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6f1d2f789b
When a GDB built with -D_GLIBCXX_DEBUG=1 reads a binary with a single
character name, we hit this assertion failure:
$ ./gdb -q --data-directory=data-directory -nx ./x
/usr/include/c++/12.1.0/string_view:239: constexpr const std::basic_string_view<_CharT, _Traits>::value_type& std::basic_string_view<_CharT, _Traits>::operator[](size_type) const [with _CharT = char; _Traits = std::char_traits<char>; const_reference = const char&; size_type = long unsigned int]: Assertion '__pos < this->_M_len' failed.
The backtrace:
#3 0x00007ffff6c0f002 in std::__glibcxx_assert_fail (file=<optimized out>, line=<optimized out>, function=<optimized out>, condition=<optimized out>) at /usr/src/debug/gcc/libstdc++-v3/src/c++11/debug.cc:60
#4 0x000055555da8a864 in std::basic_string_view<char, std::char_traits<char> >::operator[] (this=0x7fffffffcc30, __pos=1) at /usr/include/c++/12.1.0/string_view:239
#5 0x00005555609dcb88 in path_join[abi:cxx11](gdb::array_view<std::basic_string_view<char, std::char_traits<char> > const>) (paths=...) at /home/simark/src/binutils-gdb/gdbsupport/pathstuff.cc:203
#6 0x000055555e0443f4 in path_join<char const*, char const*> () at /home/simark/src/binutils-gdb/gdb/../gdbsupport/pathstuff.h:84
#7 0x00005555609dc336 in gdb_realpath_keepfile[abi:cxx11](char const*) (filename=0x6060000a8d40 "/home/simark/build/binutils-gdb-one-target/gdb/./x") at /home/simark/src/binutils-gdb/gdbsupport/pathstuff.cc:122
#8 0x000055555ebd2794 in exec_file_attach (filename=0x7fffffffe0f9 "./x", from_tty=1) at /home/simark/src/binutils-gdb/gdb/exec.c:471
#9 0x000055555f2b3fb0 in catch_command_errors (command=0x55555ebd1ab6 <exec_file_attach(char const*, int)>, arg=0x7fffffffe0f9 "./x", from_tty=1, do_bp_actions=false) at /home/simark/src/binutils-gdb/gdb/main.c:513
#10 0x000055555f2b7e11 in captured_main_1 (context=0x7fffffffdb60) at /home/simark/src/binutils-gdb/gdb/main.c:1209
#11 0x000055555f2b9144 in captured_main (data=0x7fffffffdb60) at /home/simark/src/binutils-gdb/gdb/main.c:1319
#12 0x000055555f2b9226 in gdb_main (args=0x7fffffffdb60) at /home/simark/src/binutils-gdb/gdb/main.c:1344
#13 0x000055555d938c5e in main (argc=5, argv=0x7fffffffdcf8) at /home/simark/src/binutils-gdb/gdb/gdb.c:32
The problem is this line in path_join:
gdb_assert (strlen (path) == 0 || !IS_ABSOLUTE_PATH (path));
... where `path` is "x". IS_ABSOLUTE_PATH eventually calls
HAS_DRIVE_SPEC_1:
#define HAS_DRIVE_SPEC_1(dos_based, f) \
((f)[0] && ((f)[1] == ':') && (dos_based))
This macro accesses indices 0 and 1 of the input string. However, `f`
is a string_view of length 1, so it's incorrect to try to access index
1. We know that the string_view's underlying object is a null-terminated
string, so in practice there's no harm. But as far as the string_view
is concerned, index 1 is considered out of bounds.
This patch makes the easy fix, that is to change the path_join parameter
from a vector of to a vector of `const char *`. Another solution would
be to introduce a non-standard gdb::cstring_view class, which would be a
view over a null-terminated string. With that class, it would be
correct to access index 1, it would yield the NUL character. If there
is interest in having this class (it has been mentioned a few times in
the past) I can do it and use it here.
This was found by running tests such as gdb.ada/arrayidx.exp, which
produce 1-char long filenames, so adding a new test is not necessary.
Change-Id: Ia41a16c7243614636b18754fd98a41860756f7af
166 lines
5.7 KiB
C++
166 lines
5.7 KiB
C++
/* Path manipulation routines for GDB and gdbserver.
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Copyright (C) 1986-2022 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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#include "gdbsupport/array-view.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <array>
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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 std::string 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 std::string 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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/* Join elements in PATHS into a single path.
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The first element can be absolute or relative. All the others must be
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relative. */
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extern std::string path_join (gdb::array_view<const char *> paths);
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/* Same as the above, but accept paths as distinct parameters. */
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template<typename ...Args>
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std::string
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path_join (Args... paths)
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{
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/* It doesn't make sense to join less than two paths. */
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gdb_static_assert (sizeof... (Args) >= 2);
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std::array<const char *, sizeof... (Args)> path_array
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{ paths... };
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return path_join (gdb::array_view<const char *> (path_array));
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}
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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 $HOME/.cache.
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On macOS, it follows the local convention and uses
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~/Library/Caches/gdb.
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The return value is absolute and tilde-expanded. Return an empty
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string if neither XDG_CACHE_HOME (on Linux) or HOME are defined. */
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extern std::string get_standard_cache_dir ();
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/* Get the usual temporary directory for the current platform.
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On Windows, this is the TMP or TEMP environment variable.
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On the rest, this is the TMPDIR environment variable, if defined, else /tmp.
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Throw an exception on error. */
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extern std::string get_standard_temp_dir ();
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/* Get the usual user config directory for the current platform.
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On Linux, it follows the XDG Base Directory specification: use
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$XDG_CONFIG_HOME/gdb if the XDG_CONFIG_HOME environment variable is
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defined, otherwise $HOME/.config.
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On macOS, it follows the local convention and uses
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~/Library/Preferences/gdb.
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The return value is absolute and tilde-expanded. Return an empty
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string if neither XDG_CONFIG_HOME (on Linux) or HOME are defined. */
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extern std::string get_standard_config_dir ();
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/* Look for FILENAME in the standard configuration directory as returned by
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GET_STANDARD_CONFIG_DIR and return the path to the file. No check is
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performed that the file actually exists or not.
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If FILENAME begins with a '.' then the path returned will remove the
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leading '.' character, for example passing '.gdbinit' could return the
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path '/home/username/.config/gdb/gdbinit'. */
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extern std::string get_standard_config_filename (const char *filename);
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/* Look for a file called NAME in either the standard config directory or
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in the users home directory. If a suitable file is found then *BUF will
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be filled with the contents of a call to 'stat' on the found file,
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otherwise *BUF is undefined after this call.
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If NAME starts with a '.' character then, when looking in the standard
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config directory the file searched for has the '.' removed. For
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example, if NAME is '.gdbinit' then on a Linux target GDB might look for
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'~/.config/gdb/gdbinit' and then '~/.gdbinit'. */
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extern std::string find_gdb_home_config_file (const char *name,
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struct stat *buf);
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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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/* String containing the current directory (what getwd would return). */
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extern char *current_directory;
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#endif /* COMMON_PATHSTUFF_H */
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