ff8577f649
Ref.: https://bugzilla.redhat.com/show_bug.cgi?id=1728147 Ref.: https://sourceware.org/bugzilla/show_bug.cgi?id=23613 Hi, This bug has been reported against Fedora GDB, but there's also an upstream bug. The problem reported is that GDB segfaults when the working directory is deleted. It's pretty use to reproduce it: mkdir bla cd bla rmdir ../bla gdb echo Debugging the problem is a bit tricky, because, since the current directory doesn't exist anymore, a corefile cannot be saved there. After a few attempts, I came up with the following: gdb -ex 'shell mkdir bla' -ex 'cd bla' -ex 'shell rmdir ../bla' -ex 'r echo' ./gdb/gdb This assumes that you're inside a build directory which contains ./gdb/gdb, of course. After investigating it, I found that the problem happens at gdb_abspath, where we're dereferencing 'current_directory' without checking if it's NULL: ... (concat (current_directory, IS_DIR_SEPARATOR (current_directory[strlen (current_directory) - 1]) ? "" : SLASH_STRING, ... So I fixed the problem with the patch below. The idea is that, if 'current_directory' is NULL, then the final string returned should be just the "path". After fixing the bug, I found a similar one reported against our bugzilla: PR gdb/23613. The problem is the same, but the reproducer is a bit different. I really tried writing a testcase for this, but unfortunately it's apparently not possible to start GDB inside a non-existent directory with DejaGNU. I regression tested this patch on the BuildBot, and no regressions were found. gdb/ChangeLog: 2019-12-14 Sergio Durigan Junior <sergiodj@redhat.com> https://bugzilla.redhat.com/show_bug.cgi?id=1728147 PR gdb/23613 * bsd-kvm.c (bsd_kvm_target_open): Use 'gdb_abspath'. * corelow.c: Include 'gdbsupport/pathstuff.h'. (core_target_open): Use 'gdb_abspath'. * gdbsupport/pathstuff.c (gdb_abspath): Guard against 'current_directory == NULL' case. * gdbsupport/pathstuff.h (gdb_abspath): Expand comment and explain what happens when 'current_directory' is NULL. * go32-nat.c (go32_nat_target::wait): Check if 'current_directory' is NULL before call to 'chdir'. * source.c (add_path): Use 'gdb_abspath'. * top.c: Include 'gdbsupport/pathstuff.h'. (init_history): Use 'gdb_abspath'. (set_history_filename): Likewise. * tracefile-tfile.c: Include 'gdbsupport/pathstuff.h'. (tfile_target_open): Use 'gdb_abspath'. Change-Id: Ibb0932fa25bc5c2d3ae4a7f64bd7f32885ca403b
98 lines
3.4 KiB
C++
98 lines
3.4 KiB
C++
/* Path manipulation routines for GDB and gdbserver.
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Copyright (C) 1986-2019 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef COMMON_PATHSTUFF_H
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#define COMMON_PATHSTUFF_H
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#include "gdbsupport/byte-vector.h"
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/* Path utilities. */
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/* Return the real path of FILENAME, expanding all the symbolic links.
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Contrary to "gdb_abspath", this function does not use
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CURRENT_DIRECTORY for path expansion. Instead, it relies on the
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current working directory (CWD) of GDB or gdbserver. */
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extern gdb::unique_xmalloc_ptr<char> gdb_realpath (const char *filename);
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/* Return a copy of FILENAME, with its directory prefix canonicalized
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by gdb_realpath. */
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extern gdb::unique_xmalloc_ptr<char>
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gdb_realpath_keepfile (const char *filename);
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/* Return PATH in absolute form, performing tilde-expansion if necessary.
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PATH cannot be NULL or the empty string.
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This does not resolve symlinks however, use gdb_realpath for that.
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Contrary to "gdb_realpath", this function uses CURRENT_DIRECTORY
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for the path expansion. This may lead to scenarios the current
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working directory (CWD) is different than CURRENT_DIRECTORY.
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If CURRENT_DIRECTORY is NULL, this function returns a copy of
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PATH. */
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extern gdb::unique_xmalloc_ptr<char> gdb_abspath (const char *path);
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/* If the path in CHILD is a child of the path in PARENT, return a
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pointer to the first component in the CHILD's pathname below the
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PARENT. Otherwise, return NULL. */
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extern const char *child_path (const char *parent, const char *child);
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/* Return whether PATH contains a directory separator character. */
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extern bool contains_dir_separator (const char *path);
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/* Get the usual user cache directory for the current platform.
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On Linux, it follows the XDG Base Directory specification: use
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$XDG_CACHE_HOME/gdb if the XDG_CACHE_HOME environment variable is
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defined, otherwise $HOME/.cache.
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On macOS, it follows the local convention and uses
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~/Library/Caches/gdb.
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The return value is absolute and tilde-expanded. Return an empty
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string if neither XDG_CACHE_HOME (on Linux) or HOME are defined. */
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extern std::string get_standard_cache_dir ();
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/* Get the usual temporary directory for the current platform.
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On Windows, this is the TMP or TEMP environment variable.
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On the rest, this is the TMPDIR environment variable, if defined, else /tmp.
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Throw an exception on error. */
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extern std::string get_standard_temp_dir ();
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/* Return the file name of the user's shell. Normally this comes from
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the SHELL environment variable. */
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extern const char *get_shell ();
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/* Make a filename suitable to pass to mkstemp based on F (e.g.
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/tmp/foo -> /tmp/foo-XXXXXX). */
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extern gdb::char_vector make_temp_filename (const std::string &f);
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#endif /* COMMON_PATHSTUFF_H */
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