Fix some issues with quoted output and shorten it in some cases.

Output quoted suitable for re-input to the shell occurs in
various cases such as 'set', 'trap'.

Bugfix: *, ? and [ must be quoted (except sole [)
Bugfix: ~ and # must be quoted (really only sometimes, but keep it simple)
Bugfix: space, tab and newline must always be quoted
Shortening: other IFS characters do not need quoting
Bugfix: send to correct output file, not hard-coded stdout
Shortening: avoid unnecessary '' with \'

Approved by:	ed (mentor)

1 files changed, 15 insertions, 9 deletions

diff --git a/bin/sh/output.c b/bin/sh/output.c
index b59e11e0e870..0d55fdfcb28e 100644
--- a/bin/sh/output.c
+++ b/bin/sh/output.c
@@ -133,32 +133,38 @@ void
 outqstr(const char *p, struct output *file)
 {
 	char ch;
+	int inquotes;
 
 	if (p[0] == '\0') {
 		outstr("''", file);
 		return;
 	}
-	if (p[strcspn(p, "|&;<>()$`\\\"'")] == '\0' && (!ifsset() ||
-	    p[strcspn(p, ifsval())] == '\0')) {
+	/* Caller will handle '=' if necessary */
+	if (p[strcspn(p, "|&;<>()$`\\\"' \t\n*?[~#")] == '\0' ||
+			strcmp(p, "[") == 0) {
 		outstr(p, file);
 		return;
 	}
 
-	out1c('\'');
+	inquotes = 0;
 	while ((ch = *p++) != '\0') {
 		switch (ch) {
 		case '\'':
-			/*
-			 * Can't quote single quotes inside single quotes;
-			 * close them, write escaped single quote, open again.
-			 */
-			outstr("'\\''", file);
+			/* Can't quote single quotes inside single quotes. */
+			if (inquotes)
+				outc('\'', file);
+			inquotes = 0;
+			outstr("\\'", file);
 			break;
 		default:
+			if (!inquotes)
+				outc('\'', file);
+			inquotes = 1;
 			outc(ch, file);
 		}
 	}
-	out1c('\'');
+	if (inquotes)
+		outc('\'', file);
 }
 
 STATIC char out_junk[16];