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578d3588ee
binutils-gdb/gdb/corefile.c
Pedro Alves 578d3588ee Stop using errno values around target_xfer interfaces and memory errors. 
target_read_memory & friends build on top of target_read (thus on top
of the target_xfer machinery), but turn all errors to EIO, an errno
value.  I think we'd better convert all these to return a
target_xfer_error too, like target_xfer_partial in a previous patch.
The patch starts by doing that.

(The patch does not add a enum target_xfer_error value for '0'/no
error, and likewise does not change the return type of several of
these functions to enum target_xfer_error, because different functions
return '0' with different semantics.)

I audited the tree for memory_error calls, EIO checks, places where
GDB hardcodes 'errno = EIO', and also for strerror calls.  What I
found is that nowadays there's really no need to handle random errno
values, other than the EIOs gdb itself hardcodes.  No doubt errno
values would appear in common code back in the day when
target_xfer_memory was the main interface to access memory, but
nowadays, any errno value that deprecated interface could return is
just absorved by default_xfer_partial:

      else if (xfered == 0 && errno == 0)
	/* "deprecated_xfer_memory" uses 0, cross checked against
           ERRNO as one indication of an error.  */
	return 0;
      else
	return -1;

There are two places in the code that check for EIO and print "out of
bounds", and defer to strerror for other errors.  That's
c-lang.c:c_get_string, and valprint.c.:val_print_string.  AFAICT, the
strerror branch can never be reached nowadays, as the only error
possible to get at those points is EIO, given that it's GDB itself
that set that errno value (in target_read_memory, etc.).

breakpoint.c:insert_bp_location always prints the error val as if an
errno, returned by target_insert_breakpoint, with strerr.  Now the
error here is either always EIO for mem-break.c targets (again
hardcoded by the target_read_memory/target_write_memory functions), so
this always prints "Input/output error" or similar (depending on
host), or, for remote targets (and probably others), this gem:

  Error accessing memory address 0x80200400: Unknown error -1.

This patch makes these 3 places print the exact same error
memory_error prints.  This changes output, but I think this is better,
for making memory error output consistent with other commands, and, it
means we have a central place to tweak for memory errors.

E.g., this changes:

 Cannot insert breakpoint 1.
 Error accessing memory address 0x5fc660: Input/output error.

to:

 Cannot insert breakpoint 1.
 Cannot access memory at address 0x5fc660

Which I find pretty much acceptable.

Surprisingly, only py-prettyprint.exp had a regression, for needing an
adjustment.  I also grepped the testsuite for the old errors, and
found no other hits.

Now that errno values aren't used anywhere in any of these memory
access related routines, I made memory_error itself take a
target_xfer_error instead of an errno.  The new
target_xfer_memory_error function added recently is no longer
necessary, and is thus removed.

Tested on x86_64 Fedora 17, native and gdbserver.

gdb/
2013-10-09  Pedro Alves  <palves@redhat.com>

	* breakpoint.c (insert_bp_location): Use memory_error_message to
	build the memory error string.
	* c-lang.c: Include "gdbcore.h".
	(c_get_string): Use memory_error to throw error.
	(target_xfer_memory_error): Delete.
	(memory_error_message): New, factored out from
	target_xfer_memory_error.
	(memory_error): Change parameter type to target_xfer_error.
	Rewrite.
	(read_memory): Use memory_error instead of
	target_xfer_memory_error.
	* gdbcore.h: Include "target.h".
	(memory_error): Change parameter type to target_xfer_error.
	(memory_error_message): Declare function.
	* target.c (target_read_memory, target_read_stack)
	(target_write_memory, target_write_raw_memory): Return
	TARGET_XFER_E_IO on error.  Adjust comments.
	(get_target_memory): Pass TARGET_XFER_E_IO to memory_error,
	instead of EIO.
	* target.h (target_read, target_insert_breakpoint)
	(target_remove_breakpoint): Adjust comments.
	* valprint.c (partial_memory_read): Rename parameter, and adjust
	comment.
	(val_print_string): Use memory_error_message to build the memory
	error string.

gdb/testsuite/
2013-10-09  Pedro Alves  <palves@redhat.com>

	* gdb.python/py-prettyprint.exp (run_lang_tests): Adjust expected
	output.
2013-10-09 17:00:00 +00:00

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/* Core dump and executable file functions above target vector, for GDB.
Copyright (C) 1986-2013 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 3 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, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "gdb_string.h"
#include <errno.h>
#include <signal.h>
#include <fcntl.h>
#include "inferior.h"
#include "symtab.h"
#include "command.h"
#include "gdbcmd.h"
#include "bfd.h"
#include "target.h"
#include "gdbcore.h"
#include "dis-asm.h"
#include "gdb_stat.h"
#include "completer.h"
#include "exceptions.h"
#include "observer.h"
#include "cli/cli-utils.h"
/* Local function declarations. */
extern void _initialize_core (void);
static void call_extra_exec_file_hooks (char *filename);
/* You can have any number of hooks for `exec_file_command' command to
call. If there's only one hook, it is set in exec_file_display
hook. If there are two or more hooks, they are set in
exec_file_extra_hooks[], and deprecated_exec_file_display_hook is
set to a function that calls all of them. This extra complexity is
needed to preserve compatibility with old code that assumed that
only one hook could be set, and which called
deprecated_exec_file_display_hook directly. */
typedef void (*hook_type) (char *);
hook_type deprecated_exec_file_display_hook; /* The original hook. */
static hook_type *exec_file_extra_hooks; /* Array of additional
hooks. */
static int exec_file_hook_count = 0; /* Size of array. */
/* Binary file diddling handle for the core file. */
bfd *core_bfd = NULL;
/* corelow.c target. It is never NULL after GDB initialization. */
struct target_ops *core_target;
/* Backward compatability with old way of specifying core files. */
void
core_file_command (char *filename, int from_tty)
{
dont_repeat (); /* Either way, seems bogus. */
gdb_assert (core_target != NULL);
if (!filename)
(core_target->to_detach) (core_target, filename, from_tty);
else
(core_target->to_open) (filename, from_tty);
}
/* If there are two or more functions that wish to hook into
exec_file_command, this function will call all of the hook
functions. */
static void
call_extra_exec_file_hooks (char *filename)
{
int i;
for (i = 0; i < exec_file_hook_count; i++)
(*exec_file_extra_hooks[i]) (filename);
}
/* Call this to specify the hook for exec_file_command to call back.
This is called from the x-window display code. */
void
specify_exec_file_hook (void (*hook) (char *))
{
hook_type *new_array;
if (deprecated_exec_file_display_hook != NULL)
{
/* There's already a hook installed. Arrange to have both it
and the subsequent hooks called. */
if (exec_file_hook_count == 0)
{
/* If this is the first extra hook, initialize the hook
array. */
exec_file_extra_hooks = (hook_type *)
xmalloc (sizeof (hook_type));
exec_file_extra_hooks[0] = deprecated_exec_file_display_hook;
deprecated_exec_file_display_hook = call_extra_exec_file_hooks;
exec_file_hook_count = 1;
}
/* Grow the hook array by one and add the new hook to the end.
Yes, it's inefficient to grow it by one each time but since
this is hardly ever called it's not a big deal. */
exec_file_hook_count++;
new_array = (hook_type *)
xrealloc (exec_file_extra_hooks,
exec_file_hook_count * sizeof (hook_type));
exec_file_extra_hooks = new_array;
exec_file_extra_hooks[exec_file_hook_count - 1] = hook;
}
else
deprecated_exec_file_display_hook = hook;
}
void
reopen_exec_file (void)
{
char *filename;
int res;
struct stat st;
struct cleanup *cleanups;
/* Don't do anything if there isn't an exec file. */
if (exec_bfd == NULL)
return;
/* If the timestamp of the exec file has changed, reopen it. */
filename = xstrdup (bfd_get_filename (exec_bfd));
cleanups = make_cleanup (xfree, filename);
res = stat (filename, &st);
if (exec_bfd_mtime && exec_bfd_mtime != st.st_mtime)
exec_file_attach (filename, 0);
else
/* If we accessed the file since last opening it, close it now;
this stops GDB from holding the executable open after it
exits. */
bfd_cache_close_all ();
do_cleanups (cleanups);
}
/* If we have both a core file and an exec file,
print a warning if they don't go together. */
void
validate_files (void)
{
if (exec_bfd && core_bfd)
{
if (!core_file_matches_executable_p (core_bfd, exec_bfd))
warning (_("core file may not match specified executable file."));
else if (bfd_get_mtime (exec_bfd) > bfd_get_mtime (core_bfd))
warning (_("exec file is newer than core file."));
}
}
/* Return the name of the executable file as a string.
ERR nonzero means get error if there is none specified;
otherwise return 0 in that case. */
char *
get_exec_file (int err)
{
if (exec_filename)
return exec_filename;
if (!err)
return NULL;
error (_("No executable file specified.\n\
Use the \"file\" or \"exec-file\" command."));
return NULL;
}
char *
memory_error_message (enum target_xfer_error err,
struct gdbarch *gdbarch, CORE_ADDR memaddr)
{
switch (err)
{
case TARGET_XFER_E_IO:
/* Actually, address between memaddr and memaddr + len was out of
bounds. */
return xstrprintf (_("Cannot access memory at address %s"),
paddress (gdbarch, memaddr));
case TARGET_XFER_E_UNAVAILABLE:
return xstrprintf (_("Memory at address %s unavailable."),
paddress (gdbarch, memaddr));
default:
internal_error (__FILE__, __LINE__,
"unhandled target_xfer_error: %s (%s)",
target_xfer_error_to_string (err),
plongest (err));
}
}
/* Report a memory error by throwing a suitable exception. */
void
memory_error (enum target_xfer_error err, CORE_ADDR memaddr)
{
char *str;
/* Build error string. */
str = memory_error_message (err, target_gdbarch (), memaddr);
make_cleanup (xfree, str);
/* Choose the right error to throw. */
switch (err)
{
case TARGET_XFER_E_IO:
err = MEMORY_ERROR;
break;
case TARGET_XFER_E_UNAVAILABLE:
err = NOT_AVAILABLE_ERROR;
break;
}
/* Throw it. */
throw_error (err, ("%s"), str);
}
/* Same as target_read_memory, but report an error if can't read. */
void
read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
{
LONGEST xfered = 0;
while (xfered < len)
{
LONGEST xfer = target_xfer_partial (current_target.beneath,
TARGET_OBJECT_MEMORY, NULL,
myaddr + xfered, NULL,
memaddr + xfered, len - xfered);
if (xfer == 0)
memory_error (TARGET_XFER_E_IO, memaddr + xfered);
if (xfer < 0)
memory_error (xfer, memaddr + xfered);
xfered += xfer;
QUIT;
}
}
/* Same as target_read_stack, but report an error if can't read. */
void
read_stack (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len)
{
int status;
status = target_read_stack (memaddr, myaddr, len);
if (status != 0)
memory_error (status, memaddr);
}
/* Argument / return result struct for use with
do_captured_read_memory_integer(). MEMADDR and LEN are filled in
by gdb_read_memory_integer(). RESULT is the contents that were
successfully read from MEMADDR of length LEN. */
struct captured_read_memory_integer_arguments
{
CORE_ADDR memaddr;
int len;
enum bfd_endian byte_order;
LONGEST result;
};
/* Helper function for gdb_read_memory_integer(). DATA must be a
pointer to a captured_read_memory_integer_arguments struct.
Return 1 if successful. Note that the catch_errors() interface
will return 0 if an error occurred while reading memory. This
choice of return code is so that we can distinguish between
success and failure. */
static int
do_captured_read_memory_integer (void *data)
{
struct captured_read_memory_integer_arguments *args
= (struct captured_read_memory_integer_arguments*) data;
CORE_ADDR memaddr = args->memaddr;
int len = args->len;
enum bfd_endian byte_order = args->byte_order;
args->result = read_memory_integer (memaddr, len, byte_order);
return 1;
}
/* Read memory at MEMADDR of length LEN and put the contents in
RETURN_VALUE. Return 0 if MEMADDR couldn't be read and non-zero
if successful. */
int
safe_read_memory_integer (CORE_ADDR memaddr, int len,
enum bfd_endian byte_order,
LONGEST *return_value)
{
int status;
struct captured_read_memory_integer_arguments args;
args.memaddr = memaddr;
args.len = len;
args.byte_order = byte_order;
status = catch_errors (do_captured_read_memory_integer, &args,
"", RETURN_MASK_ALL);
if (status)
*return_value = args.result;
return status;
}
LONGEST
read_memory_integer (CORE_ADDR memaddr, int len,
enum bfd_endian byte_order)
{
gdb_byte buf[sizeof (LONGEST)];
read_memory (memaddr, buf, len);
return extract_signed_integer (buf, len, byte_order);
}
ULONGEST
read_memory_unsigned_integer (CORE_ADDR memaddr, int len,
enum bfd_endian byte_order)
{
gdb_byte buf[sizeof (ULONGEST)];
read_memory (memaddr, buf, len);
return extract_unsigned_integer (buf, len, byte_order);
}
void
read_memory_string (CORE_ADDR memaddr, char *buffer, int max_len)
{
char *cp;
int i;
int cnt;
cp = buffer;
while (1)
{
if (cp - buffer >= max_len)
{
buffer[max_len - 1] = '\0';
break;
}
cnt = max_len - (cp - buffer);
if (cnt > 8)
cnt = 8;
read_memory (memaddr + (int) (cp - buffer), (gdb_byte *) cp, cnt);
for (i = 0; i < cnt && *cp; i++, cp++)
; /* null body */
if (i < cnt && !*cp)
break;
}
}
CORE_ADDR
read_memory_typed_address (CORE_ADDR addr, struct type *type)
{
gdb_byte *buf = alloca (TYPE_LENGTH (type));
read_memory (addr, buf, TYPE_LENGTH (type));
return extract_typed_address (buf, type);
}
/* Same as target_write_memory, but report an error if can't
write. */
void
write_memory (CORE_ADDR memaddr,
const bfd_byte *myaddr, ssize_t len)
{
int status;
status = target_write_memory (memaddr, myaddr, len);
if (status != 0)
memory_error (status, memaddr);
}
/* Same as write_memory, but notify 'memory_changed' observers. */
void
write_memory_with_notification (CORE_ADDR memaddr, const bfd_byte *myaddr,
ssize_t len)
{
write_memory (memaddr, myaddr, len);
observer_notify_memory_changed (current_inferior (), memaddr, len, myaddr);
}
/* Store VALUE at ADDR in the inferior as a LEN-byte unsigned
integer. */
void
write_memory_unsigned_integer (CORE_ADDR addr, int len,
enum bfd_endian byte_order,
ULONGEST value)
{
gdb_byte *buf = alloca (len);
store_unsigned_integer (buf, len, byte_order, value);
write_memory (addr, buf, len);
}
/* Store VALUE at ADDR in the inferior as a LEN-byte signed
integer. */
void
write_memory_signed_integer (CORE_ADDR addr, int len,
enum bfd_endian byte_order,
LONGEST value)
{
gdb_byte *buf = alloca (len);
store_signed_integer (buf, len, byte_order, value);
write_memory (addr, buf, len);
}
/* The current default bfd target. Points to storage allocated for
gnutarget_string. */
char *gnutarget;
/* Same thing, except it is "auto" not NULL for the default case. */
static char *gnutarget_string;
static void
show_gnutarget_string (struct ui_file *file, int from_tty,
struct cmd_list_element *c,
const char *value)
{
fprintf_filtered (file,
_("The current BFD target is \"%s\".\n"), value);
}
static void set_gnutarget_command (char *, int,
struct cmd_list_element *);
static void
set_gnutarget_command (char *ignore, int from_tty,
struct cmd_list_element *c)
{
char *gend = gnutarget_string + strlen (gnutarget_string);
gend = remove_trailing_whitespace (gnutarget_string, gend);
*gend = '\0';
if (strcmp (gnutarget_string, "auto") == 0)
gnutarget = NULL;
else
gnutarget = gnutarget_string;
}
/* A completion function for "set gnutarget". */
static VEC (char_ptr) *
complete_set_gnutarget (struct cmd_list_element *cmd,
const char *text, const char *word)
{
static const char **bfd_targets;
if (bfd_targets == NULL)
{
int last;
bfd_targets = bfd_target_list ();
for (last = 0; bfd_targets[last] != NULL; ++last)
;
bfd_targets = xrealloc (bfd_targets, (last + 2) * sizeof (const char **));
bfd_targets[last] = "auto";
bfd_targets[last + 1] = NULL;
}
return complete_on_enum (bfd_targets, text, word);
}
/* Set the gnutarget. */
void
set_gnutarget (char *newtarget)
{
if (gnutarget_string != NULL)
xfree (gnutarget_string);
gnutarget_string = xstrdup (newtarget);
set_gnutarget_command (NULL, 0, NULL);
}
void
_initialize_core (void)
{
struct cmd_list_element *c;
c = add_cmd ("core-file", class_files, core_file_command, _("\
Use FILE as core dump for examining memory and registers.\n\
No arg means have no core file. This command has been superseded by the\n\
`target core' and `detach' commands."), &cmdlist);
set_cmd_completer (c, filename_completer);
c = add_setshow_string_noescape_cmd ("gnutarget", class_files,
&gnutarget_string, _("\
Set the current BFD target."), _("\
Show the current BFD target."), _("\
Use `set gnutarget auto' to specify automatic detection."),
set_gnutarget_command,
show_gnutarget_string,
&setlist, &showlist);
set_cmd_completer (c, complete_set_gnutarget);
add_alias_cmd ("g", "gnutarget", class_files, 1, &setlist);
if (getenv ("GNUTARGET"))
set_gnutarget (getenv ("GNUTARGET"));
else
set_gnutarget ("auto");
}
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