Fix Bugzilla 24725 - core.sys.linux: feature detect glibc functions a…

druntime/.gitignore

@@ -11,3 +11,6 @@ trace.log
 /msvc*.obj
 make
 *.lst
+
+# generated during the build
+/src/core/sys/linux/config.d

druntime/Makefile

@@ -370,6 +370,10 @@ $(IMPDIR)/%.h : src/%.h
 	@mkdir -p $(dir $@)
 	@cp $< $@
 
+################### Feature tests for druntime bindings #########################
+
+include features/GNUmakefile
+
 ######################## Build DMD if non-existent ##############################
 
 ../generated/$(OS)/$(BUILD)/$(MODEL)/dmd$(DOTEXE):

druntime/features/.gitignore

@@ -0,0 +1 @@
+/tmp

druntime/features/GNUmakefile

@@ -0,0 +1,19 @@
+SED:=sed
+ifeq ($(OS),$(filter $(OS),freebsd osx))
+    SED_INPLACE:=-i ''
+else
+    SED_INPLACE:=-i''
+endif
+
+export FEATURE_TMPDIR:=$(CURDIR)/features/tmp
+export CC
+
+src/core/sys/linux/config.d: src/core/sys/linux/config.d.in
+	@cp $< $@
+	@if [ "$(OS)" = linux ] \
+	    && ./features/cc_has_function.sh 'closefrom' '#include <unistd.h>'; \
+	then \
+	$(SED) $(SED_INPLACE) "s/@HAVE_CLOSEFROM@/true/" $@; \
+	else \
+	$(SED) $(SED_INPLACE) "s/@HAVE_CLOSEFROM@/false/" $@; \
+	fi

druntime/features/cc_has_function.sh

@@ -0,0 +1,35 @@
+#!/bin/sh
+
+die () {
+	[ $# -ne 0 ] && echo "${@}"
+	exit 1
+}
+
+usage () {
+	echo "Usage: $0 <function_name> <header>"
+}
+
+[ $# -ne 2 ] && usage && die "Invalid usage!"
+
+tmp="${FEATURE_TMPDIR}"
+
+mkdir -p "${tmp}" || die "Could not create temp directory"
+outfile="${tmp}/check_${1}.c"
+
+# Check taken from the meson build system
+cat > "${outfile}" <<DRUNTIME_CHECK_EOF || die "Could not generate sample C program"
+${2}
+int main(void) {{
+	void *a = (void*) &${1};
+	long long b = (long long) a;
+	return (int) b;
+}}
+DRUNTIME_CHECK_EOF
+
+echo -n "Checking for the existence of '${1}'... "
+${CC} -o "${outfile}.prog" "${outfile}" > /dev/null 2>&1
+res=$?
+[ "${res}" -eq 0 ] && echo "found" || echo "NOT found"
+
+rm -f "${outfile}" "${outfile}.prog"
+exit "${res}"

druntime/src/core/sys/linux/config.d → druntime/src/core/sys/linux/config.d.in

@@ -30,3 +30,5 @@ deprecated("use _ATFILE_SOURCE")
 enum __USE_ATFILE = _ATFILE_SOURCE;
 deprecated("use _GNU_SOURCE")
 enum __USE_GNU = _GNU_SOURCE;
+
+enum __HAVE_CLOSEFROM = @HAVE_CLOSEFROM@;

druntime/src/core/sys/linux/unistd.d

@@ -1,6 +1,7 @@
 module core.sys.linux.unistd;
 
 public import core.sys.posix.unistd;
+import core.sys.linux.config;
 
 version (linux):
 extern(C):
@@ -23,5 +24,6 @@ char* getpass(const(char)* prompt);
 // Exit all threads in a process
 void exit_group(int status);
 
+static if (__HAVE_CLOSEFROM)
 /// Close all open file descriptors greater or equal to `lowfd`
 void closefrom(int lowfd);