X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/2f43ad4af98a7f1a6fa70b15ffa0bd29ce777418..dc4dc04e65b8011b9242c47099ab1f87f5143b3e:/src/OS/os.h-Linux

diff --git a/src/OS/os.h-Linux b/src/OS/os.h-Linux
index 8d87df0b8..3fead17d7 100644
--- a/src/OS/os.h-Linux
+++ b/src/OS/os.h-Linux
@@ -1,7 +1,12 @@
-/* $Cambridge: exim/src/OS/os.h-Linux,v 1.5 2006/12/20 19:54:23 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
@@ -10,10 +15,10 @@
 #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 */
 
@@ -52,4 +57,16 @@ extern struct ip_address_item *os_find_running_interfaces_linux(void);
 
 #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
+
+
 /* End */