/* 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>
+#include <sys/types.h>
+
+
#define CRYPT_H
#define GLIBC_IP_OPTIONS
#define HAVE_MMAP
#define NO_IP_VAR_H
#define SIG_IGN_WORKS
-/* When using the DKIM, setting HAVE_LINUX_SENDFILE can increase
+/* When using DKIM, setting OS_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. */
+defined as part of the Linux CFLAGS. As of 2017 those are declared
+to be too old to build by default. */
-/* #define HAVE_LINUX_SENDFILE */
+#define OS_SENDFILE
+extern ssize_t os_sendfile(int, int, off_t *, size_t);
#define F_FREESP O_TRUNC
typedef struct flock flock_t;
#define OS_STRSIGNAL
#if defined(__linux__) || defined(__FreeBSD_kernel__) || defined(__NetBSD_kernel__)
-#define SIOCGIFCONF_GIVES_ADDR
-#define HAVE_SYS_MOUNT_H
+# define SIOCGIFCONF_GIVES_ADDR
+# define HAVE_SYS_MOUNT_H
#endif
#if defined(__linux__)
#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
+
+/* TCP Fast Open support */
+
+#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
+#define EXIM_HAVE_TCPI_UNACKED
+
+
/* End */