binutils-gdb/gdb/common/pathstuff.h
Sergio Durigan Junior 25e3c82c0e Make gdbserver work with filename-only binaries
Simon mentioned on IRC that, after the startup-with-shell feature has
been implemented on gdbserver, it is not possible to specify a
filename-only binary, like:

  $ gdbserver :1234 a.out
  /bin/bash: line 0: exec: a.out: not found
  During startup program exited with code 127.
  Exiting

This happens on systems where the current directory "." is not listed
in the PATH environment variable.  Although including "." in the PATH
variable is a possible workaround, this can be considered a regression
because before startup-with-shell it was possible to use only the
filename (due to reason that gdbserver used "exec*" directly).

The idea of the patch is to verify if the program path provided by the
user (or by the remote protocol) contains a directory separator
character.  If it doesn't, it means we're dealing with a filename-only
binary, so we call "gdb_abspath" to properly expand it and transform
it into a full path.  Otherwise, we leave the program path untouched.
This mimicks the behaviour seen on GDB (look at "openp" and
"attach_inferior", for example).

I am also submitting a testcase which exercises the scenario described
above.  This test requires gdbserver to be executed in a different CWD
than the original, so I also created a helper function, "with_cwd" (on
testsuite/lib/gdb.exp), which takes care of cd'ing into and out of the
specified dir.

Built and regtested on BuildBot, without regressions.

gdb/ChangeLog:
2018-02-28  Sergio Durigan Junior  <sergiodj@redhat.com>
	    Simon Marchi  <simon.marchi@polymtl.ca>

	* common/common-utils.c: Include "sys/stat.h".
	(is_regular_file): Move here from "source.c"; change return
	type to "bool".
	* common/common-utils.h (is_regular_file): New prototype.
	* common/pathstuff.c (contains_dir_separator): New function.
	* common/pathstuff.h (contains_dir_separator): New prototype.
	* source.c: Don't include "sys/stat.h".
	(is_regular_file): Move to "common/common-utils.c".

gdb/gdbserver/ChangeLog:
2018-02-28  Sergio Durigan Junior  <sergiodj@redhat.com>

	* server.c: Include "filenames.h" and "pathstuff.h".
	(program_name): Delete variable.
	(program_path): New anonymous class.
	(get_exec_wrapper): Use "program_path" instead of
	"program_name".
	(handle_v_run): Likewise.
	(captured_main): Likewise.
	(process_serial_event): Likewise.

gdb/testsuite/ChangeLog:
2018-02-28  Sergio Durigan Junior  <sergiodj@redhat.com>

	* gdb.server/abspath.exp: New file.
	* lib/gdb.exp (with_cwd): New procedure.
2018-02-28 11:37:10 -05:00

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C

/* Path manipulation routines for GDB and gdbserver.
Copyright (C) 1986-2018 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/>. */
#ifndef PATHSTUFF_H
#define PATHSTUFF_H
/* Path utilities. */
/* Return the real path of FILENAME, expanding all the symbolic links.
Contrary to "gdb_abspath", this function does not use
CURRENT_DIRECTORY for path expansion. Instead, it relies on the
current working directory (CWD) of GDB or gdbserver. */
extern gdb::unique_xmalloc_ptr<char> gdb_realpath (const char *filename);
/* Return a copy of FILENAME, with its directory prefix canonicalized
by gdb_realpath. */
extern gdb::unique_xmalloc_ptr<char>
gdb_realpath_keepfile (const char *filename);
/* Return PATH in absolute form, performing tilde-expansion if necessary.
PATH cannot be NULL or the empty string.
This does not resolve symlinks however, use gdb_realpath for that.
Contrary to "gdb_realpath", this function uses CURRENT_DIRECTORY
for the path expansion. This may lead to scenarios the current
working directory (CWD) is different than CURRENT_DIRECTORY. */
extern gdb::unique_xmalloc_ptr<char> gdb_abspath (const char *path);
/* Return whether PATH contains a directory separator character. */
extern bool contains_dir_separator (const char *path);
#endif /* PATHSTUFF_H */