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binutils-gdb/gdb/gdbcore.h
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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/* Machine independent variables that describe the core file under 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/>. */
/* Interface routines for core, executable, etc. */
#if !defined (GDBCORE_H)
#define GDBCORE_H 1
struct type;
struct regcache;
#include "bfd.h"
#include "exec.h"
#include "target.h"
/* 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. */
extern char *get_exec_file (int err);
/* Nonzero if there is a core file. */
extern int have_core_file_p (void);
/* Report a memory error with error(). */
extern void memory_error (enum target_xfer_error status, CORE_ADDR memaddr);
/* The string 'memory_error' would use as exception message. Space
for the result is malloc'd, caller must free. */
extern char *memory_error_message (enum target_xfer_error err,
struct gdbarch *gdbarch, CORE_ADDR memaddr);
/* Like target_read_memory, but report an error if can't read. */
extern void read_memory (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len);
/* Like target_read_stack, but report an error if can't read. */
extern void read_stack (CORE_ADDR memaddr, gdb_byte *myaddr, ssize_t len);
/* Read an integer from debugged memory, given address and number of
bytes. */
extern LONGEST read_memory_integer (CORE_ADDR memaddr,
int len, enum bfd_endian byte_order);
extern int safe_read_memory_integer (CORE_ADDR memaddr, int len,
enum bfd_endian byte_order,
LONGEST *return_value);
/* Read an unsigned integer from debugged memory, given address and
number of bytes. */
extern ULONGEST read_memory_unsigned_integer (CORE_ADDR memaddr,
int len,
enum bfd_endian byte_order);
/* Read a null-terminated string from the debuggee's memory, given
address, a buffer into which to place the string, and the maximum
available space. */
extern void read_memory_string (CORE_ADDR, char *, int);
/* Read the pointer of type TYPE at ADDR, and return the address it
represents. */
CORE_ADDR read_memory_typed_address (CORE_ADDR addr, struct type *type);
/* This takes a char *, not void *. This is probably right, because
passing in an int * or whatever is wrong with respect to
byteswapping, alignment, different sizes for host vs. target types,
etc. */
extern void write_memory (CORE_ADDR memaddr, const gdb_byte *myaddr,
ssize_t len);
/* Same as write_memory, but notify 'memory_changed' observers. */
extern void write_memory_with_notification (CORE_ADDR memaddr,
const bfd_byte *myaddr,
ssize_t len);
/* Store VALUE at ADDR in the inferior as a LEN-byte unsigned integer. */
extern void write_memory_unsigned_integer (CORE_ADDR addr, int len,
enum bfd_endian byte_order,
ULONGEST value);
/* Store VALUE at ADDR in the inferior as a LEN-byte unsigned integer. */
extern void write_memory_signed_integer (CORE_ADDR addr, int len,
enum bfd_endian byte_order,
LONGEST value);
/* Hook for `exec_file_command' command to call. */
extern void (*deprecated_exec_file_display_hook) (char *filename);
/* Hook for "file_command", which is more useful than above
(because it is invoked AFTER symbols are read, not before). */
extern void (*deprecated_file_changed_hook) (char *filename);
extern void specify_exec_file_hook (void (*hook) (char *filename));
/* Binary File Diddler for the core file. */
extern bfd *core_bfd;
extern struct target_ops *core_target;
/* Whether to open exec and core files read-only or read-write. */
extern int write_files;
extern void core_file_command (char *filename, int from_tty);
extern void exec_file_attach (char *filename, int from_tty);
extern void exec_file_clear (int from_tty);
extern void validate_files (void);
/* The current default bfd target. */
extern char *gnutarget;
extern void set_gnutarget (char *);
/* Structure to keep track of core register reading functions for
various core file types. */
struct core_fns
{
/* BFD flavour that a core file handler is prepared to read. This
can be used by the handler's core tasting function as a first
level filter to reject BFD's that don't have the right
flavour. */
enum bfd_flavour core_flavour;
/* Core file handler function to call to recognize corefile
formats that BFD rejects. Some core file format just don't fit
into the BFD model, or may require other resources to identify
them, that simply aren't available to BFD (such as symbols from
another file). Returns nonzero if the handler recognizes the
format, zero otherwise. */
int (*check_format) (bfd *);
/* Core file handler function to call to ask if it can handle a
given core file format or not. Returns zero if it can't,
nonzero otherwise. */
int (*core_sniffer) (struct core_fns *, bfd *);
/* Extract the register values out of the core file and supply them
into REGCACHE.
CORE_REG_SECT points to the register values themselves, read into
memory.
CORE_REG_SIZE is the size of that area.
WHICH says which set of registers we are handling:
0 --- integer registers
2 --- floating-point registers, on machines where they are
discontiguous
3 --- extended floating-point registers, on machines where
these are present in yet a third area. (GNU/Linux uses
this to get at the SSE registers.)
REG_ADDR is the offset from u.u_ar0 to the register values relative to
core_reg_sect. This is used with old-fashioned core files to locate the
registers in a large upage-plus-stack ".reg" section. Original upage
address X is at location core_reg_sect+x+reg_addr. */
void (*core_read_registers) (struct regcache *regcache,
char *core_reg_sect,
unsigned core_reg_size,
int which, CORE_ADDR reg_addr);
/* Finds the next struct core_fns. They are allocated and
initialized in whatever module implements the functions pointed
to; an initializer calls deprecated_add_core_fns to add them to
the global chain. */
struct core_fns *next;
};
/* NOTE: cagney/2004-04-05: Replaced by "regset.h" and
regset_from_core_section(). */
extern void deprecated_add_core_fns (struct core_fns *cf);
extern int default_core_sniffer (struct core_fns *cf, bfd * abfd);
extern int default_check_format (bfd * abfd);
struct target_section *deprecated_core_resize_section_table (int num_added);
#endif /* !defined (GDBCORE_H) */
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