From 087b29c53e13299e195942e48ae309817f4f1d93 Mon Sep 17 00:00:00 2001
From: Tavian Barnes <tavianator@tavianator.com>
Date: Sat, 22 Oct 2016 19:59:42 -0400
Subject: Check for POSIX timers before using them.

---
 eval.c  | 28 +++++++++++++++++++++++-----
 parse.c | 27 +++++++++++++++++++++++++--
 2 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/eval.c b/eval.c
index d66c9f6..4778b5d 100644
--- a/eval.c
+++ b/eval.c
@@ -777,6 +777,27 @@ bool eval_xtype(const struct expr *expr, struct eval_state *state) {
 	return false;
 }
 
+#if _POSIX_MONOTONIC_CLOCK > 0
+#	define BFS_CLOCK CLOCK_MONOTONIC
+#elif _POSIX_TIMERS > 0
+#	define BFS_CLOCK CLOCK_REALTIME
+#endif
+
+/**
+ * Call clock_gettime(), if available.
+ */
+static int eval_gettime(struct timespec *ts) {
+#ifdef BFS_CLOCK
+	int ret = clock_gettime(BFS_CLOCK, ts);
+	if (ret != 0) {
+		perror("clock_gettime()");
+	}
+	return ret;
+#else
+	return -1;
+#endif
+}
+
 /**
  * Record the time that elapsed evaluating an expression.
  */
@@ -799,8 +820,7 @@ static bool eval_expr(struct expr *expr, struct eval_state *state) {
 	struct timespec start, end;
 	bool time = state->cmdline->debug & DEBUG_RATES;
 	if (time) {
-		if (clock_gettime(CLOCK_MONOTONIC, &start) != 0) {
-			perror("clock_gettime()");
+		if (eval_gettime(&start) != 0) {
 			time = false;
 		}
 	}
@@ -808,10 +828,8 @@ static bool eval_expr(struct expr *expr, struct eval_state *state) {
 	bool ret = expr->eval(expr, state);
 
 	if (time) {
-		if (clock_gettime(CLOCK_MONOTONIC, &end) == 0) {
+		if (eval_gettime(&end) == 0) {
 			add_elapsed(expr, &start, &end);
-		} else {
-			perror("clock_gettime()");
 		}
 	}
 
diff --git a/parse.c b/parse.c
index 5761dc3..023d414 100644
--- a/parse.c
+++ b/parse.c
@@ -22,6 +22,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/time.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <time.h>
@@ -1954,6 +1955,29 @@ void dump_cmdline(const struct cmdline *cmdline, bool verbose) {
 	fputs("\n", stderr);
 }
 
+/**
+ * Get the current time.
+ */
+static int parse_gettime(struct timespec *ts) {
+#if _POSIX_TIMERS > 0
+	int ret = clock_gettime(CLOCK_REALTIME, ts);
+	if (ret != 0) {
+		perror("clock_gettime()");
+	}
+	return ret;
+#else
+	struct timeval tv;
+	int ret = gettimeofday(&tv, NULL);
+	if (ret == 0) {
+		ts->tv_sec = tv.tv_sec;
+		ts->tv_nsec = tv.tv_usec * 1000L;
+	} else {
+		perror("gettimeofday()");
+	}
+	return ret;
+#endif
+}
+
 /**
  * Parse the command line.
  */
@@ -1987,8 +2011,7 @@ struct cmdline *parse_cmdline(int argc, char *argv[]) {
 		.just_info = false,
 	};
 
-	if (clock_gettime(CLOCK_REALTIME, &state.now) != 0) {
-		perror("clock_gettime()");
+	if (parse_gettime(&state.now) != 0) {
 		goto fail;
 	}
 
-- 
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