[svn-r20894] Purpose:

    Updates configure definitions on linux.

Description:
    We only define _POSIX_SOURCE which only allows for the lowest level of
POSIX support (IEEE 1003.1), which is unsuitable for clock_gettime() functionality on modern linux systems. This symbol was changed to _POSIX_C_SOURCE=199506L, which gives the 1996 version of POSIX support and allows clock_gettime() and CLOCK_MONOTONIC to be found.

    We do not link to the BSD compatibility library, even though we define
_BSD_SOURCE.  -lbsd-compat was added to AM_LDFLAGS in accordance with GNU
recommendations.  This does not appear to change anything in the current
library.

Tested on:
    jam(linux32-LE) This was tested with various configure settings including
parallel, threadsafe, C++ and FORTRAN enabled.

1 files changed, 11 insertions, 7 deletions

diff --git a/configure.in b/configure.in
index c761e5a..fb488c7 100644
--- a/configure.in
+++ b/configure.in
@@ -1378,19 +1378,23 @@ case "$host_cpu-$host_vendor-$host_os" in
     dnl H5_CPPFLAGS because fdopen and HDfdopen fail without it. HDfdopen
     dnl is used only by H5_debug_mask which is used only when debugging in
     dnl H5_init_library (all in H5.c).  When the flag was removed this was
-    dnl the only compile failure noted;  however, defining the Macro 
-    dnl makes available the functionality from the POSIX.1 standard as well
-    dnl as all or the ISO C facilities, according to a discussion of 
-    dnl defining the _POSIX_SOURCE, _BSD_SOURCE, and _POSIX_C_SOURCE Macros
-    dnl and their interaction found at 
-    dnl http://www.gnu.org/s/libc/manual/html_node/Feature-Test-Macros.html.
-    H5_CPPFLAGS="-D_POSIX_SOURCE $H5_CPPFLAGS"
+    dnl the only compile failure noted.
+    dnl This was originally defined as _POSIX_SOURCE which was updated to
+    dnl _POSIX_C_SOURCE=199506L to expose a greater amount of POSIX
+    dnl functionality so clock_gettime and CLOCK_MONOTONIC are defined
+    dnl correctly.
+    dnl POSIX feature information can be found in the gcc manual at:
+    dnl http://www.gnu.org/s/libc/manual/html_node/Feature-Test-Macros.html
+    H5_CPPFLAGS="-D_POSIX_C_SOURCE=199506L $H5_CPPFLAGS"
 
     dnl Also add BSD support on Linux systems, so <features.h> defines
     dnl __USE_BSD, which is required to get the prototype for strdup
     dnl defined correctly in <string.h> and snprintf & vsnprintf defined
     dnl correctly in <stdio.h>
+    dnl Linking to the bsd-compat library is required as per the gcc manual:
+    dnl http://www.gnu.org/s/libc/manual/html_node/Feature-Test-Macros.html
     AM_CPPFLAGS="-D_BSD_SOURCE $AM_CPPFLAGS"
+    AM_LDFLAGS="-lbsd-compat $AM_LDFLAGS"
     ;;
 esac