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/* Algorithm::GDiffDelta implementation.
 *
 * Copyright (C) 2003 Davide Libenzi (code derived from libxdiff)
 * Copyright 2004, Geoff Richards
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#ifdef __cplusplus
extern "C" {
#endif
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
#ifdef __cplusplus
}
#endif

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>

#undef assert
#include <assert.h>

#define QEF_BUFSZ 8192

#if 0
#define QEF_DEBUG_IO
#endif


#include "util.c"


static void
careful_fread (void *ptr, size_t size, SV *f, const char *from)
{
#ifdef QEF_DEBUG_IO
    fprintf(stderr, "read from %p (%s): %u bytes ->%p\n", (void *) f, from,
            (unsigned int) size, ptr);
#endif

    if (sv_isobject(f)) {
        I32 n;
        SV *ret, *buf;
        STRLEN len;
        char *str;

        dSP;
        ENTER;
        SAVETMPS;
        PUSHMARK(SP);
        XPUSHs(f);
        /* TODO - possibly use newSVpvn_share to avoid the memcpy
         * and extra allocation for buf? */
        XPUSHs(sv_2mortal(buf = newSVpvn("", 0)));
        XPUSHs(sv_2mortal(newSVuv(size)));
        PUTBACK;
        n = call_method("read", G_SCALAR);
        assert(n == 0 || n == 1);
        SPAGAIN;
        ret = n ? POPs : &PL_sv_undef;
        if (!SvOK(ret))
            croak("error reading from %s: %s", from,
                  SvPV_nolen(get_sv("!", FALSE)));
        if (SvUV(ret) != size)
            croak("%s ends unexpectedly", from);
        if (!SvPOK(buf) || SvCUR(buf) != size)
            croak("'read' method left buffer badly set up", from);
        str = SvPV(buf, len);
        assert(len == size);
        memcpy(ptr, str, size);
        PUTBACK;
        FREETMPS;
        LEAVE;
    }
    else {
        int r = PerlIO_read(IoIFP(sv_2io(f)), ptr, size);
        if (r < 0)
            croak("error reading from %s: %s", from, strerror(errno));
        else if ((size_t) r != size)
            croak("%s ends unexpectedly", from);
    }
}

static void
careful_fwrite (const void *ptr, size_t size, SV *f, const char *to)
{
    I32 n;
    SV *ret;

#ifdef QEF_DEBUG_IO
    fprintf(stderr, "write to %p (%s): %u bytes <-%p\n", (void *) f, to,
            (unsigned int) size, ptr);
#endif

    if (sv_isobject(f)) {
        dSP;
        ENTER;
        SAVETMPS;
        PUSHMARK(SP);
        XPUSHs(f);
        XPUSHs(sv_2mortal(newSVpvn(ptr, size)));
        XPUSHs(sv_2mortal(newSVuv(size)));
        PUTBACK;
        n = call_method("write", G_SCALAR);
        assert(n == 0 || n == 1);
        SPAGAIN;
        ret = n ? POPs : &PL_sv_no;
        n = SvTRUE(ret);
        PUTBACK;
        FREETMPS;
        LEAVE;
        if (!n)
            croak("error writing to %s: %s", to,
                  SvPV_nolen(get_sv("!", FALSE)));
    }
    else {
        if ((size_t) PerlIO_write(IoIFP(sv_2io(f)), ptr, size) != size)
            croak("error writing to %s: %s", to, strerror(errno));
    }
}

static void
careful_fseek_whence (SV *f, Off_t offset, const char *from, int whence)
{
    assert(whence == SEEK_SET || whence == SEEK_CUR || whence == SEEK_END);
#ifdef QEF_DEBUG_IO
    fprintf(stderr, "seek %p (%s): %s %u\n", (void *) f, from,
            (whence == SEEK_SET ? "SEEK_SET" :
             whence == SEEK_CUR ? "SEEK_CUR" : "SEEK_END"),
            (unsigned int) offset);
#endif

    if (sv_isobject(f)) {
        I32 n;
        SV *ret;

        dSP;
        ENTER;
        SAVETMPS;
        PUSHMARK(SP);
        XPUSHs(f);
        XPUSHs(sv_2mortal(newSVuv(offset)));
        XPUSHs(sv_2mortal(newSVuv(whence)));
        PUTBACK;
        n = call_method("seek", G_SCALAR);
        assert(n == 0 || n == 1);
        SPAGAIN;
        ret = n ? POPs : &PL_sv_undef;
        n = SvTRUE(ret);
        PUTBACK;
        FREETMPS;
        LEAVE;
        if (!n)
            croak("error seeking in %s: %s", from,
                  SvPV_nolen(get_sv("!", FALSE)));
    }
    else {
        if (PerlIO_seek(IoIFP(sv_2io(f)), offset, whence))
            croak("error seeking in %s: %s", from, strerror(errno));
    }
}

QEF_INLINE static void
careful_fseek (SV *f, Off_t offset, const char *from)
{
    careful_fseek_whence(f, offset, from, SEEK_SET);
}

static Off_t
careful_ftell (SV *f, const char *from)
{
    Off_t offset;

    if (sv_isobject(f)) {
        I32 n;
        SV *ret;

        dSP;
        ENTER;
        SAVETMPS;
        PUSHMARK(SP);
        XPUSHs(f);
        PUTBACK;
        n = call_method("tell", G_SCALAR);
        assert(n == 0 || n == 1);
        SPAGAIN;
        offset = (Off_t) -1;