musl compat (#314)

* include: use __swab i/o __bswap_constant

Some C standard libs like musl don't support __bswap_constant_{16,32}.

Importing the "simple" macros could be enough, but they are under LGPL.
Using __swab from linux/swab.h seems easier.

Suggested-by: Ossama Othman <[email protected]>
Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>

* mptcpize: define error() if not available

Some libc like musl don't support it.

It is easy enough to define a simple version for our need.

Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>

* config: special case for default logger

The current version taking an unlimited number of args, and with
multiple levels of helpers doesn't seem to be supported on some embedded
environments, e.g. Alpine Linux:

  configuration.c: In function 'mptcpd_config_create':
  configuration.c:54:47: error: pasting "l_log_set_" and "(" does not give a valid preprocessing token
     54 | #define MPTCPD_SET_LOG_FUNCTION MPTCPD_CONCAT(l_log_set_, MPTCPD_LOGGER)
        |                                               ^~~~~~~~~~
  configuration.c:42:36: note: in definition of macro 'MPTCPD_CONCAT_IMPL'
     42 | #define MPTCPD_CONCAT_IMPL(x, ...) x ## __VA_ARGS__
        |                                    ^
  configuration.c:54:33: note: in expansion of macro 'MPTCPD_CONCAT'
     54 | #define MPTCPD_SET_LOG_FUNCTION MPTCPD_CONCAT(l_log_set_, MPTCPD_LOGGER)
        |                                 ^~~~~~~~~~~~~
  configuration.c:802:9: note: in expansion of macro 'MPTCPD_SET_LOG_FUNCTION'
    802 |         MPTCPD_SET_LOG_FUNCTION();  // For early logging.
        |         ^~~~~~~~~~~~~~~~~~~~~~~
  configuration.c:54:47: error: implicit declaration of function 'l_log_set_'; did you mean 'l_log_set_null'? [-Werror=implicit-function-declaration]
     54 | #define MPTCPD_SET_LOG_FUNCTION MPTCPD_CONCAT(l_log_set_, MPTCPD_LOGGER)
        |                                               ^~~~~~~~~~
  configuration.c:42:36: note: in definition of macro 'MPTCPD_CONCAT_IMPL'
     42 | #define MPTCPD_CONCAT_IMPL(x, ...) x ## __VA_ARGS__
        |                                    ^
  configuration.c:54:33: note: in expansion of macro 'MPTCPD_CONCAT'
     54 | #define MPTCPD_SET_LOG_FUNCTION MPTCPD_CONCAT(l_log_set_, MPTCPD_LOGGER)
        |                                 ^~~~~~~~~~~~~
  configuration.c:802:9: note: in expansion of macro 'MPTCPD_SET_LOG_FUNCTION'
    802 |         MPTCPD_SET_LOG_FUNCTION();  // For early logging.
        |         ^~~~~~~~~~~~~~~~~~~~~~~
  configuration.c:54:47: error: called object is not a function or function pointer
     54 | #define MPTCPD_SET_LOG_FUNCTION MPTCPD_CONCAT(l_log_set_, MPTCPD_LOGGER)
        |                                               ^~~~~~~~~~
  configuration.c:42:36: note: in definition of macro 'MPTCPD_CONCAT_IMPL'
     42 | #define MPTCPD_CONCAT_IMPL(x, ...) x ## __VA_ARGS__
        |                                    ^
  configuration.c:54:33: note: in expansion of macro 'MPTCPD_CONCAT'
     54 | #define MPTCPD_SET_LOG_FUNCTION MPTCPD_CONCAT(l_log_set_, MPTCPD_LOGGER)
        |                                 ^~~~~~~~~~~~~
  configuration.c:802:9: note: in expansion of macro 'MPTCPD_SET_LOG_FUNCTION'
    802 |         MPTCPD_SET_LOG_FUNCTION();  // For early logging.
        |         ^~~~~~~~~~~~~~~~~~~~~~~

It is not clear to me why it is failing, and simplifying the
concatenation to two items, plus modifying the main helper to take the
prefix in argument don't seem to help . A simple workaround is to have a
special case for the default value, and do the concatenation only with
the other cases.

Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>

* scripts: use short stat options

Busybox's stat doesn't understand the long options:

  stat: unrecognized option: dereference

But it does support '-L'.

Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>

---------

Signed-off-by: Matthieu Baerts (NGI0) <[email protected]>

Author: matttbe

configure.ac

@@ -108,6 +108,13 @@ AC_DEFINE_UNQUOTED([MPTCPD_LOGGER],
                    [Log message destination.])
 AC_SUBST([mptcpd_logger],[$enable_logging])
 
+AH_TEMPLATE([MPTCPD_LOGGER_STDERR],
+            [Define to 1 if the stderr logger is used.])
+AS_IF([test "x$enable_logging" = "xstderr"],
+      [AC_DEFINE([MPTCPD_LOGGER_STDERR])
+       AC_MSG_NOTICE([default logger: stderr])],
+      [AC_MSG_NOTICE([custom logger: $enable_logging])])
+
 # Allow the user to choose support for either the upstream or
 # multipath-tcp.org kernel.
 AC_ARG_WITH([kernel],
@@ -273,6 +280,11 @@ AC_CHECK_FUNC([l_netlink_message_new_sized],
                          [ELL has l_netlink_message_new_sized()])])
 LIBS=$mptcpd_save_libs
 
+# ---------------------------------------------------------------
+# Checks for header files.
+# ---------------------------------------------------------------
+AC_CHECK_HEADERS([error.h])
+
 # ---------------------------------------------------------------
 # Enable additional C compiler warnings.  We do this after all
 # Autoconf tests have been run since not all autoconf macros are

include/mptcpd/private/sockaddr.h

@@ -15,6 +15,7 @@
 #include <byteswap.h>
 
 #include <netinet/in.h>   // For in_addr_t.
+#include <linux/swab.h>   // For __constant_swab*.
 
 #include <mptcpd/export.h>
 
@@ -26,8 +27,8 @@
  */
 ///@{
 #if __BYTE_ORDER == __LITTLE_ENDIAN
-# define MPTCPD_CONSTANT_HTONS(hs) __bswap_constant_16(hs)
-# define MPTCPD_CONSTANT_HTONL(hl) __bswap_constant_32(hl)
+# define MPTCPD_CONSTANT_HTONS(hs) __swab16(hs)
+# define MPTCPD_CONSTANT_HTONL(hl) __swab32(hl)
 #else
 // No need to swap bytes on big endian platforms.
 // host byte order == network byte order

scripts/check-permissions

@@ -19,7 +19,7 @@ exit_status=0
 
 for p in $@; do
     # Access rights in human readable form (e.g. "drwxrwxr-x")
-    perms=`stat --dereference --format=%A $p`
+    perms=`stat -L -c %A $p`
 
     # The write mode for "others".
     other_write=`echo $perms | sed -e 's/.*\(.\).$/\1/'`

src/configuration.c

@@ -50,8 +50,13 @@
 // This should never occur!
 # error Problem configuring default log message destination.
 #endif
-/// Name of the default logging function determined at compile-time.
-#define MPTCPD_SET_LOG_FUNCTION MPTCPD_CONCAT(l_log_set_, MPTCPD_LOGGER)
+// Optimisation for C standard library not supporting the concat macros.
+#ifdef MPTCPD_LOGGER_STDERR
+# define MPTCPD_SET_LOG_FUNCTION l_log_set_stderr
+#else
+/// Name of the logging function determined at compile-time.
+# define MPTCPD_SET_LOG_FUNCTION MPTCPD_CONCAT(l_log_set_, MPTCPD_LOGGER)
+#endif
 
 /**
  * @brief Get the function that sets the log message destination.

src/mptcpize.c

@@ -18,7 +18,6 @@
 #include <argp.h>
 #include <dlfcn.h>
 #include <errno.h>
-#include <error.h>
 #include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -29,6 +28,10 @@
 # include <mptcpd/private/config.h>
 #endif
 
+#ifdef HAVE_ERROR_H
+# include <error.h>
+#endif
+
 #define SYSTEMD_ENV_VAR		"Environment="
 #define SYSTEMD_UNIT_VAR	"FragmentPath="
 #define SYSTEMD_SERVICE_TAG	"[Service]"
@@ -55,6 +58,20 @@ static char doc[] =
         "\tdisable <unit>            Update the systemd <unit>, removing\n"
         "\t                          the above launcher.\n";
 
+#ifndef HAVE_ERROR_H
+# define ERROR_HELPER(status, errnum, format, ...) do {		\
+	if (errnum) {						\
+		errno = errnum;					\
+		perror(format);					\
+	} else {						\
+		fprintf(stderr, format "%s", __VA_ARGS__);	\
+	}							\
+	if (status)						\
+		exit(status);					\
+   } while(0)
+# define error(...) ERROR_HELPER(__VA_ARGS__, "\n")
+#endif
+
 static struct argp const argp = { 0, 0, args_doc, doc, 0, 0, 0 };
 
 static void help(void)