binutils-gdb/gdbsupport/gdb_tilde_expand.cc
Lancelot SIX d3ee35dbf7 Improve gdb_tilde_expand logic.
Before this patch, gdb_tilde_expand would use glob(3) in order to expand
tilde at the begining of a path. This implementation has limitation when
expanding a tilde leading path to a non existing file since glob fails to
expand.

This patch proposes to use glob only to expand the tilde component of the
path and leaves the rest of the path unchanged.

This patch is a followup to the following discution:
https://sourceware.org/pipermail/gdb-patches/2021-January/174776.html

Before the patch:

	gdb_tilde_expand("~") -> "/home/lsix"
	gdb_tilde_expand("~/a/c/b") -> error() is called

After the patch:

	gdb_tilde_expand("~") -> "/home/lsix"
	gdb_tilde_expand("~/a/c/b") -> "/home/lsix/a/c/b"

Tested on x84_64 linux.

gdb/ChangeLog:

	* Makefile.in (SELFTESTS_SRCS): Add
	unittests/gdb_tilde_expand-selftests.c.
	* unittests/gdb_tilde_expand-selftests.c: New file.

gdbsupport/ChangeLog:

	* gdb_tilde_expand.cc (gdb_tilde_expand): Improve
	implementation.
	(gdb_tilde_expand_up): Delegate logic to gdb_tilde_expand.
	* gdb_tilde_expand.h (gdb_tilde_expand): Update description.
2021-01-23 17:17:38 +00:00

114 lines
3.2 KiB
C++

/* Perform tilde expansion on paths for GDB and gdbserver.
Copyright (C) 2017-2021 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 "common-defs.h"
#include <algorithm>
#include "filenames.h"
#include "gdb_tilde_expand.h"
#include <glob.h>
/* RAII-style class wrapping "glob". */
class gdb_glob
{
public:
/* Construct a "gdb_glob" object by calling "glob" with the provided
parameters. This function can throw if "glob" fails. */
gdb_glob (const char *pattern, int flags,
int (*errfunc) (const char *epath, int eerrno))
{
int ret = glob (pattern, flags, errfunc, &m_glob);
if (ret != 0)
{
if (ret == GLOB_NOMATCH)
error (_("Could not find a match for '%s'."), pattern);
else
error (_("glob could not process pattern '%s'."),
pattern);
}
}
/* Destroy the object and free M_GLOB. */
~gdb_glob ()
{
globfree (&m_glob);
}
/* Return the GL_PATHC component of M_GLOB. */
int pathc () const
{
return m_glob.gl_pathc;
}
/* Return the GL_PATHV component of M_GLOB. */
char **pathv () const
{
return m_glob.gl_pathv;
}
private:
/* The actual glob object we're dealing with. */
glob_t m_glob;
};
/* See gdbsupport/gdb_tilde_expand.h. */
std::string
gdb_tilde_expand (const char *dir)
{
if (dir[0] != '~')
return std::string (dir);
/* This function uses glob in order to expand the ~. However, this function
will fail to expand if the actual dir we are looking for does not exist.
Given "~/does/not/exist", glob will fail.
In order to avoid such limitation, we only use glob to expand "~" and keep
"/does/not/exist" unchanged.
Similarly, to expand ~gdb/might/not/exist, we only expand "~gdb" using
glob and leave "/might/not/exist" unchanged. */
const std::string d (dir);
/* Look for the first dir separator (if any) and split d around it. */
const auto first_sep
= std::find_if (d.cbegin (), d.cend(),
[] (const char c) -> bool
{
return IS_DIR_SEPARATOR (c);
});
const std::string to_expand (d.cbegin (), first_sep);
const std::string remainder (first_sep, d.cend ());
const gdb_glob glob (to_expand.c_str (), GLOB_TILDE_CHECK, nullptr);
gdb_assert (glob.pathc () == 1);
return std::string (glob.pathv ()[0]) + remainder;
}
/* See gdbsupport/gdb_tilde_expand.h. */
gdb::unique_xmalloc_ptr<char>
gdb_tilde_expand_up (const char *dir)
{
const std::string expanded = gdb_tilde_expand (dir);
return make_unique_xstrdup (expanded.c_str ());
}