path: root/libdwarf/dwarf_sort_line.c

/*
  Copyright (C) 2000-2006 Silicon Graphics, Inc.  All Rights Reserved.
  Portions Copyright (C) 2007-2011 David Anderson. All Rights Reserved.

  This program is free software; you can redistribute it and/or modify it
  under the terms of version 2.1 of the GNU Lesser General Public License 
  as published by the Free Software Foundation.

  This program is distributed in the hope that it would be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  

  Further, this software is distributed without any warranty that it is
  free of the rightful claim of any third person regarding infringement 
  or the like.  Any license provided herein, whether implied or 
  otherwise, applies only to this software file.  Patent licenses, if
  any, provided herein do not apply to combinations of this program with 
  other software, or any other product whatsoever.  

  You should have received a copy of the GNU Lesser General Public 
  License along with this program; if not, write the Free Software 
  Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston MA 02110-1301,
  USA.

  Contact information:  Silicon Graphics, Inc., 1500 Crittenden Lane,
  Mountain View, CA 94043, or:

  http://www.sgi.com

  For further information regarding this notice, see:

  http://oss.sgi.com/projects/GenInfo/NoticeExplan

*/
/* The address of the Free Software Foundation is
   Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, 
   Boston, MA 02110-1301, USA.
   SGI has moved from the Crittenden Lane address.
*/


/*  This file was designed for SGI IRIX compiler use.
    The static linker can rearrange the order of functions
    in the layout in memory
    and provided each has the right  form
    this will (when called by the SGI IRIX
    static linker) rearrange the table so the line table
    is arranged in the same order as the memory layout. */



#include "config.h"
#include "dwarf_incl.h"
#include <stdio.h>
#include <stdlib.h>
#include "dwarf_line.h"
#ifdef HAVE_ALLOCA_H
#include <alloca.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif

#define MINIMUM_POSSIBLE_PROLOG_LEN 10  /* 10 is based on */
/*  the definition of the DWARF2/3 line table prolog. The value
    here should be >8 (accounting for a 64 bit read) and <= the
    length of a legal DWARF2/3 line prolog, which is at least 10 
    bytes long (but can be longer). What this constant helps
    avoid is reading past the end of a malloc'd buffer in
    _dwarf_update_line_sec(). */

static int
_dwarf_update_line_sec(Dwarf_Small * line_ptr,
    unsigned long remaining_bytes,
    int *any_change,
    int length_size,
    int *err_code, Dwarf_Small ** new_line_ptr);

/*  Used to construct
    a linked list of so we can sort and reorder the line info.  */
struct a_line_area {
    Dwarf_Addr ala_address;     /* from DW_LNE_set_address */
    Dwarf_Unsigned ala_offset;  /* byte offset in buffer */
    Dwarf_Unsigned ala_length;  /* byte length in buffer */
    long ala_entry_num;         /* to guarantee stable sort */
    struct a_line_area *ala_next;
};


/*  Written to support the SGI IRIX static linker. 
    It helps SGI IRIX ld 
    rearrange lines in .debug_line in a .o created with a text
    section per function.   The SGI IRIX linker option is: 
        -OPT:procedure_reorder=ON
    where ld-cord (cord(1)ing by ld, 
    not by cord(1)) may have changed the function order.

    Returns
    DW_DLV_OK if nothing went wrong.
    DW_DLV_ERROR if could not do anything due to
        error.  the original buffer is unchanged.

    is_64_bit must be passed in by caller and tells
    if this is a 32 or 64bit pointer object section
    being processed.

    err_code must be a non-null pointer to integer.
    If DW_DLV_ERROR is returned that integer is set
    to a dwarf error code so the caller may
    print it for diagnostic purposes.

    *any_change is set here 
        set 0 if no sorting (movement) done.
        set 1 if some sorting (movement) done.
    on all returns. On error return sets to 0.
        
    The _dwarf name form is now obsolete,
    the dwarf_ name for is preferred.
    Both names supported.  */
int
_dwarf_ld_sort_lines(void *orig_buffer,
    unsigned long buffer_len,
    int is_64_bit, int *any_change, int *err_code)
{
    return dwarf_ld_sort_lines(orig_buffer,buffer_len,
        is_64_bit,any_change,err_code);
}
int
dwarf_ld_sort_lines(void *orig_buffer,
    unsigned long buffer_len,
    int is_64_bit, int *any_change, int *err_code)
{

    int length_size = 4;
    Dwarf_Small *orig_line_ptr; /* our local copy of the user's input
        buffer */
    Dwarf_Small *line_ptr;      /* starts at orig_line_ptr, gets
        incremented thru to end of our copy
        of the input buffer */
    Dwarf_Small *new_line_ptr;  /* output of _dwarf_update_line_sec(),
        used to update line_ptr as we pass
        thru compilation units in a .o
        .debug_line */

    unsigned long remaining_bytes = buffer_len; /* total length of
        original area left to be processed.  Changes as we pass
        thru compilation units in a .o .debug_line */

    int sec_res;
    int lany_change = 0;
    int did_change = 0;

    if (is_64_bit)
        length_size = 8;

    *any_change = 0;
    line_ptr = malloc(buffer_len);
    if (!line_ptr) {
        *err_code = DW_DLE_ALLOC_FAIL;
        return DW_DLV_ERROR;
    }
    orig_line_ptr = line_ptr;
    memcpy(line_ptr, orig_buffer, buffer_len);


    /*  We must iterate thru each of a set of prologues and line data.
        We process each set in turn. If all pass, we update the
        passed-in buffer. */
    sec_res = DW_DLV_OK;

    for (sec_res = _dwarf_update_line_sec(line_ptr,
        remaining_bytes, &lany_change, length_size, err_code, &new_line_ptr);
        (sec_res == DW_DLV_OK) && (remaining_bytes > 0);
        sec_res = _dwarf_update_line_sec(line_ptr,
            remaining_bytes, &lany_change, length_size,
            err_code, &new_line_ptr)) {
        long bytes_used = new_line_ptr - line_ptr;

        line_ptr = new_line_ptr;
        remaining_bytes -= bytes_used;
        if (lany_change) {
            did_change = 1;
        }
        if (remaining_bytes > 0) {
            continue;
        }
        break;
    }
    if (sec_res == DW_DLV_ERROR) {
        free(orig_line_ptr);
        return sec_res;
    }


    /* all passed */
    if (did_change) {
        /*  So update the passed in buffer orig_buffer is caller's input 
            area. orig_line_ptr is our modified copy of input area. */
        memcpy(orig_buffer, orig_line_ptr, buffer_len);
        *any_change = 1;
    }
    free(orig_line_ptr);

    return sec_res;
}


/*  By setting ala_entry_num we guarantee a stable sort,
    no duplicates
    Sorting in address order.
*/
static int
cmpr(const void *lin, const void *rin)
{
    const struct a_line_area *l = lin;
    const struct a_line_area *r = rin;

    if (l->ala_address < r->ala_address) {
        return -1;
    }
    if (l->ala_address > r->ala_address) {
        return 1;
    }
    if (l->ala_entry_num < r->ala_entry_num) {
        return -1;
    }
    if (l->ala_entry_num > r->ala_entry_num) {
        return 1;
    }
    return 0;                   /* should never happen. */
}

/*  The list of line area records is no longer needed.
    Free the data allocated. */
static void
free_area_data(struct a_line_area *arp)
{
    while(arp) {
        struct a_line_area *next = arp->ala_next;
        free(arp);
        arp = next;
    }    
}

/*  On entry:
    line_ptr must point to first
    byte of a line group for one (original) .o
          
    remaining_bytes is the size of the area pointed to
    by line_ptr: may be larger than the
    current original compilation unit .

    length size is 4 for 32bit pointers, 8 for 64bit pointers
    in the data pointed to.


    On return:
    return DW_DLV_OK if all ok.  (ignore 
    *err_code in this case)

    return DW_DLV_ERROR and set *err_code if an error.

    If some line data was moved around, set *any_change to 1.
    If error or no movement, set *any_change to 0;

    Set *new_line_ptr to one-byte-past the end of the
    current original compilation unit  (not necessary
    if returning DW_DLV_ERROR, but not harmful).

    This copies the entire array to a malloc area, then
    mallocs pieces of it (another malloc) for sorting a CU entries
    and copying back.  Then at end  the whole new thing copied in.
    The result is that on error, the input is not touched.

    An alternative would be to just update a piece at a time
    and on error stop updating but leave what was done, done.
    This alternative would save some temporary malloc space.  */
static int
_dwarf_update_line_sec(Dwarf_Small * line_ptr,
    unsigned long remaining_bytes,
    int *any_change,
    int length_size,
    int *err_code, Dwarf_Small ** new_line_ptr)
{
    /*  This points to the last byte of the .debug_line portion for the
        current cu. */
    Dwarf_Small *line_ptr_end = 0;

    /*  This points to the end of the statement program prologue for the 
        current cu, and serves to check that the prologue was correctly
        decoded. */

    Dwarf_Small *orig_line_ptr = 0;

    /* These are the fields of the statement program header. */
    struct Dwarf_Debug_s dbg_data;
    Dwarf_Debug dbg = &dbg_data;

    /* These are the state machine state variables. */
    Dwarf_Addr address = 0;
    Dwarf_Word line = 1;
    Dwarf_Bool is_stmt = false;

    /* Dwarf_Bool prologue_end; Dwarf_Bool epilogue_begin; */
    Dwarf_Small isa = 0;


    struct a_line_area *area_base = 0;
    struct a_line_area *area_current = 0;
    long area_count = 0;

    Dwarf_Addr last_address = 0;
    int need_to_sort = 0;

    /* This is the current opcode read from the statement program. */
    Dwarf_Small opcode = 0;


    /*  These variables are used to decode leb128 numbers. Leb128_num
        holds the decoded number, and leb128_length is its length in
        bytes. */
    Dwarf_Word leb128_num = 0;
    Dwarf_Sword advance_line = 0;

    /*  This is the operand of the latest fixed_advance_pc extended
        opcode. */
    Dwarf_Half fixed_advance_pc = 0;

    /* This is the length of an extended opcode instr.  */
    Dwarf_Word instr_length = 0;
    Dwarf_Small ext_opcode = 0;
    struct Line_Table_Prefix_s prefix;



    memset(dbg, 0, sizeof(struct Dwarf_Debug_s));
    dbg->de_copy_word = memcpy;
    /*  Following is a straightforward decoding of the statement program 
        prologue information. */
    *any_change = 0;


    orig_line_ptr = line_ptr;
    if (remaining_bytes < MINIMUM_POSSIBLE_PROLOG_LEN) {
        /*  We are at the end. Remaining should be zero bytes, padding.
            This is really just 'end of CU buffer' not an error. The is
            no 'entry' left so report there is none. We don't want to
            READ_UNALIGNED the total_length below and then belatedly
            discover that we read off the end already. */
        return (DW_DLV_NO_ENTRY);
    }

    dwarf_init_line_table_prefix(&prefix);
    {
        Dwarf_Small *line_ptr_out = 0;
        Dwarf_Error error;
        int dres = dwarf_read_line_table_prefix(dbg,
            line_ptr,
            remaining_bytes,
            &line_ptr_out,
            &prefix, 
            NULL, NULL,&error,
            NULL);

        if (dres == DW_DLV_ERROR) {
            dwarf_free_line_table_prefix(&prefix);
            *err_code = dwarf_errno(error);
            dwarf_dealloc(dbg, error, DW_DLA_ERROR);
            free_area_data(area_base);
            return dres;
        }
        if (dres == DW_DLV_NO_ENTRY) {
            dwarf_free_line_table_prefix(&prefix);
            return dres;
        }
        line_ptr_end = prefix.pf_line_ptr_end;
        line_ptr = line_ptr_out;
    }

    /* Initialize the state machine.  */
    /* file = 1; */
    /* column = 0; */
    is_stmt = prefix.pf_default_is_stmt;
    /* basic_block = false; */
    /* end_sequence = false; */
    /* prologue_end = false; */
    /* epilogue_begin = false; */
    isa = 0;


    /* Start of statement program.  */
    while (line_ptr < line_ptr_end) {
        int type;
        Dwarf_Small *stmt_prog_entry_start = line_ptr;

        opcode = *(Dwarf_Small *) line_ptr;
        line_ptr++;
        /* 'type' is the output */
        WHAT_IS_OPCODE(type, opcode, prefix.pf_opcode_base,
            prefix.pf_opcode_length_table, line_ptr,
            prefix.pf_std_op_count);

        if (type == LOP_DISCARD) {
            int oc;
            int opcnt = prefix.pf_opcode_length_table[opcode];

            for (oc = 0; oc < opcnt; oc++) {
                /*  Read and discard operands we don't
                    understand.
                    arbitrary choice of unsigned read.
                    signed read would work as well.  */
                Dwarf_Unsigned utmp2;

                DECODE_LEB128_UWORD(line_ptr, utmp2);
            }

        } else if (type == LOP_SPECIAL) {
            opcode = opcode - prefix.pf_opcode_base;
            address = address + prefix.pf_minimum_instruction_length *
                (opcode / prefix.pf_line_range);
            line =
                line + prefix.pf_line_base +
                opcode % prefix.pf_line_range;

            /* basic_block = false; */
        } else if (type == LOP_STANDARD) {
            switch (opcode) {
            case DW_LNS_copy:{
                /* basic_block = false; */
                break;
                }

            case DW_LNS_advance_pc:{
                Dwarf_Unsigned utmp2;

                DECODE_LEB128_UWORD(line_ptr, utmp2);
                leb128_num = (Dwarf_Word) utmp2;
                address = address +
                    prefix.pf_minimum_instruction_length * leb128_num;
                break;
                }

            case DW_LNS_advance_line:{
                Dwarf_Signed stmp;

                DECODE_LEB128_SWORD(line_ptr, stmp);
                advance_line = (Dwarf_Sword) stmp;
                line = line + advance_line;
                break;
                }

            case DW_LNS_set_file:{
                Dwarf_Unsigned utmp2;

                DECODE_LEB128_UWORD(line_ptr, utmp2);
                /* file = (Dwarf_Word)utmp2; */
                break;
                }

            case DW_LNS_set_column:{
                Dwarf_Unsigned utmp2;

                DECODE_LEB128_UWORD(line_ptr, utmp2);
                /* column = (Dwarf_Word)utmp2; */
                break;
                }

            case DW_LNS_negate_stmt:{
                is_stmt = !is_stmt;
                break;
                }

            case DW_LNS_set_basic_block:{
                /* basic_block = true; */
                break;
                }

            case DW_LNS_const_add_pc:{
                opcode = MAX_LINE_OP_CODE - prefix.pf_opcode_base;
                address = address +
                    prefix.pf_minimum_instruction_length * 
                    (opcode / prefix.  pf_line_range);
                break;
                }

            case DW_LNS_fixed_advance_pc:{

                READ_UNALIGNED(dbg, fixed_advance_pc, Dwarf_Half,
                    line_ptr, sizeof(Dwarf_Half));
                line_ptr += sizeof(Dwarf_Half);
                address = address + fixed_advance_pc;
                break;
                }
                /* New in DWARF3 */
            case DW_LNS_set_prologue_end:{
                /* prologue_end = true; */
                break;


                }
                /* New in DWARF3 */
            case DW_LNS_set_epilogue_begin:{
                /* epilogue_begin = true; */
                break;
                }

                /* New in DWARF3 */
            case DW_LNS_set_isa:{
                Dwarf_Unsigned utmp2;

                DECODE_LEB128_UWORD(line_ptr, utmp2);
                isa = utmp2;
                if (isa != utmp2) {
                    /*  The value of the isa did not fit in our
                        local so we record it wrong. declare an
                        error. */
                    dwarf_free_line_table_prefix(&prefix);
                    *err_code = DW_DLE_LINE_NUM_OPERANDS_BAD;
                    free_area_data(area_base);
                    return (DW_DLV_ERROR);
                }
                break;
                }
            }
        } else if (type == LOP_EXTENDED) {
            Dwarf_Unsigned utmp3 = 0;

            DECODE_LEB128_UWORD(line_ptr, utmp3);
            instr_length = (Dwarf_Word) utmp3;
            ext_opcode = *(Dwarf_Small *) line_ptr;
            line_ptr++;
            switch (ext_opcode) {

            case DW_LNE_end_sequence:{
                /* end_sequence = true; */

                address = 0;
                /* file = 1; */
                line = 1;
                /* column = 0; */
                is_stmt = prefix.pf_default_is_stmt;
                /* basic_block = false; */
                /* end_sequence = false; */
                /* prologue_end = false; */
                /* epilogue_begin = false; */
                }
                break;
            case DW_LNE_set_address:{
                struct a_line_area *area = 0;

                READ_UNALIGNED(dbg, address, Dwarf_Addr,
                    line_ptr, length_size);
                /*  Here we need to remember the offset into the 
                    buffer and check to see if address went
                    down. */
                if (address < last_address) {
                    need_to_sort = 1;
                }
                last_address = address;

                area = malloc(sizeof(struct a_line_area));
                area->ala_address = address;
                area->ala_offset = stmt_prog_entry_start -
                    orig_line_ptr;
                area->ala_entry_num = area_count;
                area->ala_next = 0;
                area->ala_length = 0;
                if (area_current) {
                    area_current->ala_next = area;
                    area_current->ala_length =
                        area->ala_offset -
                        area_current->ala_offset;
                }
                ++area_count;
                area_current = area;
                if (area_base == 0) {
                    area_base = area;
                }

                line_ptr += length_size;
                }
                break;

            case DW_LNE_define_file:{
                break;
                }

            default:{
                Dwarf_Unsigned remaining_bytes = instr_length -1;
                line_ptr += remaining_bytes;
                break;
                }
            }

        }
    }


    *new_line_ptr = line_ptr;
    if (!need_to_sort) {
        dwarf_free_line_table_prefix(&prefix);
        free_area_data(area_base);
        return (DW_DLV_OK);
    }

    /*  So now we have something to sort. First, finish off the last
        area record: */
    area_current->ala_length = (line_ptr - orig_line_ptr)
        -area_current->ala_offset;

    /*  Build and sort a simple array of sections. Forcing a stable sort 
        by comparing on sequence number. We will use the sorted list to
        move sections of this part of the line table. Each 'section'
        starting with a DW_LNE_set_address opcode, on the assumption
        that such only get out of order where there was an ld-cord
        function rearrangement and that it is meaningful to restart the
        line info there. */
    {
        struct a_line_area *ala_array;
        struct a_line_area *local;
        long start_len;
        Dwarf_Small *new_area;
        long i;

        ala_array = malloc(area_count * sizeof(struct a_line_area));
        if (!ala_array) {
            dwarf_free_line_table_prefix(&prefix);
            *err_code = DW_DLE_ALLOC_FAIL;
            free_area_data(area_base);
            return DW_DLV_ERROR;
        }

        for (local = area_base, i = 0; local;
            local = local->ala_next, ++i) {

            ala_array[i] = *local;
        }
        free_area_data(area_base);
        /* Zero the stale pointers so we don't use them accidentally. */
        area_base = 0;
        area_current = 0;

        qsort(ala_array, area_count, sizeof(struct a_line_area), cmpr);

        /* Now we must rearrange the pieces of the line table. */

        start_len =
            (prefix.pf_line_prologue_start +
            prefix.pf_prologue_length) - orig_line_ptr;
        new_area = malloc(remaining_bytes);
        if (!new_area) {
            free(ala_array);
            *err_code = DW_DLE_ALLOC_FAIL;
            dwarf_free_line_table_prefix(&prefix);
            return DW_DLV_ERROR;
        }
        memcpy(new_area, orig_line_ptr, start_len);
        line_ptr = new_area + start_len;
        for (i = 0; i < area_count; ++i) {
            memcpy(line_ptr, orig_line_ptr +
                ala_array[i].ala_offset, ala_array[i].ala_length);
            line_ptr += ala_array[i].ala_length;
        }

        memcpy(orig_line_ptr, new_area, remaining_bytes);

        free(new_area);
        free(ala_array);
        ala_array = 0;
        new_area = 0;
    }

    *any_change = 1;
    dwarf_free_line_table_prefix(&prefix);
    return (DW_DLV_OK);
}