This includes the P2810R4 (is_debugger_present is_replaceable) changes, allowing std::is_debugger_present to be replaced by the program.
It would be good to provide a macOS definition of is_debugger_present as per https://developer.apple.com/library/archive/qa/qa1361/_index.html but that isn't included in this change. libstdc++-v3/ChangeLog: * config.h.in: Regenerate. * configure: Regenerate. * configure.ac: Check for facilities needed by <debugging>. * include/Makefile.am: Add new header. * include/Makefile.in: Regenerate. * include/bits/version.def (debugging): Add. * include/bits/version.h: Regenerate. * src/c++26/Makefile.am: Add new file. * src/c++26/Makefile.in: Regenerate. * include/std/debugging: New file. * src/c++26/debugging.cc: New file. * testsuite/19_diagnostics/debugging/breakpoint.cc: New test. * testsuite/19_diagnostics/debugging/breakpoint_if_debugging.cc: New test. * testsuite/19_diagnostics/debugging/is_debugger_present.cc: New test. * testsuite/19_diagnostics/debugging/is_debugger_present-2.cc: New test. --- This v3 patch uses #elif for the SYS_PTRACE_H group, as suggested by Tomasz, adds more systemtap probes, and fixes the known debuggers checks to match LLDB properly and to match gdbserver. Tested with gdb, gdbserver, and lldb on Fedora 41. This is experimental, so whether we keep the attach_debugger(bool) function is undecided. It might be that GDB will end up using a different approach, maybe based on the probe points. It would be nice if GDB would break at the top of std::breakpoint() and not on the asm later in the function. Ideally it would even break in the user code where std::breakpoint() is called, and not show the std::breakpoint() internals at all. But we can't easily experiment with any of that in GDB until there's something working on libstdc++. Tested x86_64-linux. libstdc++-v3/config.h.in | 9 + libstdc++-v3/configure | 22 +++ libstdc++-v3/configure.ac | 9 + libstdc++-v3/include/Makefile.am | 1 + libstdc++-v3/include/Makefile.in | 1 + libstdc++-v3/include/bits/version.def | 8 + libstdc++-v3/include/bits/version.h | 10 + libstdc++-v3/include/std/debugging | 77 ++++++++ libstdc++-v3/src/c++26/Makefile.am | 4 +- libstdc++-v3/src/c++26/Makefile.in | 7 +- libstdc++-v3/src/c++26/debugging.cc | 172 ++++++++++++++++++ .../19_diagnostics/debugging/breakpoint.cc | 13 ++ .../debugging/breakpoint_if_debugging.cc | 13 ++ .../debugging/is_debugger_present-2.cc | 19 ++ .../debugging/is_debugger_present.cc | 14 ++ 15 files changed, 376 insertions(+), 3 deletions(-) create mode 100644 libstdc++-v3/include/std/debugging create mode 100644 libstdc++-v3/src/c++26/debugging.cc create mode 100644 libstdc++-v3/testsuite/19_diagnostics/debugging/breakpoint.cc create mode 100644 libstdc++-v3/testsuite/19_diagnostics/debugging/breakpoint_if_debugging.cc create mode 100644 libstdc++-v3/testsuite/19_diagnostics/debugging/is_debugger_present-2.cc create mode 100644 libstdc++-v3/testsuite/19_diagnostics/debugging/is_debugger_present.cc diff --git a/libstdc++-v3/config.h.in b/libstdc++-v3/config.h.in index 77bbaf1beaa..3f1331ff36f 100644 --- a/libstdc++-v3/config.h.in +++ b/libstdc++-v3/config.h.in @@ -70,6 +70,9 @@ /* Define to 1 if you have the `cosl' function. */ #undef HAVE_COSL +/* Define to 1 if you have the <debugapi.h> header file. */ +#undef HAVE_DEBUGAPI_H + /* Define to 1 if you have the declaration of `strnlen', and to 0 if you don't. */ #undef HAVE_DECL_STRNLEN @@ -439,6 +442,9 @@ /* Define to 1 if you have the <sys/param.h> header file. */ #undef HAVE_SYS_PARAM_H +/* Define to 1 if you have the <sys/ptrace.h> header file. */ +#undef HAVE_SYS_PTRACE_H + /* Define to 1 if you have the <sys/resource.h> header file. */ #undef HAVE_SYS_RESOURCE_H @@ -850,6 +856,9 @@ /* Define if nl_langinfo_l should be used for std::text_encoding. */ #undef _GLIBCXX_USE_NL_LANGINFO_L +/* Define if /proc/self/status should be used for <debugging>. */ +#undef _GLIBCXX_USE_PROC_SELF_STATUS + /* Define if pthreads_num_processors_np is available in <pthread.h>. */ #undef _GLIBCXX_USE_PTHREADS_NUM_PROCESSORS_NP diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure index 819a1d82876..8143df91c38 100755 --- a/libstdc++-v3/configure +++ b/libstdc++-v3/configure @@ -54700,6 +54700,28 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu +# For std::is_debugger_present +case "$target_os" in + linux*) + +$as_echo "#define _GLIBCXX_USE_PROC_SELF_STATUS 1" >>confdefs.h + + ;; +esac +for ac_header in sys/ptrace.h debugapi.h +do : + as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh` +ac_fn_c_check_header_mongrel "$LINENO" "$ac_header" "$as_ac_Header" "$ac_includes_default" +if eval test \"x\$"$as_ac_Header"\" = x"yes"; then : + cat >>confdefs.h <<_ACEOF +#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1 +_ACEOF + +fi + +done + + # Define documentation rules conditionally. # See if makeinfo has been installed and is modern enough diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac index a6c01b29e94..83adb46454e 100644 --- a/libstdc++-v3/configure.ac +++ b/libstdc++-v3/configure.ac @@ -587,6 +587,15 @@ GLIBCXX_CHECK_FILEBUF_NATIVE_HANDLES # For std::text_encoding GLIBCXX_CHECK_TEXT_ENCODING +# For std::is_debugger_present +case "$target_os" in + linux*) + AC_DEFINE([_GLIBCXX_USE_PROC_SELF_STATUS],1, + [Define if /proc/self/status should be used for <debugging>.]) + ;; +esac +AC_CHECK_HEADERS([sys/ptrace.h debugapi.h]) + # Define documentation rules conditionally. # See if makeinfo has been installed and is modern enough diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am index 537774c2668..6bb3f3dc3d6 100644 --- a/libstdc++-v3/include/Makefile.am +++ b/libstdc++-v3/include/Makefile.am @@ -67,6 +67,7 @@ std_headers = \ ${std_srcdir}/codecvt \ ${std_srcdir}/complex \ ${std_srcdir}/condition_variable \ + ${std_srcdir}/debugging \ ${std_srcdir}/deque \ ${std_srcdir}/execution \ ${std_srcdir}/filesystem \ diff --git a/libstdc++-v3/include/Makefile.in b/libstdc++-v3/include/Makefile.in index 7b96b2207f8..81c3cfce4c4 100644 --- a/libstdc++-v3/include/Makefile.in +++ b/libstdc++-v3/include/Makefile.in @@ -423,6 +423,7 @@ std_freestanding = \ @GLIBCXX_HOSTED_TRUE@ ${std_srcdir}/codecvt \ @GLIBCXX_HOSTED_TRUE@ ${std_srcdir}/complex \ @GLIBCXX_HOSTED_TRUE@ ${std_srcdir}/condition_variable \ +@GLIBCXX_HOSTED_TRUE@ ${std_srcdir}/debugging \ @GLIBCXX_HOSTED_TRUE@ ${std_srcdir}/deque \ @GLIBCXX_HOSTED_TRUE@ ${std_srcdir}/execution \ @GLIBCXX_HOSTED_TRUE@ ${std_srcdir}/filesystem \ diff --git a/libstdc++-v3/include/bits/version.def b/libstdc++-v3/include/bits/version.def index 0afaf0dec24..8f92f2e5b92 100644 --- a/libstdc++-v3/include/bits/version.def +++ b/libstdc++-v3/include/bits/version.def @@ -1841,6 +1841,14 @@ ftms = { }; }; +ftms = { + name = debugging; + values = { + v = 202403; + cxxmin = 26; + }; +}; + ftms = { name = fstream_native_handle; values = { diff --git a/libstdc++-v3/include/bits/version.h b/libstdc++-v3/include/bits/version.h index 980fee641e9..126d959c92d 100644 --- a/libstdc++-v3/include/bits/version.h +++ b/libstdc++-v3/include/bits/version.h @@ -2054,6 +2054,16 @@ #endif /* !defined(__cpp_lib_constexpr_new) && defined(__glibcxx_want_constexpr_new) */ #undef __glibcxx_want_constexpr_new +#if !defined(__cpp_lib_debugging) +# if (__cplusplus > 202302L) +# define __glibcxx_debugging 202403L +# if defined(__glibcxx_want_all) || defined(__glibcxx_want_debugging) +# define __cpp_lib_debugging 202403L +# endif +# endif +#endif /* !defined(__cpp_lib_debugging) && defined(__glibcxx_want_debugging) */ +#undef __glibcxx_want_debugging + #if !defined(__cpp_lib_fstream_native_handle) # if (__cplusplus > 202302L) && _GLIBCXX_HOSTED # define __glibcxx_fstream_native_handle 202306L diff --git a/libstdc++-v3/include/std/debugging b/libstdc++-v3/include/std/debugging new file mode 100644 index 00000000000..4cf7e4acbc4 --- /dev/null +++ b/libstdc++-v3/include/std/debugging @@ -0,0 +1,77 @@ +// Debugging support -*- C++ -*- + +// Copyright The GNU Toolchain Authors. +// +// This file is part of the GNU ISO C++ Library. This library 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. + +// This library 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. + +// Under Section 7 of GPL version 3, you are granted additional +// permissions described in the GCC Runtime Library Exception, version +// 3.1, as published by the Free Software Foundation. + +// You should have received a copy of the GNU General Public License and +// a copy of the GCC Runtime Library Exception along with this program; +// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see +// <http://www.gnu.org/licenses/>. + +/** @file include/debugging + * This is a Standard C++ Library header. + */ + +#ifndef _GLIBCXX_DEBUGGING +#define _GLIBCXX_DEBUGGING 1 + +#define __glibcxx_want_debugging +#include <bits/version.h> + +#if __cpp_lib_debugging // C++ >= 26 +namespace std _GLIBCXX_VISIBILITY(default) +{ +// N.B. _GLIBCXX_BEGIN_NAMESPACE_VERSION is not used here. + +/** Try to determine if the program is running under control of a debugger. + * + * On GNU/Linux systems this function will only return true if the program + * is being traced by another program which is known to be a debugger. + * This is determined by checking the command name of the tracing program + * against a list of known debuggers, such as "gdb". + * + * On other POSIX-based systems, this function will return true if the + * program is being traced by any other process, which means it can return + * true for non-debugger utilities that use the ptrace system call. + * + * @since C++26 + */ +bool +is_debugger_present() noexcept; + +/** Stop the program with a breakpoint or debug trap. + * + * The details of how a breakpoint is implemented are platform-specific. + * Some systems provide a special instruction, such as `int3` in x86. + * When no more appropriate mechanism is available, this will stop the + * program using `__builtin_trap()`. It might not be possible for the + * program to continue after such a breakpoint. + * + * @since C++26 + */ +void +breakpoint() noexcept; + +/** Stop the program if it is running under control of a debugger. + * + * @since C++26 + */ +void +breakpoint_if_debugging() noexcept; + +} // namespace std +#endif +#endif // _GLIBCXX_DEBUGGING diff --git a/libstdc++-v3/src/c++26/Makefile.am b/libstdc++-v3/src/c++26/Makefile.am index 5defa4ac481..4123b7dd369 100644 --- a/libstdc++-v3/src/c++26/Makefile.am +++ b/libstdc++-v3/src/c++26/Makefile.am @@ -35,7 +35,9 @@ else inst_sources = endif -sources = text_encoding.cc +sources = \ + debugging.cc \ + text_encoding.cc vpath % $(top_srcdir)/src/c++26 diff --git a/libstdc++-v3/src/c++26/Makefile.in b/libstdc++-v3/src/c++26/Makefile.in index 77e73b2b265..1c317d6ac7c 100644 --- a/libstdc++-v3/src/c++26/Makefile.in +++ b/libstdc++-v3/src/c++26/Makefile.in @@ -121,7 +121,7 @@ CONFIG_CLEAN_FILES = CONFIG_CLEAN_VPATH_FILES = LTLIBRARIES = $(noinst_LTLIBRARIES) libc__26convenience_la_LIBADD = -am__objects_1 = text_encoding.lo +am__objects_1 = debugging.lo text_encoding.lo am__objects_2 = @GLIBCXX_HOSTED_TRUE@am_libc__26convenience_la_OBJECTS = \ @GLIBCXX_HOSTED_TRUE@ $(am__objects_1) $(am__objects_2) @@ -430,7 +430,10 @@ headers = # XTEMPLATE_FLAGS = -fno-implicit-templates @ENABLE_EXTERN_TEMPLATE_TRUE@inst_sources = -sources = text_encoding.cc +sources = \ + debugging.cc \ + text_encoding.cc + @GLIBCXX_HOSTED_FALSE@libc__26convenience_la_SOURCES = @GLIBCXX_HOSTED_TRUE@libc__26convenience_la_SOURCES = $(sources) $(inst_sources) diff --git a/libstdc++-v3/src/c++26/debugging.cc b/libstdc++-v3/src/c++26/debugging.cc new file mode 100644 index 00000000000..de7ddb14478 --- /dev/null +++ b/libstdc++-v3/src/c++26/debugging.cc @@ -0,0 +1,172 @@ +// Implementation of <debugging> -*- C++ -*- + +// Copyright The GNU Toolchain Authors. +// +// This file is part of the GNU ISO C++ Library. This library 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. + +// This library 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. + +// Under Section 7 of GPL version 3, you are granted additional +// permissions described in the GCC Runtime Library Exception, version +// 3.1, as published by the Free Software Foundation. + +// You should have received a copy of the GNU General Public License and +// a copy of the GCC Runtime Library Exception along with this program; +// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see +// <http://www.gnu.org/licenses/>. + +#include <debugging> + +#if __cpp_lib_debugging + +#if _GLIBCXX_USE_PROC_SELF_STATUS +# include <fstream> +# include <string> +#endif + +#if _GLIBCXX_HAVE_SYS_PTRACE_H +# include <sys/ptrace.h> +# include <errno.h> +#endif + +#if _GLIBCXX_HAVE_DEBUGAPI_H +# include <debugapi.h> +#endif + +#ifdef _GLIBCXX_HAVE_SYS_SDT_H +# include <sys/sdt.h> +/* We only want to use stap probes starting with v3. Earlier versions + added too much startup cost. */ +# if defined (STAP_PROBE) && _SDT_NOTE_TYPE >= 3 +# define PROBE(name) STAP_PROBE(libstdcxx, name) +# endif +#endif + +#ifndef PROBE +# define PROBE(name) +#endif + +namespace +{ + volatile bool debugger_attached = false; +} + +namespace __gnu_cxx +{ + // This should be called by debuggers when they attach and detach. + void attach_debugger(bool attached) + { + PROBE(__gnu_cxx::attach_debugger); + debugger_attached = attached; + } +} + +_GLIBCXX_WEAK_DEFINITION +bool +std::is_debugger_present() noexcept +{ + PROBE(std::is_debugger_present); + + if (debugger_attached) + return true; + +#if _GLIBCXX_HOSTED +# if _GLIBCXX_USE_PROC_SELF_STATUS + const string_view prefix = "TracerPid:\t"; // populated since Linux 2.6.0 + ifstream in("/proc/self/status"); + string line; + while (std::getline(in, line)) + { + if (!line.starts_with(prefix)) + continue; + + string_view tracer = line; + tracer.remove_prefix(prefix.size()); + if (tracer.size() == 1 && tracer[0] == '0') [[likely]] + return false; // Not being traced. + + in.close(); + string_view cmd; + string proc_dir = "/proc/" + string(tracer) + '/'; + in.open(proc_dir + "comm"); // since Linux 2.6.33 + if (std::getline(in, line)) [[likely]] + cmd = line; + else + { + in.close(); + in.open(proc_dir + "cmdline"); + if (std::getline(in, line)) + cmd = line.c_str(); // Only up to first '\0' + else + return false; + } + + for (auto i : {"gdb", "gdbserver", "lldb-server"}) // known debuggers + if (cmd.ends_with(i)) + return true; + + // We found the TracerPid line, no need to do any more work. + return false; + } +# elif _GLIBCXX_HAVE_SYS_PTRACE_H + if (::ptrace(PTRACE_TRACEME, 0, 1, 0) == -1) + return errno == EPERM; +# endif +# if _GLIBCXX_HAVE_DEBUGAPI_H && defined(_WIN32) && !defined(__CYGWIN__) + return IsDebuggerPresent(); +# endif +#endif // HOSTED + return false; +} + +void +std::breakpoint() noexcept +{ + PROBE(std::breakpoint); + +#if _GLIBCXX_HAVE_DEBUGAPI_H && defined(_WIN32) && !defined(__CYGWIN__) + DebugBreak(); +#elif __has_builtin(__builtin_debugtrap) + __builtin_debugtrap(); // Clang +#elif defined(__i386__) || defined(__x86_64__) + __asm__ volatile ("int3; nop"); +#elifdef __thumb__ + __asm__ volatile (".inst 0xde01"); +#elifdef __aarch64__ + __asm__ volatile (".inst 0xd4200000"); +#elifdef __arm__ + __asm__ volatile (".inst 0xe7f001f0"); +#elifdef __riscv + /* section 2.8 in the RISC-V unprivileged ISA manual says for semi-hosted + * environments we want the sequence: + * slli x0, x0, 0x1f # Entry NOP + * ebreak # Break to debugger + * srai x0, x0, 7 # NOP encoding the semihosting call number 7 + */ + __asm__ volatile (".4byte 0x00100073"); +#elifdef __powerpc__ + __asm__ volatile(".4byte 0x7d821008"); +#else + __builtin_trap(); +#endif +} // If the debugger stops here, std::breakpoint() was called. + +// This is intentionally not defined inline. A non-inline definition allows +// debuggers to insert a breakpoint on calls to the function, avoiding the +// overhead of calling `is_debugger_present()`. +void +std::breakpoint_if_debugging() noexcept +{ + PROBE(std::breakpoint_if_debugging); + + if (std::is_debugger_present()) [[unlikely]] + std::breakpoint(); +} + +#endif // __cpp_lib_debugging diff --git a/libstdc++-v3/testsuite/19_diagnostics/debugging/breakpoint.cc b/libstdc++-v3/testsuite/19_diagnostics/debugging/breakpoint.cc new file mode 100644 index 00000000000..ad24177f644 --- /dev/null +++ b/libstdc++-v3/testsuite/19_diagnostics/debugging/breakpoint.cc @@ -0,0 +1,13 @@ +// { dg-do run { target c++26 xfail c++26 } } +// { dg-options "-lstdc++exp" } +// { dg-require-cpp-feature-test __cpp_lib_debugging } +#include <debugging> +#include <type_traits> + +static_assert( noexcept(std::breakpoint()) ); +static_assert( std::is_void_v<decltype(std::breakpoint())> ); + +int main() +{ + std::breakpoint(); +} diff --git a/libstdc++-v3/testsuite/19_diagnostics/debugging/breakpoint_if_debugging.cc b/libstdc++-v3/testsuite/19_diagnostics/debugging/breakpoint_if_debugging.cc new file mode 100644 index 00000000000..26461836ef7 --- /dev/null +++ b/libstdc++-v3/testsuite/19_diagnostics/debugging/breakpoint_if_debugging.cc @@ -0,0 +1,13 @@ +// { dg-do run { target c++26 } } +// { dg-options "-lstdc++exp" } +// { dg-require-cpp-feature-test __cpp_lib_debugging } +#include <debugging> +#include <type_traits> + +static_assert( noexcept(std::breakpoint_if_debugging()) ); +static_assert( std::is_void_v<decltype(std::breakpoint_if_debugging())> ); + +int main() +{ + std::breakpoint_if_debugging(); +} diff --git a/libstdc++-v3/testsuite/19_diagnostics/debugging/is_debugger_present-2.cc b/libstdc++-v3/testsuite/19_diagnostics/debugging/is_debugger_present-2.cc new file mode 100644 index 00000000000..aa4690c5540 --- /dev/null +++ b/libstdc++-v3/testsuite/19_diagnostics/debugging/is_debugger_present-2.cc @@ -0,0 +1,19 @@ +// { dg-do run { target c++26 } } +// { dg-options "-lstdc++exp" } +// { dg-require-cpp-feature-test __cpp_lib_debugging } +// { dg-xfail-run-if "no replaceable functions on AIX" { powerpc-ibm-aix* } } + +// P2810R4 is_debugger_present is_replaceable + +#include <debugging> +#include <testsuite_hooks.h> + +bool called = false; + +bool std::is_debugger_present() noexcept { called = true; return true; } + +int main() +{ + VERIFY( std::is_debugger_present() ); + VERIFY( called ); +} diff --git a/libstdc++-v3/testsuite/19_diagnostics/debugging/is_debugger_present.cc b/libstdc++-v3/testsuite/19_diagnostics/debugging/is_debugger_present.cc new file mode 100644 index 00000000000..8dbfa694243 --- /dev/null +++ b/libstdc++-v3/testsuite/19_diagnostics/debugging/is_debugger_present.cc @@ -0,0 +1,14 @@ +// { dg-do run { target c++26 } } +// { dg-options "-lstdc++exp" } +// { dg-require-cpp-feature-test __cpp_lib_debugging } +#include <debugging> +#include <type_traits> +#include <testsuite_hooks.h> + +static_assert( noexcept(std::is_debugger_present()) ); +static_assert( std::is_same_v<decltype(std::is_debugger_present()), bool> ); + +int main() +{ + VERIFY( ! std::is_debugger_present() ); +} -- 2.49.0
