[PATCH v2] gdbsupport: add path_join function
Simon Marchi
simon.marchi@polymtl.ca
Wed Apr 20 00:20:05 GMT 2022
From: Simon Marchi <simon.marchi@efficios.com>
New in v2:
- Add some Windows tests. I didn't add much because I don't know what
kind of corner cases is important to test. It would take someone
who knows and cares about Windows to improve them, if need be.
- Change the behavior to look more like concatenation of
std::filesystem::path objects (from C++17). Our implementation
isn't as complete as the std::filesystem one though. If we need
something that is even closer to std::filesystem::path, perhaps we
can make a local import of the libstdc++ implementation, like we did
for string_view, rather than trying to re-implement it.
- Replace the variadic function with a templated function.
In this review [1], Eli pointed out that we should be careful when
concatenating file names to avoid duplicated slashes. On Windows, a
double slash at the beginning of a file path has a special meaning. So
naively concatenating "/" and "foo/bar" would give "//foo/bar", which
would not give the desired results. We already have a few spots doing:
if (first_path ends with a slash)
path = first_path + second_path
else
path = first_path + slash + second_path
In general, I think it's nice to avoid superfluous slashes in file
paths, since they might end up visible to the user and look a bit
unprofessional.
Introduce the path_join function that can be used to join multiple path
components together (along with unit tests).
The behavior is based on what concatenating std::filesystem::path
objects (available in C++17) would do. With this behavior, joining with
an absolute path on the right hand side, like this:
path_join ("/foo", "/bar");
results in just the right hand side being kept. In this example, the
result is "/bar".
I initially wanted to make it possible to join two absolute paths, to
support the use case of prepending a sysroot path to a target file path,
or the prepending the debug-file-directory to a target file path. But
the code in solib_find_1 shows that it is more complex than this anyway
(for example, when the right hand side is a Windows path with a drive
letter). So I don't think we need to support that case in path_join.
Change a few spots to use path_join to show how it can be used. I
believe that all the spots I changed are guarded by some checks that
ensure the right hand side operand is not an absolute path. So we
shouldn't fall into the case described just above.
Regression-tested on Ubuntu 18.04. Built-tested on Windows, and I also
ran the new unit-test there.
[1] https://sourceware.org/pipermail/gdb-patches/2022-April/187559.html
Change-Id: I0df889f7e3f644e045f42ff429277b732eb6c752
---
gdb/Makefile.in | 1 +
gdb/buildsym.c | 5 +-
gdb/dwarf2/line-header.c | 3 +-
gdb/dwarf2/read.c | 42 ++++++-------
gdb/macrotab.c | 3 +-
gdb/unittests/path-join-selftests.c | 92 +++++++++++++++++++++++++++++
gdbsupport/gdb_string_view.h | 2 +-
gdbsupport/pathstuff.cc | 46 ++++++++++-----
gdbsupport/pathstuff.h | 24 ++++++++
9 files changed, 175 insertions(+), 43 deletions(-)
create mode 100644 gdb/unittests/path-join-selftests.c
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index c8e140b55449..ec0e55dd803c 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -465,6 +465,7 @@ SELFTESTS_SRCS = \
unittests/optional-selftests.c \
unittests/parallel-for-selftests.c \
unittests/parse-connection-spec-selftests.c \
+ unittests/path-join-selftests.c \
unittests/ptid-selftests.c \
unittests/main-thread-selftests.c \
unittests/mkdir-recursive-selftests.c \
diff --git a/gdb/buildsym.c b/gdb/buildsym.c
index 628903d674f4..b0d794409876 100644
--- a/gdb/buildsym.c
+++ b/gdb/buildsym.c
@@ -20,6 +20,7 @@
#include "buildsym-legacy.h"
#include "bfd.h"
#include "gdbsupport/gdb_obstack.h"
+#include "gdbsupport/pathstuff.h"
#include "symtab.h"
#include "symfile.h"
#include "objfiles.h"
@@ -507,8 +508,8 @@ buildsym_compunit::start_subfile (const char *name)
&& !IS_ABSOLUTE_PATH (subfile->name)
&& !m_comp_dir.empty ())
{
- subfile_name_holder = string_printf ("%s/%s", m_comp_dir.c_str (),
- subfile->name.c_str ());
+ subfile_name_holder = path_join (m_comp_dir.c_str (),
+ subfile->name.c_str ());
subfile_name = subfile_name_holder.c_str ();
}
else
diff --git a/gdb/dwarf2/line-header.c b/gdb/dwarf2/line-header.c
index 77e7e553b21e..8f4eb4f124cf 100644
--- a/gdb/dwarf2/line-header.c
+++ b/gdb/dwarf2/line-header.c
@@ -24,6 +24,7 @@
#include "dwarf2/read.h"
#include "complaints.h"
#include "filenames.h"
+#include "gdbsupport/pathstuff.h"
void
line_header::add_include_dir (const char *include_dir)
@@ -73,7 +74,7 @@ line_header::file_file_name (int file) const
{
const char *dir = fe->include_dir (this);
if (dir != NULL)
- return string_printf ("%s/%s", dir, fe->name);
+ return path_join (dir, fe->name);
}
return fe->name;
diff --git a/gdb/dwarf2/read.c b/gdb/dwarf2/read.c
index 6dcd446e5f46..1fd39e903dc0 100644
--- a/gdb/dwarf2/read.c
+++ b/gdb/dwarf2/read.c
@@ -1343,7 +1343,7 @@ static const char *compute_include_file_name
(const struct line_header *lh,
const file_entry &fe,
const file_and_directory &cu_info,
- gdb::unique_xmalloc_ptr<char> *name_holder);
+ std::string &name_holder);
static htab_up allocate_signatured_type_table ();
@@ -2809,9 +2809,9 @@ dw2_get_file_names_reader (const struct die_reader_specs *reader,
{
for (const auto &entry : lh->file_names ())
{
- gdb::unique_xmalloc_ptr<char> name_holder;
+ std::string name_holder;
const char *include_name =
- compute_include_file_name (lh.get (), entry, fnd, &name_holder);
+ compute_include_file_name (lh.get (), entry, fnd, name_holder);
if (include_name != nullptr)
{
include_name = per_objfile->objfile->intern (include_name);
@@ -11166,14 +11166,13 @@ open_dwo_file (dwarf2_per_objfile *per_objfile,
if (comp_dir != NULL)
{
- gdb::unique_xmalloc_ptr<char> path_to_try
- (concat (comp_dir, SLASH_STRING, file_name, (char *) NULL));
+ std::string path_to_try = path_join (comp_dir, file_name);
/* NOTE: If comp_dir is a relative path, this will also try the
search path, which seems useful. */
- gdb_bfd_ref_ptr abfd (try_open_dwop_file (per_objfile, path_to_try.get (),
- 0 /*is_dwp*/,
- 1 /*search_cwd*/));
+ gdb_bfd_ref_ptr abfd (try_open_dwop_file
+ (per_objfile, path_to_try.c_str (), 0 /*is_dwp*/, 1 /*search_cwd*/));
+
if (abfd != NULL)
return abfd;
}
@@ -19751,14 +19750,14 @@ dwarf_decode_line_header (sect_offset sect_off, struct dwarf2_cu *cu)
static const char *
compute_include_file_name (const struct line_header *lh, const file_entry &fe,
const file_and_directory &cu_info,
- gdb::unique_xmalloc_ptr<char> *name_holder)
+ std::string &name_holder)
{
const char *include_name = fe.name;
const char *include_name_to_compare = include_name;
const char *dir_name = fe.include_dir (lh);
- gdb::unique_xmalloc_ptr<char> hold_compare;
+ std::string hold_compare;
if (!IS_ABSOLUTE_PATH (include_name)
&& (dir_name != nullptr || cu_info.get_comp_dir () != nullptr))
{
@@ -19785,27 +19784,24 @@ compute_include_file_name (const struct line_header *lh, const file_entry &fe,
if (dir_name != NULL)
{
- name_holder->reset (concat (dir_name, SLASH_STRING,
- include_name, (char *) NULL));
- include_name = name_holder->get ();
+ name_holder = path_join (dir_name, include_name);
+ include_name = name_holder.c_str ();
include_name_to_compare = include_name;
}
if (!IS_ABSOLUTE_PATH (include_name)
&& cu_info.get_comp_dir () != nullptr)
{
- hold_compare.reset (concat (cu_info.get_comp_dir (), SLASH_STRING,
- include_name, (char *) NULL));
- include_name_to_compare = hold_compare.get ();
+ hold_compare = path_join (cu_info.get_comp_dir (), include_name);
+ include_name_to_compare = hold_compare.c_str ();
}
}
- gdb::unique_xmalloc_ptr<char> copied_name;
+ std::string copied_name;
const char *cu_filename = cu_info.get_name ();
if (!IS_ABSOLUTE_PATH (cu_filename) && cu_info.get_comp_dir () != nullptr)
{
- copied_name.reset (concat (cu_info.get_comp_dir (), SLASH_STRING,
- cu_filename, (char *) NULL));
- cu_filename = copied_name.get ();
+ copied_name = path_join (cu_info.get_comp_dir (), cu_filename);
+ cu_filename = copied_name.c_str ();
}
if (FILENAME_CMP (include_name_to_compare, cu_filename) == 0)
@@ -20540,7 +20536,7 @@ static void
dwarf2_start_subfile (struct dwarf2_cu *cu, const char *filename,
const char *dirname)
{
- gdb::unique_xmalloc_ptr<char> copy;
+ std::string copy;
/* In order not to lose the line information directory,
we concatenate it to the filename when it makes sense.
@@ -20551,8 +20547,8 @@ dwarf2_start_subfile (struct dwarf2_cu *cu, const char *filename,
if (!IS_ABSOLUTE_PATH (filename) && dirname != NULL)
{
- copy.reset (concat (dirname, SLASH_STRING, filename, (char *) NULL));
- filename = copy.get ();
+ copy = path_join (dirname, filename);
+ filename = copy.c_str ();
}
cu->get_builder ()->start_subfile (filename);
diff --git a/gdb/macrotab.c b/gdb/macrotab.c
index 7ca3f312d330..108e6f1bbaed 100644
--- a/gdb/macrotab.c
+++ b/gdb/macrotab.c
@@ -19,6 +19,7 @@
#include "defs.h"
#include "gdbsupport/gdb_obstack.h"
+#include "gdbsupport/pathstuff.h"
#include "splay-tree.h"
#include "filenames.h"
#include "symtab.h"
@@ -1071,5 +1072,5 @@ macro_source_fullname (struct macro_source_file *file)
if (comp_dir == NULL || IS_ABSOLUTE_PATH (file->filename))
return file->filename;
- return std::string (comp_dir) + SLASH_STRING + file->filename;
+ return path_join (comp_dir, file->filename);
}
diff --git a/gdb/unittests/path-join-selftests.c b/gdb/unittests/path-join-selftests.c
new file mode 100644
index 000000000000..c43e78b7144e
--- /dev/null
+++ b/gdb/unittests/path-join-selftests.c
@@ -0,0 +1,92 @@
+/* Self tests for path_join for GDB, the GNU debugger.
+
+ Copyright (C) 2022 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 "defs.h"
+#include "gdbsupport/pathstuff.h"
+#include "gdbsupport/selftest.h"
+
+#if __cplusplus >= 201703L
+#include <filesystem>
+#endif
+
+namespace selftests {
+namespace path_join {
+
+template <typename ...Args>
+static void
+test_one (const char *expected, Args... paths)
+{
+ std::string actual = ::path_join (paths...);
+ SELF_CHECK (actual == expected);
+
+ /* If building with C++17 or later, verify that path_join gives the same
+ result as concatenating with std::filesystem::path. */
+#if __cplusplus >= 201703L
+ std::filesystem::path std_path;
+
+ for (const char *p : {paths...})
+ std_path /= p;
+
+ SELF_CHECK (std_path == actual);
+#endif
+}
+
+/* Test path_join. */
+
+static void
+test ()
+{
+ test_one ("/foo/bar", "/foo", "bar");
+ test_one ("/bar", "/foo", "/bar");
+ test_one ("/bar", "/", "bar");
+ test_one ("/bar", "/", "/bar");
+ test_one ("/bar", "foo/", "/bar");
+ test_one ("foo/bar/", "foo", "bar", "");
+ test_one ("/foo", "", "/foo");
+ test_one ("foo", "", "foo");
+ test_one ("foo/bar", "foo", "", "bar");
+ test_one ("foo/", "foo", "");
+ test_one ("foo/", "foo/", "");
+
+ test_one ("D:/foo/bar", "D:/foo", "bar");
+ test_one ("D:/foo/bar", "D:/foo/", "bar");
+
+#if defined(_WIN32)
+ /* The current implementation doesn't recognize backslashes as directory
+ separators on Unix-like systems, so only run these tests on Windows. If
+ we ever switch our implementation to use std::filesystem::path, they
+ should work anywhere, in theory. */
+ test_one ("D:\\foo/bar", "D:\\foo", "bar");
+ test_one ("D:\\foo\\bar", "D:\\foo\\", "bar");
+ test_one ("\\\\server\\dir\\file", "\\\\server\\dir\\", "file");
+ test_one ("\\\\server\\dir/file", "\\\\server\\dir", "file");
+#endif /* _WIN32 */
+}
+
+}
+}
+
+void _initialize_path_join_selftests ();
+void
+_initialize_path_join_selftests ()
+{
+ selftests::register_test ("path_join",
+ selftests::path_join::test);
+}
+
diff --git a/gdbsupport/gdb_string_view.h b/gdbsupport/gdb_string_view.h
index f8150288ee57..4e26bd8ff2c1 100644
--- a/gdbsupport/gdb_string_view.h
+++ b/gdbsupport/gdb_string_view.h
@@ -34,7 +34,7 @@
//
-#if __cplusplus >= 201703L
+#if __cplusplus >= 201703L && 0
#include <string_view>
diff --git a/gdbsupport/pathstuff.cc b/gdbsupport/pathstuff.cc
index ac65651d4492..d80d54740ee4 100644
--- a/gdbsupport/pathstuff.cc
+++ b/gdbsupport/pathstuff.cc
@@ -119,10 +119,7 @@ gdb_realpath_keepfile (const char *filename)
directory separator, avoid doubling it. */
gdb::unique_xmalloc_ptr<char> path_storage = gdb_realpath (dir_name);
const char *real_path = path_storage.get ();
- if (IS_DIR_SEPARATOR (real_path[strlen (real_path) - 1]))
- return string_printf ("%s%s", real_path, base_name);
- else
- return string_printf ("%s/%s", real_path, base_name);
+ return path_join (real_path, base_name);
}
/* See gdbsupport/pathstuff.h. */
@@ -138,12 +135,7 @@ gdb_abspath (const char *path)
if (IS_ABSOLUTE_PATH (path) || current_directory == NULL)
return path;
- /* Beware the // my son, the Emacs barfs, the botch that catch... */
- return string_printf
- ("%s%s%s", current_directory,
- (IS_DIR_SEPARATOR (current_directory[strlen (current_directory) - 1])
- ? "" : SLASH_STRING),
- path);
+ return path_join (current_directory, path);
}
/* See gdbsupport/pathstuff.h. */
@@ -198,6 +190,30 @@ child_path (const char *parent, const char *child)
/* See gdbsupport/pathstuff.h. */
+std::string
+path_join (gdb::array_view<const gdb::string_view> paths)
+{
+ std::string ret;
+
+ for (gdb::string_view path : paths)
+ {
+ if (!path.empty () && IS_ABSOLUTE_PATH (path))
+ {
+ ret = to_string (path);
+ continue;
+ }
+
+ if (!ret.empty () && !IS_DIR_SEPARATOR (ret.back ()))
+ ret += '/';
+
+ ret.append (path.data (), path.length ());
+ }
+
+ return ret;
+}
+
+/* See gdbsupport/pathstuff.h. */
+
bool
contains_dir_separator (const char *path)
{
@@ -227,7 +243,7 @@ get_standard_cache_dir ()
{
/* Make sure the path is absolute and tilde-expanded. */
std::string abs = gdb_abspath (xdg_cache_home);
- return string_printf ("%s/gdb", abs.c_str ());
+ return path_join (abs.c_str (), "gdb");
}
#endif
@@ -236,7 +252,7 @@ get_standard_cache_dir ()
{
/* Make sure the path is absolute and tilde-expanded. */
std::string abs = gdb_abspath (home);
- return string_printf ("%s/" HOME_CACHE_DIR "/gdb", abs.c_str ());
+ return path_join (abs.c_str (), HOME_CACHE_DIR, "gdb");
}
#ifdef WIN32
@@ -245,7 +261,7 @@ get_standard_cache_dir ()
{
/* Make sure the path is absolute and tilde-expanded. */
std::string abs = gdb_abspath (win_home);
- return string_printf ("%s/gdb", abs.c_str ());
+ return path_join (abs.c_str (), "gdb", nullptr);
}
#endif
@@ -294,7 +310,7 @@ get_standard_config_dir ()
{
/* Make sure the path is absolute and tilde-expanded. */
std::string abs = gdb_abspath (xdg_config_home);
- return string_printf ("%s/gdb", abs.c_str ());
+ return path_join (abs.c_str (), "gdb");
}
#endif
@@ -303,7 +319,7 @@ get_standard_config_dir ()
{
/* Make sure the path is absolute and tilde-expanded. */
std::string abs = gdb_abspath (home);
- return string_printf ("%s/" HOME_CONFIG_DIR "/gdb", abs.c_str ());
+ return path_join (abs.c_str (), HOME_CONFIG_DIR, "gdb");
}
return {};
diff --git a/gdbsupport/pathstuff.h b/gdbsupport/pathstuff.h
index f6c51e9de887..2e5893466c67 100644
--- a/gdbsupport/pathstuff.h
+++ b/gdbsupport/pathstuff.h
@@ -21,6 +21,7 @@
#define COMMON_PATHSTUFF_H
#include "gdbsupport/byte-vector.h"
+#include "gdbsupport/array-view.h"
#include <sys/types.h>
#include <sys/stat.h>
@@ -60,6 +61,29 @@ extern std::string gdb_abspath (const char *path);
extern const char *child_path (const char *parent, const char *child);
+/* Join elements in PATHS into a single path.
+
+ This function is intended to have the same behavior as concatenating
+ std::filesystem::path objects with std::filesystem::operator/ (which was
+ introduced in C++17). */
+
+extern std::string path_join (gdb::array_view<const gdb::string_view> paths);
+
+/* Same as the above, but accept paths as distinct parameters. */
+
+template<typename ...Args>
+std::string
+path_join (Args... paths)
+{
+ /* It doesn't make sense to join less than two paths. */
+ gdb_static_assert (sizeof... (Args) >= 2);
+
+ std::array<gdb::string_view, sizeof... (Args)> views
+ { gdb::string_view (paths)... };
+
+ return path_join (gdb::array_view<const gdb::string_view> (views));
+}
+
/* Return whether PATH contains a directory separator character. */
extern bool contains_dir_separator (const char *path);
base-commit: 6ea673e2d643b7b2283aa73d35b02dfc9aa7115f
--
2.35.2
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