-/* $Cambridge: exim/src/OS/os.h-Linux,v 1.7 2007/10/04 13:28:06 tom Exp $ */
-
/* Exim: OS-specific C header file for Linux */
+/* Some old systems we've received bug-reports for have a <limits.h> which
+does not pull in <features.h>. Best to just pull it in now and have done
+with the issue. */
+
+#include <features.h>
+
+
#define CRYPT_H
#define GLIBC_IP_OPTIONS
#define HAVE_MMAP
#define NO_IP_VAR_H
#define SIG_IGN_WORKS
-/* When using the experimental Domainkeys/DKIM extensions, setting
-HAVE_LINUX_SENDFILE can increase performance on outgoing mail a bit.
-Note: With older glibc versions this setting will conflict with the
-_FILE_OFFSET_BITS=64 setting defined as part of the Linux CFLAGS. */
+/* When using the DKIM, setting HAVE_LINUX_SENDFILE can increase
+performance on outgoing mail a bit. Note: With older glibc versions
+this setting will conflict with the _FILE_OFFSET_BITS=64 setting
+defined as part of the Linux CFLAGS. */
/* #define HAVE_LINUX_SENDFILE */
#define NEED_SYNC_DIRECTORY
-/* Other OS have "const" in here */
-#define ICONV_ARG2_TYPE char **
-
#define os_find_running_interfaces os_find_running_interfaces_linux
/* Need a prototype for the Linux-specific function. The structure hasn't
#endif /* __linux__ */
+/* Some folks running "unusual" setups with very old libc environments have
+found that _GNU_SOURCE=1 before <features.h> is not sufficient to define some
+constants needed for 64-bit arithmetic. If you encounter build errors based
+on LLONG_MIN being undefined and various other escape hatches have not helped,
+then change the 0 to 1 in the next block. */
+
+#if 0
+# define LLONG_MIN LONG_LONG_MIN
+# define LLONG_MAX LONG_LONG_MAX
+#endif
+
+#if _POSIX_C_SOURCE >= 200809L || _ATFILE_SOUCE
+# define EXIM_HAVE_OPENAT
+#endif
+
+#include <netinet/tcp.h> /* for TCP_FASTOPEN */
+#include <sys/socket.h> /* for MSG_FASTOPEN */
+#if defined(TCP_FASTOPEN) && !defined(MSG_FASTOPEN)
+# define MSG_FASTOPEN 0x20000000
+#endif
+
+
/* End */