[libc-commits] [libc] [libc][signal] clean up usage of sighandler_t (PR #125745)
Nick Desaulniers via libc-commits
libc-commits at lists.llvm.org
Tue Feb 4 11:04:47 PST 2025
https://github.com/nickdesaulniers created https://github.com/llvm/llvm-project/pull/125745
`man 3 signal`'s declaration has a face _only a mother could love_.
sighandler_t and __sighandler_t are not defined in the C standard, or POSIX.
They are helpful typedefs provided by glibc since working with function
pointers' syntax can be painful. But we should not rely on them; in C++ we have
`auto*` and `using` statements.
Remove the proxy header, and only include typedefs for these two typedefs when
targeting Linux, for compatibility with glibc.
Also, adds a typedef for non-double-underscore-prefixed sighandler_t that we
were missing.
Fixes: #125598
>From 62e8a9c228080a9cc13e5a5c321f037b1dccbbc6 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers at google.com>
Date: Tue, 4 Feb 2025 10:27:44 -0800
Subject: [PATCH 1/4] [libc][signal] clean up sighandler_t declarations
---
libc/hdr/types/sighandler_t.h | 2 --
libc/include/llvm-libc-macros/gpu/signal-macros.h | 6 +++---
libc/include/llvm-libc-macros/linux/signal-macros.h | 6 +++---
libc/include/llvm-libc-types/__sighandler_t.h | 1 +
libc/include/llvm-libc-types/struct_sigaction.h | 2 --
libc/include/signal.yaml | 11 ++++++-----
6 files changed, 13 insertions(+), 15 deletions(-)
diff --git a/libc/hdr/types/sighandler_t.h b/libc/hdr/types/sighandler_t.h
index bc40dd8b4c8f4a..8d7e04d6788683 100644
--- a/libc/hdr/types/sighandler_t.h
+++ b/libc/hdr/types/sighandler_t.h
@@ -13,8 +13,6 @@
#include "include/llvm-libc-types/__sighandler_t.h"
-using sighandler_t = __sighandler_t;
-
#else // overlay mode
#include <signal.h>
diff --git a/libc/include/llvm-libc-macros/gpu/signal-macros.h b/libc/include/llvm-libc-macros/gpu/signal-macros.h
index 2d8159240de8bf..f0d49ea34fe0ef 100644
--- a/libc/include/llvm-libc-macros/gpu/signal-macros.h
+++ b/libc/include/llvm-libc-macros/gpu/signal-macros.h
@@ -16,9 +16,9 @@
#define SIGSEGV 11
#define SIGTERM 15
-#define SIG_DFL ((__sighandler_t)(0))
-#define SIG_IGN ((__sighandler_t)(1))
-#define SIG_ERR ((__sighandler_t)(-1))
+#define SIG_DFL ((void (*)(int))(0))
+#define SIG_IGN ((void (*)(int))(1))
+#define SIG_ERR ((void (*)(int))(-1))
// Max signal number
#define NSIG 64
diff --git a/libc/include/llvm-libc-macros/linux/signal-macros.h b/libc/include/llvm-libc-macros/linux/signal-macros.h
index 0b7317ebc9b80a..6afa7facd8091f 100644
--- a/libc/include/llvm-libc-macros/linux/signal-macros.h
+++ b/libc/include/llvm-libc-macros/linux/signal-macros.h
@@ -86,9 +86,9 @@
#error "Signal stack sizes not defined for your platform."
#endif
-#define SIG_DFL ((__sighandler_t)0)
-#define SIG_IGN ((__sighandler_t)1)
-#define SIG_ERR ((__sighandler_t)-1)
+#define SIG_DFL ((void (*)(int))0)
+#define SIG_IGN ((void (*)(int))1)
+#define SIG_ERR ((void (*)(int))-1)
// SIGCHLD si_codes
#define CLD_EXITED 1 // child has exited
diff --git a/libc/include/llvm-libc-types/__sighandler_t.h b/libc/include/llvm-libc-types/__sighandler_t.h
index 9c1ac997fc4ee0..1b1b40d60384c8 100644
--- a/libc/include/llvm-libc-types/__sighandler_t.h
+++ b/libc/include/llvm-libc-types/__sighandler_t.h
@@ -10,5 +10,6 @@
#define LLVM_LIBC_TYPES___SIGHANDLER_T_H
typedef void (*__sighandler_t)(int);
+typedef __sighandler_t sighandler_t;
#endif // LLVM_LIBC_TYPES___SIGHANDLER_T_H
diff --git a/libc/include/llvm-libc-types/struct_sigaction.h b/libc/include/llvm-libc-types/struct_sigaction.h
index b4d0c965a4c633..907418b5e0f9a0 100644
--- a/libc/include/llvm-libc-types/struct_sigaction.h
+++ b/libc/include/llvm-libc-types/struct_sigaction.h
@@ -25,6 +25,4 @@ struct sigaction {
#endif
};
-typedef void (*__sighandler_t)(int);
-
#endif // LLVM_LIBC_TYPES_STRUCT_SIGACTION_H
diff --git a/libc/include/signal.yaml b/libc/include/signal.yaml
index 576e77576ac740..ad05b9a04df989 100644
--- a/libc/include/signal.yaml
+++ b/libc/include/signal.yaml
@@ -2,13 +2,14 @@ header: signal.h
header_template: signal.h.def
macros: []
types:
+ - type_name: __sighandler_t
- type_name: pid_t
- - type_name: stack_t
+ - type_name: sig_atomic_t
- type_name: siginfo_t
- - type_name: struct_sigaction
- type_name: sigset_t
+ - type_name: stack_t
+ - type_name: struct_sigaction
- type_name: union_sigval
- - type_name: sig_atomic_t
enums: []
objects: []
functions:
@@ -69,10 +70,10 @@ functions:
- name: signal
standards:
- stdc
- return_type: __sighandler_t
+ return_type: sighandler_t
arguments:
- type: int
- - type: __sighandler_t
+ - type: sighandler_t
- name: sigprocmask
standards:
- POSIX
>From c84b8f2cf4c2fa6ab5c75856670df8e739336865 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers at google.com>
Date: Tue, 4 Feb 2025 10:46:02 -0800
Subject: [PATCH 2/4] clean up our usage of sighandler_t
---
libc/hdr/types/CMakeLists.txt | 9 ---------
libc/hdr/types/sighandler_t.h | 22 ----------------------
libc/src/signal/linux/CMakeLists.txt | 1 -
libc/src/signal/linux/signal.cpp | 6 ++++--
libc/src/signal/signal.h | 3 +--
libc/test/UnitTest/FPExceptMatcher.cpp | 2 +-
libc/test/src/signal/CMakeLists.txt | 1 -
libc/test/src/signal/signal_test.cpp | 4 +---
8 files changed, 7 insertions(+), 41 deletions(-)
delete mode 100644 libc/hdr/types/sighandler_t.h
diff --git a/libc/hdr/types/CMakeLists.txt b/libc/hdr/types/CMakeLists.txt
index 3dfa38a020fad0..83c01fd6aeafef 100644
--- a/libc/hdr/types/CMakeLists.txt
+++ b/libc/hdr/types/CMakeLists.txt
@@ -250,15 +250,6 @@ add_proxy_header_library(
libc.include.locale
)
-add_proxy_header_library(
- sighandler_t
- HDRS
- sighandler_t.h
- FULL_BUILD_DEPENDS
- libc.include.llvm-libc-types.__sighandler_t
- libc.include.signal
-)
-
add_proxy_header_library(
stack_t
HDRS
diff --git a/libc/hdr/types/sighandler_t.h b/libc/hdr/types/sighandler_t.h
deleted file mode 100644
index 8d7e04d6788683..00000000000000
--- a/libc/hdr/types/sighandler_t.h
+++ /dev/null
@@ -1,22 +0,0 @@
-//===-- Definition of macros from __sighandler_t.h ------------------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_LIBC_HDR_TYPES_SIGHANDLER_T_H
-#define LLVM_LIBC_HDR_TYPES_SIGHANDLER_T_H
-
-#ifdef LIBC_FULL_BUILD
-
-#include "include/llvm-libc-types/__sighandler_t.h"
-
-#else // overlay mode
-
-#include <signal.h>
-
-#endif // LLVM_LIBC_FULL_BUILD
-
-#endif // LLVM_LIBC_HDR_TYPES_SIGHANDLER_T_H
diff --git a/libc/src/signal/linux/CMakeLists.txt b/libc/src/signal/linux/CMakeLists.txt
index f7457d31cf4f85..c0dd61e473881b 100644
--- a/libc/src/signal/linux/CMakeLists.txt
+++ b/libc/src/signal/linux/CMakeLists.txt
@@ -127,7 +127,6 @@ add_entrypoint_object(
DEPENDS
.sigaction
libc.hdr.signal_macros
- libc.hdr.types.sighandler_t
)
add_entrypoint_object(
diff --git a/libc/src/signal/linux/signal.cpp b/libc/src/signal/linux/signal.cpp
index 1da0ef8c97a206..f196aa52634e47 100644
--- a/libc/src/signal/linux/signal.cpp
+++ b/libc/src/signal/linux/signal.cpp
@@ -8,14 +8,16 @@
#include "src/signal/signal.h"
#include "hdr/signal_macros.h"
-#include "hdr/types/sighandler_t.h"
#include "src/__support/common.h"
#include "src/__support/macros/config.h"
#include "src/signal/sigaction.h"
namespace LIBC_NAMESPACE_DECL {
-LLVM_LIBC_FUNCTION(sighandler_t, signal, (int signum, sighandler_t handler)) {
+// Our LLVM_LIBC_FUNCTION macro doesn't handle function pointer return types.
+using signal_handler = void (*)(int);
+
+LLVM_LIBC_FUNCTION(signal_handler, signal, (int signum, signal_handler handler)) {
struct sigaction action, old;
action.sa_handler = handler;
action.sa_flags = SA_RESTART;
diff --git a/libc/src/signal/signal.h b/libc/src/signal/signal.h
index 06e77e11bf0bd3..e1f31a8e126c58 100644
--- a/libc/src/signal/signal.h
+++ b/libc/src/signal/signal.h
@@ -9,12 +9,11 @@
#ifndef LLVM_LIBC_SRC_SIGNAL_SIGNAL_H
#define LLVM_LIBC_SRC_SIGNAL_SIGNAL_H
-#include "hdr/types/sighandler_t.h"
#include "src/__support/macros/config.h"
namespace LIBC_NAMESPACE_DECL {
-sighandler_t signal(int signum, sighandler_t handler);
+void (*signal(int signum, void (*handler)(int)))(int);
} // namespace LIBC_NAMESPACE_DECL
diff --git a/libc/test/UnitTest/FPExceptMatcher.cpp b/libc/test/UnitTest/FPExceptMatcher.cpp
index 119a06985b8f1c..d66066023984e5 100644
--- a/libc/test/UnitTest/FPExceptMatcher.cpp
+++ b/libc/test/UnitTest/FPExceptMatcher.cpp
@@ -37,7 +37,7 @@ static void sigfpeHandler(int sig) {
}
FPExceptMatcher::FPExceptMatcher(FunctionCaller *func) {
- sighandler_t oldSIGFPEHandler = signal(SIGFPE, &sigfpeHandler);
+ auto *oldSIGFPEHandler = signal(SIGFPE, &sigfpeHandler);
caughtExcept = false;
fenv_t oldEnv;
diff --git a/libc/test/src/signal/CMakeLists.txt b/libc/test/src/signal/CMakeLists.txt
index a27f5b8f1000e9..f86ce2ae96857c 100644
--- a/libc/test/src/signal/CMakeLists.txt
+++ b/libc/test/src/signal/CMakeLists.txt
@@ -74,7 +74,6 @@ add_libc_unittest(
SRCS
signal_test.cpp
DEPENDS
- libc.hdr.types.sighandler_t
libc.src.errno.errno
libc.src.signal.raise
libc.src.signal.signal
diff --git a/libc/test/src/signal/signal_test.cpp b/libc/test/src/signal/signal_test.cpp
index 4b57311eee2d86..bac9c3b8b68bb2 100644
--- a/libc/test/src/signal/signal_test.cpp
+++ b/libc/test/src/signal/signal_test.cpp
@@ -13,14 +13,12 @@
#include "test/UnitTest/ErrnoSetterMatcher.h"
#include "test/UnitTest/Test.h"
-#include "hdr/types/sighandler_t.h"
-
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Fails;
using LIBC_NAMESPACE::testing::ErrnoSetterMatcher::Succeeds;
TEST(LlvmLibcSignal, Invalid) {
LIBC_NAMESPACE::libc_errno = 0;
- sighandler_t valid = +[](int) {};
+ auto *valid = +[](int) {};
EXPECT_THAT((void *)LIBC_NAMESPACE::signal(0, valid),
Fails(EINVAL, (void *)SIG_ERR));
EXPECT_THAT((void *)LIBC_NAMESPACE::signal(65, valid),
>From 669bb96c3093f596330d745eb1f02852d2c7a9f0 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers at google.com>
Date: Tue, 4 Feb 2025 10:48:55 -0800
Subject: [PATCH 3/4] only include __sighandler_t.h on linux
---
libc/include/llvm-libc-types/__sighandler_t.h | 4 ++++
libc/include/signal.h.def | 4 ++++
libc/include/signal.yaml | 1 -
3 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/libc/include/llvm-libc-types/__sighandler_t.h b/libc/include/llvm-libc-types/__sighandler_t.h
index 1b1b40d60384c8..0fa412568a6912 100644
--- a/libc/include/llvm-libc-types/__sighandler_t.h
+++ b/libc/include/llvm-libc-types/__sighandler_t.h
@@ -9,6 +9,10 @@
#ifndef LLVM_LIBC_TYPES___SIGHANDLER_T_H
#define LLVM_LIBC_TYPES___SIGHANDLER_T_H
+#ifndef __linux__
+#error "sighandler_t only available on linux"
+#endif
+
typedef void (*__sighandler_t)(int);
typedef __sighandler_t sighandler_t;
diff --git a/libc/include/signal.h.def b/libc/include/signal.h.def
index 50a5f44c7337aa..11e56138879d59 100644
--- a/libc/include/signal.h.def
+++ b/libc/include/signal.h.def
@@ -16,6 +16,10 @@
#include "llvm-libc-macros/signal-macros.h"
+#ifdef __linux__
+#include "llvm-libc-types/__sighandler_t.h"
+#endif
+
%%public_api()
#endif // LLVM_LIBC_SIGNAL_H
diff --git a/libc/include/signal.yaml b/libc/include/signal.yaml
index ad05b9a04df989..91e307e00d21c9 100644
--- a/libc/include/signal.yaml
+++ b/libc/include/signal.yaml
@@ -2,7 +2,6 @@ header: signal.h
header_template: signal.h.def
macros: []
types:
- - type_name: __sighandler_t
- type_name: pid_t
- type_name: sig_atomic_t
- type_name: siginfo_t
>From 19e518a20a1acae3113efcd22ce87a82c73461b6 Mon Sep 17 00:00:00 2001
From: Nick Desaulniers <ndesaulniers at google.com>
Date: Tue, 4 Feb 2025 10:56:09 -0800
Subject: [PATCH 4/4] update signal.h hdrgen
---
libc/include/signal.yaml | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/libc/include/signal.yaml b/libc/include/signal.yaml
index 91e307e00d21c9..5530d63c4bff97 100644
--- a/libc/include/signal.yaml
+++ b/libc/include/signal.yaml
@@ -69,10 +69,15 @@ functions:
- name: signal
standards:
- stdc
- return_type: sighandler_t
+ # May the Geneva Convention have mercy on my soul... Why this insanity?
+ # Well: signal returns a function pointer to a function with no return
+ # value and which accepts an int. The parameter list appears on the far
+ # right of the declaration. i.e.
+ # void (*signal(int, void (*)(int)))(int);
+ return_type: void (*
arguments:
- type: int
- - type: sighandler_t
+ - type: void (*)(int)))(int
- name: sigprocmask
standards:
- POSIX
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