Propagate output finalization errors

Makefile.am

@@ -309,6 +309,7 @@ EXTRA_DIST=								\
 	tests/08-passphrase-file.sh					\
 	tests/09-explicit-params.sh					\
 	tests/10-check-params.sh					\
+	tests/11-output-finalization.sh				\
 	tests/shared_test_functions.sh					\
 	tests/shared_valgrind_functions.sh				\
 	tests/test_scrypt.sh						\

main.c

@@ -180,8 +180,19 @@ scrypt_mode_enc_dec(struct scryptenc_params params,
 	/* Close any files we opened. */
 	if ((infile != stdin) && fclose(infile))
 		warnp("fclose");
-	if ((outfile != stdout) && fclose(outfile))
-		warnp("fclose");
+	if (outfile != stdout) {
+		if (fclose(outfile)) {
+			if (rc == SCRYPT_OK)
+				rc = SCRYPT_EWRFILE;
+			else
+				warnp("fclose");
+		}
+	} else if ((outfilename == NULL) && fflush(outfile)) {
+		if (rc == SCRYPT_OK)
+			rc = SCRYPT_EWRFILE;
+		else
+			warnp("fflush");
+	}
 
 	/* If we failed, print the right error message and exit. */
 	if (rc != SCRYPT_OK) {

tests/11-output-finalization.sh

@@ -0,0 +1,51 @@
+#!/bin/sh
+
+### Constants
+input_file="${s_basename}-input.txt"
+named_stderr="${s_basename}-named.stderr"
+stdout_stderr="${s_basename}-stdout.stderr"
+
+scenario_cmd() {
+	# /dev/full is available on Linux but not on every test platform.
+	if [ ! -c /dev/full ]; then
+		setup_check "scrypt enc named output close failure"
+		echo "-1" > "${c_exitfile}"
+		setup_check "scrypt enc named output close error"
+		echo "-1" > "${c_exitfile}"
+		setup_check "scrypt enc stdout flush failure"
+		echo "-1" > "${c_exitfile}"
+		setup_check "scrypt enc stdout flush error"
+		echo "-1" > "${c_exitfile}"
+		return
+	fi
+
+	# Keep the output small enough that the write error is delayed until
+	# fclose(3) or fflush(3), rather than being returned by fwrite(3).
+	printf "x" > "${input_file}"
+
+	# A delayed failure while closing a named output file must fail the
+	# command, rather than merely printing a warning and exiting 0.
+	setup_check "scrypt enc named output close failure"
+	printf "%s\n" "${password}" | "${bindir}/scrypt"		\
+	    enc --logN 10 -r 1 -p 1				\
+	    --passphrase dev:stdin-once				\
+	    "${input_file}" /dev/full 2> "${named_stderr}"
+	expected_exitcode 1 $? > "${c_exitfile}"
+
+	setup_check "scrypt enc named output close error"
+	grep -q "Error writing file: /dev/full" "${named_stderr}"
+	echo $? > "${c_exitfile}"
+
+	# stdout also needs an explicit flush check; exit(3) cannot propagate a
+	# delayed stdio error into the process exit status.
+	setup_check "scrypt enc stdout flush failure"
+	printf "%s\n" "${password}" | "${bindir}/scrypt"		\
+	    enc --logN 10 -r 1 -p 1				\
+	    --passphrase dev:stdin-once				\
+	    "${input_file}" > /dev/full 2> "${stdout_stderr}"
+	expected_exitcode 1 $? > "${c_exitfile}"
+
+	setup_check "scrypt enc stdout flush error"
+	grep -q "Error writing file: standard output" "${stdout_stderr}"
+	echo $? > "${c_exitfile}"
+}