Github user zasdfgbnm commented on a diff in the pull request:
https://github.com/apache/spark/pull/14231#discussion_r72276770
--- Diff: bin/spark-class ---
@@ -65,24 +65,25 @@ fi
# characters that would be otherwise interpreted by the shell. Read that
in a while loop, populating
# an array that will be used to exec the final command.
#
-# The exit code of the launcher is appended to the output, so the parent
shell removes it from the
-# command array and checks the value to see if the launcher succeeded.
-build_command() {
- "$RUNNER" -Xmx128m -cp "$LAUNCH_CLASSPATH"
org.apache.spark.launcher.Main "$@"
- printf "%d\0" $?
-}
+# To keep both the output and the exit code of the launcher, the output is
first converted to a hex
+# dump which prevents the bash from getting rid of the NULL character, and
the exit code retrieved
+# from the bash array ${PIPESTATUS[@]}.
+#
+# Note that the seperator NULL character can not be replace with space or
'\n' so that the command
+# won't fail if some path of the user contain special characher such as
'\n' or space
+#
+# Also note that when the launcher fails, it might not output something
ending with '\0' [SPARK-16586]
+_CMD=$("$RUNNER" -Xmx128m -cp "$LAUNCH_CLASSPATH"
org.apache.spark.launcher.Main "$@"|xxd -p|tr -d '\n';exit ${PIPESTATUS[0]})
--- End diff --
Since bash don't allow us to store \0 in a variable, we need to find some
way to deal with it. One way to deal with it is to run the launcher in a
subshell and pipe the output of the subshell to the current shell by using the
"read" provided by bash (see the original code line 76-78). In this way, the $?
will be the exit status of some command in the while loop of this shell, not
the exit code of launcher in the subshell. That's why in the origin
implementation, $? is appended in the end. Another way to deal with \0, which
is what I have proposed in this PR is, to make a hexdump of the output with
'\0' and store the hexdump into a variable and when we just decode it we need
to use the output with '\0'. In this way, the $? will be the exit status of
"tr" rather than of the launcher.
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