sh: Detect and flag write errors on stdout in builtins.

If there is a write error on stdout, a message will be printed (to stderr)
and the exit status will be changed to 2 if it would have been 0 or 1.

PR:		bin/158206

3 files changed, 22 insertions, 0 deletions

diff --git a/bin/sh/eval.c b/bin/sh/eval.c
index 8973f69..2e1315e 100644
--- a/bin/sh/eval.c
+++ b/bin/sh/eval.c
@@ -1070,6 +1070,7 @@ evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 		}
 		handler = &jmploc;
 		redirect(cmd->ncmd.redirect, mode);
+		outclearerror(out1);
 		/*
 		 * If there is no command word, redirection errors should
 		 * not be fatal but assignment errors should.
@@ -1085,6 +1086,11 @@ evalcommand(union node *cmd, int flags, struct backcmd *backcmd)
 		builtin_flags = flags;
 		exitstatus = (*builtinfunc[cmdentry.u.index])(argc, argv);
 		flushall();
+		if (outiserror(out1)) {
+			warning("write error on stdout");
+			if (exitstatus == 0 || exitstatus == 1)
+				exitstatus = 2;
+		}
 cmddone:
 		if (argc > 0)
 			bltinunsetlocale();
diff --git a/bin/sh/output.c b/bin/sh/output.c
index b4dab51..d26adce 100644
--- a/bin/sh/output.c
+++ b/bin/sh/output.c
@@ -239,6 +239,20 @@ freestdout(void)
 }
 
 
+int
+outiserror(struct output *file)
+{
+	return (file->flags & OUTPUT_ERR);
+}
+
+
+void
+outclearerror(struct output *file)
+{
+	file->flags &= ~OUTPUT_ERR;
+}
+
+
 void
 outfmt(struct output *file, const char *fmt, ...)
 {
diff --git a/bin/sh/output.h b/bin/sh/output.h
index 5e3b048..51974d8 100644
--- a/bin/sh/output.h
+++ b/bin/sh/output.h
@@ -66,6 +66,8 @@ void emptyoutbuf(struct output *);
 void flushall(void);
 void flushout(struct output *);
 void freestdout(void);
+int outiserror(struct output *);
+void outclearerror(struct output *);
 void outfmt(struct output *, const char *, ...) __printflike(2, 3);
 void out1fmt(const char *, ...) __printflike(1, 2);
 void out2fmt_flush(const char *, ...) __printflike(1, 2);