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8sa1-binutils-gdb/gdb/exec.c
Andrew Burgess 336aa7b740 gdb: move get_section_table from exec_target to dummy_target 
The only target that implements target_ops::get_section_table in a
meaningful way is exec_target.  This target calls back into the
program space to return the current global section_table.

The global section table is populated whenever the user provides GDB
with an executable, or when a symbol file is loaded, e.g. when a
dynamic library is loaded, or when the user does add-symbol-file.

I recently ran into a situation where a user, debugging a remote
target, was not supplying GDB with a main executable at all.  Instead
the user attached to the target then did add-symbol-file, and then
proceeded to debug the target.

This works fine, but it was noticed that even when
trust-readonly-sections was on GDB was still accessing the target to
get the contents of readonly sections.

The problem is that by not providing an executable there was no
exec_target in the target stack, and so when GDB calls the
target_ops::get_section_table function GDB ends up in
dummy_target::get_section_table, which just returns NULL.

What I want is that even when GDB doesn't have an exec_target in the
target stack, a call to target_ops::get_section_table will still
return the section_table from the current program space.

When considering how to achieve this my first though was, why is the
request for the section table going via the target stack at all?  The
set of sections loaded is a property of the program space, not the
target.  This is, after all, why the data is being stored in the
program space.

So I initially tried changing target_get_section_table so that,
instead of calling into the target it just returns
current_program_space->target_sections ().

This would be fine except for one issue, target_bfd (from
bfd-target.c).  This code is used from solib-svr4.c to create a
temporary target_ops structure that implements two functions
target_bfd::xfer_partial and target_bfd::get_section_table.

The purpose behind the code is to enable two targets, ppc64 and frv to
decode function descriptors from the dynamic linker, based on the
non-relocated addresses from within the dynamic linker bfd object.

Both of the implemented functions in target_bfd rely on the target_bfd
object holding a section table, and the ppc64 target requires that the
target_bfd implement ::get_section_table.

The frv target doesn't require ::get_section_table, instead it
requires the ::xfer_partial.  We could in theory change the ppc64
target to use the same approach as frv, however, this would be a bad
idea.  I believe that the frv target approach is broken.  I'll
explain:

The frv target calls get_target_memory_unsigned to read the function
descriptor.  The address being read is the non-relocated address read
from the dynamic linker in solib-srv4.c:enable_break.  Calling
get_target_memory_unsigned eventually ends up in target_xfer_partial
with an object type of TARGET_OBJECT_RAW_MEMORY.  This will then call
memory_xfer_check_region.  I believe that it is quite possible that a
the non-relocated addresses pulled from the dynamic linker could be in
a memory region that is not readable, while the relocated addresses
are in a readable memory region.  If this was ever the case for the
frv target then GDB would reject the attempt to read the non-relocated
function pointer.

In contrast the ppc64 target calls target_section_by_addr, which calls
target_get_section_table, which then calls the ::get_section_table
function on the target.

Thus, when reflecting on target_bfd we see two functions,
::xfer_partial and ::get_section_table.  The former is required by the
frv target, but that target is (I think) potentially broken.  While
the latter is required by the ppc64 target, but this forces
::get_section_table to exist as a target_ops member function.

So my original plan, have target_get_section_table NOT call a
target_ops member function appears to be flawed.

My next idea was to remove exec_target::get_section_table, and instead
move the implementation into dummy_target::get_section_table.
Currently the dummy_target implementation always returns NULL
indicating no section table, but plenty of other dummy_target member
functions do more than just return null values.

So now, dummy_target::get_section_table returns the section table from
the current program space.  This allows target_bfd to remain
unchanged, so ppc64 and frv should not be affected.

Making this change removes the requirement for the user to provide an
executable, GDB can now always access the section_table, as the
dummy_target always exists in the target stack.

Finally, there's a test that the target_section table is not empty in
the case where the user does add-symbol-file without providing an
executable.

gdb/ChangeLog:

	* exec.c (exec_target::get_section_table): Delete member function.
	(section_table_read_available_memory): Use current_top_target, not
	just the exec_ops target.
	* target-delegates.c: Regenerate.
	* target.c (default_get_section_table): New function.
	* target.h (target_ops::get_section_table): Change default
	behaviour to call default_get_section_table.
	(default_get_section_table): Declare.
2021-02-24 16:58:04 +00:00

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/* Work with executable files, for GDB.
Copyright (C) 1988-2021 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 "frame.h"
#include "inferior.h"
#include "target.h"
#include "gdbcmd.h"
#include "language.h"
#include "filenames.h"
#include "symfile.h"
#include "objfiles.h"
#include "completer.h"
#include "value.h"
#include "exec.h"
#include "observable.h"
#include "arch-utils.h"
#include "gdbthread.h"
#include "progspace.h"
#include "progspace-and-thread.h"
#include "gdb_bfd.h"
#include "gcore.h"
#include "source.h"
#include "build-id.h"
#include <fcntl.h>
#include "readline/tilde.h"
#include "gdbcore.h"
#include <ctype.h>
#include <sys/stat.h>
#include "solist.h"
#include <algorithm>
#include "gdbsupport/pathstuff.h"
#include "cli/cli-style.h"
void (*deprecated_file_changed_hook) (const char *);
static const target_info exec_target_info = {
"exec",
N_("Local exec file"),
N_("Use an executable file as a target.\n\
Specify the filename of the executable file.")
};
/* The target vector for executable files. */
struct exec_target final : public target_ops
{
const target_info &info () const override
{ return exec_target_info; }
strata stratum () const override { return file_stratum; }
void close () override;
enum target_xfer_status xfer_partial (enum target_object object,
const char *annex,
gdb_byte *readbuf,
const gdb_byte *writebuf,
ULONGEST offset, ULONGEST len,
ULONGEST *xfered_len) override;
void files_info () override;
bool has_memory () override;
gdb::unique_xmalloc_ptr<char> make_corefile_notes (bfd *, int *) override;
int find_memory_regions (find_memory_region_ftype func, void *data) override;
};
static exec_target exec_ops;
/* How to handle a mismatch between the current exec file and the exec
file determined from target. */
static const char *const exec_file_mismatch_names[]
= {"ask", "warn", "off", NULL };
enum exec_file_mismatch_mode
{
exec_file_mismatch_ask, exec_file_mismatch_warn, exec_file_mismatch_off
};
static const char *exec_file_mismatch = exec_file_mismatch_names[0];
static enum exec_file_mismatch_mode exec_file_mismatch_mode
= exec_file_mismatch_ask;
/* Show command. */
static void
show_exec_file_mismatch_command (struct ui_file *file, int from_tty,
struct cmd_list_element *c, const char *value)
{
fprintf_filtered (gdb_stdout,
_("exec-file-mismatch handling is currently \"%s\".\n"),
exec_file_mismatch_names[exec_file_mismatch_mode]);
}
/* Set command. Change the setting for range checking. */
static void
set_exec_file_mismatch_command (const char *ignore,
int from_tty, struct cmd_list_element *c)
{
for (enum exec_file_mismatch_mode mode = exec_file_mismatch_ask;
;
mode = static_cast<enum exec_file_mismatch_mode>(1 + (int) mode))
{
if (strcmp (exec_file_mismatch, exec_file_mismatch_names[mode]) == 0)
{
exec_file_mismatch_mode = mode;
return;
}
if (mode == exec_file_mismatch_off)
internal_error (__FILE__, __LINE__,
_("Unrecognized exec-file-mismatch setting: \"%s\""),
exec_file_mismatch);
}
}
/* Whether to open exec and core files read-only or read-write. */
bool write_files = false;
static void
show_write_files (struct ui_file *file, int from_tty,
struct cmd_list_element *c, const char *value)
{
fprintf_filtered (file, _("Writing into executable and core files is %s.\n"),
value);
}
static void
exec_target_open (const char *args, int from_tty)
{
target_preopen (from_tty);
exec_file_attach (args, from_tty);
}
/* This is the target_close implementation. Clears all target
sections and closes all executable bfds from all program spaces. */
void
exec_target::close ()
{
for (struct program_space *ss : program_spaces)
{
ss->clear_target_sections ();
ss->exec_close ();
}
}
/* See gdbcore.h. */
void
try_open_exec_file (const char *exec_file_host, struct inferior *inf,
symfile_add_flags add_flags)
{
struct gdb_exception prev_err;
/* exec_file_attach and symbol_file_add_main may throw an error if the file
cannot be opened either locally or remotely.
This happens for example, when the file is first found in the local
sysroot (above), and then disappears (a TOCTOU race), or when it doesn't
exist in the target filesystem, or when the file does exist, but
is not readable.
Even without a symbol file, the remote-based debugging session should
continue normally instead of ending abruptly. Hence we catch thrown
errors/exceptions in the following code. */
try
{
/* We must do this step even if exec_file_host is NULL, so that
exec_file_attach will clear state. */
exec_file_attach (exec_file_host, add_flags & SYMFILE_VERBOSE);
}
catch (gdb_exception_error &err)
{
if (err.message != NULL)
warning ("%s", err.what ());
prev_err = std::move (err);
}
if (exec_file_host != NULL)
{
try
{
symbol_file_add_main (exec_file_host, add_flags);
}
catch (const gdb_exception_error &err)
{
if (!exception_print_same (prev_err, err))
warning ("%s", err.what ());
}
}
}
/* See gdbcore.h. */
void
validate_exec_file (int from_tty)
{
/* If user asked to ignore the mismatch, do nothing. */
if (exec_file_mismatch_mode == exec_file_mismatch_off)
return;
const char *current_exec_file = get_exec_file (0);
struct inferior *inf = current_inferior ();
/* Try to determine a filename from the process itself. */
const char *pid_exec_file = target_pid_to_exec_file (inf->pid);
bool build_id_mismatch = false;
/* If we cannot validate the exec file, return. */
if (current_exec_file == NULL || pid_exec_file == NULL)
return;
/* Try validating via build-id, if available. This is the most
reliable check. */
/* In case current_exec_file was changed, reopen_exec_file ensures
an up to date build_id (will do nothing if the file timestamp
did not change). If exec file changed, reopen_exec_file has
allocated another file name, so get_exec_file again. */
reopen_exec_file ();
current_exec_file = get_exec_file (0);
const bfd_build_id *exec_file_build_id
= build_id_bfd_get (current_program_space->exec_bfd ());
if (exec_file_build_id != nullptr)
{
/* Prepend the target prefix, to force gdb_bfd_open to open the
file on the remote file system (if indeed remote). */
std::string target_pid_exec_file
= std::string (TARGET_SYSROOT_PREFIX) + pid_exec_file;
gdb_bfd_ref_ptr abfd (gdb_bfd_open (target_pid_exec_file.c_str (),
gnutarget, -1, false));
if (abfd != nullptr)
{
const bfd_build_id *target_exec_file_build_id
= build_id_bfd_get (abfd.get ());
if (target_exec_file_build_id != nullptr)
{
if (exec_file_build_id->size == target_exec_file_build_id->size
&& memcmp (exec_file_build_id->data,
target_exec_file_build_id->data,
exec_file_build_id->size) == 0)
{
/* Match. */
return;
}
else
build_id_mismatch = true;
}
}
}
if (build_id_mismatch)
{
std::string exec_file_target (pid_exec_file);
/* In case the exec file is not local, exec_file_target has to point at
the target file system. */
if (is_target_filename (current_exec_file) && !target_filesystem_is_local ())
exec_file_target = TARGET_SYSROOT_PREFIX + exec_file_target;
warning
(_("Build ID mismatch between current exec-file %ps\n"
"and automatically determined exec-file %ps\n"
"exec-file-mismatch handling is currently \"%s\""),
styled_string (file_name_style.style (), current_exec_file),
styled_string (file_name_style.style (), exec_file_target.c_str ()),
exec_file_mismatch_names[exec_file_mismatch_mode]);
if (exec_file_mismatch_mode == exec_file_mismatch_ask)
{
symfile_add_flags add_flags = SYMFILE_MAINLINE;
if (from_tty)
{
add_flags |= SYMFILE_VERBOSE;
add_flags |= SYMFILE_ALWAYS_CONFIRM;
}
try
{
symbol_file_add_main (exec_file_target.c_str (), add_flags);
exec_file_attach (exec_file_target.c_str (), from_tty);
}
catch (gdb_exception_error &err)
{
warning (_("loading %ps %s"),
styled_string (file_name_style.style (),
exec_file_target.c_str ()),
err.message != NULL ? err.what () : "error");
}
}
}
}
/* See gdbcore.h. */
void
exec_file_locate_attach (int pid, int defer_bp_reset, int from_tty)
{
char *exec_file_target;
symfile_add_flags add_flags = 0;
/* Do nothing if we already have an executable filename. */
if (get_exec_file (0) != NULL)
return;
/* Try to determine a filename from the process itself. */
exec_file_target = target_pid_to_exec_file (pid);
if (exec_file_target == NULL)
{
warning (_("No executable has been specified and target does not "
"support\n"
"determining executable automatically. "
"Try using the \"file\" command."));
return;
}
gdb::unique_xmalloc_ptr<char> exec_file_host
= exec_file_find (exec_file_target, NULL);
if (defer_bp_reset)
add_flags |= SYMFILE_DEFER_BP_RESET;
if (from_tty)
add_flags |= SYMFILE_VERBOSE;
/* Attempt to open the exec file. */
try_open_exec_file (exec_file_host.get (), current_inferior (), add_flags);
}
/* Set FILENAME as the new exec file.
This function is intended to be behave essentially the same
as exec_file_command, except that the latter will detect when
a target is being debugged, and will ask the user whether it
should be shut down first. (If the answer is "no", then the
new file is ignored.)
This file is used by exec_file_command, to do the work of opening
and processing the exec file after any prompting has happened.
And, it is used by child_attach, when the attach command was
given a pid but not a exec pathname, and the attach command could
figure out the pathname from the pid. (In this case, we shouldn't
ask the user whether the current target should be shut down --
we're supplying the exec pathname late for good reason.) */
void
exec_file_attach (const char *filename, int from_tty)
{
/* First, acquire a reference to the exec_bfd. We release
this at the end of the function; but acquiring it now lets the
BFD cache return it if this call refers to the same file. */
gdb_bfd_ref_ptr exec_bfd_holder
= gdb_bfd_ref_ptr::new_reference (current_program_space->exec_bfd ());
/* Remove any previous exec file. */
current_program_space->exec_close ();
/* Now open and digest the file the user requested, if any. */
if (!filename)
{
if (from_tty)
printf_unfiltered (_("No executable file now.\n"));
set_gdbarch_from_file (NULL);
}
else
{
int load_via_target = 0;
const char *scratch_pathname, *canonical_pathname;
int scratch_chan;
char **matching;
if (is_target_filename (filename))
{
if (target_filesystem_is_local ())
filename += strlen (TARGET_SYSROOT_PREFIX);
else
load_via_target = 1;
}
gdb::unique_xmalloc_ptr<char> canonical_storage, scratch_storage;
if (load_via_target)
{
/* gdb_bfd_fopen does not support "target:" filenames. */
if (write_files)
warning (_("writing into executable files is "
"not supported for %s sysroots"),
TARGET_SYSROOT_PREFIX);
scratch_pathname = filename;
scratch_chan = -1;
canonical_pathname = scratch_pathname;
}
else
{
scratch_chan = openp (getenv ("PATH"), OPF_TRY_CWD_FIRST,
filename, write_files ?
O_RDWR | O_BINARY : O_RDONLY | O_BINARY,
&scratch_storage);
#if defined(__GO32__) || defined(_WIN32) || defined(__CYGWIN__)
if (scratch_chan < 0)
{
int first_errno = errno;
char *exename = (char *) alloca (strlen (filename) + 5);
strcat (strcpy (exename, filename), ".exe");
scratch_chan = openp (getenv ("PATH"), OPF_TRY_CWD_FIRST,
exename, write_files ?
O_RDWR | O_BINARY
: O_RDONLY | O_BINARY,
&scratch_storage);
if (scratch_chan < 0)
errno = first_errno;
}
#endif
if (scratch_chan < 0)
perror_with_name (filename);
scratch_pathname = scratch_storage.get ();
/* gdb_bfd_open (and its variants) prefers canonicalized
pathname for better BFD caching. */
canonical_storage = gdb_realpath (scratch_pathname);
canonical_pathname = canonical_storage.get ();
}
gdb_bfd_ref_ptr temp;
if (write_files && !load_via_target)
temp = gdb_bfd_fopen (canonical_pathname, gnutarget,
FOPEN_RUB, scratch_chan);
else
temp = gdb_bfd_open (canonical_pathname, gnutarget, scratch_chan);
current_program_space->set_exec_bfd (std::move (temp));
if (!current_program_space->exec_bfd ())
{
error (_("\"%ps\": could not open as an executable file: %s."),
styled_string (file_name_style.style (), scratch_pathname),
bfd_errmsg (bfd_get_error ()));
}
/* gdb_realpath_keepfile resolves symlinks on the local
filesystem and so cannot be used for "target:" files. */
gdb_assert (current_program_space->exec_filename == nullptr);
if (load_via_target)
current_program_space->exec_filename
= (make_unique_xstrdup
(bfd_get_filename (current_program_space->exec_bfd ())));
else
current_program_space->exec_filename
= gdb_realpath_keepfile (scratch_pathname);
if (!bfd_check_format_matches (current_program_space->exec_bfd (),
bfd_object, &matching))
{
/* Make sure to close exec_bfd, or else "run" might try to use
it. */
current_program_space->exec_close ();
error (_("\"%ps\": not in executable format: %s"),
styled_string (file_name_style.style (), scratch_pathname),
gdb_bfd_errmsg (bfd_get_error (), matching).c_str ());
}
target_section_table sections
= build_section_table (current_program_space->exec_bfd ());
current_program_space->ebfd_mtime
= bfd_get_mtime (current_program_space->exec_bfd ());
validate_files ();
set_gdbarch_from_file (current_program_space->exec_bfd ());
/* Add the executable's sections to the current address spaces'
list of sections. This possibly pushes the exec_ops
target. */
current_program_space->add_target_sections (&current_program_space->ebfd,
sections);
/* Tell display code (if any) about the changed file name. */
if (deprecated_exec_file_display_hook)
(*deprecated_exec_file_display_hook) (filename);
}
bfd_cache_close_all ();
gdb::observers::executable_changed.notify ();
}
/* Process the first arg in ARGS as the new exec file.
Note that we have to explicitly ignore additional args, since we can
be called from file_command(), which also calls symbol_file_command()
which can take multiple args.
If ARGS is NULL, we just want to close the exec file. */
static void
exec_file_command (const char *args, int from_tty)
{
if (from_tty && target_has_execution ()
&& !query (_("A program is being debugged already.\n"
"Are you sure you want to change the file? ")))
error (_("File not changed."));
if (args)
{
/* Scan through the args and pick up the first non option arg
as the filename. */
gdb_argv built_argv (args);
char **argv = built_argv.get ();
for (; (*argv != NULL) && (**argv == '-'); argv++)
{;
}
if (*argv == NULL)
error (_("No executable file name was specified"));
gdb::unique_xmalloc_ptr<char> filename (tilde_expand (*argv));
exec_file_attach (filename.get (), from_tty);
}
else
exec_file_attach (NULL, from_tty);
}
/* 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? */
static void
file_command (const 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);
if (deprecated_file_changed_hook)
deprecated_file_changed_hook (arg);
}
/* Builds a section table, given args BFD, TABLE. */
target_section_table
build_section_table (struct bfd *some_bfd)
{
target_section_table table;
for (asection *asect : gdb_bfd_sections (some_bfd))
{
flagword aflag;
/* Check the section flags, but do not discard zero-length
sections, since some symbols may still be attached to this
section. For instance, we encountered on sparc-solaris 2.10
a shared library with an empty .bss section to which a symbol
named "_end" was attached. The address of this symbol still
needs to be relocated. */
aflag = bfd_section_flags (asect);
if (!(aflag & SEC_ALLOC))
continue;
table.emplace_back (bfd_section_vma (asect),
bfd_section_vma (asect) + bfd_section_size (asect),
asect);
}
return table;
}
/* Add the sections array defined by [SECTIONS..SECTIONS_END[ to the
current set of target sections. */
void
program_space::add_target_sections (void *owner,
const target_section_table &sections)
{
if (!sections.empty ())
{
for (const target_section &s : sections)
{
m_target_sections.push_back (s);
m_target_sections.back ().owner = owner;
}
scoped_restore_current_pspace_and_thread restore_pspace_thread;
/* If these are the first file sections we can provide memory
from, push the file_stratum target. Must do this in all
inferiors sharing the program space. */
for (inferior *inf : all_inferiors ())
{
if (inf->pspace != this)
continue;
if (inf->target_is_pushed (&exec_ops))
continue;
switch_to_inferior_no_thread (inf);
push_target (&exec_ops);
}
}
}
/* Add the sections of OBJFILE to the current set of target sections. */
void
program_space::add_target_sections (struct objfile *objfile)
{
struct obj_section *osect;
gdb_assert (objfile != nullptr);
/* Compute the number of sections to add. */
ALL_OBJFILE_OSECTIONS (objfile, osect)
{
if (bfd_section_size (osect->the_bfd_section) == 0)
continue;
m_target_sections.emplace_back (obj_section_addr (osect),
obj_section_endaddr (osect),
osect->the_bfd_section, (void *) objfile);
}
}
/* Remove all target sections owned by OWNER.
OWNER must be the same value passed to add_target_sections. */
void
program_space::remove_target_sections (void *owner)
{
gdb_assert (owner != NULL);
auto it = std::remove_if (m_target_sections.begin (),
m_target_sections.end (),
[&] (target_section &sect)
{
return sect.owner == owner;
});
m_target_sections.erase (it, m_target_sections.end ());
/* If we don't have any more sections to read memory from,
remove the file_stratum target from the stack of each
inferior sharing the program space. */
if (m_target_sections.empty ())
{
scoped_restore_current_pspace_and_thread restore_pspace_thread;
for (inferior *inf : all_inferiors ())
{
if (inf->pspace != this)
continue;
switch_to_inferior_no_thread (inf);
unpush_target (&exec_ops);
}
}
}
/* See exec.h. */
void
exec_on_vfork ()
{
if (!current_program_space->target_sections ().empty ())
push_target (&exec_ops);
}
enum target_xfer_status
exec_read_partial_read_only (gdb_byte *readbuf, ULONGEST offset,
ULONGEST len, ULONGEST *xfered_len)
{
/* It's unduly pedantic to refuse to look at the executable for
read-only pieces; so do the equivalent of readonly regions aka
QTro packet. */
if (current_program_space->exec_bfd () != NULL)
{
asection *s;
bfd_size_type size;
bfd_vma vma;
for (s = current_program_space->exec_bfd ()->sections; s; s = s->next)
{
if ((s->flags & SEC_LOAD) == 0
|| (s->flags & SEC_READONLY) == 0)
continue;
vma = s->vma;
size = bfd_section_size (s);
if (vma <= offset && offset < (vma + size))
{
ULONGEST amt;
amt = (vma + size) - offset;
if (amt > len)
amt = len;
amt = bfd_get_section_contents (current_program_space->exec_bfd (), s,
readbuf, offset - vma, amt);
if (amt == 0)
return TARGET_XFER_EOF;
else
{
*xfered_len = amt;
return TARGET_XFER_OK;
}
}
}
}
/* Indicate failure to find the requested memory block. */
return TARGET_XFER_E_IO;
}
/* Return all read-only memory ranges found in the target section
table defined by SECTIONS and SECTIONS_END, starting at (and
intersected with) MEMADDR for LEN bytes. */
static std::vector<mem_range>
section_table_available_memory (CORE_ADDR memaddr, ULONGEST len,
const target_section_table &sections)
{
std::vector<mem_range> memory;
for (const target_section &p : sections)
{
if ((bfd_section_flags (p.the_bfd_section) & SEC_READONLY) == 0)
continue;
/* Copy the meta-data, adjusted. */
if (mem_ranges_overlap (p.addr, p.endaddr - p.addr, memaddr, len))
{
ULONGEST lo1, hi1, lo2, hi2;
lo1 = memaddr;
hi1 = memaddr + len;
lo2 = p.addr;
hi2 = p.endaddr;
CORE_ADDR start = std::max (lo1, lo2);
int length = std::min (hi1, hi2) - start;
memory.emplace_back (start, length);
}
}
return memory;
}
enum target_xfer_status
section_table_read_available_memory (gdb_byte *readbuf, ULONGEST offset,
ULONGEST len, ULONGEST *xfered_len)
{
const target_section_table *table
= target_get_section_table (current_top_target ());
std::vector<mem_range> available_memory
= section_table_available_memory (offset, len, *table);
normalize_mem_ranges (&available_memory);
for (const mem_range &r : available_memory)
{
if (mem_ranges_overlap (r.start, r.length, offset, len))
{
CORE_ADDR end;
enum target_xfer_status status;
/* Get the intersection window. */
end = std::min<CORE_ADDR> (offset + len, r.start + r.length);
gdb_assert (end - offset <= len);
if (offset >= r.start)
status = exec_read_partial_read_only (readbuf, offset,
end - offset,
xfered_len);
else
{
*xfered_len = r.start - offset;
status = TARGET_XFER_UNAVAILABLE;
}
return status;
}
}
*xfered_len = len;
return TARGET_XFER_UNAVAILABLE;
}
enum target_xfer_status
section_table_xfer_memory_partial (gdb_byte *readbuf, const gdb_byte *writebuf,
ULONGEST offset, ULONGEST len,
ULONGEST *xfered_len,
const target_section_table &sections,
gdb::function_view<bool
(const struct target_section *)> match_cb)
{
int res;
ULONGEST memaddr = offset;
ULONGEST memend = memaddr + len;
gdb_assert (len != 0);
for (const target_section &p : sections)
{
struct bfd_section *asect = p.the_bfd_section;
bfd *abfd = asect->owner;
if (match_cb != nullptr && !match_cb (&p))
continue; /* not the section we need. */
if (memaddr >= p.addr)
{
if (memend <= p.endaddr)
{
/* Entire transfer is within this section. */
if (writebuf)
res = bfd_set_section_contents (abfd, asect,
writebuf, memaddr - p.addr,
len);
else
res = bfd_get_section_contents (abfd, asect,
readbuf, memaddr - p.addr,
len);
if (res != 0)
{
*xfered_len = len;
return TARGET_XFER_OK;
}
else
return TARGET_XFER_EOF;
}
else if (memaddr >= p.endaddr)
{
/* This section ends before the transfer starts. */
continue;
}
else
{
/* This section overlaps the transfer. Just do half. */
len = p.endaddr - memaddr;
if (writebuf)
res = bfd_set_section_contents (abfd, asect,
writebuf, memaddr - p.addr,
len);
else
res = bfd_get_section_contents (abfd, asect,
readbuf, memaddr - p.addr,
len);
if (res != 0)
{
*xfered_len = len;
return TARGET_XFER_OK;
}
else
return TARGET_XFER_EOF;
}
}
}
return TARGET_XFER_EOF; /* We can't help. */
}
enum target_xfer_status
exec_target::xfer_partial (enum target_object object,
const char *annex, gdb_byte *readbuf,
const gdb_byte *writebuf,
ULONGEST offset, ULONGEST len, ULONGEST *xfered_len)
{
const target_section_table *table = target_get_section_table (this);
if (object == TARGET_OBJECT_MEMORY)
return section_table_xfer_memory_partial (readbuf, writebuf,
offset, len, xfered_len,
*table);
else
return TARGET_XFER_E_IO;
}
void
print_section_info (const target_section_table *t, bfd *abfd)
{
struct gdbarch *gdbarch = gdbarch_from_bfd (abfd);
/* FIXME: 16 is not wide enough when gdbarch_addr_bit > 64. */
int wid = gdbarch_addr_bit (gdbarch) <= 32 ? 8 : 16;
printf_filtered ("\t`%ps', ",
styled_string (file_name_style.style (),
bfd_get_filename (abfd)));
wrap_here (" ");
printf_filtered (_("file type %s.\n"), bfd_get_target (abfd));
if (abfd == current_program_space->exec_bfd ())
{
/* gcc-3.4 does not like the initialization in
<p == t->sections_end>. */
bfd_vma displacement = 0;
bfd_vma entry_point;
bool found = false;
for (const target_section &p : *t)
{
struct bfd_section *psect = p.the_bfd_section;
if ((bfd_section_flags (psect) & (SEC_ALLOC | SEC_LOAD))
!= (SEC_ALLOC | SEC_LOAD))
continue;
if (bfd_section_vma (psect) <= abfd->start_address
&& abfd->start_address < (bfd_section_vma (psect)
+ bfd_section_size (psect)))
{
displacement = p.addr - bfd_section_vma (psect);
found = true;
break;
}
}
if (!found)
warning (_("Cannot find section for the entry point of %ps."),
styled_string (file_name_style.style (),
bfd_get_filename (abfd)));
entry_point = gdbarch_addr_bits_remove (gdbarch,
bfd_get_start_address (abfd)
+ displacement);
printf_filtered (_("\tEntry point: %s\n"),
paddress (gdbarch, entry_point));
}
for (const target_section &p : *t)
{
struct bfd_section *psect = p.the_bfd_section;
bfd *pbfd = psect->owner;
printf_filtered ("\t%s", hex_string_custom (p.addr, wid));
printf_filtered (" - %s", hex_string_custom (p.endaddr, wid));
/* FIXME: A format of "08l" is not wide enough for file offsets
larger than 4GB. OTOH, making it "016l" isn't desirable either
since most output will then be much wider than necessary. It
may make sense to test the size of the file and choose the
format string accordingly. */
/* FIXME: i18n: Need to rewrite this sentence. */
if (info_verbose)
printf_filtered (" @ %s",
hex_string_custom (psect->filepos, 8));
printf_filtered (" is %s", bfd_section_name (psect));
if (pbfd != abfd)
printf_filtered (" in %ps",
styled_string (file_name_style.style (),
bfd_get_filename (pbfd)));
printf_filtered ("\n");
}
}
void
exec_target::files_info ()
{
if (current_program_space->exec_bfd ())
print_section_info (&current_program_space->target_sections (),
current_program_space->exec_bfd ());
else
puts_filtered (_("\t<no file loaded>\n"));
}
static void
set_section_command (const char *args, int from_tty)
{
const 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 (target_section &p : current_program_space->target_sections ())
{
if (!strncmp (secname, bfd_section_name (p.the_bfd_section), seclen)
&& bfd_section_name (p.the_bfd_section)[seclen] == '\0')
{
offset = secaddr - p.addr;
p.addr += offset;
p.endaddr += offset;
if (from_tty)
exec_ops.files_info ();
return;
}
}
if (seclen >= sizeof (secprint))
seclen = sizeof (secprint) - 1;
strncpy (secprint, secname, seclen);
secprint[seclen] = '\0';
error (_("Section %s not found"), secprint);
}
/* If we can find a section in FILENAME with BFD index INDEX, adjust
it to ADDRESS. */
void
exec_set_section_address (const char *filename, int index, CORE_ADDR address)
{
for (target_section &p : current_program_space->target_sections ())
{
if (filename_cmp (filename,
bfd_get_filename (p.the_bfd_section->owner)) == 0
&& index == p.the_bfd_section->index)
{
p.endaddr += address - p.addr;
p.addr = address;
}
}
}
bool
exec_target::has_memory ()
{
/* We can provide memory if we have any file/target sections to read
from. */
return !current_program_space->target_sections ().empty ();
}
gdb::unique_xmalloc_ptr<char>
exec_target::make_corefile_notes (bfd *obfd, int *note_size)
{
error (_("Can't create a corefile"));
}
int
exec_target::find_memory_regions (find_memory_region_ftype func, void *data)
{
return objfile_find_memory_regions (this, func, data);
}
void _initialize_exec ();
void
_initialize_exec ()
{
struct cmd_list_element *c;
if (!dbx_commands)
{
c = add_cmd ("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."), &cmdlist);
set_cmd_completer (c, filename_completer);
}
c = add_cmd ("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."), &cmdlist);
set_cmd_completer (c, filename_completer);
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_setshow_boolean_cmd ("write", class_support, &write_files, _("\
Set writing into executable and core files."), _("\
Show writing into executable and core files."), NULL,
NULL,
show_write_files,
&setlist, &showlist);
add_setshow_enum_cmd ("exec-file-mismatch", class_support,
exec_file_mismatch_names,
&exec_file_mismatch,
_("\
Set exec-file-mismatch handling (ask|warn|off)."),
_("\
Show exec-file-mismatch handling (ask|warn|off)."),
_("\
Specifies how to handle a mismatch between the current exec-file\n\
loaded by GDB and the exec-file automatically determined when attaching\n\
to a process:\n\n\
ask - warn the user and ask whether to load the determined exec-file.\n\
warn - warn the user, but do not change the exec-file.\n\
off - do not check for mismatch.\n\
\n\
GDB detects a mismatch by comparing the build IDs of the files.\n\
If the user confirms loading the determined exec-file, then its symbols\n\
will be loaded as well."),
set_exec_file_mismatch_command,
show_exec_file_mismatch_command,
&setlist, &showlist);
add_target (exec_target_info, exec_target_open, filename_completer);
}
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