp = PerlIO_stdin();
		IoTYPE(io) = IoTYPE_STD;
		if (num_svs > 1) {
		    Perl_croak(aTHX_ "More than one argument to '<%c' open",IoTYPE_STD);
		}
	    }
	    else {
		if (!num_svs) {
		    namesv = sv_2mortal(newSVpvn(type,strlen(type)));
		    num_svs = 1;
		    svp = &namesv;
		    type = Nullch;
		}
		fp = PerlIO_openn(aTHX_ type,mode,-1,0,0,NULL,num_svs,svp);
	    }
	    if (!fp && type && *type && *type != ':' && !isIDFIRST(*type))
	       goto unknown_open_mode;
	} /* IoTYPE_RDONLY */
	else if ((num_svs && /* '-|...' or '...|' */
		  type[0] == IoTYPE_STD && type[1] == IoTYPE_PIPE) ||
	         (!num_svs && tend > type+1 && tend[-1] == IoTYPE_PIPE)) {
	    if (num_svs) {
		type += 2;   /* skip over '-|' */
	    }
	    else {
		*--tend = '\0';
		while (tend > type && isSPACE(tend[-1]))
		    *--tend = '\0';
		/*SUPPRESS 530*/
		for (; isSPACE(*type); type++) ;
		name = type;
	        len  = tend-type;
	    }
	    if (*name == '\0') {
		/* command is missing 19990114 */
		if (ckWARN(WARN_PIPE))
		    Perl_warner(aTHX_ packWARN(WARN_PIPE), "Missing command in piped open");
		errno = EPIPE;
		goto say_false;
	    }
	    if (!(*name == '-' && name[1] == '\0') || num_svs)
		TAINT_ENV();
	    TAINT_PROPER("piped open");
	    mode[0] = 'r';
	    if (in_raw)
		strcat(mode, "b");
	    else if (in_crlf)
		strcat(mode, "t");
	    if (num_svs > 1) {
		fp = PerlProc_popen_list(mode,num_svs,svp);
	    }
	    else {
		fp = PerlProc_popen(name,mode);
	    }
	    IoTYPE(io) = IoTYPE_PIPE;
	    if (num_svs) {
		for (; isSPACE(*type); type++) ;
		if (*type) {
		    if (PerlIO_apply_layers(aTHX_ fp, mode, type) != 0) {
			goto say_false;
		    }
		}
	    }
	}
	else { /* layer(Args) */
	    if (num_svs)
		goto unknown_open_mode;
	    name = type;
	    IoTYPE(io) = IoTYPE_RDONLY;
	    /*SUPPRESS 530*/
	    for (; isSPACE(*name); name++) ;
	    mode[0] = 'r';
	    if (in_raw)
		strcat(mode, "b");
	    else if (in_crlf)
		strcat(mode, "t");
	    if (*name == '-' && name[1] == '\0') {
		fp = PerlIO_stdin();
		IoTYPE(io) = IoTYPE_STD;
	    }
	    else {
		if (!num_svs) {
		    namesv = sv_2mortal(newSVpvn(type,strlen(type)));
		    num_svs = 1;
		    svp = &namesv;
		    type = Nullch;
		}
		fp = PerlIO_openn(aTHX_ type,mode,-1,0,0,NULL,num_svs,svp);
	    }
	}
    }
    if (!fp) {
	if (ckWARN(WARN_NEWLINE) && IoTYPE(io) == IoTYPE_RDONLY && strchr(name, '\n'))
	    Perl_warner(aTHX_ packWARN(WARN_NEWLINE), PL_warn_nl, "open");
	goto say_false;
    }

    if (ckWARN(WARN_IO)) {
	if ((IoTYPE(io) == IoTYPE_RDONLY) &&
	    (fp == PerlIO_stdout() || fp == PerlIO_stderr())) {
		Perl_warner(aTHX_ packWARN(WARN_IO),
			    "Filehandle STD%s reopened as %s only for input",
			    ((fp == PerlIO_stdout()) ? "OUT" : "ERR"),
			    GvENAME(gv));
	}
	else if ((IoTYPE(io) == IoTYPE_WRONLY) && fp == PerlIO_stdin()) {
		Perl_warner(aTHX_ packWARN(WARN_IO),
			    "Filehandle STDIN reopened as %s only for output",
			    GvENAME(gv));
	}
    }

    fd = PerlIO_fileno(fp);
    /* If there is no fd (e.g. PerlIO::scalar) assume it isn't a
     * socket - this covers PerlIO::scalar - otherwise unless we "know" the
     * type probe for socket-ness.
     */
    if (IoTYPE(io) && IoTYPE(io) != IoTYPE_PIPE && IoTYPE(io) != IoTYPE_STD && fd >= 0) {
	if (PerlLIO_fstat(fd,&PL_statbuf) < 0) {
	    /* If PerlIO claims to have fd we had better be able to fstat() it. */
	    (void) PerlIO_close(fp);
	    goto say_false;
	}
#ifndef PERL_MICRO
	if (S_ISSOCK(PL_statbuf.st_mode))
	    IoTYPE(io) = IoTYPE_SOCKET;	/* in case a socket was passed in to us */
#ifdef HAS_SOCKET
	else if (
#ifdef S_IFMT
	    !(PL_statbuf.st_mode & S_IFMT)
#else
	    !PL_statbuf.st_mode
#endif
	    && IoTYPE(io) != IoTYPE_WRONLY  /* Dups of STD* filehandles already have */
	    && IoTYPE(io) != IoTYPE_RDONLY  /* type so they aren't marked as sockets */
	) {				    /* on OS's that return 0 on fstat()ed pipe */
	     char tmpbuf[256];
	     Sock_size_t buflen = sizeof tmpbuf;
	     if (PerlSock_getsockname(fd, (struct sockaddr *)tmpbuf, &buflen) >= 0
		      || errno != ENOTSOCK)
		    IoTYPE(io) = IoTYPE_SOCKET; /* some OS's return 0 on fstat()ed socket */
				                /* but some return 0 for streams too, sigh */
	}
#endif /* HAS_SOCKET */
#endif /* !PERL_MICRO */
    }

    /* Eeek - FIXME !!!
     * If this is a standard handle we discard all the layer stuff
     * and just dup the fd into whatever was on the handle before !
     */

    if (saveifp) {		/* must use old fp? */
        /* If fd is less that PL_maxsysfd i.e. STDIN..STDERR
           then dup the new fileno down
         */
	if (saveofp) {
	    PerlIO_flush(saveofp);	/* emulate PerlIO_close() */
	    if (saveofp != saveifp) {	/* was a socket? */
		PerlIO_close(saveofp);
	    }
	}
	if (savefd != fd) {
	    /* Still a small can-of-worms here if (say) PerlIO::scalar
	       is assigned to (say) STDOUT - for now let dup2() fail
	       and provide the error
	     */
	    if (PerlLIO_dup2(fd, savefd) < 0) {
		(void)PerlIO_close(fp);
		goto say_false;
	    }
#ifdef VMS
	    if (savefd != PerlIO_fileno(PerlIO_stdin())) {
                char newname[FILENAME_MAX+1];
                if (PerlIO_getname(fp, newname)) {
                    if (fd == PerlIO_fileno(PerlIO_stdout()))
                        Perl_vmssetuserlnm(aTHX_ "SYS$OUTPUT", newname);
                    if (fd == PerlIO_fileno(PerlIO_stderr()))
                        Perl_vmssetuserlnm(aTHX_ "SYS$ERROR",  newname);
                }
	    }
#endif

#if !defined(WIN32)
           /* PL_fdpid isn't used on Windows, so avoid this useless work.
            * XXX Probably the same for a lot of other places. */
            {
                Pid_t pid;
                SV *sv;

                LOCK_FDPID_MUTEX;
                sv = *av_fetch(PL_fdpid,fd,TRUE);
                (void)SvUPGRADE(sv, SVt_IV);
                pid = SvIVX(sv);
                SvIVX(sv) = 0;
                sv = *av_fetch(PL_fdpid,savefd,TRUE);
                (void)SvUPGRADE(sv, SVt_IV);
                SvIVX(sv) = pid;
                UNLOCK_FDPID_MUTEX;
            }
#endif

	    if (was_fdopen) {
                /* need to close fp without closing underlying fd */
                int ofd = PerlIO_fileno(fp);
                int dupfd = PerlLIO_dup(ofd);
#if defined(HAS_FCNTL) && defined(F_SETFD)
		/* Assume if we have F_SETFD we have F_GETFD */
                int coe = fcntl(ofd,F_GETFD);
#endif
                PerlIO_close(fp);
                PerlLIO_dup2(dupfd,ofd);
#if defined(HAS_FCNTL) && defined(F_SETFD)
		/* The dup trick has lost close-on-exec on ofd */
		fcntl(ofd,F_SETFD, coe);
#endif
                PerlLIO_close(dupfd);
	    }
            else
		PerlIO_close(fp);
	}
	fp = saveifp;
	PerlIO_clearerr(fp);
	fd = PerlIO_fileno(fp);
    }
#if defined(HAS_FCNTL) && defined(F_SETFD)
    if (fd >= 0) {
	int save_errno = errno;
	fcntl(fd,F_SETFD,fd > PL_maxsysfd); /* can change errno */
	errno = save_errno;
    }
#endif
    IoIFP(io) = fp;

    IoFLAGS(io) &= ~IOf_NOLINE;
    if (writing) {
	if (IoTYPE(io) == IoTYPE_SOCKET
	    || (IoTYPE(io) == IoTYPE_WRONLY && fd >= 0 && S_ISCHR(PL_statbuf.st_mode)) ) {
	    char *s = mode;
	    if (*s == IoTYPE_IMPLICIT || *s == IoTYPE_NUMERIC)
	      s++;
	    *s = 'w';
	    if (!(IoOFP(io) = PerlIO_openn(aTHX_ type,s,fd,0,0,NULL,0,svp))) {
		PerlIO_close(fp);
		IoIFP(io) = Nullfp;
		goto say_false;
	    }
	}
	else
	    IoOFP(io) = fp;
    }
    return TRUE;

say_false:
    IoIFP(io) = saveifp;
    IoOFP(io) = saveofp;
    IoTYPE(io) = savetype;
    return FALSE;
}

PerlIO *
Perl_nextargv(pTHX_ register GV *gv)
{
    register SV *sv;
#ifndef FLEXFILENAMES
    int filedev;
    int fileino;
#endif
    Uid_t fileuid;
    Gid_t filegid;
    IO *io = GvIOp(gv);

    if (!PL_argvoutgv)
	PL_argvoutgv = gv_fetchpv("ARGVOUT",TRUE,SVt_PVIO);
    if (io && (IoFLAGS(io) & IOf_ARGV) && (IoFLAGS(io) & IOf_START)) {
	IoFLAGS(io) &= ~IOf_START;
	if (PL_inplace) {
	    if (!PL_argvout_stack)
		PL_argvout_stack = newAV();
	    av_push(PL_argvout_stack, SvREFCNT_inc(PL_defoutgv));
	}
    }
    if (PL_filemode & (S_ISUID|S_ISGID)) {
	PerlIO_flush(IoIFP(GvIOn(PL_argvoutgv)));  /* chmod must follow last write */
#ifdef HAS_FCHMOD
	if (PL_lastfd != -1)
	    (void)fchmod(PL_lastfd,PL_filemode);
#else
	(void)PerlLIO_chmod(PL_oldname,PL_filemode);
#endif
    }
    PL_lastfd = -1;
    PL_filemode = 0;
    if (!GvAV(gv))
        return Nullfp;
    while (av_len(GvAV(gv)) >= 0) {
	STRLEN oldlen;
	sv = av_shift(GvAV(gv));
	SAVEFREESV(sv);
	sv_setsv(GvSV(gv),sv);
	SvSETMAGIC(GvSV(gv));
	PL_oldname = SvPVx(GvSV(gv), oldlen);
	if (do_open(gv,PL_oldname,oldlen,PL_inplace!=0,O_RDONLY,0,Nullfp)) {
	    if (PL_inplace) {
		TAINT_PROPER("inplace open");
		if (oldlen == 1 && *PL_oldname == '-') {
		    setdefout(gv_fetchpv("STDOUT",TRUE,SVt_PVIO));
		    return IoIFP(GvIOp(gv));
		}
#ifndef FLEXFILENAMES
		filedev = PL_statbuf.st_dev;
		fileino = PL_statbuf.st_ino;
#endif
		PL_filemode = PL_statbuf.st_mode;
		fileuid = PL_statbuf.st_uid;
		filegid = PL_statbuf.st_gid;
		if (!S_ISREG(PL_filemode)) {
		    if (ckWARN_d(WARN_INPLACE))	
		        Perl_warner(aTHX_ packWARN(WARN_INPLACE),
			    "Can't do inplace edit: %s is not a regular file",
		            PL_oldname );
		    do_close(gv,FALSE);
		    continue;
		}
		if (*PL_inplace) {
		    char *star = strchr(PL_inplace, '*');
		    if (star) {
			char *begin = PL_inplace;
			sv_setpvn(sv, "", 0);
			do {
			    sv_catpvn(sv, begin, star - begin);
			    sv_catpvn(sv, PL_oldname, oldlen);
			    begin = ++star;
			} while ((star = strchr(begin, '*')));
			if (*begin)
			    sv_catpv(sv,begin);
		    }
		    else {
			sv_catpv(sv,PL_inplace);
		    }
#ifndef FLEXFILENAMES
		    if ((PerlLIO_stat(SvPVX(sv),&PL_statbuf) >= 0
			 && PL_statbuf.st_dev == filedev
			 && PL_statbuf.st_ino == fileino)
#ifdef DJGPP
			|| ((_djstat_fail_bits & _STFAIL_TRUENAME)!=0)
#endif
                      )
		    {
			if (ckWARN_d(WARN_INPLACE))	
			    Perl_warner(aTHX_ packWARN(WARN_INPLACE),
			      "Can't do inplace edit: %"SVf" would not be unique",
			      sv);
			do_close(gv,FALSE);
			continue;
		    }
#endif
#ifdef HAS_RENAME
#if !defined(DOSISH) && !defined(__CYGWIN__) && !defined(EPOC)
		    if (PerlLIO_rename(PL_oldname,SvPVX(sv)) < 0) {
		        if (ckWARN_d(WARN_INPLACE))	
			    Perl_warner(aTHX_ packWARN(WARN_INPLACE),
			      "Can't rename %s to %"SVf": %s, skipping file",
			      PL_oldname, sv, Strerror(errno) );
			do_close(gv,FALSE);
			continue;
		    }
#else
		    do_close(gv,FALSE);
		    (void)PerlLIO_unlink(SvPVX(sv));
		    (void)PerlLIO_rename(PL_oldname,SvPVX(sv));
		    do_open(gv,SvPVX(sv),SvCUR(sv),PL_inplace!=0,O_RDONLY,0,Nullfp);
#endif /* DOSISH */
#else
		    (void)UNLINK(SvPVX(sv));
		    if (link(PL_oldname,SvPVX(sv)) < 0) {
		        if (ckWARN_d(WARN_INPLACE))	
			    Perl_warner(aTHX_ packWARN(WARN_INPLACE),
			      "Can't rename %s to %"SVf": %s, skipping file",
			      PL_oldname, sv, Strerror(errno) );
			do_close(gv,FALSE);
			continue;
		    }
		    (void)UNLINK(PL_oldname);
#endif
		}
		else {
#if !defined(DOSISH) && !defined(AMIGAOS)
#  ifndef VMS  /* Don't delete; use automatic file versioning */
		    if (UNLINK(PL_oldname) < 0) {
		        if (ckWARN_d(WARN_INPLACE))	
			    Perl_warner(aTHX_ packWARN(WARN_INPLACE),
			      "Can't remove %s: %s, skipping file",
			      PL_oldname, Strerror(errno) );
			do_close(gv,FALSE);
			continue;
		    }
#  endif
#else
		    Perl_croak(aTHX_ "Can't do inplace edit without backup");
#endif
		}

		sv_setpvn(sv,">",!PL_inplace);
		sv_catpvn(sv,PL_oldname,oldlen);
		SETERRNO(0,0);		/* in case sprintf set errno */
#ifdef VMS
		if (!do_open(PL_argvoutgv,SvPVX(sv),SvCUR(sv),PL_inplace!=0,
                 O_WRONLY|O_CREAT|O_TRUNC,0,Nullfp))
#else
		if (!do_open(PL_argvoutgv,SvPVX(sv),SvCUR(sv),PL_inplace!=0,
			     O_WRONLY|O_CREAT|OPEN_EXCL,0666,Nullfp))
#endif
		{
		    if (ckWARN_d(WARN_INPLACE))	
		        Perl_warner(aTHX_ packWARN(WARN_INPLACE), "Can't do inplace edit on %s: %s",
		          PL_oldname, Strerror(errno) );
		    do_close(gv,FALSE);
		    continue;
		}
		setdefout(PL_argvoutgv);
		PL_lastfd = PerlIO_fileno(IoIFP(GvIOp(PL_argvoutgv)));
		(void)PerlLIO_fstat(PL_lastfd,&PL_statbuf);
#ifdef HAS_FCHMOD
		(void)fchmod(PL_lastfd,PL_filemode);
#else
#  if !(defined(WIN32) && defined(__BORLANDC__))
		/* Borland runtime creates a readonly file! */
		(void)PerlLIO_chmod(PL_oldname,PL_filemode);
#  endif
#endif
		if (fileuid != PL_statbuf.st_uid || filegid != PL_statbuf.st_gid) {
#ifdef HAS_FCHOWN
		    (void)fchown(PL_lastfd,fileuid,filegid);
#else
#ifdef HAS_CHOWN
		    (void)PerlLIO_chown(PL_oldname,fileuid,filegid);
#endif
#endif
		}
	    }
	    return IoIFP(GvIOp(gv));
	}
	else {
	    if (ckWARN_d(WARN_INPLACE)) {
		int eno = errno;
		if (PerlLIO_stat(PL_oldname, &PL_statbuf) >= 0
		    && !S_ISREG(PL_statbuf.st_mode))	
		{
		    Perl_warner(aTHX_ packWARN(WARN_INPLACE),
				"Can't do inplace edit: %s is not a regular file",
				PL_oldname);
		}
		else
		    Perl_warner(aTHX_ packWARN(WARN_INPLACE), "Can't open %s: %s",
				PL_oldname, Strerror(eno));
	    }
	}
    }
    if (io && (IoFLAGS(io) & IOf_ARGV))
	IoFLAGS(io) |= IOf_START;
    if (PL_inplace) {
	(void)do_close(PL_argvoutgv,FALSE);
	if (io && (IoFLAGS(io) & IOf_ARGV)
	    && PL_argvout_stack && AvFILLp(PL_argvout_stack) >= 0)
	{
	    GV *oldout = (GV*)av_pop(PL_argvout_stack);
	    setdefout(oldout);
	    SvREFCNT_dec(oldout);
	    return Nullfp;
	}
	setdefout(gv_fetchpv("STDOUT",TRUE,SVt_PVIO));
    }
    return Nullfp;
}

#ifdef HAS_PIPE
void
Perl_do_pipe(pTHX_ SV *sv, GV *rgv, GV *wgv)
{
    register IO *rstio;
    register IO *wstio;
    int fd[2];

    if (!rgv)
	goto badexit;
    if (!wgv)
	goto badexit;

    rstio = GvIOn(rgv);
    wstio = GvIOn(wgv);

    if (IoIFP(rstio))
	do_close(rgv,FALSE);
    if (IoIFP(wstio))
	do_close(wgv,FALSE);

    if (PerlProc_pipe(fd) < 0)
	goto badexit;
    IoIFP(rstio) = PerlIO_fdopen(fd[0], "r"PIPE_OPEN_MODE);
    IoOFP(wstio) = PerlIO_fdopen(fd[1], "w"PIPE_OPEN_MODE);
    IoOFP(rstio) = IoIFP(rstio);
    IoIFP(wstio) = IoOFP(wstio);
    IoTYPE(rstio) = IoTYPE_RDONLY;
    IoTYPE(wstio) = IoTYPE_WRONLY;
    if (!IoIFP(rstio) || !IoOFP(wstio)) {
	if (IoIFP(rstio)) PerlIO_close(IoIFP(rstio));
	else PerlLIO_close(fd[0]);
	if (IoOFP(wstio)) PerlIO_close(IoOFP(wstio));
	else PerlLIO_close(fd[1]);
	goto badexit;
    }

    sv_setsv(sv,&PL_sv_yes);
    return;

badexit:
    sv_setsv(sv,&PL_sv_undef);
    return;
}
#endif

/* explicit renamed to avoid C++ conflict    -- kja */
bool
Perl_do_close(pTHX_ GV *gv, bool not_implicit)
{
    bool retval;
    IO *io;

    if (!gv)
	gv = PL_argvgv;
    if (!gv || SvTYPE(gv) != SVt_PVGV) {
	if (not_implicit)
	    SETERRNO(EBADF,SS_IVCHAN);
	return FALSE;
    }
    io = GvIO(gv);
    if (!io) {		/* never opened */
	if (not_implicit) {
	    if (ckWARN(WARN_UNOPENED)) /* no check for closed here */
		report_evil_fh(gv, io, PL_op->op_type);
	    SETERRNO(EBADF,SS_IVCHAN);
	}
	return FALSE;
    }
    retval = io_close(io, not_implicit);
    if (not_implicit) {
	IoLINES(io) = 0;
	IoPAGE(io) = 0;
	IoLINES_LEFT(io) = IoPAGE_LEN(io);
    }
    IoTYPE(io) = IoTYPE_CLOSED;
    return retval;
}

bool
Perl_io_close(pTHX_ IO *io, bool not_implicit)
{
    bool retval = FALSE;
    int status;

    if (IoIFP(io)) {
	if (IoTYPE(io) == IoTYPE_PIPE) {
	    status = PerlProc_pclose(IoIFP(io));
	    if (not_implicit) {
		STATUS_NATIVE_SET(status);
		retval = (STATUS_POSIX == 0);
	    }
	    else {
		retval = (status != -1);
	    }
	}
	else if (IoTYPE(io) == IoTYPE_STD)
	    retval = TRUE;
	else {
	    if (IoOFP(io) && IoOFP(io) != IoIFP(io)) {		/* a socket */
		retval = (PerlIO_close(IoOFP(io)) != EOF);
		PerlIO_close(IoIFP(io));	/* clear stdio, fd already closed */
	    }
	    else
		retval = (PerlIO_close(IoIFP(io)) != EOF);
	}
	IoOFP(io) = IoIFP(io) = Nullfp;
    }
    else if (not_implicit) {
	SETERRNO(EBADF,SS_IVCHAN);
    }

    return retval;
}

bool
Perl_do_eof(pTHX_ GV *gv)
{
    register IO *io;
    int ch;

    io = GvIO(gv);

    if (!io)
	return TRUE;
    else if (ckWARN(WARN_IO) && (IoTYPE(io) == IoTYPE_WRONLY))
	report_evil_fh(gv, io, OP_phoney_OUTPUT_ONLY);

    while (IoIFP(io)) {
        int saverrno;

        if (PerlIO_has_cntptr(IoIFP(io))) {	/* (the code works without this) */
	    if (PerlIO_get_cnt(IoIFP(io)) > 0)	/* cheat a little, since */
		return FALSE;			/* this is the most usual case */
        }

	saverrno = errno; /* getc and ungetc can stomp on errno */
	ch = PerlIO_getc(IoIFP(io));
	if (ch != EOF) {
	    (void)PerlIO_ungetc(IoIFP(io),ch);
	    errno = saverrno;
	    return FALSE;
	}
	errno = saverrno;

        if (PerlIO_has_cntptr(IoIFP(io)) && PerlIO_canset_cnt(IoIFP(io))) {
	    if (PerlIO_get_cnt(IoIFP(io)) < -1)
		PerlIO_set_cnt(IoIFP(io),-1);
	}
	if (PL_op->op_flags & OPf_SPECIAL) { /* not necessarily a real EOF yet? */
	    if (gv != PL_argvgv || !nextargv(gv))	/* get another fp handy */
		return TRUE;
	}
	else
	    return TRUE;		/* normal fp, definitely end of file */
    }
    return TRUE;
}

Off_t
Perl_do_tell(pTHX_ GV *gv)
{
    register IO *io = 0;
    register PerlIO *fp;

    if (gv && (io = GvIO(gv)) && (fp = IoIFP(io))) {
#ifdef ULTRIX_STDIO_BOTCH
	if (PerlIO_eof(fp))
	    (void)PerlIO_seek(fp, 0L, 2);	/* ultrix 1.2 workaround */
#endif
	return PerlIO_tell(fp);
    }
    if (ckWARN2(WARN_UNOPENED,WARN_CLOSED))
	report_evil_fh(gv, io, PL_op->op_type);
    SETERRNO(EBADF,RMS_IFI);
    return (Off_t)-1;
}

bool
Perl_do_seek(pTHX_ GV *gv, Off_t pos, int whence)
{
    register IO *io = 0;
    register PerlIO *fp;

    if (gv && (io = GvIO(gv)) && (fp = IoIFP(io))) {
#ifdef ULTRIX_STDIO_BOTCH
	if (PerlIO_eof(fp))
	    (void)PerlIO_seek(fp, 0L, 2);	/* ultrix 1.2 workaround */
#endif
	return PerlIO_seek(fp, pos, whence) >= 0;
    }
    if (ckWARN2(WARN_UNOPENED,WARN_CLOSED))
	report_evil_fh(gv, io, PL_op->op_type);
    SETERRNO(EBADF,RMS_IFI);
    return FALSE;
}

Off_t
Perl_do_sysseek(pTHX_ GV *gv, Off_t pos, int whence)
{
    register IO *io = 0;
    register PerlIO *fp;

    if (gv && (io = GvIO(gv)) && (fp = IoIFP(io)))
	return PerlLIO_lseek(PerlIO_fileno(fp), pos, whence);
    if (ckWARN2(WARN_UNOPENED,WARN_CLOSED))
	report_evil_fh(gv, io, PL_op->op_type);
    SETERRNO(EBADF,RMS_IFI);
    return (Off_t)-1;
}

int
Perl_mode_from_discipline(pTHX_ SV *discp)
{
    int mode = O_BINARY;
    if (discp) {
	STRLEN len;
	char *s = SvPV(discp,len);
	while (*s) {
	    if (*s == ':') {
		switch (s[1]) {
		case 'r':
		    if (s[2] == 'a' && s[3] == 'w'
			&& (!s[4] || s[4] == ':' || isSPACE(s[4])))
		    {
			mode = O_BINARY;
			s += 4;
			len -= 4;
			break;
		    }
		    /* FALL THROUGH */
		case 'c':
		    if (s[2] == 'r' && s[3] == 'l' && s[4] == 'f'
			&& (!s[5] || s[5] == ':' || isSPACE(s[5])))
		    {
			mode = O_TEXT;
			s += 5;
			len -= 5;
			break;
		    }
		    /* FALL THROUGH */
		default:
		    goto fail_discipline;
		}
	    }
	    else if (isSPACE(*s)) {
		++s;
		--len;
	    }
	    else {
		char *end;
fail_discipline:
		end = strchr(s+1, ':');
		if (!end)
		    end = s+len;
#ifndef PERLIO_LAYERS
		Perl_croak(aTHX_ "IO layers (like '%.*s') unavailable", end-s, s);
#else
		len -= end-s;
		s = end;
#endif
	    }
	}
    }
    return mode;
}

int
Perl_do_binmode(pTHX_ PerlIO *fp, int iotype, int mode)
{
 /* The old body of this is now in non-LAYER part of perlio.c
  * This is a stub for any XS code which might have been calling it.
  */
 char *name = ":raw";
#ifdef PERLIO_USING_CRLF
 if (!(mode & O_BINARY))
     name = ":crlf";
#endif
 return PerlIO_binmode(aTHX_ fp, iotype, mode, name);
}

#if !defined(HAS_TRUNCATE) && !defined(HAS_CHSIZE) && defined(F_FREESP)
	/* code courtesy of William Kucharski */
#define HAS_CHSIZE

I32 my_chsize(fd, length)
I32 fd;			/* file descriptor */
Off_t length;		/* length to set file to */
{
    struct flock fl;
    Stat_t filebuf;

    if (PerlLIO_fstat(fd, &filebuf) < 0)
	return -1;

    if (filebuf.st_size < length) {

	/* extend file length */

	if ((PerlLIO_lseek(fd, (length - 1), 0)) < 0)
	    return -1;

	/* write a "0" byte */

	if ((PerlLIO_write(fd, "", 1)) != 1)
	    return -1;
    }
    else {
	/* truncate length */

	fl.l_whence = 0;
	fl.l_len = 0;
	fl.l_start = length;
	fl.l_type = F_WRLCK;    /* write lock on file space */

	/*
	* This relies on the UNDOCUMENTED F_FREESP argument to
	* fcntl(2), which truncates the file so that it ends at the
	* position indicated by fl.l_start.
	*
	* Will minor miracles never cease?
	*/

	if (fcntl(fd, F_FREESP, &fl) < 0)
	    return -1;

    }

    return 0;
}
#endif /* F_FREESP */

bool
Perl_do_print(pTHX_ register SV *sv, PerlIO *fp)
{
    register char *tmps;
    STRLEN len;

    /* assuming fp is checked earlier */
    if (!sv)
	return TRUE;
    if (PL_ofmt) {
	if (SvGMAGICAL(sv))
	    mg_get(sv);
        if (SvIOK(sv) && SvIVX(sv) != 0) {
	    PerlIO_printf(fp, PL_ofmt, (NV)SvIVX(sv));
	    return !PerlIO_error(fp);
	}
	if (  (SvNOK(sv) && SvNVX(sv) != 0.0)
	   || (looks_like_number(sv) && sv_2nv(sv) != 0.0) ) {
	    PerlIO_printf(fp, PL_ofmt, SvNVX(sv));
	    return !PerlIO_error(fp);
	}
    }
    switch (SvTYPE(sv)) {
    case SVt_NULL:
	if (ckWARN(WARN_UNINITIALIZED))
	    report_uninit(sv);
	return TRUE;
    case SVt_IV:
	if (SvIOK(sv)) {
	    if (SvGMAGICAL(sv))
		mg_get(sv);
	    if (SvIsUV(sv))
		PerlIO_printf(fp, "%"UVuf, (UV)SvUVX(sv));
	    else
		PerlIO_printf(fp, "%"IVdf, (IV)SvIVX(sv));
	    return !PerlIO_error(fp);
	}
	/* FALL THROUGH */
    default:
	if (PerlIO_isutf8(fp)) {
	    if (!SvUTF8(sv))
		sv_utf8_upgrade_flags(sv = sv_mortalcopy(sv),
				      SV_GMAGIC|SV_UTF8_NO_ENCODING);
	}
	else if (DO_UTF8(sv)) {
	    if (!sv_utf8_downgrade((sv = sv_mortalcopy(sv)), TRUE)
		&& ckWARN_d(WARN_UTF8))
	    {
		Perl_warner(aTHX_ packWARN(WARN_UTF8), "Wide character in print");
	    }
	}
	tmps = SvPV(sv, len);
	break;
    }
    /* To detect whether the process is about to overstep its
     * filesize limit we would need getrlimit().  We could then
     * also transparently raise the limit with setrlimit() --
     * but only until the system hard limit/the filesystem limit,
     * at which we would get EPERM.  Note that when using buffered
     * io the write failure can be delayed until the flush/close. --jhi */
    if (len && (PerlIO_write(fp,tmps,len) == 0))
	return FALSE;
    return !PerlIO_error(fp);
}

I32
Perl_my_stat(pTHX)
{
    dSP;
    IO *io;
    GV* gv;

    if (PL_op->op_flags & OPf_REF) {
	EXTEND(SP,1);
	gv = cGVOP_gv;
      do_fstat:
	io = GvIO(gv);
	if (io && IoIFP(io)) {
	    PL_statgv = gv;
	    sv_setpv(PL_statname,"");
	    PL_laststype = OP_STAT;
	    return (PL_laststatval = PerlLIO_fstat(PerlIO_fileno(IoIFP(io)), &PL_statcache));
	}
	else {
	    if (gv == PL_defgv)
		return PL_laststatval;
	    if (ckWARN2(WARN_UNOPENED,WARN_CLOSED))
		report_evil_fh(gv, io, PL_op->op_type);
	    PL_statgv = Nullgv;
	    sv_setpv(PL_statname,"");
	    return (PL_laststatval = -1);
	}
    }
    else if (PL_op->op_private & OPpFT_STACKED) {
	return PL_laststatval;
    }
    else {
	SV* sv = POPs;
	char *s;
	STRLEN len;
	PUTBACK;
	if (SvTYPE(sv) == SVt_PVGV) {
	    gv = (GV*)sv;
	    goto do_fstat;
	}
	else if (SvROK(sv) && SvTYPE(SvRV(sv)) == SVt_PVGV) {
	    gv = (GV*)SvRV(sv);
	    goto do_fstat;
	}

	s = SvPV(sv, len);
	PL_statgv = Nullgv;
	sv_setpvn(PL_statname, s, len);
	s = SvPVX(PL_statname);		/* s now NUL-terminated */
	PL_laststype = OP_STAT;
	PL_laststatval = PerlLIO_stat(s, &PL_statcache);
	if (PL_laststatval < 0 && ckWARN(WARN_NEWLINE) && strchr(s, '\n'))
	    Perl_warner(aTHX_ packWARN(WARN_NEWLINE), PL_warn_nl, "stat");
	return PL_laststatval;
    }
}

static char no_prev_lstat[] = "The stat preceding -l _ wasn't an lstat";

I32
Perl_my_lstat(pTHX)
{
    dSP;
    SV *sv;
    STRLEN n_a;
    if (PL_op->op_flags & OPf_REF) {
	EXTEND(SP,1);
	if (cGVOP_gv == PL_defgv) {
	    if (PL_laststype != OP_LSTAT)
		Perl_croak(aTHX_ no_prev_lstat);
	    return PL_laststatval;
	}
	if (ckWARN(WARN_IO)) {
	    Perl_warner(aTHX_ packWARN(WARN_IO), "Use of -l on filehandle %s",
		    GvENAME(cGVOP_gv));
	    return (PL_laststatval = -1);
	}
    }
    else if (ckWARN(WARN_IO) && PL_laststype != OP_LSTAT
	    && (PL_op->op_private & OPpFT_STACKED))
	Perl_croak(aTHX_ no_prev_lstat);

    PL_laststype = OP_LSTAT;
    PL_statgv = Nullgv;
    sv = POPs;
    PUTBACK;
    if (SvROK(sv) && SvTYPE(SvRV(sv)) == SVt_PVGV && ckWARN(WARN_IO)) {
	Perl_warner(aTHX_ packWARN(WARN_IO), "Use of -l on filehandle %s",
		GvENAME((GV*) SvRV(sv)));
	return (PL_laststatval = -1);
    }
    sv_setpv(PL_statname,SvPV(sv, n_a));
    PL_laststatval = PerlLIO_lstat(SvPV(sv, n_a),&PL_statcache);
    if (PL_laststatval < 0 && ckWARN(WARN_NEWLINE) && strchr(SvPV(sv, n_a), '\n'))
	Perl_warner(aTHX_ packWARN(WARN_NEWLINE), PL_warn_nl, "lstat");
    return PL_laststatval;
}

#ifndef OS2
bool
Perl_do_aexec(pTHX_ SV *really, register SV **mark, register SV **sp)
{
    return do_aexec5(really, mark, sp, 0, 0);
}
#endif

bool
Perl_do_aexec5(pTHX_ SV *really, register SV **mark, register SV **sp,
	       int fd, int do_report)
{
#ifdef MACOS_TRADITIONAL
    Perl_croak(aTHX_ "exec? I'm not *that* kind of operating system");
#else
    register char **a;
    char *tmps = Nullch;
    STRLEN n_a;

    if (sp > mark) {
	New(401,PL_Argv, sp - mark + 1, char*);
	a = PL_Argv;
	while (++mark <= sp) {
	    if (*mark)
		*a++ = SvPVx(*mark, n_a);
	    else
		*a++ = "";
	}
	*a = Nullch;
	if (really)
	    tmps = SvPV(really, n_a);
	if ((!really && *PL_Argv[0] != '/') ||
	    (really && *tmps != '/'))		/* will execvp use PATH? */
	    TAINT_ENV();		/* testing IFS here is overkill, probably */
	PERL_FPU_PRE_EXEC
	if (really && *tmps)
	    PerlProc_execvp(tmps,EXEC_ARGV_CAST(PL_Argv));
	else
	    PerlProc_execvp(PL_Argv[0],EXEC_ARGV_CAST(PL_Argv));
	PERL_FPU_POST_EXEC
	if (ckWARN(WARN_EXEC))
	    Perl_warner(aTHX_ packWARN(WARN_EXEC), "Can't exec \"%s\": %s",
		(really ? tmps : PL_Argv[0]), Strerror(errno));
	if (do_report) {
	    int e = errno;

	    PerlLIO_write(fd, (void*)&e, sizeof(int));
	    PerlLIO_close(fd);
	}
    }
    do_execfree();
#endif
    return FALSE;
}

void
Perl_do_execfree(pTHX)
{
    if (PL_Argv) {
	Safefree(PL_Argv);
	PL_Argv = Null(char **);
    }
    if (PL_Cmd) {
	Safefree(PL_Cmd);
	PL_Cmd = Nullch;
    }
}

#if !defined(OS2) && !defined(WIN32) && !defined(DJGPP) && !defined(EPOC) && !defined(MACOS_TRADITIONAL)

bool
Perl_do_exec(pTHX_ char *cmd)
{
    return do_exec3(cmd,0,0);
}

bool
Perl_do_exec3(pTHX_ char *cmd, int fd, int do_report)
{
    register char **a;
    register char *s;

    while (*cmd && isSPACE(*cmd))
	cmd++;

    /* save an extra exec if possible */

#ifdef CSH
    {
        char flags[10];
	if (strnEQ(cmd,PL_cshname,PL_cshlen) &&
	    strnEQ(cmd+PL_cshlen," -c",3)) {
	  strcpy(flags,"-c");
	  s = cmd+PL_cshlen+3;
	  if (*s == 'f') {
	      s++;
	      strcat(flags,"f");
	  }
	  if (*s == ' ')
	      s++;
	  if (*s++ == '\'') {
	      char *ncmd = s;

	      while (*s)
		  s++;
	      if (s[-1] == '\n')
		  *--s = '\0';
	      if (s[-1] == '\'') {
		  *--s = '\0';
		  PERL_FPU_PRE_EXEC
		  PerlProc_execl(PL_cshname,"csh", flags, ncmd, (char*)0);
		  PERL_FPU_POST_EXEC
		  *s = '\'';
		  return FALSE;
	      }
	  }
	}
    }
#endif /* CSH */

    /* see if there are shell metacharacters in it */

    if (*cmd == '.' && isSPACE(cmd[1]))
	goto doshell;

    if (strnEQ(cmd,"exec",4) && isSPACE(cmd[4]))
	goto doshell;

    for (s = cmd; *s && isALNUM(*s); s++) ;	/* catch VAR=val gizmo */
    if (*s == '=')
	goto doshell;

    for (s = cmd; *s; s++) {
	if (*s != ' ' && !isALPHA(*s) &&
	    strchr("$&*(){}[]'\";\\|?<>~`\n",*s)) {
	    if (*s == '\n' && !s[1]) {
		*s = '\0';
		break;
	    }
	    /* handle the 2>&1 construct at the end */
	    if (*s == '>' && s[1] == '&' && s[2] == '1'
		&& s > cmd + 1 && s[-1] == '2' && isSPACE(s[-2])
		&& (!s[3] || isSPACE(s[3])))
	    {
		char *t = s + 3;

		while (*t && isSPACE(*t))
		    ++t;
		if (!*t && (PerlLIO_dup2(1,2) != -1)) {
		    s[-2] = '\0';
		    break;
		}
	    }
	  doshell:
	    PERL_FPU_PRE_EXEC
	    PerlProc_execl(PL_sh_path, "sh", "-c", cmd, (char*)0);
	    PERL_FPU_POST_EXEC
	    return FALSE;
	}
    }

    New(402,PL_Argv, (s - cmd) / 2 + 2, char*);
    PL_Cmd = savepvn(cmd, s-cmd);
    a = PL_Argv;
    for (s = PL_Cmd; *s;) {
	while (*s && isSPACE(*s)) s++;
	if (*s)
	    *(a++) = s;
	while (*s && !isSPACE(*s)) s++;
	if (*s)
	    *s++ = '\0';
    }
    *a = Nullch;
    if (PL_Argv[0]) {
	PERL_FPU_PRE_EXEC
	PerlProc_execvp(PL_Argv[0],PL_Argv);
	PERL_FPU_POST_EXEC
	if (errno == ENOEXEC) {		/* for system V NIH syndrome */
	    do_execfree();
	    goto doshell;
	}
	{
	    int e = errno;

	    if (ckWARN(WARN_EXEC))
		Perl_warner(aTHX_ packWARN(WARN_EXEC), "Can't exec \"%s\": %s",
		    PL_Argv[0], Strerror(errno));
	    if (do_report) {
		PerlLIO_write(fd, (void*)&e, sizeof(int));
		PerlLIO_close(fd);
	    }
	}
    }
    do_execfree();
    return FALSE;
}

#endif /* OS2 || WIN32 */

I32
Perl_apply(pTHX_ I32 type, register SV **mark, register SV **sp)
{
    register I32 val;
    register I32 val2;
    register I32 tot = 0;
    char *what;
    char *s;
    SV **oldmark = mark;
    STRLEN n_a;

#define APPLY_TAINT_PROPER() \
    STMT_START {							\
	if (PL_tainted) { TAINT_PROPER(what); }				\
    } STMT_END

    /* This is a first heuristic; it doesn't catch tainting magic. */
    if (PL_tainting) {
	while (++mark <= sp) {
	    if (SvTAINTED(*mark)) {
		TAINT;
		break;
	    }
	}
	mark = oldmark;
    }
    switch (type) {
    case OP_CHMOD:
	what = "chmod";
	APPLY_TAINT_PROPER();
	if (++mark <= sp) {
	    val = SvIVx(*mark);
	    APPLY_TAINT_PROPER();
	    tot = sp - mark;
	    while (++mark <= sp) {
		char *name = SvPVx(*mark, n_a);
		APPLY_TAINT_PROPER();
		if (PerlLIO_chmod(name, val))
		    tot--;
	    }
	}
	break;
#ifdef HAS_CHOWN
    case OP_CHOWN:
	what = "chown";
	APPLY_TAINT_PROPER();
	if (sp - mark > 2) {
	    val = SvIVx(*++mark);
	    val2 = SvIVx(*++mark);
	    APPLY_TAINT_PROPER();
	    tot = sp - mark;
	    while (++mark <= sp) {
		char *name = SvPVx(*mark, n_a);
		APPLY_TAINT_PROPER();
		if (PerlLIO_chown(name, val, val2))
		    tot--;
	    }
	}
	break;
#endif
/*
XXX Should we make lchown() directly available from perl?
For now, we'll let Configure test for HAS_LCHOWN, but do
nothing in the core.
    --AD  5/1998
*/
#ifdef HAS_KILL
    case OP_KILL:
	what = "kill";
	APPLY_TAINT_PROPER();
	if (mark == sp)
	    break;
	s = SvPVx(*++mark, n_a);
	if (isALPHA(*s)) {
	    if (*s == 'S' && s[1] == 'I' && s[2] == 'G')
		s += 3;
	    if ((val = whichsig(s)) < 0)
		Perl_croak(aTHX_ "Unrecognized signal name \"%s\"",s);
	}
	else
	    val = SvIVx(*mark);
	APPLY_TAINT_PROPER();
	tot = sp - mark;
#ifdef VMS
	/* kill() doesn't do process groups (job trees?) under VMS */
	if (val < 0) val = -val;
	if (val == SIGKILL) {
#	    include <starlet.h>
	    /* Use native sys$delprc() to insure that target process is
	     * deleted; supervisor-mode images don't pay attention to
	     * CRTL's emulation of Unix-style signals and kill()
	     */
	    while (++mark <= sp) {
		I32 proc = SvIVx(*mark);
		register unsigned long int __vmssts;
		APPLY_TAINT_PROPER();
		if (!((__vmssts = sys$delprc(&proc,0)) & 1)) {
		    tot--;
		    switch (__vmssts) {
			case SS$_NONEXPR:
			case SS$_NOSUCHNODE:
			    SETERRNO(ESRCH,__vmssts);
			    break;
			case SS$_NOPRIV:
			    SETERRNO(EPERM,__vmssts);
			    break;
			default:
			    SETERRNO(EVMSERR,__vmssts);
		    }
		}
	    }
	    break;
	}
#endif
	if (val < 0) {
	    val = -val;
	    while (++mark <= sp) {
		I32 proc = SvIVx(*mark);
		APPLY_TAINT_PROPER();
#ifdef HAS_KILLPG
		if (PerlProc_killpg(proc,val))	/* BSD */
#else
		if (PerlProc_kill(-proc,val))	/* SYSV */
#endif
		    tot--;
	    }
	}
	else {
	    while (++mark <= sp) {
		I32 proc = SvIVx(*mark);
		APPLY_TAINT_PROPER();
		if (PerlProc_kill(proc, val))
		    tot--;
	    }
	}
	break;
#endif
    case OP_UNLINK:
	what = "unlink";
	APPLY_TAINT_PROPER();
	tot = sp - mark;
	while (++mark <= sp) {
	    s = SvPVx(*mark, n_a);
	    APPLY_TAINT_PROPER();
	    if (PL_euid || PL_unsafe) {
		if (UNLINK(s))
		    tot--;
	    }
	    else {	/* don't let root wipe out directories without -U */
		if (PerlLIO_lstat(s,&PL_statbuf) < 0 || S_ISDIR(PL_statbuf.st_mode))
		    tot--;
		else {
		    if (UNLINK(s))
			tot--;
		}
	    }
	}
	break;
#ifdef HAS_UTIME
    case OP_UTIME:
	what = "utime";
	APPLY_TAINT_PROPER();
	if (sp - mark > 2) {
#if defined(I_UTIME) || defined(VMS)
	    struct utimbuf utbuf;
#else
	    struct {
		Time_t	actime;
		Time_t	modtime;
	    } utbuf;
#endif

           SV* accessed = *++mark;
           SV* modified = *++mark;
           void * utbufp = &utbuf;

           /* Be like C, and if both times are undefined, let the C
            * library figure out what to do.  This usually means
            * "current time". */

           if ( accessed == &PL_sv_undef && modified == &PL_sv_undef )
                utbufp = NULL;
           else {
                Zero(&utbuf, sizeof utbuf, char);
#ifdef BIG_TIME
                utbuf.actime = (Time_t)SvNVx(accessed);  /* time accessed */
                utbuf.modtime = (Time_t)SvNVx(modified); /* time modified */
#else
                utbuf.actime = (Time_t)SvIVx(accessed);  /* time accessed */
                utbuf.modtime = (Time_t)SvIVx(modified); /* time modified */
#endif
            }
            APPLY_TAINT_PROPER();
	    tot = sp - mark;
	    while (++mark <= sp) {
		char *name = SvPVx(*mark, n_a);
		APPLY_TAINT_PROPER();
               if (PerlLIO_utime(name, utbufp))
		    tot--;
	    }
	}
	else
	    tot = 0;
	break;
#endif
    }
    return tot;

#undef APPLY_TAINT_PROPER
}

/* Do the permissions allow some operation?  Assumes statcache already set. */
#ifndef VMS /* VMS' cando is in vms.c */
bool
Perl_cando(pTHX_ Mode_t mode, Uid_t effective, register Stat_t *statbufp)
/* Note: we use `effective' both for uids and gids.
 * Here we are betting on Uid_t being equal or wider than Gid_t.  */
{
#ifdef DOSISH
    /* [Comments and code from Len Reed]
     * MS-DOS "user" is similar to UNIX's "superuser," but can't write
     * to write-protected files.  The execute permission bit is set
     * by the Miscrosoft C library stat() function for the following:
     *		.exe files
     *		.com files
     *		.bat files
     *		directories
     * All files and directories are readable.
     * Directories and special files, e.g. "CON", cannot be
     * write-protected.
     * [Comment by Tom Dinger -- a directory can have the write-protect
     *		bit set in the file system, but DOS permits changes to
     *		the directory anyway.  In addition, all bets are off
     *		here for networked software, such as Novell and
     *		Sun's PC-NFS.]
     */

     /* Atari stat() does pretty much the same thing. we set x_bit_set_in_stat
      * too so it will actually look into the files for magic numbers
      */
     return (mode & statbufp->st_mode) ? TRUE : FALSE;

#else /* ! DOSISH */
    if ((effective ? PL_euid : PL_uid) == 0) {	/* root is special */
	if (mode == S_IXUSR) {
	    if (statbufp->st_mode & 0111 || S_ISDIR(statbufp->st_mode))
		return TRUE;
	}
	else
	    return TRUE;		/* root reads and writes anything */
	return FALSE;
    }
    if (statbufp->st_uid == (effective ? PL_euid : PL_uid) ) {
	if (statbufp->st_mode & mode)
	    return TRUE;	/* ok as "user" */
    }
    else if (ingroup(statbufp->st_gid,effective)) {
	if (statbufp->st_mode & mode >> 3)
	    return TRUE;	/* ok as "group" */
    }
    else if (statbufp->st_mode & mode >> 6)
	return TRUE;	/* ok as "other" */
    return FALSE;
#endif /* ! DOSISH */
}
#endif /* ! VMS */

bool
Perl_ingroup(pTHX_ Gid_t testgid, Uid_t effective)
{
#ifdef MACOS_TRADITIONAL
    /* This is simply not correct for AppleShare, but fix it yerself. */
    return TRUE;
#else
    if (testgid == (effective ? PL_egid : PL_gid))
	return TRUE;
#ifdef HAS_GETGROUPS
#ifndef NGROUPS
#define NGROUPS 32
#endif
    {
	Groups_t gary[NGROUPS];
	I32 anum;

	anum = getgroups(NGROUPS,gary);
	while (--anum >= 0)
	    if (gary[anum] == testgid)
		return TRUE;
    }
#endif
    return FALSE;
#endif
}

#if defined(HAS_MSG) || defined(HAS_SEM) || defined(HAS_SHM)

I32
Perl_do_ipcget(pTHX_ I32 optype, SV **mark, SV **sp)
{
    key_t key;
    I32 n, flags;

    key = (key_t)SvNVx(*++mark);
    n = (optype == OP_MSGGET) ? 0 : SvIVx(*++mark);
    flags = SvIVx(*++mark);
    SETERRNO(0,0);
    switch (optype)
    {
#ifdef HAS_MSG
    case OP_MSGGET:
	return msgget(key, flags);
#endif
#ifdef HAS_SEM
    case OP_SEMGET:
	return semget(key, n, flags);
#endif
#ifdef HAS_SHM
    case OP_SHMGET:
	return shmget(key, n, flags);
#endif
#if !defined(HAS_MSG) || !defined(HAS_SEM) || !defined(HAS_SHM)
    default:
	Perl_croak(aTHX_ "%s not implemented", PL_op_desc[optype]);
#endif
    }
    return -1;			/* should never happen */
}

I32
Perl_do_ipcctl(pTHX_ I32 optype, SV **mark, SV **sp)
{
    SV *astr;
    char *a;
    I32 id, n, cmd, infosize, getinfo;
    I32 ret = -1;

    id = SvIVx(*++mark);
    n = (optype == OP_SEMCTL) ? SvIVx(*++mark) : 0;
    cmd = SvIVx(*++mark);
    astr = *++mark;
    infosize = 0;
    getinfo = (cmd == IPC_STAT);

    switch (optype)
    {
#ifdef HAS_MSG
    case OP_MSGCTL:
	if (cmd == IPC_STAT || cmd == IPC_SET)
	    infosize = sizeof(struct msqid_ds);
	break;
#endif
#ifdef HAS_SHM
    case OP_SHMCTL:
	if (cmd == IPC_STAT || cmd == IPC_SET)
	    infosize = sizeof(struct shmid_ds);
	break;
#endif
#ifdef HAS_SEM
    case OP_SEMCTL:
#ifdef Semctl
	if (cmd == IPC_STAT || cmd == IPC_SET)
	    infosize = sizeof(struct semid_ds);
	else if (cmd == GETALL || cmd == SETALL)
	{
	    struct semid_ds semds;
	    union semun semun;
#ifdef EXTRA_F_IN_SEMUN_BUF
            semun.buff = &semds;
#else
            semun.buf = &semds;
#endif
	    getinfo = (cmd == GETALL);
	    if (Semctl(id, 0, IPC_STAT, semun) == -1)
		return -1;
	    infosize = semds.sem_nsems * sizeof(short);
		/* "short" is technically wrong but much more portable
		   than guessing about u_?short(_t)? */
	}
#else
	Perl_croak(aTHX_ "%s not implemented", PL_op_desc[optype]);
#endif
	break;
#endif
#if !defined(HAS_MSG) || !defined(HAS_SEM) || !defined(HAS_SHM)
    default:
	Perl_croak(aTHX_ "%s not implemented", PL_op_desc[optype]);
#endif
    }

    if (infosize)
    {
	STRLEN len;
	if (getinfo)
	{
	    SvPV_force(astr, len);
	    a = SvGROW(astr, infosize+1);
	}
	else
	{
	    a = SvPV(astr, len);
	    if (len != infosize)
		Perl_croak(aTHX_ "Bad arg length for %s, is %lu, should be %ld",
		      PL_op_desc[optype],
		      (unsigned long)len,
		      (long)infosize);
	}
    }
    else
    {
	IV i = SvIV(astr);
	a = INT2PTR(char *,i);		/* ouch */
    }
    SETERRNO(0,0);
    switch (optype)
    {
#ifdef HAS_MSG
    case OP_MSGCTL:
	ret = msgctl(id, cmd, (struct msqid_ds *)a);
	break;
#endif
#ifdef HAS_SEM
    case OP_SEMCTL: {
#ifdef Semctl
            union semun unsemds;

#ifdef EXTRA_F_IN_SEMUN_BUF
            unsemds.buff = (struct semid_ds *)a;
#else
            unsemds.buf = (struct semid_ds *)a;
#endif
	    ret = Semctl(id, n, cmd, unsemds);
#else
	    Perl_croak(aTHX_ "%s not implemented", PL_op_desc[optype]);
#endif
        }
	break;
#endif
#ifdef HAS_SHM
    case OP_SHMCTL:
	ret = shmctl(id, cmd, (struct shmid_ds *)a);
	break;
#endif
    }
    if (getinfo && ret >= 0) {
	SvCUR_set(astr, infosize);
	*SvEND(astr) = '\0';
	SvSETMAGIC(astr);
    }
    return ret;
}

I32
Perl_do_msgsnd(pTHX_ SV **mark, SV **sp)
{
#ifdef HAS_MSG
    SV *mstr;
    char *mbuf;
    I32 id, msize, flags;
    STRLEN len;

    id = SvIVx(*++mark);
    mstr = *++mark;
    flags = SvIVx(*++mark);
    mbuf = SvPV(mstr, len);
    if ((msize = len - sizeof(long)) < 0)
	Perl_croak(aTHX_ "Arg too short for msgsnd");
    SETERRNO(0,0);
    return msgsnd(id, (struct msgbuf *)mbuf, msize, flags);
#else
    Perl_croak(aTHX_ "msgsnd not implemented");
#endif
}

I32
Perl_do_msgrcv(pTHX_ SV **mark, SV **sp)
{
#ifdef HAS_MSG
    SV *mstr;
    char *mbuf;
    long mtype;
    I32 id, msize, flags, ret;
    STRLEN len;

    id = SvIVx(*++mark);
    mstr = *++mark;
    /* suppress warning when reading into undef var --jhi */
    if (! SvOK(mstr))
	sv_setpvn(mstr, "", 0);
    msize = SvIVx(*++mark);
    mtype = (long)SvIVx(*++mark);
    flags = SvIVx(*++mark);
    SvPV_force(mstr, len);
    mbuf = SvGROW(mstr, sizeof(long)+msize+1);

    SETERRNO(0,0);
    ret = msgrcv(id, (struct msgbuf *)mbuf, msize, mtype, flags);
    if (ret >= 0) {
	SvCUR_set(mstr, sizeof(long)+ret);
	*SvEND(mstr) = '\0';
#ifndef INCOMPLETE_TAINTS
	/* who knows who has been playing with this message? */
	SvTAINTED_on(mstr);
#endif
    }
    return ret;
#else
    Perl_croak(aTHX_ "msgrcv not implemented");
#endif
}

I32
Perl_do_semop(pTHX_ SV **mark, SV **sp)
{
#ifdef HAS_SEM
    SV *opstr;
    char *opbuf;
    I32 id;
    STRLEN opsize;

    id = SvIVx(*++mark);
    opstr = *++mark;
    opbuf = SvPV(opstr, opsize);
    if (opsize < 3 * SHORTSIZE
	|| (opsize % (3 * SHORTSIZE))) {
	SETERRNO(EINVAL,LIB_INVARG);
	return -1;
    }
    SETERRNO(0,0);
    /* We can't assume that sizeof(struct sembuf) == 3 * sizeof(short). */
    {
        int nsops  = opsize / (3 * sizeof (short));
        int i      = nsops;
        short *ops = (short *) opbuf;
        short *o   = ops;
        struct sembuf *temps, *t;
        I32 result;

        New (0, temps, nsops, struct sembuf);
        t = temps;
        while (i--) {
            t->sem_num = *o++;
            t->sem_op  = *o++;
            t->sem_flg = *o++;
            t++;
        }
        result = semop(id, temps, nsops);
        t = temps;
        o = ops;
        i = nsops;
        while (i--) {
            *o++ = t->sem_num;
            *o++ = t->sem_op;
            *o++ = t->sem_flg;
            t++;
        }
        Safefree(temps);
        return result;
    }
#else
    Perl_croak(aTHX_ "semop not implemented");
#endif
}

I32
Perl_do_shmio(pTHX_ I32 optype, SV **mark, SV **sp)
{
#ifdef HAS_SHM
    SV *mstr;
    char *mbuf, *shm;
    I32 id, mpos, msize;
    STRLEN len;
    struct shmid_ds shmds;

    id = SvIVx(*++mark);
    mstr = *++mark;
    mpos = SvIVx(*++mark);
    msize = SvIVx(*++mark);
    SETERRNO(0,0);
    if (shmctl(id, IPC_STAT, &shmds) == -1)
	return -1;
    if (mpos < 0 || msize < 0 || mpos + msize > shmds.shm_segsz) {
	SETERRNO(EFAULT,SS_ACCVIO);		/* can't do as caller requested */
	return -1;
    }
    shm = (char *)shmat(id, (char*)NULL, (optype == OP_SHMREAD) ? SHM_RDONLY : 0);
    if (shm == (char *)-1)	/* I hate System V IPC, I really do */
	return -1;
    if (optype == OP_SHMREAD) {
	/* suppress warning when reading into undef var (tchrist 3/Mar/00) */
	if (! SvOK(mstr))
	    sv_setpvn(mstr, "", 0);
	SvPV_force(mstr, len);
	mbuf = SvGROW(mstr, msize+1);

	Copy(shm + mpos, mbuf, msize, char);
	SvCUR_set(mstr, msize);
	*SvEND(mstr) = '\0';
	SvSETMAGIC(mstr);
#ifndef INCOMPLETE_TAINTS
	/* who knows who has been playing with this shared memory? */
	SvTAINTED_on(mstr);
#endif
    }
    else {
	I32 n;

	mbuf = SvPV(mstr, len);
	if ((n = len) > msize)
	    n = msize;
	Copy(mbuf, shm + mpos, n, char);
	if (n < msize)
	    memzero(shm + mpos + n, msize - n);
    }
    return shmdt(shm);
#else
    Perl_croak(aTHX_ "shm I/O not implemented");
#endif
}

#endif /* SYSV IPC */

/*
=head1 IO Functions

=for apidoc start_glob

Function called by C<do_readline> to spawn a glob (or do the glob inside
perl on VMS). This code used to be inline, but now perl uses C<File::Glob>
this glob starter is only used by miniperl during the build process.
Moving it away shrinks pp_hot.c; shrinking pp_hot.c helps speed perl up.

=cut
*/

PerlIO *
Perl_start_glob (pTHX_ SV *tmpglob, IO *io)
{
    SV *tmpcmd = NEWSV(55, 0);
    PerlIO *fp;
    ENTER;
    SAVEFREESV(tmpcmd);
#ifdef VMS /* expand the wildcards right here, rather than opening a pipe, */
           /* since spawning off a process is a real performance hit */
    {
#include <descrip.h>
#include <lib$routines.h>
#include <nam.h>
#include <rmsdef.h>
	char rslt[NAM$C_MAXRSS+1+sizeof(unsigned short int)] = {'\0','\0'};
	char vmsspec[NAM$C_MAXRSS+1];
	char *rstr = rslt + sizeof(unsigned short int), *begin, *end, *cp;
	$DESCRIPTOR(dfltdsc,"SYS$DISK:[]*.*;");
	PerlIO *tmpfp;
	STRLEN i;
	struct dsc$descriptor_s wilddsc
	    = {0, DSC$K_DTYPE_T, DSC$K_CLASS_S, 0};
	struct dsc$descriptor_vs rsdsc
	    = {sizeof rslt, DSC$K_DTYPE_VT, DSC$K_CLASS_VS, rslt};
	unsigned long int cxt = 0, sts = 0, ok = 1, hasdir = 0, hasver = 0, isunix = 0;

	/* We could find out if there's an explicit dev/dir or version
	   by peeking into lib$find_file's internal context at
	   ((struct NAM *)((struct FAB *)cxt)->fab$l_nam)->nam$l_fnb
	   but that's unsupported, so I don't want to do it now and
	   have it bite someone in the future. */
	cp = SvPV(tmpglob,i);
	for (; i; i--) {
	    if (cp[i] == ';') hasver = 1;
	    if (cp[i] == '.') {
		if (sts) hasver = 1;
		else sts = 1;
	    }
	    if (cp[i] == '/') {
		hasdir = isunix = 1;
		break;
	    }
	    if (cp[i] == ']' || cp[i] == '>' || cp[i] == ':') {
		hasdir = 1;
		break;
	    }
	}
       if ((tmpfp = PerlIO_tmpfile()) != NULL) {
	    Stat_t st;
	    if (!PerlLIO_stat(SvPVX(tmpglob),&st) && S_ISDIR(st.st_mode))
		ok = ((wilddsc.dsc$a_pointer = tovmspath(SvPVX(tmpglob),vmsspec)) != NULL);
	    else ok = ((wilddsc.dsc$a_pointer = tovmsspec(SvPVX(tmpglob),vmsspec)) != NULL);
	    if (ok) wilddsc.dsc$w_length = (unsigned short int) strlen(wilddsc.dsc$a_pointer);
	    for (cp=wilddsc.dsc$a_pointer; ok && cp && *cp; cp++)
		if (*cp == '?') *cp = '%';  /* VMS style single-char wildcard */
	    while (ok && ((sts = lib$find_file(&wilddsc,&rsdsc,&cxt,
					       &dfltdsc,NULL,NULL,NULL))&1)) {
		/* with varying string, 1st word of buffer contains result length */
		end = rstr + *((unsigned short int*)rslt);
		if (!hasver) while (*end != ';' && end > rstr) end--;
		*(end++) = '\n';  *end = '\0';
		for (cp = rstr; *cp; cp++) *cp = _tolower(*cp);
		if (hasdir) {
		    if (isunix) trim_unixpath(rstr,SvPVX(tmpglob),1);
		    begin = rstr;
		}
		else {
		    begin = end;
		    while (*(--begin) != ']' && *begin != '>') ;
		    ++begin;
		}
		ok = (PerlIO_puts(tmpfp,begin) != EOF);
	    }
	    if (cxt) (void)lib$find_file_end(&cxt);
	    if (ok && sts != RMS$_NMF &&
		sts != RMS$_DNF && sts != RMS_FNF) ok = 0;
	    if (!ok) {
		if (!(sts & 1)) {
		    SETERRNO((sts == RMS$_SYN ? EINVAL : EVMSERR),sts);
		}
		PerlIO_close(tmpfp);
		fp = NULL;
	    }
	    else {
		PerlIO_rewind(tmpfp);
		IoTYPE(io) = IoTYPE_RDONLY;
		IoIFP(io) = fp = tmpfp;
		IoFLAGS(io) &= ~IOf_UNTAINT;  /* maybe redundant */
	    }
	}
    }
#else /* !VMS */
#ifdef MACOS_TRADITIONAL
    sv_setpv(tmpcmd, "glob ");
    sv_catsv(tmpcmd, tmpglob);
    sv_catpv(tmpcmd, " |");
#else
#ifdef DOSISH
#ifdef OS2
    sv_setpv(tmpcmd, "for a in ");
    sv_catsv(tmpcmd, tmpglob);
    sv_catpv(tmpcmd, "; do echo \"$a\\0\\c\"; done |");
#else
#ifdef DJGPP
    sv_setpv(tmpcmd, "/dev/dosglob/"); /* File System Extension */
    sv_catsv(tmpcmd, tmpglob);
#else
    sv_setpv(tmpcmd, "perlglob ");
    sv_catsv(tmpcmd, tmpglob);
    sv_catpv(tmpcmd, " |");
#endif /* !DJGPP */
#endif /* !OS2 */
#else /* !DOSISH */
#if defined(CSH)
    sv_setpvn(tmpcmd, PL_cshname, PL_cshlen);
    sv_catpv(tmpcmd, " -cf 'set nonomatch; glob ");
    sv_catsv(tmpcmd, tmpglob);
    sv_catpv(tmpcmd, "' 2>/dev/null |");
#else
    sv_setpv(tmpcmd, "echo ");
    sv_catsv(tmpcmd, tmpglob);
#if 'z' - 'a' == 25
    sv_catpv(tmpcmd, "|tr -s ' \t\f\r' '\\012\\012\\012\\012'|");
#else
    sv_catpv(tmpcmd, "|tr -s ' \t\f\r' '\\n\\n\\n\\n'|");
#endif
#endif /* !CSH */
#endif /* !DOSISH */
#endif /* MACOS_TRADITIONAL */
    (void)do_open(PL_last_in_gv, SvPVX(tmpcmd), SvCUR(tmpcmd),
		  FALSE, O_RDONLY, 0, Nullfp);
    fp = IoIFP(io);
#endif /* !VMS */
    LEAVE;
    return fp;
}