Emulate O_CLOEXEC on systems that don't support it

cmake/ConkyPlatformChecks.cmake

@@ -34,6 +34,9 @@ check_include_files(dirent.h HAVE_DIRENT_H)
 # Check for some functions
 check_function_exists(strndup HAVE_STRNDUP)
 
+check_symbol_exists(pipe2 "unistd.h" HAVE_PIPE2)
+check_symbol_exists(O_CLOEXEC "fcntl.h" HAVE_O_CLOEXEC)
+
 AC_SEARCH_LIBS(clock_gettime "time.h" CLOCK_GETTIME_LIB "rt")
 if(NOT CLOCK_GETTIME_LIB)
 	message(FATAL_ERROR "clock_gettime not found.")

cmake/config.h.in

@@ -33,6 +33,9 @@
 #cmakedefine HAVE_FOPENCOOKIE 1
 #cmakedefine HAVE_FUNOPEN 1
 
+#cmakedefine HAVE_PIPE2 1
+#cmakedefine HAVE_O_CLOEXEC 1
+
 #cmakedefine BUILD_X11 1
 
 #cmakedefine OWN_WINDOW 1

src/c++wrap.cc

@@ -27,6 +27,38 @@
 
 #include <string.h>
 
+#if !defined(HAVE_PIPE2) || !defined(HAVE_O_CLOEXEC)
+#include <fcntl.h>
+
+namespace {
+	int pipe2_emulate(int pipefd[2], int flags)
+	{
+		if(pipe(pipefd) == -1)
+			return -1;
+
+		if(flags & O_CLOEXEC) {
+			// we emulate O_CLOEXEC if the system does not have it
+			// not very thread-safe, but at least it works
+
+			for(int i = 0; i < 2; ++i) {
+				int r = fcntl(pipefd[i], F_GETFD);
+				if(r == -1)
+					return -1;
+
+				if(fcntl(pipefd[i], F_SETFD, r | FD_CLOEXEC) == -1)
+					return -1;
+			}
+		}
+
+		return 0;
+	}
+
+	int (* const pipe2_ptr)(int[2], int) = &pipe2_emulate;
+}
+#else
+	int (* const pipe2_ptr)(int[2], int) = &pipe2;
+#endif
+
 std::string strerror_r(int errnum)
 {
 	char buf[100];
@@ -36,7 +68,7 @@ std::string strerror_r(int errnum)
 std::pair<int, int> pipe2(int flags)
 {
 	int fd[2];
-	if(pipe2(fd, flags) == -1)
+	if(pipe2_ptr(fd, flags) == -1)
 		throw errno_error("pipe2");
 	else
 		return std::pair<int, int>(fd[0], fd[1]);

src/c++wrap.hh

@@ -24,7 +24,11 @@
 #ifndef CPPWRAP_HH
 #define CPPWRAP_HH
 
+#ifdef HAVE_O_CLOEXEC
 #include <fcntl.h>
+#else
+enum { O_CLOEXEC = 02000000 };
+#endif
 
 #include <cerrno>
 #include <stdexcept>