setting sockets non-blocking using more portable code and configure macros

from the libcurl project (written by me)

acinclude.m4

@@ -147,3 +147,144 @@ AC_DEFUN([CURL_CC_DEBUG_OPTS],
     CFLAGS=$NEWFLAGS
 
 ]) dnl end of AC_DEFUN()
+
+dnl CURL_CHECK_NONBLOCKING_SOCKET
+dnl -------------------------------------------------
+dnl Check for how to set a socket to non-blocking state. There seems to exist
+dnl four known different ways, with the one used almost everywhere being POSIX
+dnl and XPG3, while the other different ways for different systems (old BSD,
+dnl Windows and Amiga).
+dnl
+dnl There are two known platforms (AIX 3.x and SunOS 4.1.x) where the
+dnl O_NONBLOCK define is found but does not work. This condition is attempted
+dnl to get caught in this script by using an excessive number of #ifdefs...
+dnl
+AC_DEFUN([CURL_CHECK_NONBLOCKING_SOCKET],
+[
+  AC_MSG_CHECKING([non-blocking sockets style])
+
+  AC_TRY_COMPILE([
+/* headers for O_NONBLOCK test */
+#include <sys/types.h>
+#include <unistd.h>
+#include <fcntl.h>
+],[
+/* try to compile O_NONBLOCK */
+
+#if defined(sun) || defined(__sun__) || defined(__SUNPRO_C) || defined(__SUNPRO_CC)
+# if defined(__SVR4) || defined(__srv4__)
+#  define PLATFORM_SOLARIS
+# else
+#  define PLATFORM_SUNOS4
+# endif
+#endif
+#if (defined(_AIX) || defined(__xlC__)) && !defined(_AIX4)
+# define PLATFORM_AIX_V3
+#endif
+
+#if defined(PLATFORM_SUNOS4) || defined(PLATFORM_AIX_V3) || defined(__BEOS__)
+#error "O_NONBLOCK does not work on this platform"
+#endif
+  int socket;
+  int flags = fcntl(socket, F_SETFL, flags | O_NONBLOCK);
+],[
+dnl the O_NONBLOCK test was fine
+nonblock="O_NONBLOCK"
+AC_DEFINE(HAVE_O_NONBLOCK, 1, [use O_NONBLOCK for non-blocking sockets])
+],[
+dnl the code was bad, try a different program now, test 2
+
+  AC_TRY_COMPILE([
+/* headers for FIONBIO test */
+#include <unistd.h>
+#include <stropts.h>
+],[
+/* FIONBIO source test (old-style unix) */
+ int socket;
+ int flags = ioctl(socket, FIONBIO, &flags);
+],[
+dnl FIONBIO test was good
+nonblock="FIONBIO"
+AC_DEFINE(HAVE_FIONBIO, 1, [use FIONBIO for non-blocking sockets])
+],[
+dnl FIONBIO test was also bad
+dnl the code was bad, try a different program now, test 3
+
+  AC_TRY_COMPILE([
+/* headers for ioctlsocket test (Windows) */
+#undef inline
+#ifdef HAVE_WINDOWS_H
+#ifndef WIN32_LEAN_AND_MEAN
+#define WIN32_LEAN_AND_MEAN
+#endif
+#include <windows.h>
+#ifdef HAVE_WINSOCK2_H
+#include <winsock2.h>
+#else
+#ifdef HAVE_WINSOCK_H
+#include <winsock.h>
+#endif
+#endif
+#endif
+],[
+/* ioctlsocket source code */
+ SOCKET sd;
+ unsigned long flags = 0;
+ sd = socket(0, 0, 0);
+ ioctlsocket(sd, FIONBIO, &flags);
+],[
+dnl ioctlsocket test was good
+nonblock="ioctlsocket"
+AC_DEFINE(HAVE_IOCTLSOCKET, 1, [use ioctlsocket() for non-blocking sockets])
+],[
+dnl ioctlsocket didnt compile!, go to test 4
+
+  AC_TRY_LINK([
+/* headers for IoctlSocket test (Amiga?) */
+#include <sys/ioctl.h>
+],[
+/* IoctlSocket source code */
+ int socket;
+ int flags = IoctlSocket(socket, FIONBIO, (long)1);
+],[
+dnl ioctlsocket test was good
+nonblock="IoctlSocket"
+AC_DEFINE(HAVE_IOCTLSOCKET_CASE, 1, [use Ioctlsocket() for non-blocking sockets])
+],[
+dnl Ioctlsocket didnt compile, do test 5!
+  AC_TRY_COMPILE([
+/* headers for SO_NONBLOCK test (BeOS) */
+#include <socket.h>
+],[
+/* SO_NONBLOCK source code */
+ long b = 1;
+ int socket;
+ int flags = setsockopt(socket, SOL_SOCKET, SO_NONBLOCK, &b, sizeof(b));
+],[
+dnl the SO_NONBLOCK test was good
+nonblock="SO_NONBLOCK"
+AC_DEFINE(HAVE_SO_NONBLOCK, 1, [use SO_NONBLOCK for non-blocking sockets])
+],[
+dnl test 5 didnt compile!
+nonblock="nada"
+AC_DEFINE(HAVE_DISABLED_NONBLOCKING, 1, [disabled non-blocking sockets])
+])
+dnl end of fifth test
+
+])
+dnl end of forth test
+
+])
+dnl end of third test
+
+])
+dnl end of second test
+
+])
+dnl end of non-blocking try-compile test
+  AC_MSG_RESULT($nonblock)
+
+  if test "$nonblock" = "nada"; then
+    AC_MSG_WARN([non-block sockets disabled])
+  fi
+])

configure.in

@@ -227,6 +227,8 @@ AC_CHECK_FUNCS(poll gettimeofday select)
 AC_C_CONST
 AC_C_INLINE
 
+CURL_CHECK_NONBLOCKING_SOCKET
+
 AC_CONFIG_FILES([Makefile
                  src/Makefile
                  tests/Makefile

src/channel.c

@@ -43,6 +43,76 @@
 
 #include <inttypes.h>
 
+
+/*
+ * _libssh2_nonblock() sets the given socket to either blocking or
+ * non-blocking mode based on the 'nonblock' boolean argument. This function
+ * is copied from the libcurl sources with permission.
+ */
+static int _libssh2_nonblock(int sockfd,    /* operate on this */
+			     int nonblock   /* TRUE or FALSE */)
+{
+#undef SETBLOCK
+#define SETBLOCK 0
+#ifdef HAVE_O_NONBLOCK
+  /* most recent unix versions */
+  int flags;
+
+  flags = fcntl(sockfd, F_GETFL, 0);
+  if (nonblock)
+    return fcntl(sockfd, F_SETFL, flags | O_NONBLOCK);
+  else
+    return fcntl(sockfd, F_SETFL, flags & (~O_NONBLOCK));
+#undef SETBLOCK
+#define SETBLOCK 1
+#endif
+
+#if defined(HAVE_FIONBIO) && (SETBLOCK == 0)
+  /* older unix versions */
+  int flags;
+
+  flags = nonblock;
+  return ioctl(sockfd, FIONBIO, &flags);
+#undef SETBLOCK
+#define SETBLOCK 2
+#endif
+
+#if defined(HAVE_IOCTLSOCKET) && (SETBLOCK == 0)
+  /* Windows? */
+  unsigned long flags;
+  flags = nonblock;
+
+  return ioctlsocket(sockfd, FIONBIO, &flags);
+#undef SETBLOCK
+#define SETBLOCK 3
+#endif
+
+#if defined(HAVE_IOCTLSOCKET_CASE) && (SETBLOCK == 0)
+  /* presumably for Amiga */
+  return IoctlSocket(sockfd, FIONBIO, (long)nonblock);
+#undef SETBLOCK
+#define SETBLOCK 4
+#endif
+
+#if defined(HAVE_SO_NONBLOCK) && (SETBLOCK == 0)
+  /* BeOS */
+  long b = nonblock ? 1 : 0;
+  return setsockopt(sockfd, SOL_SOCKET, SO_NONBLOCK, &b, sizeof(b));
+#undef SETBLOCK
+#define SETBLOCK 5
+#endif
+
+#ifdef HAVE_DISABLED_NONBLOCKING
+  return 0; /* returns success */
+#undef SETBLOCK
+#define SETBLOCK 6
+#endif
+
+#if (SETBLOCK == 0)
+#error "no non-blocking method was found/used/set"
+#endif
+}
+
 /* {{{ libssh2_channel_nextid
  * Determine the next channel ID we can use at our end
  */
@@ -775,20 +845,8 @@ int _libssh2_channel_set_blocking(LIBSSH2_CHANNEL *channel,
 	}
 	channel->blocking = blocking;
 
-#ifdef F_SETFL
+	_libssh2_nonblock(channel->session->socket_fd, !blocking);
-	/* FIXME: this can/should be done in a more portable manner */
-	rc = fcntl(channel->session->socket_fd, F_GETFL, 0);
-	if(!blocking) {
-		rc |= O_NONBLOCK;
-	}
-	else {
-		rc &= ~O_NONBLOCK;
-	}
 
-	fcntl(channel->session->socket_fd, F_SETFL, rc);
-#else
-#error "add support for setting the socket non-blocking here"
-#endif
 	return bl;
 }
 /* }}} */