document the new flags behaviour and why

[perl5.git] / deb.c

/*    deb.c
 *
 *    Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000, 2001,
 *    2002, 2003, 2004, 2005, 2006, 2007, 2008 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.
 *
 */

/*
 * 'Didst thou think that the eyes of the White Tower were blind?  Nay,
 *  I have seen more than thou knowest, Grey Fool.'        --Denethor
 *
 *     [p.853 of _The Lord of the Rings_, V/vii: "The Pyre of Denethor"]
 */

/*
 * This file contains various utilities for producing debugging output
 * (mainly related to displaying the stack)
 */

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

#if defined(MULTIPLICITY)
void
Perl_deb_nocontext(const char *pat, ...)
{
#ifdef DEBUGGING
    dTHX;
    va_list args;
    PERL_ARGS_ASSERT_DEB_NOCONTEXT;
    va_start(args, pat);
    vdeb(pat, &args);
    va_end(args);
#else
    PERL_UNUSED_ARG(pat);
#endif /* DEBUGGING */
}
#endif

void
Perl_deb(pTHX_ const char *pat, ...)
{
    va_list args;
    PERL_ARGS_ASSERT_DEB;
    va_start(args, pat);
#ifdef DEBUGGING
    vdeb(pat, &args);
#else
    PERL_UNUSED_CONTEXT;
#endif /* DEBUGGING */
    va_end(args);
}

void
Perl_vdeb(pTHX_ const char *pat, va_list *args)
{
#ifdef DEBUGGING
    const char* const file = PL_curcop ? OutCopFILE(PL_curcop) : "<null>";
    const char* const display_file = file ? file : "<free>";
    const long line = PL_curcop ? (long)CopLINE(PL_curcop) : 0;

    PERL_ARGS_ASSERT_VDEB;

    if (DEBUG_v_TEST)
        PerlIO_printf(Perl_debug_log, "(%ld:%s:%ld)\t",
                      (long)PerlProc_getpid(), display_file, line);
    else
        PerlIO_printf(Perl_debug_log, "(%s:%ld)\t", display_file, line);
    (void) PerlIO_vprintf(Perl_debug_log, pat, *args);
#else
    PERL_UNUSED_CONTEXT;
    PERL_UNUSED_ARG(pat);
    PERL_UNUSED_ARG(args);
#endif /* DEBUGGING */
}

I32
Perl_debstackptrs(pTHX)
{
#ifdef DEBUGGING
    PerlIO_printf(Perl_debug_log,
                  "%8" UVxf " %8" UVxf " %8" IVdf " %8" IVdf " %8" IVdf "\n",
                  PTR2UV(PL_curstack), PTR2UV(PL_stack_base),
                  (IV)*PL_markstack_ptr, (IV)(PL_stack_sp-PL_stack_base),
                  (IV)(PL_stack_max-PL_stack_base));
    PerlIO_printf(Perl_debug_log,
                  "%8" UVxf " %8" UVxf " %8" UVuf " %8" UVuf " %8" UVuf "\n",
                  PTR2UV(PL_mainstack), PTR2UV(AvARRAY(PL_curstack)),
                  PTR2UV(PL_mainstack), PTR2UV(AvFILLp(PL_curstack)),
                  PTR2UV(AvMAX(PL_curstack)));
#else
    PERL_UNUSED_CONTEXT;
#endif /* DEBUGGING */
    return 0;
}


/* dump the contents of a particular stack
 * Display stack_base[stack_min+1 .. stack_max],
 * and display the marks whose offsets are contained in addresses
 * PL_markstack[mark_min+1 .. mark_max] and whose values are in the range
 * of the stack values being displayed
 *
 * Only displays top 30 max
 */

STATIC void
S_deb_stack_n(pTHX_ SV** stack_base, I32 stack_min, I32 stack_max,
        I32 mark_min, I32 mark_max)
{
#ifdef DEBUGGING
    I32 i = stack_max - 30;
    const I32 *markscan = PL_markstack + mark_min;

    PERL_ARGS_ASSERT_DEB_STACK_N;

    if (i < stack_min)
        i = stack_min;
    
    while (++markscan <= PL_markstack + mark_max)
        if (*markscan >= i)
            break;

    if (i > stack_min)
        PerlIO_printf(Perl_debug_log, "... ");

    if (stack_base[0] != &PL_sv_undef || stack_max < 0)
        PerlIO_printf(Perl_debug_log, " [STACK UNDERFLOW!!!]\n");
    do {
        ++i;
        if (markscan <= PL_markstack + mark_max && *markscan < i) {
            do {
                ++markscan;
                (void)PerlIO_putc(Perl_debug_log, '*');
            }
            while (markscan <= PL_markstack + mark_max && *markscan < i);
            PerlIO_printf(Perl_debug_log, "  ");
        }
        if (i > stack_max)
            break;
        PerlIO_printf(Perl_debug_log, "%-4s  ", SvPEEK(stack_base[i]));
    }
    while (1);
    PerlIO_printf(Perl_debug_log, "\n");
#else
    PERL_UNUSED_CONTEXT;
    PERL_UNUSED_ARG(stack_base);
    PERL_UNUSED_ARG(stack_min);
    PERL_UNUSED_ARG(stack_max);
    PERL_UNUSED_ARG(mark_min);
    PERL_UNUSED_ARG(mark_max);
#endif /* DEBUGGING */
}


/* dump the current stack */

I32
Perl_debstack(pTHX)
{
#ifndef SKIP_DEBUGGING
    if (CopSTASH_eq(PL_curcop, PL_debstash) && !DEBUG_J_TEST_)
        return 0;

    PerlIO_printf(Perl_debug_log, "    =>  ");
    deb_stack_n(PL_stack_base,
                0,
                PL_stack_sp - PL_stack_base,
                PL_curstackinfo->si_markoff,
                PL_markstack_ptr - PL_markstack);


#endif /* SKIP_DEBUGGING */
    return 0;
}


#ifdef DEBUGGING
static const char * const si_names[] = {
    "UNKNOWN",
    "UNDEF",
    "MAIN",
    "MAGIC",
    "SORT",
    "SIGNAL",
    "OVERLOAD",
    "DESTROY",
    "WARNHOOK",
    "DIEHOOK",
    "REQUIRE",
    "MULTICALL"
};
#endif

/* display all stacks */


void
Perl_deb_stack_all(pTHX)
{
#ifdef DEBUGGING
    I32 si_ix;
    const PERL_SI *si;

    /* rewind to start of chain */
    si = PL_curstackinfo;
    while (si->si_prev)
        si = si->si_prev;

    si_ix=0;
    for (;;)
    {
        const size_t si_name_ix = si->si_type+1; /* -1 is a valid index */
        const char * const si_name =
            si_name_ix < C_ARRAY_LENGTH(si_names) ?
            si_names[si_name_ix] : "????";
        I32 ix;
        PerlIO_printf(Perl_debug_log, "STACK %" IVdf ": %s\n",
                                                (IV)si_ix, si_name);

        for (ix=0; ix<=si->si_cxix; ix++) {

            const PERL_CONTEXT * const cx = &(si->si_cxstack[ix]);
            PerlIO_printf(Perl_debug_log,
                    "  CX %" IVdf ": %-6s => ",
                    (IV)ix, PL_block_type[CxTYPE(cx)]
            );
            /* substitution contexts don't save stack pointers etc) */
            if (CxTYPE(cx) == CXt_SUBST)
                PerlIO_printf(Perl_debug_log, "\n");
            else {

                /* Find the current context's stack range by searching
                 * forward for any higher contexts using this stack; failing
                 * that, it will be equal to the size of the stack for old
                 * stacks, or PL_stack_sp for the current stack
                 */

                I32 i, stack_min, stack_max, mark_min, mark_max;
                const PERL_CONTEXT *cx_n = NULL;
                const PERL_SI *si_n;

                /* there's a separate argument stack per SI, so only
                 * search this one */

                for (i=ix+1; i<=si->si_cxix; i++) {
                    const PERL_CONTEXT *this_cx = &(si->si_cxstack[i]);
                    if (CxTYPE(this_cx) == CXt_SUBST)
                        continue;
                    cx_n = this_cx;
                    break;
                }

                stack_min = cx->blk_oldsp;

                if (cx_n) {
                    stack_max = cx_n->blk_oldsp;
                }
                else if (si == PL_curstackinfo) {
                    stack_max = PL_stack_sp - AvARRAY(si->si_stack);
                }
                else {
                    stack_max = AvFILLp(si->si_stack);
                }

                /* for the markstack, there's only one stack shared
                 * between all SIs */

                si_n = si;
                i = ix;
                cx_n = NULL;
                for (;;) {
                    i++;
                    if (i > si_n->si_cxix) {
                        if (si_n == PL_curstackinfo)
                            break;
                        else {
                            si_n = si_n->si_next;
                            i = 0;
                        }
                    }
                    if (CxTYPE(&(si_n->si_cxstack[i])) == CXt_SUBST)
                        continue;
                    cx_n = &(si_n->si_cxstack[i]);
                    break;
                }

                mark_min  = cx->blk_oldmarksp;
                if (cx_n) {
                    mark_max  = cx_n->blk_oldmarksp;
                }
                else {
                    mark_max = PL_markstack_ptr - PL_markstack;
                }

                deb_stack_n(AvARRAY(si->si_stack),
                        stack_min, stack_max, mark_min, mark_max);

                if (CxTYPE(cx) == CXt_EVAL || CxTYPE(cx) == CXt_SUB
                        || CxTYPE(cx) == CXt_FORMAT)
                {
                    const OP * const retop = cx->blk_sub.retop;

                    PerlIO_printf(Perl_debug_log, "  retop=%s\n",
                            retop ? OP_NAME(retop) : "(null)"
                    );
                }
            }
        } /* next context */


        if (si == PL_curstackinfo)
            break;
        si = si->si_next;
        si_ix++;
        if (!si)
            break; /* shouldn't happen, but just in case.. */
    } /* next stackinfo */

    PerlIO_printf(Perl_debug_log, "\n");
#else
    PERL_UNUSED_CONTEXT;
#endif /* DEBUGGING */
}

/*
 * ex: set ts=8 sts=4 sw=4 et:
 */