Make writing to files work properly. (Fixes to BFD are also needed.)

[deliverable/binutils-gdb.git] / gdb / exec.c

/* Work with executable files, for GDB. 
   Copyright (C) 1988, 1989 Free Software Foundation, Inc.

This file is part of GDB.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include <stdio.h>
#include "defs.h"
#include "param.h"
#include "frame.h"
#include "inferior.h"
#include "target.h"
#include "gdbcmd.h"

#ifdef USG
#include <sys/types.h>
#endif

#include <sys/param.h>
#include <fcntl.h>
#include <string.h>

#include "gdbcore.h"

#ifdef STILL_NEEDED_FOR_DECSTATION
#include <sys/dir.h>		/* For DECstations */
#include <sys/user.h>		/* After a.out.h  */
#include <sys/file.h>
#endif

#include <ctype.h>
#include <sys/stat.h>

extern char *getenv();
extern void child_create_inferior (), child_attach ();
extern void symbol_file_command ();

/* The Binary File Descriptor handle for the executable file.  */

bfd *exec_bfd = NULL;

/* Whether to open exec and core files read-only or read-write.  */

int write_files = 0;

/* Forward decl */

extern struct target_ops exec_ops;

/* ARGSUSED */
void
exec_close (quitting)
     int quitting;
{
  if (exec_bfd) {
    bfd_close (exec_bfd);
    exec_bfd = NULL;
  }
  if (exec_ops.sections) {
    free (exec_ops.sections);
    exec_ops.sections = NULL;
    exec_ops.sections_end = NULL;
  }
}

void
exec_file_command (filename, from_tty)
     char *filename;
     int from_tty;
{
  target_preopen (from_tty);

  /* Remove any previous exec file.  */
  unpush_target (&exec_ops);

  /* Now open and digest the file the user requested, if any.  */

  if (filename)
    {
      char *scratch_pathname;
      int scratch_chan;
      
      filename = tilde_expand (filename);
      make_cleanup (free, filename);
      
      scratch_chan = openp (getenv ("PATH"), 1, filename, 
			    write_files? O_RDWR: O_RDONLY, 0,
			    &scratch_pathname);
      if (scratch_chan < 0)
	perror_with_name (filename);

      exec_bfd = bfd_fdopenr (scratch_pathname, NULL, scratch_chan);
      if (!exec_bfd)
	error ("Could not open `%s' as an executable file: %s",
	       scratch_pathname, bfd_errmsg (bfd_error));
      if (!bfd_check_format (exec_bfd, bfd_object))
	error ("\"%s\": not in executable format: %s.",
	       scratch_pathname, bfd_errmsg (bfd_error));

#if FIXME
/* This code needs to be incorporated into BFD */
#ifdef COFF_ENCAPSULATE
	/* If we have a coff header, it can give us better values for
	   text_start and exec_data_start.  This is particularly useful
	   for remote debugging of embedded systems.  */
	if (N_FLAGS(exec_aouthdr) & N_FLAGS_COFF_ENCAPSULATE)
	{
		struct coffheader ch;
		int val;
		val = lseek (execchan, -(sizeof (AOUTHDR) + sizeof (ch)), 1);
		if (val == -1)
			perror_with_name (filename);
		val = myread (execchan, &ch, sizeof (ch));
		if (val < 0)
			perror_with_name (filename);
		text_start = ch.text_start;
		exec_data_start = ch.data_start;
	} else
#endif
	       {
		text_start =
		  IS_OBJECT_FILE (exec_aouthdr) ? 0 : N_TXTADDR (exec_aouthdr);
		exec_data_start = IS_OBJECT_FILE (exec_aouthdr)
		  ? exec_aouthdr.a_text : N_DATADDR (exec_aouthdr);
	}
#endif FIXME

      if (build_section_table (exec_bfd, &exec_ops.sections,
				&exec_ops.sections_end))
	error ("Can't find the file sections in `%s': %s", 
		exec_bfd->filename, bfd_errmsg (bfd_error));

      validate_files ();

      push_target (&exec_ops);

      /* Tell display code (if any) about the changed file name.  */
      if (exec_file_display_hook)
	(*exec_file_display_hook) (filename);
    }
  else if (from_tty)
    printf ("No exec file now.\n");
}

/* Set both the exec file and the symbol file, in one command.  
   What a novelty.  Why did GDB go through four major releases before this
   command was added?  */

void
file_command (arg, from_tty)
     char *arg;
     int from_tty;
{
  /* FIXME, if we lose on reading the symbol file, we should revert
     the exec file, but that's rough.  */
  exec_file_command (arg, from_tty);
  symbol_file_command (arg, from_tty);
}

\f
/* Locate all mappable sections of a BFD file. 
   table_pp_char is a char * to get it through bfd_map_over_sections;
   we cast it back to its proper type.  */

void
add_to_section_table (abfd, asect, table_pp_char)
     bfd *abfd;
     sec_ptr asect;
     char *table_pp_char;
{
  struct section_table **table_pp = (struct section_table **)table_pp_char;
  flagword aflag;

  aflag = bfd_get_section_flags (abfd, asect);
  /* FIXME, we need to handle BSS segment here...it alloc's but doesn't load */
  if (!(aflag & SEC_LOAD))
    return;
  (*table_pp)->bfd = abfd;
  (*table_pp)->sec_ptr = asect;
  (*table_pp)->addr = bfd_section_vma (abfd, asect);
  (*table_pp)->endaddr = (*table_pp)->addr + bfd_section_size (abfd, asect);
  (*table_pp)++;
}

int
build_section_table (some_bfd, start, end)
     bfd *some_bfd;
     struct section_table **start, **end;
{
  unsigned count;

  count = bfd_count_sections (some_bfd);
  if (count == 0)
    abort();	/* return 1? */
  if (*start)
    free (*start);
  *start = (struct section_table *) xmalloc (count * sizeof (**start));
  *end = *start;
  bfd_map_over_sections (some_bfd, add_to_section_table, (char *)end);
  if (*end > *start + count)
    abort();
  /* We could realloc the table, but it probably loses for most files.  */
  return 0;
}
\f
/* Read or write the exec file.

   Args are address within a BFD file, address within gdb address-space,
   length, and a flag indicating whether to read or write.

   Result is a length:

	0:    We cannot handle this address and length.
	> 0:  We have handled N bytes starting at this address.
	      (If N == length, we did it all.)  We might be able
	      to handle more bytes beyond this length, but no
	      promises.
	< 0:  We cannot handle this address, but if somebody
	      else handles (-N) bytes, we can start from there.

    The same routine is used to handle both core and exec files;
    we just tail-call it with more arguments to select between them.  */

int
xfer_memory (memaddr, myaddr, len, write, target)
     CORE_ADDR memaddr;
     char *myaddr;
     int len;
     int write;
     struct target_ops *target;
{
  boolean res;
  struct section_table *p;
  CORE_ADDR nextsectaddr, memend;
  boolean (*xfer_fn) ();

  if (len <= 0)
    abort();

  memend = memaddr + len;
  xfer_fn = write? bfd_set_section_contents: bfd_get_section_contents;
  nextsectaddr = memend;

  for (p = target->sections; p < target->sections_end; p++)
    {
      if (p->addr <= memaddr)
	if (p->endaddr >= memend)
	  {
	    /* Entire transfer is within this section.  */
	    res = xfer_fn (p->bfd, p->sec_ptr, myaddr, memaddr - p->addr, len);
	    return (res != false)? len: 0;
	  }
	else if (p->endaddr <= memaddr)
	  {
	    /* This section ends before the transfer starts.  */
	    continue;
	  }
	else 
	  {
	    /* This section overlaps the transfer.  Just do half.  */
	    len = p->endaddr - memaddr;
	    res = xfer_fn (p->bfd, p->sec_ptr, myaddr, memaddr - p->addr, len);
	    return (res != false)? len: 0;
	  }
      else if (p->addr < nextsectaddr)
	nextsectaddr = p->addr;
    }

  if (nextsectaddr >= memend)
    return 0;				/* We can't help */
  else
    return - (nextsectaddr - memaddr);	/* Next boundary where we can help */
}

#ifdef FIXME
#ifdef REG_STACK_SEGMENT
/* MOVE TO BFD... */
    /* Pyramids and AM29000s have an extra segment in the virtual address space
       for the (control) stack of register-window frames.  The AM29000 folk
       call it the "register stack" rather than the "memory stack".  */
    else if (memaddr >= reg_stack_start && memaddr < reg_stack_end)
      {
	i = min (len, reg_stack_end - memaddr);
	fileptr = memaddr - reg_stack_start + reg_stack_offset;
	wanna_xfer = coredata;
      }
#endif				/* REG_STACK_SEGMENT */
#endif FIXME
\f
static void
exec_files_info ()
{
  struct section_table *p;

  printf ("\tExecutable file `%s'.\n", bfd_get_filename(exec_bfd));

  for (p = exec_ops.sections; p < exec_ops.sections_end; p++)
    printf("\texecutable from 0x%08x to 0x%08x is %s\n",
	p->addr, p->endaddr,
	bfd_section_name (exec_bfd, p->sec_ptr));
}

static void
set_section_command (args, from_tty)
     char *args;
     int from_tty;
{
  struct section_table *p;
  char *secname;
  unsigned seclen;
  unsigned long secaddr;
  char secprint[100];
  long offset;

  if (args == 0)
    error ("Must specify section name and its virtual address");

  /* Parse out section name */
  for (secname = args; !isspace(*args); args++) ;
  seclen = args - secname;

  /* Parse out new virtual address */
  secaddr = parse_and_eval_address (args);

  for (p = exec_ops.sections; p < exec_ops.sections_end; p++) {
    if (!strncmp (secname, bfd_section_name (exec_bfd, p->sec_ptr), seclen)
	&& bfd_section_name (exec_bfd, p->sec_ptr)[seclen] == '\0') {
      offset = secaddr - p->addr;
      p->addr += offset;
      p->endaddr += offset;
      exec_files_info();
      return;
    }
  } 
  if (seclen >= sizeof (secprint))
    seclen = sizeof (secprint) - 1;
  strncpy (secprint, secname, seclen);
  secprint[seclen] = '\0';
  error ("Section %s not found", secprint);
}

struct target_ops exec_ops = {
	"exec", "Local exec file",
	"Use an executable file as a target.\n\
Specify the filename of the executable file.",
	exec_file_command, exec_close, /* open, close */
	child_attach, 0, 0, 0, /* attach, detach, resume, wait, */
	0, 0, /* fetch_registers, store_registers, */
	0, 0, 0, /* prepare_to_store, conv_to, conv_from, */
	xfer_memory, exec_files_info,
	0, 0, /* insert_breakpoint, remove_breakpoint, */
	0, 0, 0, 0, 0, /* terminal stuff */
	0, 0, /* kill, load */
	0, 0, /* call fn, lookup sym */
	child_create_inferior,
	0, /* mourn_inferior */
	file_stratum, 0, /* next */
	0, 1, 0, 0, 0,	/* all mem, mem, stack, regs, exec */
	0, 0,			/* section pointers */
	OPS_MAGIC,		/* Always the last thing */
};

void
_initialize_exec()
{

  add_com ("file", class_files, file_command,
	   "Use FILE as program to be debugged.\n\
It is read for its symbols, for getting the contents of pure memory,\n\
and it is the program executed when you use the `run' command.\n\
If FILE cannot be found as specified, your execution directory path\n\
($PATH) is searched for a command of that name.\n\
No arg means to have no executable file and no symbols.");

  add_com ("exec-file", class_files, exec_file_command,
	   "Use FILE as program for getting contents of pure memory.\n\
If FILE cannot be found as specified, your execution directory path\n\
is searched for a command of that name.\n\
No arg means have no executable file.");

  add_com ("section", class_files, set_section_command,
   "Change the base address of section SECTION of the exec file to ADDR.\n\
This can be used if the exec file does not contain section addresses,\n\
(such as in the a.out format), or when the addresses specified in the\n\
file itself are wrong.  Each section must be changed separately.  The\n\
``info files'' command lists all the sections and their addresses.");

  add_show_from_set
    (add_set_cmd ("write", class_support, var_boolean, (char *)&write_files,
		  "Set writing into executable and core files.",
		  &setlist),
     &showlist);
  
  add_target (&exec_ops);
}