asa: Rewrite to fix line termination issue.

The standard is somewhat unclear, but on the balance, I believe that the
phrase “the rest of the input line” should be interpreted to mean the
rest of the input line including the terminating newline if and only if
there is one.  This means the current implementation is incorrect on two
points:

- First, it suppresses the previous line's newline in the '1' case.

- Second, it unconditionally emits a newline at the end of the output
  for non-empty input, even if the input did not end with a newline.

Resolve this by rewriting the main loop.  Instead of special-casing the
first line and then assuming that every line ends with a newline, we
remember how each line ends and emit that either at the beginning of
the next line or at the end of the file except in the one case ('+')
where the standard explicitly says not to.

While here, try to reduce diff to upstream a little and update their
RCS tag to reflect the fact that while we've diverged significantly
from them, we've incorporated all their changes.  Remove the useless
second RCS tag.

We also update the tests to account for the change in interpretation
of the '1' case and add a test case for unterminated input.

MFC after:	1 week
Sponsored by:	Klara, Inc.
Reviewed by:	kevans
Differential Revision:	https://reviews.freebsd.org/D43326

usr.bin/asa/asa.c

@@ -1,4 +1,4 @@
-/*	$NetBSD: asa.c,v 1.11 1997/09/20 14:55:00 lukem Exp $	*/
+/*	$NetBSD: asa.c,v 1.17 2016/09/05 00:40:28 sevan Exp $	*/
 
 /*-
  * SPDX-License-Identifier: BSD-4-Clause
@@ -32,13 +32,8 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sys/cdefs.h>
-#if 0
-#ifndef lint
-__RCSID("$NetBSD: asa.c,v 1.11 1997/09/20 14:55:00 lukem Exp $");
-#endif
-#endif
 #include <err.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -50,38 +45,33 @@ static void usage(void) __dead2;
 int
 main(int argc, char *argv[])
 {
-	int ch, exval;
 	FILE *fp;
-	const char *fn;
+	int ch, exval;
 
 	while ((ch = getopt(argc, argv, "")) != -1) {
 		switch (ch) {
-		case '?':
 		default:
 			usage();
-			/*NOTREACHED*/
 		}
 	}
 	argc -= optind;
 	argv += optind;
 
 	exval = 0;
-	if (argc == 0)
+	if (*argv == NULL) {
 		asa(stdin);
-	else {
-		while ((fn = *argv++) != NULL) {
-			if (strcmp(fn, "-") == 0) {
+	} else {
+		do {
+			if (strcmp(*argv, "-") == 0) {
 				asa(stdin);
+			} else if ((fp = fopen(*argv, "r")) == NULL) {
+				warn("%s", *argv);
+				exval = 1;
 			} else {
-				if ((fp = fopen(fn, "r")) == NULL) {
-					warn("%s", fn);
-					exval = 1;
-					continue;
-				}
 				asa(fp);
 				fclose(fp);
 			}
-		}
+		} while (*++argv != NULL);
 	}
 
 	if (fflush(stdout) != 0)
@@ -93,7 +83,6 @@ main(int argc, char *argv[])
 static void
 usage(void)
 {
-
 	fprintf(stderr, "usage: asa [file ...]\n");
 	exit(1);
 }
@@ -101,52 +90,53 @@ usage(void)
 static void
 asa(FILE *f)
 {
-	size_t len;
 	char *buf;
+	size_t len;
+	bool eol = false;
 
-	if ((buf = fgetln(f, &len)) != NULL) {
-		if (buf[len - 1] == '\n')
-			buf[--len] = '\0';
-		/* special case the first line */
+	while ((buf = fgetln(f, &len)) != NULL) {
+		/* in all cases but '+', terminate previous line, if any */
+		if (buf[0] != '+' && eol)
+			putchar('\n');
+		/* examine and translate the control character */
 		switch (buf[0]) {
+		default:
+			/*
+			 * “It is suggested that implementations treat
+			 * characters other than 0, 1, and '+' as <space>
+			 * in the absence of any compelling reason to do
+			 * otherwise” (POSIX.1-2017)
+			 */
+		case ' ':
+			/* nothing */
+			break;
 		case '0':
 			putchar('\n');
 			break;
 		case '1':
 			putchar('\f');
 			break;
-		}
-
-		if (len > 1 && buf[0] && buf[1])
-			printf("%.*s", (int)(len - 1), buf + 1);
-
-		while ((buf = fgetln(f, &len)) != NULL) {
-			if (buf[len - 1] == '\n')
-				buf[--len] = '\0';
-			switch (buf[0]) {
-			default:
-			case ' ':
-				putchar('\n');
-				break;
-			case '0':
-				putchar('\n');
-				putchar('\n');
-				break;
-			case '1':
-				putchar('\f');
-				break;
-			case '+':
+		case '+':
+			/*
+			 * “If the '+' is the first character in the
+			 * input, it shall be equivalent to <space>.”
+			 * (POSIX.1-2017)
+			 */
+			if (eol)
 				putchar('\r');
-				break;
-			}
-
-			if (len > 1 && buf[0] && buf[1])
-				printf("%.*s", (int)(len - 1), buf + 1);
+			break;
 		}
-
-		putchar('\n');
+		/* trim newline if there is one */
+		if ((eol = (buf[len - 1] == '\n')))
+			--len;
+		/* print the rest of the input line */
+		if (len > 1 && buf[0] && buf[1])
+			fwrite(buf + 1, 1, len - 1, stdout);
 	}
-
+	/* terminate the last line, if any */
+	if (eol)
+		putchar('\n');
+	/* check for output errors */
 	if (ferror(stdout) != 0)
 		err(1, "stdout");
 }

usr.bin/asa/tests/asa_test.sh

@@ -38,8 +38,8 @@ one_head() {
 	atf_set descr "First character on line is '1'"
 }
 one_body() {
-	printf " %s\n1%s\n" "$a" "$b" >infile
-	printf "%s\f%s\n" "$a" "$b" >outfile
+	printf "1%s\n1%s\n" "$a" "$b" >infile
+	printf "\f%s\n\f%s\n" "$a" "$b" >outfile
 	atf_check_asa infile outfile
 }
 
@@ -87,6 +87,16 @@ dashdash_body() {
 	atf_check -o inline:"$a $b\n" asa -- -infile
 }
 
+atf_test_case unterminated
+unterminated_head() {
+	atf_set descr "Unterminated input"
+}
+unterminated_body() {
+	printf " %s\n %s" "$a" "$b" >infile
+	printf "%s\n%s" "$a" "$b" >outfile
+	atf_check_asa infile outfile
+}
+
 atf_init_test_cases()
 {
 	atf_add_test_case space
@@ -96,4 +106,5 @@ atf_init_test_cases()
 	atf_add_test_case plus_top
 	atf_add_test_case stdout
 	atf_add_test_case dashdash
+	atf_add_test_case unterminated
 }