Fix strftime test race condition.

1 files changed, 26 insertions, 8 deletions

diff --git a/test/strftime.awk b/test/strftime.awk
index 775cd4e5..a52957f0 100644
--- a/test/strftime.awk
+++ b/test/strftime.awk
@@ -2,18 +2,36 @@
 #
 # input is the output of `date', see Makefile.in
 #
-# The mucking about with $0 and $N is to avoid problems
+# The mucking about with $0 and $NF is to avoid problems
 # on cygwin, where the timezone field is empty and there
 # are two consecutive blanks.
 
-# Additional mucking about to lop off the seconds field;
-# helps decrease chance of difference due to a second boundary
+BEGIN {
+	maxtries = 10
+	datecmd = "date"
+	fmt = "%a %b %d %H:%M:%S %Z %Y"
 
-{
-	$3 = sprintf("%02d", $3 + 0)
-	$4 = substr($4, 1, 5)
-	print > "strftime.ok"
-	$0 = strftime("%a %b %d %H:%M %Z %Y")
+	# loop until before equals after, thereby protecting
+	# against a race condition where the seconds field might have
+	# incremented between running date and strftime
+	i = 0
+	while (1) {
+		if (++i > maxtries) {
+			printf "Warning: this system is so slow that after %d attempts, we could never get two sequential invocations of strftime to give the same result!\n", maxtries > "/dev/stderr"
+			break
+		}
+		before = strftime(fmt)
+		datecmd | getline sd
+		after = strftime(fmt)
+		close(datecmd)
+		if (before == after) {
+			if (i > 1)
+				printf "Notice: it took %d loops to get the before and after strftime values to match\n", i > "/dev/stderr"
+			break
+		}
+	}
+	print sd > "strftime.ok"
+	$0 = after
 	$NF = $NF
 	print > OUTPUT
 }