source.c

早期freebsd实现

	/* Name is $cwd -- insert current directory name instead.  */
	int newlen;

	/* First, realloc the filename buffer if too short. */
	len = strlen (current_directory);
	newlen = len + strlen (string) + 2;
	if (newlen > alloclen) {
	  alloclen = newlen;
	  filename = (char *) alloca (alloclen);
	}
	strcpy (filename, current_directory);
      } else {
	/* Normal file name in path -- just use it.  */
	strncpy (filename, p, len);
	filename[len] = 0;
      }

      /* Remove trailing slashes */
      while (len > 0 && filename[len-1] == '/')
       filename[--len] = 0;

      strcat (filename+len, "/");
      strcat (filename, string);

      fd = open (filename, mode, prot);
      if (fd >= 0) break;
    }

 done:
  if (filename_opened)
    if (fd < 0)
      *filename_opened = (char *) 0;
    else if (filename[0] == '/')
      *filename_opened = savestring (filename, strlen (filename));
    else
      {
	/* Beware the // my son, the Emacs barfs, the botch that catch... */
	   
	*filename_opened = concat (current_directory, 
	   '/' == current_directory[strlen(current_directory)-1]? "": "/",
				   filename, NULL);
      }

  return fd;
}

/* Open a source file given a symtab S.  Returns a file descriptor
   or negative number for error.  */

static int
open_source_file (s)
     struct symtab *s;
{
  char *path = source_path;
  char *p;
  int result;
  char *fullname;

  /* Quick way out if we already know its full name */
  if (s->fullname) 
    {
      result = open (s->fullname, O_RDONLY);
      if (result >= 0)
        return result;
      /* Didn't work -- free old one, try again. */
      mfree (s->objfile->md, s->fullname);
      s->fullname = NULL;
    }

  if (s->dirname != NULL)
    {
      /* Replace a path entry of  $cdir  with the compilation directory name */
#define	cdir_len	5
      /* We cast strstr's result in case an ANSIhole has made it const,
	 which produces a "required warning" when assigned to a nonconst. */
      p = (char *)strstr (source_path, "$cdir");
      if (p && (p == path || p[-1] == ':')
	    && (p[cdir_len] == ':' || p[cdir_len] == '\0')) {
	int len;

	path = (char *)
	       alloca (strlen (source_path) + 1 + strlen (s->dirname) + 1);
	len = p - source_path;
	strncpy (path, source_path, len);		/* Before $cdir */
	strcpy (path + len, s->dirname);		/* new stuff */
	strcat (path + len, source_path + len + cdir_len); /* After $cdir */
      }
    }

  result = openp (path, 0, s->filename, O_RDONLY, 0, &s->fullname);
  if (result < 0)
    {
      /* Didn't work.  Try using just the basename. */
      p = basename (s->filename);
      if (p != s->filename)
	result = openp(path, 0, p, O_RDONLY,0, &s->fullname);
    }
  if (result >= 0)
    {
      fullname = s -> fullname;
      s -> fullname = mstrsave (s -> objfile -> md, s -> fullname);
      free (fullname);
    }
  return result;
}


/* Create and initialize the table S->line_charpos that records
   the positions of the lines in the source file, which is assumed
   to be open on descriptor DESC.
   All set S->nlines to the number of such lines.  */

static void
find_source_lines (s, desc)
     struct symtab *s;
     int desc;
{
  struct stat st;
  char c;
  register char *data, *p, *end;
  int nlines = 0;
  int lines_allocated = 1000;
  int *line_charpos;
  long exec_mtime;
  int size;

  line_charpos = (int *) xmmalloc (s -> objfile -> md,
				   lines_allocated * sizeof (int));
  if (fstat (desc, &st) < 0)
   perror_with_name (s->filename);

  if (exec_bfd) {
    exec_mtime = bfd_get_mtime(exec_bfd);
    if (exec_mtime && exec_mtime < st.st_mtime)
     printf_filtered ("Source file is more recent than executable.\n");
  }

#ifdef LSEEK_NOT_LINEAR
  /* Have to read it byte by byte to find out where the chars live */

   line_charpos[0] = tell(desc);
   nlines = 1;
   while (myread(desc, &c, 1)>0) 
   {
     if (c == '\n') 
     {
       if (nlines == lines_allocated) 
       {
	 lines_allocated *= 2;
	 line_charpos =
	  (int *) xmrealloc (s -> objfile -> md, (char *) line_charpos,
			     sizeof (int) * lines_allocated);
       }
       line_charpos[nlines++] = tell(desc);
     }
   }

#else
  /* st_size might be a large type, but we only support source files whose 
     size fits in an int.  FIXME. */
  size = (int) st.st_size;

#ifdef BROKEN_LARGE_ALLOCA
  data = (char *) xmalloc (size);
  make_cleanup (free, data);
#else
  data = (char *) alloca (size);
#endif
  if (myread (desc, data, size) < 0)
   perror_with_name (s->filename);
  end = data + size;
  p = data;
  line_charpos[0] = 0;
  nlines = 1;
  while (p != end)
  {
    if (*p++ == '\n'
	/* A newline at the end does not start a new line.  */
	&& p != end)
    {
      if (nlines == lines_allocated)
      {
	lines_allocated *= 2;
	line_charpos =
	 (int *) xmrealloc (s -> objfile -> md, (char *) line_charpos,
			    sizeof (int) * lines_allocated);
      }
      line_charpos[nlines++] = p - data;
    }
  }
#endif
  s->nlines = nlines;
  s->line_charpos =
   (int *) xmrealloc (s -> objfile -> md, (char *) line_charpos,
		      nlines * sizeof (int));

}

/* Return the character position of a line LINE in symtab S.
   Return 0 if anything is invalid.  */


int
source_line_charpos (s, line)
     struct symtab *s;
     int line;
{
  if (!s) return 0;
  if (!s->line_charpos || line <= 0) return 0;
  if (line > s->nlines)
    line = s->nlines;
  return s->line_charpos[line - 1];
}

/* Return the line number of character position POS in symtab S.  */

int
source_charpos_line (s, chr)
    register struct symtab *s;
    register int chr;
{
  register int line = 0;
  register int *lnp;
    
  if (s == 0 || s->line_charpos == 0) return 0;
  lnp = s->line_charpos;
  /* Files are usually short, so sequential search is Ok */
  while (line < s->nlines  && *lnp <= chr)
    {
      line++;
      lnp++;
    }
  if (line >= s->nlines)
    line = s->nlines;
  return line;
}



/* Get full pathname and line number positions for a symtab.
   Return nonzero if line numbers may have changed.
   Set *FULLNAME to actual name of the file as found by `openp',
   or to 0 if the file is not found.  */

int
get_filename_and_charpos (s, fullname)
     struct symtab *s;
     char **fullname;
{
  register int desc, linenums_changed = 0;
  
  desc = open_source_file (s);
  if (desc < 0)
    {
      if (fullname)
	*fullname = NULL;
      return 0;
    }  
  if (fullname)
    *fullname = s->fullname;
  if (s->line_charpos == 0) linenums_changed = 1;
  if (linenums_changed) find_source_lines (s, desc);
  close (desc);
  return linenums_changed;
}

/* Print text describing the full name of the source file S
   and the line number LINE and its corresponding character position.
   The text starts with two Ctrl-z so that the Emacs-GDB interface
   can easily find it.

   MID_STATEMENT is nonzero if the PC is not at the beginning of that line.

   Return 1 if successful, 0 if could not find the file.  */

int
identify_source_line (s, line, mid_statement)
     struct symtab *s;
     int line;
     int mid_statement;
{
  if (s->line_charpos == 0)
    get_filename_and_charpos (s, (char **)NULL);
  if (s->fullname == 0)
    return 0;
  printf ("\032\032%s:%d:%d:%s:0x%x\n", s->fullname,
	  line, s->line_charpos[line - 1],
	  mid_statement ? "middle" : "beg",
	  get_frame_pc (get_current_frame()));
  current_source_line = line;
  first_line_listed = line;
  last_line_listed = line;
  current_source_symtab = s;
  return 1;
}

/* Print source lines from the file of symtab S,
   starting with line number LINE and stopping before line number STOPLINE.  */

void
print_source_lines (s, line, stopline, noerror)
     struct symtab *s;
     int line, stopline;
     int noerror;
{
  register int c;
  register int desc;
  register FILE *stream;
  int nlines = stopline - line;

  /* Regardless of whether we can open the file, set current_source_symtab. */
  current_source_symtab = s;
  current_source_line = line;
  first_line_listed = line;

  desc = open_source_file (s);
  if (desc < 0)
    {
      if (noerror && line + 1 == stopline)
	{
	  /* can't find the file - tell user where we are anyway */
	  current_source_symtab = s;
	  current_source_line = line;
	  first_line_listed = line;
	  last_line_listed = line;
	  printf_filtered ("%d\t(%s)\n", current_source_line++, s->filename);
	}
      else 
	{	  
          if (! noerror)
	    {
	      char *name = alloca (strlen (s->filename) + 100);
	      sprintf (name, "%s:%d", s->filename, line);
	      print_sys_errmsg (name, errno);
	    }
	}
      return;
    }

  if (s->line_charpos == 0)
    find_source_lines (s, desc);

  if (line < 1 || line > s->nlines)
    {
      close (desc);
      error ("Line number %d out of range; %s has %d lines.",
	     line, s->filename, s->nlines);
    }

  if (lseek (desc, s->line_charpos[line - 1], 0) < 0)
    {
      close (desc);
      perror_with_name (s->filename);
    }

  stream = fdopen (desc, "r");
  clearerr (stream);

  while (nlines-- > 0)
    {
      c = fgetc (stream);
      if (c == EOF) break;
      last_line_listed = current_source_line;
      printf_filtered ("%d\t", current_source_line++);
      do
	{
	  if (c < 040 && c != '\t' && c != '\n' && c != '\r')
	      printf_filtered ("^%c", c + 0100);
	  else if (c == 0177)
	    printf_filtered ("^?");
	  else
	    printf_filtered ("%c", c);
	} while (c != '\n' && (c = fgetc (stream)) >= 0);
    }

  fclose (stream);
}



/* 
  C++
  Print a list of files and line numbers which a user may choose from
  in order to list a function which was specified ambiguously
  (as with `list classname::overloadedfuncname', for example).
  The vector in SALS provides the filenames and line numbers.
  */
static void
ambiguous_line_spec (sals)
     struct symtabs_and_lines *sals;
{
  int i;

  for (i = 0; i < sals->nelts; ++i)
    printf_filtered("file: \"%s\", line number: %d\n",
		    sals->sals[i].symtab->filename, sals->sals[i].line);
}

static void
setfile_command(arg, from_tty)
  char *arg;
  int from_tty;
{
  struct symtabs_and_lines sals;
  struct symtab_and_line sal;
  struct symbol *sym;
  char *arg1;
  int linenum_beg = 0;
  char *p;

  /* Pull in a current source symtab if necessary */
  if (arg == 0 || arg[0] == 0) {
	  if (current_source_symtab == 0)
		  select_source_symtab(0);
    	  else
		  printf("%s\n", current_source_symtab->filename);
	  return;
  }
  arg1 = arg;
  sals = decode_line_1 (&arg1, 0, 0, 0);

  if (! sals.nelts)
    return;  /*  C++  */

  if (sals.nelts > 1)
    {
      ambiguous_line_spec (&sals);
      free (sals.sals);
      return;
    }

  sal = sals.sals[0];
  free (sals.sals);

  /* Record whether the BEG arg is all digits.  */

  for (p = arg; p != arg1 && *p >= '0' && *p <= '9'; ++p)
    ;
  linenum_beg = (p == arg1);

  /* if line was specified by address,
     print exactly which line, and which file.
     In this case, sal.symtab == 0 means address is outside
     of all known source files, not that user failed to give a filename.  */
  if (*arg == '*')
    {
      if (sal.symtab == 0)
	error ("No source file for address 0x%x.", sal.pc);
      sym = find_pc_function (sal.pc);
      if (sym)
	printf ("0x%x is in %s (%s, line %d).\n",
		sal.pc, SYMBOL_NAME (sym), sal.symtab->filename, sal.line);
      else
	printf ("0x%x is in %s, line %d.\n",
		sal.pc, sal.symtab->filename, sal.line);
    }

  /* If line was not specified by just a line number,
     and it does not imply a symtab, it must be an undebuggable symbol
     which means no source code.  */

  if (sal.symtab == 0)
    {
      if (! linenum_beg)
	error ("No line number known for %s.", arg);
      else
	error ("No default source file yet.  Do \"help list\".");
    }
  else
    {
      current_source_symtab = sal.symtab;
      current_source_line = sal.line;
      first_line_listed = sal.line;
    }
}

#define PUSH_STACK_SIZE 32
static struct {
	struct symtab *symtab;
	int line;
} push_stack[PUSH_STACK_SIZE];

static unsigned int push_stack_ptr;

static void
push_to_file_command (arg, from_tty)
	char *arg;
	int from_tty;
{
	struct symtab *cursym = current_source_symtab;
	int curline = current_source_line;
	register unsigned int i;