Currently gdb has a configure option:
...
$ ./src/gdb/configure --help
...
--without-included-regex
don't use included regex; this is the default on
systems with version 2 of the GNU C library (use
with caution on other system)
...
The configure option controls config.h macro USE_INCLUDED_REGEX, which is
used in gdb/gdb_regex.h to choose between:
- using regex from libiberty (which is included in the binutils-gdb.git repo,
hence the 'included' in USE_INCLUDED_REGEX), or
- using regex.h.
In the former case, the symbol regcomp is remapped to a symbol xregcomp, which
is then provided by libiberty.
In the latter case, the symbol regcomp is resolved at runtime, usually binding
to libc. However, there is no mechanism in place to enforce this.
PR27681 is an example of where that causes problems. On openSUSE Tumbleweed,
the ncurses package got the --with-pcre2 configure switch enabled, and solved
the resulting dependencies using:
...
$ cat /usr/lib64/libncursesw.so
/* GNU ld script */
-INPUT(/lib64/libncursesw.so.6 AS_NEEDED(-ltinfo -ldl))
+INPUT(/lib64/libncursesw.so.6 AS_NEEDED(-ltinfo -ldl -lpcre2-posix -lpcre2-8))
...
This lead to regcomp being bound to libpcre2-posix instead of libc.
This causes problems in several ways:
- by compiling using regex.h, we've already chosen a specific regex_t
implementation, and the one from pcre2-posix is not the same.
- in gdb_regex.c we use GNU regex function re_search, which pcre2-posix
doesn't provide, so while regcomp binds to pcre2-posix, re_search binds to
libc.
A note on the latter: it's actually a bug to compile a regex using regcomp and
then pass it to re_search. The GNU regex interface requires one to use
re_compile_pattern or re_compile_fastmap. But as long we're using one of the
GNU regex incarnations in gnulib, glibc or libiberty, we get away with this.
The PR could be fixed by adding -lc in a specific position in the link line,
to force regcomp to be bound to glibc. But this solution was considered
in the discussion in the PR as being brittle, and possibly causing problems
elsewhere.
Another solution offered was to restrict regex usage to posix, and no longer
use the GNU regex API. This however could mean having to reproduce some of
that functionality locally, which would mean maintaining the same
functionality in more than one place.
The solution chosen here, is to hardcode --with-included-regex, that is, using
libiberty.
The option of using glibc for regex was introduced because glibc became the
authorative source for GNU regex, so it offered the possibility to link
against a more up-to-date regex version.
In that aspect, this patch is a step back. But we have the option of using a
more up-to-date regex version as a follow-up step: by using the regex from
gnulib.
Tested on x86_64-linux.
gdb/ChangeLog:
2021-04-21 Tom de Vries <tdevries@suse.de>
PR build/27681
* configure.ac: Remove --without-included-regex/--with-included-regex.
* config.in: Regenerate.
* configure: Regenerate.
* gdb_regex.h: Assume USE_INCLUDED_REGEX is defined.
This commits the result of running gdb/copyright.py as per our Start
of New Year procedure...
gdb/ChangeLog
Update copyright year range in copyright header of all GDB files.
This commit applies all changes made after running the gdb/copyright.py
script.
Note that one file was flagged by the script, due to an invalid
copyright header
(gdb/unittests/basic_string_view/element_access/char/empty.cc).
As the file was copied from GCC's libstdc++-v3 testsuite, this commit
leaves this file untouched for the time being; a patch to fix the header
was sent to gcc-patches first.
gdb/ChangeLog:
Update copyright year range in all GDB files.
This patch replaces compile_rx_or_error and make_regfree_cleanup with
a class that wraps a regex_t.
gdb/ChangeLog:
2017-06-07 Pedro Alves <palves@redhat.com>
* Makefile.in (SFILES): Add gdb_regex.c.
(COMMON_OBS): Add gdb_regex.o.
* ada-lang.c (ada_add_standard_exceptions)
(ada_add_exceptions_from_frame, name_matches_regex)
(ada_add_global_exceptions, ada_exceptions_list_1): Change regex
parameter type to compiled_regex. Adjust.
(ada_exceptions_list): Use compiled_regex.
* break-catch-throw.c (exception_catchpoint::pattern): Now a
std::unique_ptr<compiled_regex>.
(exception_catchpoint::~exception_catchpoint): Remove regfree
call.
(check_status_exception_catchpoint): Adjust to use compiled_regex.
(handle_gnu_v3_exceptions): Adjust to use compiled_regex.
* breakpoint.c (solib_catchpoint::compiled): Now a
std::unique_ptr<compiled_regex>.
(solib_catchpoint::~solib_catchpoint): Remove regfree call.
(check_status_catch_solib): Adjust to use compiled_regex.
(add_solib_catchpoint): Adjust to use compiled_regex.
* cli/cli-cmds.c (apropos_command): Use compiled_regex.
* cli/cli-decode.c (apropos_cmd): Change regex parameter to
compiled_regex reference. Adjust to use it.
* cli/cli-decode.h: Remove struct re_pattern_buffer forward
declaration. Include "gdb_regex.h".
(apropos_cmd): Change regex parameter to compiled_regex reference.
* gdb_regex.c: New file.
* gdb_regex.h (make_regfree_cleanup, get_regcomp_error): Delete
declarations.
(class compiled_regex): New.
* linux-tdep.c: Include "common/gdb_optional.h".
(struct mapping_regexes): New, factored out from
mapping_is_anonymous_p, and adjusted to use compiled_regex.
(mapping_is_anonymous_p): Use mapping_regexes wrapped in a
gdb::optional and remove cleanups. Adjust to compiled_regex.
* probe.c: Include "common/gdb_optional.h".
(collect_probes): Use compiled_regex and gdb::optional and remove
cleanups.
* skip.c: Include "common/gdb_optional.h".
(skiplist_entry::compiled_function_regexp): Now a
gdb::optional<compiled_regex>.
(skiplist_entry::compiled_function_regexp_is_valid): Delete field.
(free_skiplist_entry): Remove regfree call.
(compile_skip_regexp, skip_rfunction_p): Adjust to use
compiled_regex and gdb::optional.
* symtab.c: Include "common/gdb_optional.h".
(search_symbols): Use compiled_regex and gdb::optional.
* utils.c (do_regfree_cleanup, make_regfree_cleanup)
(get_regcomp_error, compile_rx_or_error): Delete. Some bits moved
to gdb_regex.c.
This applies the second part of GDB's End of Year Procedure, which
updates the copyright year range in all of GDB's files.
gdb/ChangeLog:
Update copyright year range in all GDB files.
Later patches need regex support also in gdbserver.
gdb/ChangeLog
2015-07-15 Jan Kratochvil <jan.kratochvil@redhat.com>
* Makefile.in (HFILES_NO_SRCDIR): Change gdb_regex.h to
common/gdb_regex.h.
(COMMON_OBS): Add gdb_regex.o.
(gdb_regex.o): New.
* common/common.m4 (GDB_AC_COMMON): Add gdb_use_included_regex,
--without-included-regex and USE_INCLUDED_REGEX.
* common/gdb_regex.c: New file from utils.c functions.
* common/gdb_regex.h: Move it here from gdb_regex.h, update include
file wrapping define name.
* configure: Rebuilt.
* configure.ac (gdb_use_included_regex, --without-included-regex)
(USE_INCLUDED_REGEX): Move them to common/common.m4.
* gdb_regex.h: Move it to common/gdb_regex.h.
* utils.c: Remove include gdb_regex.h.
(do_regfree_cleanup, make_regfree_cleanup, get_regcomp_error)
(compile_rx_or_error): Move them to common/gdb_regex.c.
gdb/gdbserver/ChangeLog
2015-07-15 Jan Kratochvil <jan.kratochvil@redhat.com>
* Makefile.in (OBS): Add gdb_regex.o.
(gdb_regex.o): New.
* config.in: Rebuilt.
* configure: Rebuilt.
Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
--without-included regex option, and move it into the "Checks for
library functions" section. This makes us use the system regex
again by default on systems with version 2 of the GNU C library.
This was apparently broken.
* gdb_regex.h [!USE_INCLUDED_REGEX] (_REGEX_RE_COMP): Define.
* acconfig.h (USE_INCLUDED_REGEX): Remove.
* config.in, configure: Regenerated.
