[PATCH v2] Improve gdb_tilde_expand logic
Lancelot SIX
lsix@lancelotsix.com
Sat Jan 9 18:29:06 GMT 2021
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.
New since V1:
* Unittests added thanks to inputs and skeleton provided by
Simon Marchi.
* My copyright assignment has been signed!
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.
---
gdb/Makefile.in | 1 +
gdb/unittests/gdb_tilde_expand-selftests.c | 62 ++++++++++++++++++++++
gdbsupport/gdb_tilde_expand.cc | 45 +++++++++++-----
gdbsupport/gdb_tilde_expand.h | 3 +-
4 files changed, 97 insertions(+), 14 deletions(-)
create mode 100644 gdb/unittests/gdb_tilde_expand-selftests.c
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index 9267bea7be..c8979fe276 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -446,6 +446,7 @@ SELFTESTS_SRCS = \
unittests/filtered_iterator-selftests.c \
unittests/format_pieces-selftests.c \
unittests/function-view-selftests.c \
+ unittests/gdb_tilde_expand-selftests.c \
unittests/gmp-utils-selftests.c \
unittests/lookup_name_info-selftests.c \
unittests/memory-map-selftests.c \
diff --git a/gdb/unittests/gdb_tilde_expand-selftests.c b/gdb/unittests/gdb_tilde_expand-selftests.c
new file mode 100644
index 0000000000..464e63b2e4
--- /dev/null
+++ b/gdb/unittests/gdb_tilde_expand-selftests.c
@@ -0,0 +1,62 @@
+/* Self tests for gdb_tilde_expand
+
+ Copyright (C) 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 "gdbsupport/common-defs.h"
+#include "filenames.h"
+#include "gdbsupport/selftest.h"
+
+#include "gdbsupport/gdb_tilde_expand.h"
+
+namespace selftests {
+namespace gdb_tilde_expand_tests {
+
+static void
+do_test ()
+{
+ /* Home directory of the user running the test */
+ const std::string home = gdb_tilde_expand ("~");
+ // The result should be a absolute path
+ SELF_CHECK (IS_ABSOLUTE_PATH (home));
+
+ /* When given a path that beging by a tilde and refers to a file that
+ does not exist, gdb_tilde expand must still be able to do the tilde
+ expansion. */
+ SELF_CHECK
+ (gdb_tilde_expand ("~/non/existent/directory") ==
+ home + "/non/existent/directory");
+
+ /* gdb_tilde_expand only expands tilde and does not try to do any other
+ substitution. */
+ SELF_CHECK (gdb_tilde_expand ("~/*/a.out") == home + "/*/a.out");
+
+ /* gdb_tilde_expand does no modification to a non tilde leading path. */
+ SELF_CHECK (gdb_tilde_expand ("/some/abs/path") == "/some/abs/path");
+ SELF_CHECK (gdb_tilde_expand("relative/path") == "relative/path");
+}
+
+} /* namespace gdb_tilde_expand_tests */
+} /* namespace selftests */
+
+void _initialize_gdb_tilde_expand_selftests ();
+void
+_initialize_gdb_tilde_expand_selftests ()
+{
+ selftests::register_test
+ ("gdb_tilde_expand", selftests::gdb_tilde_expand_tests::do_test);
+}
diff --git a/gdbsupport/gdb_tilde_expand.cc b/gdbsupport/gdb_tilde_expand.cc
index b31fc48446..d060e26f50 100644
--- a/gdbsupport/gdb_tilde_expand.cc
+++ b/gdbsupport/gdb_tilde_expand.cc
@@ -17,7 +17,9 @@
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 <algorithm>
#include "common-defs.h"
+#include "filenames.h"
#include "gdb_tilde_expand.h"
#include <glob.h>
@@ -71,14 +73,37 @@ private:
std::string
gdb_tilde_expand (const char *dir)
{
- gdb_glob glob (dir, GLOB_TILDE_CHECK, NULL);
+ if (dir[0] == '~')
+ {
+ /* 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.
- gdb_assert (glob.pathc () > 0);
- /* "glob" may return more than one match to the path provided by the
- user, but we are only interested in the first match. */
- std::string expanded_dir = glob.pathv ()[0];
+ In order to avoid such limitation, we only use
+ glob to expand "~" and keep "/does/not/exist" unchanged.
- return expanded_dir;
+ 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)
+ const auto first_sep =
+ std::find_if (d.cbegin (), d.cend(),
+ [](const auto c) { return IS_DIR_SEPARATOR (c); });
+
+ // split d according to the first separator
+ const std::string to_expand (d.cbegin (), first_sep);
+ const std::string remainder (first_sep, d.cend ());
+
+ // Expand the first element
+ const gdb_glob glob (to_expand.c_str (), GLOB_TILDE_CHECK, nullptr);
+ gdb_assert (glob.pathc () == 1);
+
+ return std::string (glob.pathv ()[0]) + remainder;
+ }
+ else
+ return std::string (dir);
}
/* See gdbsupport/gdb_tilde_expand.h. */
@@ -86,10 +111,6 @@ gdb_tilde_expand (const char *dir)
gdb::unique_xmalloc_ptr<char>
gdb_tilde_expand_up (const char *dir)
{
- gdb_glob glob (dir, GLOB_TILDE_CHECK, NULL);
-
- gdb_assert (glob.pathc () > 0);
- /* "glob" may return more than one match to the path provided by the
- user, but we are only interested in the first match. */
- return make_unique_xstrdup (glob.pathv ()[0]);
+ auto const expanded = gdb_tilde_expand (dir);
+ return make_unique_xstrdup (expanded.c_str ());
}
diff --git a/gdbsupport/gdb_tilde_expand.h b/gdbsupport/gdb_tilde_expand.h
index e2d85cadad..a61f246329 100644
--- a/gdbsupport/gdb_tilde_expand.h
+++ b/gdbsupport/gdb_tilde_expand.h
@@ -20,8 +20,7 @@
#ifndef COMMON_GDB_TILDE_EXPAND_H
#define COMMON_GDB_TILDE_EXPAND_H
-/* Perform path expansion (i.e., tilde expansion) on DIR, and return
- the full path. */
+/* Perform tilde expansion on DIR, and return the full path. */
extern std::string gdb_tilde_expand (const char *dir);
/* Same as GDB_TILDE_EXPAND, but return the full path as a
--
2.29.2
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