From 69e542bd2d750b9ffa007767b2ea3b1c88028df5 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Thomas=20Wei=C3=9Fschuh?= <thomas@t-8ch.de>
Date: Fri, 5 May 2023 00:39:40 +0200
Subject: [PATCH] enosys: find syscalls at build time
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
---
 .github/workflows/cibuild-setup-ubuntu.sh |  1 +
 meson.build                               |  8 +++++++-
 misc-utils/Makemodule.am                  |  9 +++++++++
 misc-utils/enosys.c                       |  8 ++++----
 tools/Makemodule.am                       |  4 +++-
 tools/all_syscalls                        | 15 +++++++++++++++
 6 files changed, 39 insertions(+), 6 deletions(-)
 create mode 100755 tools/all_syscalls

diff --git a/.github/workflows/cibuild-setup-ubuntu.sh b/.github/workflows/cibuild-setup-ubuntu.sh
index 3ffa9fcb37..de9f8a85c5 100755
--- a/.github/workflows/cibuild-setup-ubuntu.sh
+++ b/.github/workflows/cibuild-setup-ubuntu.sh
@@ -27,6 +27,7 @@ PACKAGES=(
 	iproute2
 	dmsetup
 	python3-dev
+	gawk
 )
 
 PACKAGES_OPTIONAL=(
diff --git a/meson.build b/meson.build
index 9449501e18..e1099cf547 100644
--- a/meson.build
+++ b/meson.build
@@ -2856,9 +2856,15 @@ if not is_disabler(exe)
   bashcompletions += ['waitpid']
 endif
 
+syscalls_h = custom_target('syscalls.h',
+  input : 'tools/all_syscalls',
+  output : 'syscalls.h',
+  command : ['bash', '@INPUT@', cc.cmd_array()],
+)
+
 exe = executable(
   'enosys',
-  'misc-utils/enosys.c',
+  'misc-utils/enosys.c', syscalls_h,
   include_directories : includes,
   link_with : [lib_common],
   install_dir : usrbin_exec_dir,
diff --git a/misc-utils/Makemodule.am b/misc-utils/Makemodule.am
index 9c558994db..76fa9014ab 100644
--- a/misc-utils/Makemodule.am
+++ b/misc-utils/Makemodule.am
@@ -299,6 +299,15 @@ waitpid_CFLAGS = $(AM_CFLAGS)
 endif
 
 if BUILD_ENOSYS
+
+misc-utils/enosys.c: syscalls.h
+
+syscalls.h: $(top_srcdir)/tools/all_syscalls
+	$(top_srcdir)/tools/all_syscalls $(CC) $(CFLAGS)
+
+-include syscalls.h.deps
+CLEANFILES += syscalls.h syscalls.h.deps
+
 usrbin_exec_PROGRAMS += enosys
 MANPAGES += misc-utils/enosys.1
 dist_noinst_DATA += misc-utils/enosys.1.adoc
diff --git a/misc-utils/enosys.c b/misc-utils/enosys.c
index 79f57b2553..6ea176a599 100644
--- a/misc-utils/enosys.c
+++ b/misc-utils/enosys.c
@@ -69,11 +69,11 @@ struct syscall {
 };
 
 static const struct syscall syscalls[] = {
-	{ "move_mount", __NR_move_mount },
-	{ "open_tree", __NR_open_tree },
-	{ "fsopen", __NR_fsopen },
-	{ "fallocate", __NR_fallocate },
+#define UL_SYSCALL(name, nr) { name, nr },
+#include "syscalls.h"
+#undef UL_SYSCALL
 };
+static_assert(sizeof(syscalls) > 0, "no syscalls found");
 
 static void __attribute__((__noreturn__)) usage(void)
 {
diff --git a/tools/Makemodule.am b/tools/Makemodule.am
index dbda625872..ebee6c334f 100644
--- a/tools/Makemodule.am
+++ b/tools/Makemodule.am
@@ -56,4 +56,6 @@ EXTRA_DIST += \
 	tools/config-gen.d/non-libmount.conf \
 	\
 	tools/asciidoctor-includetracker.rb \
-	tools/asciidoctor-unicodeconverter.rb
+	tools/asciidoctor-unicodeconverter.rb \
+	\
+	tools/all_syscalls
diff --git a/tools/all_syscalls b/tools/all_syscalls
new file mode 100755
index 0000000000..9c147786cf
--- /dev/null
+++ b/tools/all_syscalls
@@ -0,0 +1,15 @@
+#!/bin/bash
+
+set -e
+
+OUTPUT=syscalls.h
+SYSCALL_INCLUDES="
+#include <sys/syscall.h>
+"
+
+trap 'rm $OUTPUT $OUTPUT.deps' ERR
+
+"$@" -MD -MF "$OUTPUT.deps" <<< "$SYSCALL_INCLUDES" -dM -E - \
+	| gawk 'match($0, /^#define __NR_([^ ]+)/, res) { print "UL_SYSCALL(\"" res[1] "\", __NR_" res[1] ")" }' \
+	| sort \
+	> "$OUTPUT"
-- 
2.47.3