autoconf: check for timer_settime()

This function will be used in a following commit.

The timer_settime() function is provided in librt on some systems.
We already use this library sometimes to get clock_gettime(), so
rework the logic so we don't link with it twice.

This function was not previously used by git. This can cause trouble
for people on systems without timer_settime if they only rely on
config.mak.uname. They will need to set NO_TIMER_SETTIME manually.

Add proper replacement function macros for setitimer() and
timer_settime() that implement timer_settime() as a wrapper for
setitimer().  In this way, if the system has setitimer() but not
timer_settime() then we will be able to call timer_create(),
timer_settime(), and timer_delete() correctly, and it will wrap to
setitimer() under the hood.

This will be used in the following commit.

Signed-off-by: Jonas 'Sortie' Termansen <sortie@maxsi.org>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

4 files changed, 51 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index dd73cc4320..c0a2584e1a 100644
--- a/Makefile
+++ b/Makefile
@@ -182,16 +182,22 @@ all::
 #
 # Define NO_SETITIMER if you don't have setitimer()
 #
+# Define NO_TIMER_SETTIME if you don't have timer_settime()
+#
 # Define NO_TIMER_T if you don't have timer_t.
+# This also implies NO_TIMER_SETTIME
 #
 # Define NO_STRUCT_TIMESPEC if you don't have struct timespec
+# This also implies NO_TIMER_SETTIME
 #
 # Define NO_STRUCT_SIGEVENT if you don't have struct sigevent
+# This also implies NO_TIMER_SETTIME
 #
 # Define NO_STRUCT_ITIMERVAL if you don't have struct itimerval
 # This also implies NO_SETITIMER
 #
 # Define NO_STRUCT_ITIMERSPEC if you don't have struct itimerspec
+# This also implies NO_TIMER_SETTIME
 #
 # Define NO_FAST_WORKING_DIRECTORY if accessing objects in pack files is
 # generally faster on your platform than accessing the working directory.
@@ -1348,12 +1354,15 @@ ifdef OBJECT_CREATION_USES_RENAMES
 endif
 ifdef NO_TIMER_T
 	COMPAT_CFLAGS += -DNO_TIMER_T
+	NO_TIMER_SETTIME = YesPlease
 endif
 ifdef NO_STRUCT_TIMESPEC
 	COMPAT_CFLAGS += -DNO_STRUCT_TIMESPEC
+	NO_TIMER_SETTIME = YesPlease
 endif
 ifdef NO_STRUCT_SIGEVENT
 	COMPAT_CFLAGS += -DNO_STRUCT_SIGEVENT
+	NO_TIMER_SETTIME = YesPlease
 endif
 ifdef NO_STRUCT_ITIMERVAL
 	COMPAT_CFLAGS += -DNO_STRUCT_ITIMERVAL
@@ -1361,10 +1370,14 @@ ifdef NO_STRUCT_ITIMERVAL
 endif
 ifdef NO_STRUCT_ITIMERSPEC
 	COMPAT_CFLAGS += -DNO_STRUCT_ITIMERSPEC
+	NO_TIMER_SETTIME = YesPlease
 endif
 ifdef NO_SETITIMER
 	COMPAT_CFLAGS += -DNO_SETITIMER
 endif
+ifdef NO_TIMER_SETTIME
+	COMPAT_CFLAGS += -DNO_TIMER_SETTIME
+endif
 ifdef NO_PREAD
 	COMPAT_CFLAGS += -DNO_PREAD
 	COMPAT_OBJS += compat/pread.o
@@ -1524,6 +1537,14 @@ endif
 
 ifdef HAVE_CLOCK_GETTIME
 	BASIC_CFLAGS += -DHAVE_CLOCK_GETTIME
+	LINK_WITH_LIBRT = YesPlease
+endif
+
+ifndef NO_TIMER_SETTIME
+	LINK_WITH_LIBRT = YesPlease
+endif
+
+ifdef LINK_WITH_LIBRT
 	EXTLIBS += -lrt
 endif
 
diff --git a/config.mak.uname b/config.mak.uname
index 3d61b64f2a..f072f07e7f 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -100,6 +100,7 @@ ifeq ($(uname_S),Darwin)
 	HAVE_DEV_TTY = YesPlease
 	NO_TIMER_T = UnfortunatelyYes
 	NO_STRUCT_ITIMERSPEC = UnfortunatelyYes
+	NO_TIMER_SETTIME = UnfortunatelyYes
 	COMPAT_OBJS += compat/precompose_utf8.o
 	BASIC_CFLAGS += -DPRECOMPOSE_UNICODE
 endif
@@ -361,6 +362,7 @@ ifeq ($(uname_S),Windows)
 	NO_STRUCT_TIMESPEC = UnfortunatelyYes
 	NO_STRUCT_SIGEVENT = UnfortunatelyYes
 	NO_STRUCT_ITIMERSPEC = UnfortunatelyYes
+	NO_TIMER_SETTIME = UnfortunatelyYes
 
 	CC = compat/vcbuild/scripts/clink.pl
 	AR = compat/vcbuild/scripts/lib.pl
@@ -514,6 +516,7 @@ ifneq (,$(findstring MINGW,$(uname_S)))
 	NO_STRUCT_TIMESPEC = UnfortunatelyYes
 	NO_STRUCT_SIGEVENT = UnfortunatelyYes
 	NO_STRUCT_ITIMERSPEC = UnfortunatelyYes
+	NO_TIMER_SETTIME = UnfortunatelyYes
 	COMPAT_CFLAGS += -D__USE_MINGW_ACCESS -D_USE_32BIT_TIME_T -DNOGDI -Icompat -Icompat/win32
 	COMPAT_CFLAGS += -DSTRIP_EXTENSION=\".exe\"
 	COMPAT_OBJS += compat/mingw.o compat/winansi.o \
diff --git a/configure.ac b/configure.ac
index 954f9ddb03..9d6ec41acc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -946,6 +946,14 @@ GIT_CHECK_FUNC(setitimer,
 [NO_SETITIMER=YesPlease])
 GIT_CONF_SUBST([NO_SETITIMER])
 #
+# Define NO_TIMER_SETTIME if you don't have timer_settime
+GIT_CHECK_FUNC(timer_settime,
+[NO_TIMER_SETTIME=],
+[AC_SEARCH_LIBS(timer_settime,[rt],
+  [NO_TIMER_SETTIME=],
+  [NO_TIMER_SETTIME=YesPlease])])
+GIT_CONF_SUBST([NO_TIMER_SETTIME])
+#
 # Define NO_STRCASESTR if you don't have strcasestr.
 GIT_CHECK_FUNC(strcasestr,
 [NO_STRCASESTR=],
diff --git a/git-compat-util.h b/git-compat-util.h
index 4ef17df86b..b236021963 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -225,7 +225,25 @@ struct itimerspec {
 #endif
 
 #ifdef NO_SETITIMER
-#define setitimer(which,value,ovalue)
+#define setitimer(which,value,ovalue) ((void) (which), (void) (value), (void) (ovalue), errno = ENOSYS, -1)
+#endif
+
+#ifdef NO_TIMER_SETTIME
+#define timer_create(clockid, sevp, timerp) ((void) (clockid), (void) (sevp), (void) (timerp), errno = ENOSYS, -1)
+
+#define timer_delete(timer) do {		\
+	struct itimerval v = {{0,},};		\
+	setitimer(ITIMER_REAL, &v, NULL);	\
+} while (0)
+
+#define timer_settime(timer, flags, value, ovalue) do {				\
+	struct itimerval _ivalue;						\
+	_ivalue.it_interval.tv_sec = value.it_interval.tv_sec;			\
+	_ivalue.it_interval.tv_usec = value.it_interval.tv_nsec / 1000L;	\
+	_ivalue.it_value.tv_sec  value.it_value.tv_sec;				\
+	_ivalue_it_value.tv_usec = value.it_value.tv_nsec / 1000L;		\
+	setitimer(ITIMER_REAL, &_ivalue, NULL);					\
+while (0)
 #endif
 
 #ifndef NO_LIBGEN_H