libdw/dwarf_getsrclines.c

/* Return line number information of CU.
   Copyright (C) 2004 Red Hat, Inc.
   Written by Ulrich Drepper <drepper@redhat.com>, 2004.

   This program is Open Source software; you can redistribute it and/or
   modify it under the terms of the Open Software License version 1.0 as
   published by the Open Source Initiative.

   You should have received a copy of the Open Software License along
   with this program; if not, you may obtain a copy of the Open Software
   License version 1.0 from http://www.opensource.org/licenses/osl.php or
   by writing the Open Source Initiative c/o Lawrence Rosen, Esq.,
   3001 King Ranch Road, Ukiah, CA 95482.   */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "dwarf.h"
#include "libdwP.h"


struct filelist
{
  Dwarf_Fileinfo info;
  struct filelist *next;
};

struct linelist
{
  Dwarf_Line line;
  struct linelist *next;
};


/* Adds a new line to the matrix.  We cannot definte a function because
   we want to use alloca.  */
#define NEW_LINE(end_seq) \
  do {									      \
    /* Add the new line.  */						      \
    new_line = (struct linelist *) alloca (sizeof (struct linelist));	      \
									      \
    /* Set the line information.  */					      \
    new_line->line.addr = address;					      \
    new_line->line.file = file;						      \
    new_line->line.line = line;						      \
    new_line->line.column = column;					      \
    new_line->line.is_stmt = is_stmt;					      \
    new_line->line.basic_block = basic_block;				      \
    new_line->line.end_sequence = end_seq;				      \
    new_line->line.prologue_end = prologue_end;				      \
    new_line->line.epilogue_begin = epilogue_begin;			      \
									      \
    new_line->next = linelist;						      \
    linelist = new_line;						      \
    ++nlinelist;							      \
  } while (0)


int
dwarf_getsrclines (Dwarf_Die *cudie, Dwarf_Lines **lines, size_t *nlines)
{
  if (unlikely (cudie == NULL || dwarf_tag (cudie) != DW_TAG_compile_unit))
    return -1;

  int res = -1;

  /* Get the information if it is not already known.  */
  struct Dwarf_CU *const cu = cudie->cu;
  if (cu->lines == NULL)
    {
      /* Failsafe mode: no data found.  */
      cu->lines = (void *) -1l;
      cu->files = (void *) -1l;

      /* The die must have a statement list associated.  */
      Dwarf_Attribute stmt_list_mem;
      Dwarf_Attribute *stmt_list = dwarf_attr (cudie, DW_AT_stmt_list,
					       &stmt_list_mem);

      /* Get the offset into the .debug_line section.  NB: this call
	 also checks whether the previous dwarf_attr call failed.  */
      Dwarf_Word offset;
      if (dwarf_formudata (stmt_list, &offset) != 0)
	goto out;

      Dwarf *dbg = cu->dbg;
      if (dbg->sectiondata[IDX_debug_line] == NULL)
	{
	  __libdw_seterrno (DWARF_E_NO_DEBUG_LINE);
	  goto out;
	}
      uint8_t *linep = dbg->sectiondata[IDX_debug_line]->d_buf + offset;
      uint8_t *lineendp = (dbg->sectiondata[IDX_debug_line]->d_buf
			   + dbg->sectiondata[IDX_debug_line]->d_size);

      /* Get the compilation directory.  */
      Dwarf_Attribute compdir_attr_mem;
      Dwarf_Attribute *compdir_attr = dwarf_attr (cudie, DW_AT_comp_dir,
						  &compdir_attr_mem);
      const char *comp_dir = dwarf_formstring (compdir_attr);

      if (unlikely (linep + 4 > lineendp))
	{
	invalid_data:
	  __libdw_seterrno (DWARF_E_INVALID_DEBUG_LINE);
	  goto out;
	}
      Dwarf_Word unit_length = read_4ubyte_unaligned_inc (dbg, linep);
      unsigned int length = 4;
      if (unlikely (unit_length == 0xffffffff))
	{
	  if (unlikely (linep + 8 > lineendp))
	    goto invalid_data;
	  unit_length = read_8ubyte_unaligned_inc (dbg, linep);
	  length = 8;
	}

      /* Check whether we have enough room in the section.  */
      if (unit_length < 2 + length + 5 * 1
	  || unlikely (linep + unit_length > lineendp))
	goto invalid_data;
      lineendp = linep + unit_length;

      /* The next element of the header is the version identifier.  */
      uint_fast16_t version = read_2ubyte_unaligned_inc (dbg, linep);
      if (unlikely (version != DWARF_VERSION))
	{
	  __libdw_seterrno (DWARF_E_VERSION);
	  goto out;
	}

      /* Next comes the header length.  */
      Dwarf_Word header_length;
      if (length == 4)
	header_length = read_4ubyte_unaligned_inc (dbg, linep);
      else
	header_length = read_8ubyte_unaligned_inc (dbg, linep);
      unsigned char *header_start = linep;

      /* Next the minimum instruction length.  */
      uint_fast8_t minimum_instr_len = *linep++;

        /* Then the flag determining the default value of the is_stmt
	   register.  */
      uint_fast8_t default_is_stmt = *linep++;

      /* Now the line base.  */
      int_fast8_t line_base = *((int_fast8_t *) linep);
      ++linep;

      /* And the line range.  */
      uint_fast8_t line_range = *linep++;

      /* The opcode base.  */
      uint_fast8_t opcode_base = *linep++;

      /* Remember array with the standard opcode length (-1 to account for
	 the opcode with value zero not being mentioned).  */
      uint8_t *standard_opcode_lengths = linep - 1;
      linep += opcode_base - 1;
      if (unlikely (linep >= lineendp))
	goto invalid_data;

      /* First comes the list of directories.  Add the compilation
	 directory first since the index zero is used for it.  */
      struct dirlist
      {
	const char *dir;
	size_t len;
	struct dirlist *next;
      } comp_dir_elem =
	{
	  .dir = comp_dir,
	  .len = comp_dir ? strlen (comp_dir) : 0,
	  .next = NULL
	};
      struct dirlist *dirlist = &comp_dir_elem;
      unsigned int ndirlist = 1;

      // XXX Directly construct array to conserve memory?
      while (*linep != 0)
	{
	  struct dirlist *new_dir =
	    (struct dirlist *) alloca (sizeof (*new_dir));

	  new_dir->dir = (char *) linep;
	  uint8_t *endp = memchr (linep, '\0', lineendp - linep);
	  if (endp == NULL)
	    goto invalid_data;
	  new_dir->len = endp - linep;
	  new_dir->next = dirlist;
	  dirlist = new_dir;
	  ++ndirlist;
	  linep = endp + 1;
	}
      /* Skip the final NUL byte.  */
      ++linep;

      /* Rearrange the list in array form.  */
      struct dirlist **dirarray
	= (struct dirlist **) alloca (ndirlist * sizeof (*dirarray));
      while (ndirlist-- > 0)
	{
	  dirarray[ndirlist] = dirlist;
	  dirlist = dirlist->next;
	}

        /* Now read the files.  */
      struct filelist null_file =
	{
	  .info =
	  {
	    .name = "???",
	    .mtime = 0,
	    .length = 0
	  },
	  .next = NULL
	};
      struct filelist *filelist = &null_file;
      unsigned int nfilelist = 1;

      if (unlikely (linep >= lineendp))
	goto invalid_data;
      while (*linep != 0)
	{
	  struct filelist *new_file =
	    (struct filelist *) alloca (sizeof (*new_file));

	  /* First comes the file name.  */
	  char *fname = (char *) linep;
	  uint8_t *endp = memchr (fname, '\0', lineendp - linep);
	  if (endp == NULL)
	    goto invalid_data;
	  size_t fnamelen = endp - (uint8_t *) fname;
	  linep = endp + 1;

	  /* Then the index.  */
	  Dwarf_Word diridx;
	  get_uleb128 (diridx, linep);
	  if (unlikely (diridx >= ndirlist))
	    {
	      __libdw_seterrno (DWARF_E_INVALID_DIR_IDX);
	      goto out;
	    }

	  if (*fname == '/')
	    /* It's an absolute path.  */
	    new_file->info.name = fname;
	  else
	    {
	      new_file->info.name = libdw_alloc (dbg, char, 1,
						 dirarray[diridx]->len + 1
						 + fnamelen + 1);
              char *cp = new_file->info.name;

              if (dirarray[diridx]->dir != NULL)
		{
		  /* This value could be NULL in case the DW_AT_comp_dir
		     was not present.  We cannot do much in this case.
		     The easiest thing is to convert the path in an
                   absolute path.  */
		  cp = stpcpy (cp, dirarray[diridx]->dir);
		}
              *cp++ = '/';
              strcpy (cp, fname);
	      assert (strlen (new_file->info.name)
		      < dirarray[diridx]->len + 1 + fnamelen + 1);
            }

	  /* Next comes the modification time.  */
	  get_uleb128 (new_file->info.mtime, linep);

	  /* Finally the length of the file.  */
	  get_uleb128 (new_file->info.length, linep);

	  new_file->next = filelist;
	  filelist = new_file;
	  ++nfilelist;
	}
      /* Skip the final NUL byte.  */
      ++linep;

      /* Consistency check.  */
      if (unlikely (linep != header_start + header_length))
	{
	  __libdw_seterrno (DWARF_E_INVALID_DWARF);
	  goto out;
	}

        /* We are about to process the statement program.  Initialize the
	   state machine registers (see 6.2.2 in the v2.1 specification).  */
      Dwarf_Word address = 0;
      size_t file = 1;
      size_t line = 1;
      size_t column = 0;
      uint_fast8_t is_stmt = default_is_stmt;
      int basic_block = 0;
      int prologue_end = 0;
      int epilogue_begin = 0;

        /* Process the instructions.  */
      struct linelist *linelist = NULL;
      unsigned int nlinelist = 0;
      while (linep < lineendp)
	{
	  struct linelist *new_line;
	  unsigned int opcode;
	  unsigned int u128;
	  int s128;

	  /* Read the opcode.  */
	  opcode = *linep++;

	  /* Is this a special opcode?  */
	  if (likely (opcode >= opcode_base))
	    {
	      /* Yes.  Handling this is quite easy since the opcode value
		 is computed with

		 opcode = (desired line increment - line_base)
		           + (line_range * address advance) + opcode_base
	      */
	      int line_increment = (line_base
				    + (opcode - opcode_base) % line_range);
	      unsigned int address_increment = (minimum_instr_len
						* ((opcode - opcode_base)
						   / line_range));

	      /* Perform the increments.  */
	      line += line_increment;
	      address += address_increment;

	      /* Add a new line with the current state machine values.  */
	      NEW_LINE (0);

	      /* Reset the flags.  */
	      basic_block = 0;
	      prologue_end = 0;
	      epilogue_begin = 0;
	    }
	  else if (opcode == 0)
	    {
	      /* This an extended opcode.  */
	      if (unlikely (linep + 2 > lineendp))
		goto invalid_data;

	      /* The length.  */
	      unsigned int len = *linep++;

	      if (unlikely (linep + len > lineendp))
		goto invalid_data;

	      /* The sub-opcode.  */
	      opcode = *linep++;

	      switch (opcode)
		{
		case DW_LNE_end_sequence:
		  /* Add a new line with the current state machine values.
		     The is the end of the sequence.  */
		  NEW_LINE (1);

		  /* Reset the registers.  */
		  address = 0;
		  file = 1;
		  line = 1;
		  column = 0;
		  is_stmt = default_is_stmt;
		  basic_block = 0;
		  prologue_end = 0;
		  epilogue_begin = 0;
		  break;

		case DW_LNE_set_address:
		  /* The value is an address.  The size is defined as
		     apporiate for the target machine.  We use the
		     address size field from the CU header.  */
		  if (cu->address_size == 4)
		    address = read_4ubyte_unaligned_inc (dbg, linep);
		  else
		    address = read_8ubyte_unaligned_inc (dbg, linep);
		  break;

		case DW_LNE_define_file:
		  {
		    char *fname = (char *) linep;
		    uint8_t *endp = memchr (linep, '\0', lineendp - linep);
		    if (endp == NULL)
		      goto invalid_data;
		    size_t fnamelen = endp - linep;
		    linep = endp + 1;

		    unsigned int diridx;
		    get_uleb128 (diridx, linep);
		    Dwarf_Word mtime;
		    get_uleb128 (mtime, linep);
		    Dwarf_Word filelength;
		    get_uleb128 (filelength, linep);

		    struct filelist *new_file =
		      (struct filelist *) alloca (sizeof (*new_file));
		    if (fname[0] == '/')
		      new_file->info.name = fname;
		    else
		      {
			new_file->info.name =
			  libdw_alloc (dbg, char, 1, (dirarray[diridx]->len + 1
						      + fnamelen + 1));
			char *cp = new_file->info.name;

			if (dirarray[diridx]->dir != NULL)
			  /* This value could be NULL in case the
			     DW_AT_comp_dir was not present.  We
			     cannot do much in this case.  The easiest
			     thing is to convert the path in an
			     absolute path.  */
			  cp = stpcpy (cp, dirarray[diridx]->dir);
			*cp++ = '/';
			strcpy (cp, fname);
		      }

		    new_file->info.mtime = mtime;
		    new_file->info.length = filelength;
		    new_file->next = filelist;
		    filelist = new_file;
		    ++nfilelist;
		  }
		  break;

		default:
		  /* Unknown, ignore it.  */
		  linep += len - 1;
		  break;
		}
	    }
	  else if (opcode <= DW_LNS_set_epilog_begin)
	    {
	      /* This is a known standard opcode.  */
	      switch (opcode)
		{
		case DW_LNS_copy:
		  /* Takes no argument.  */
		  if (unlikely (standard_opcode_lengths[opcode] != 0))
		    goto invalid_data;

		  /* Add a new line with the current state machine values.  */
		  NEW_LINE (0);

		  /* Reset the flags.  */
		  basic_block = 0;
		  /* XXX Whether the following two lines are necessary is
		     unclear.  I guess the current v2.1 specification has
		     a bug in that it says clearing these two registers is
		     not necessary.  */
		  prologue_end = 0;
		  epilogue_begin = 0;
		  break;

		case DW_LNS_advance_pc:
		  /* Takes one uleb128 parameter which is added to the
		     address.  */
		  if (unlikely (standard_opcode_lengths[opcode] != 1))
		    goto invalid_data;

		  get_uleb128 (u128, linep);
		  address += minimum_instr_len * u128;
		  break;

		case DW_LNS_advance_line:
		  /* Takes one sleb128 parameter which is added to the
		     line.  */
		  if (unlikely (standard_opcode_lengths[opcode] != 1))
		    goto invalid_data;

		  get_sleb128 (s128, linep);
		  line += s128;
		  break;

		case DW_LNS_set_file:
		  /* Takes one uleb128 parameter which is stored in file.  */
		  if (unlikely (standard_opcode_lengths[opcode] != 1))
		    goto invalid_data;

		  get_uleb128 (u128, linep);
		  file = u128;
		  break;

		case DW_LNS_set_column:
		  /* Takes one uleb128 parameter which is stored in column.  */
		  if (unlikely (standard_opcode_lengths[opcode] != 1))
		    goto invalid_data;

		  get_uleb128 (u128, linep);
		  column = u128;
		  break;

		case DW_LNS_negate_stmt:
		  /* Takes no argument.  */
		  if (unlikely (standard_opcode_lengths[opcode] != 0))
		    goto invalid_data;

		  is_stmt = 1 - is_stmt;
		  break;

		case DW_LNS_set_basic_block:
		  /* Takes no argument.  */
		  if (unlikely (standard_opcode_lengths[opcode] != 0))
		    goto invalid_data;

		  basic_block = 1;
		  break;

		case DW_LNS_const_add_pc:
		  /* Takes no argument.  */
		  if (unlikely (standard_opcode_lengths[opcode] != 0))
		    goto invalid_data;

		  address += (minimum_instr_len
			      * ((255 - opcode_base) / line_range));
		  break;

		case DW_LNS_fixed_advance_pc:
		  /* Takes one 16 bit parameter which is added to the
		     address.  */
		  if (unlikely (standard_opcode_lengths[opcode] != 1))
		    goto invalid_data;

		  address += read_2ubyte_unaligned_inc (dbg, linep);
		  break;

		case DW_LNS_set_prologue_end:
		  /* Takes no argument.  */
		  if (unlikely (standard_opcode_lengths[opcode] != 0))
		    goto invalid_data;

		  prologue_end = 1;
		  break;

		case DW_LNS_set_epilog_begin:
		  /* Takes no argument.  */
		  if (unlikely (standard_opcode_lengths[opcode] != 0))
		    goto invalid_data;

		  epilogue_begin = 1;
		  break;
		}
	    }
	  else
	    {
	      /* This is a new opcode the generator but not we know about.
		 Read the parameters associated with it but then discard
		 everything.  Read all the parameters for this opcode.  */
	      for (int n = standard_opcode_lengths[opcode]; n > 0; --n)
		get_uleb128 (u128, linep);

	      /* Next round, ignore this opcode.  */
	      continue;
	    }
	}

      /* Put all the files in an array.  */
      Dwarf_Files *files = libdw_alloc (dbg, Dwarf_Files,
					sizeof (Dwarf_Files)
					+ nfilelist * sizeof (Dwarf_Fileinfo),
				       1);
      files->nfiles = nfilelist;
      while (nfilelist-- > 0)
	{
	  files->info[nfilelist] = filelist->info;
	  filelist = filelist->next;
	}
      assert (filelist == NULL);

      /* Remember the debugging descriptor.  */
      files->dbg = dbg;

      /* Make the file data structure available through the CU.  */
      cu->files = files;

      cu->lines = libdw_alloc (dbg, Dwarf_Lines, (sizeof (Dwarf_Lines)
						  + (sizeof (Dwarf_Line)
						     * nlinelist)), 1);
      cu->lines->nlines = nlinelist;
      while (nlinelist-- > 0)
	{
	  cu->lines->info[nlinelist] = linelist->line;
	  cu->lines->info[nlinelist].files = files;
	  linelist = linelist->next;
	}
      assert (linelist == NULL);

      /* Success.  */
      res = 0;
    }
  else if (cu->lines != (void *) -1l)
    /* We already have the information.  */
    res = 0;

  if (likely (res == 0))
    {
      *lines = cu->lines;
      *nlines = cu->lines->nlines;
    }
 out:

  // XXX Eventually: unlocking here.

  return res;
}