[PATCH] Makefile: add NEEDS_LIBRT to optionally link with librt
- From
Ronald Wampler <rdwampler@gmail.com>
- Date
- Jul 7, 2016, 20:45 UTC
- Message-ID
- <20160707204554.14961-1-rdwampler@gmail.com>
We unconditionally link with librt, when HAVE_CLOCK_GETTIME is defined. But clock_gettime() has been available in most libc implementations for some time now (e.g., for glibc since version 2.17) and no longer requires linking with librt. Furthermore, commit a6c3c63 (configure.ac: check for clock_gettime() and CLOCK_MONOTONIC) will automatically determined which library (libc or librt) is required for linking when checking for clock_gettime().
The assumption to unconditionally link with librt was OK, since either almost every Unix-like system provides a version of librt for backwards compatibility or other systems, namely Windows or OS X, never provided clock_gettime(). However, in the latest release of OS X (macOS Sierra), this function has been added to OS X libc version. As a result, when running the configuration script, HAVE_CLOCK_GETTIME is set and since librt is not present, it causes a linker error.
This patches requires those not building via the configuration scripts to define NEEDS_LIBRT in addition to HAVE_CLOCK_GETTIME, if needed.
Signed-off-by: Ronald Wampler <rdwampler@gmail.com> --- I am not sure if this the correction solution. Another option I considered was to wrap the EXTLIBS += -lrt is an ifndef NO_RT and only defining NO_RT for Mac OS X in config.mak.uname.
Makefile | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/Makefile b/Makefile index de5a030..32f503e 100644 --- a/Makefile +++ b/Makefile @@ -351,9 +351,12 @@ all:: # Define GMTIME_UNRELIABLE_ERRORS if your gmtime() function does not # return NULL when it receives a bogus time_t. # -# Define HAVE_CLOCK_GETTIME if your platform has clock_gettime in librt. +# Define HAVE_CLOCK_GETTIME if your platform has clock_gettime. # -# Define HAVE_CLOCK_MONOTONIC if your platform has CLOCK_MONOTONIC in librt. +# Define HAVE_CLOCK_MONOTONIC if your platform has CLOCK_MONOTONIC. +# +# Define NEEDS_LIBRT if your platform requires linking with librt (glibc version +# before 2.17) for clock_gettime and CLOCK_MONOTONIC. # # Define USE_PARENS_AROUND_GETTEXT_N to "yes" if your compiler happily # compiles the following initialization: @@ -1465,13 +1468,16 @@ endif ifdef HAVE_CLOCK_GETTIME BASIC_CFLAGS += -DHAVE_CLOCK_GETTIME - EXTLIBS += -lrt endif ifdef HAVE_CLOCK_MONOTONIC BASIC_CFLAGS += -DHAVE_CLOCK_MONOTONIC endif +ifdef NEEDS_LIBRT + EXTLIBS += -lrt +endif + ifdef HAVE_BSD_SYSCTL BASIC_CFLAGS += -DHAVE_BSD_SYSCTL endif -- 2.8.2.874.gcf4c2cf