hush: fix and_or_and_backgrounding.tests failure

function                                             old     new   delta
done_pipe                                            133     218     +85

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

shell/hush.c

@@ -3373,12 +3373,47 @@ static void done_pipe(struct parse_context *ctx, pipe_style type)
 	debug_printf_parse("done_pipe entered, followup %d\n", type);
 	/* Close previous command */
 	not_null = done_command(ctx);
-	ctx->pipe->followup = type;
 #if HAS_KEYWORDS
 	ctx->pipe->pi_inverted = ctx->ctx_inverted;
 	ctx->ctx_inverted = 0;
 	ctx->pipe->res_word = ctx->ctx_res_w;
 #endif
+	if (type != PIPE_BG || ctx->list_head == ctx->pipe) {
+ no_conv:
+		ctx->pipe->followup = type;
+	} else {
+		/* Necessary since && and || have more precedence than &:
+		 * "cmd1 && cmd2 &" must spawn both cmds, not only cmd2,
+		 * in a backgrounded subshell.
+		 */
+		struct pipe *pi;
+		struct command *command;
+
+		/* Is this actually the case? */
+		pi = ctx->list_head;
+		while (pi != ctx->pipe) {
+			if (pi->followup != PIPE_AND && pi->followup != PIPE_OR)
+				goto no_conv;
+			pi = pi->next;
+		}
+
+		debug_printf_parse("BG with more than one pipe, converting to { p1 &&...pN; } &\n");
+		pi->followup = PIPE_SEQ; /* close pN _not_ with "&"! */
+		pi = xzalloc(sizeof(*pi));
+		pi->followup = PIPE_BG;
+		pi->num_cmds = 1;
+		pi->cmds = xzalloc(sizeof(pi->cmds[0]));
+		command = &pi->cmds[0];
+		if (CMD_NORMAL != 0) /* "if xzalloc didn't do that already" */
+			command->cmd_type = CMD_NORMAL;
+		command->group = ctx->list_head;
+#if !BB_MMU
+//TODO: is this correct?!
+		command->group_as_string = xstrdup(ctx->as_string.data);
+#endif
+		/* Replace all pipes in ctx with one newly created */
+		ctx->list_head = ctx->pipe = pi;
+	}
 
 	/* Without this check, even just <enter> on command line generates
 	 * tree of three NOPs (!). Which is harmless but annoying.

shell/hush_test/hush-parsing/and_or_and_backgrounding.right

@@ -0,0 +1,4 @@
+First
+Second
+Third
+Done

shell/hush_test/hush-parsing/and_or_and_backgrounding.tests

@@ -0,0 +1,31 @@
+# UNFIXED BUG: hush thinks that ; && || & have the same precedence.
+# According to this doc, && || have higher precedence than ; &.
+# See example below.
+# Precedence of ; is not a problem in practice. Precedence of & is.
+#
+#http://www.opengroup.org/onlinepubs/009695399/utilities/xcu_chap02.html
+#
+#2.9.3 Lists
+#
+#An AND-OR list is a sequence of one or more pipelines separated by
+#the operators "&&" and "||" .
+#
+#A list is a sequence of one or more AND-OR lists separated by the operators
+#';' and '&' and optionally terminated by ';', '&', or <newline>.
+#
+#The operators "&&" and "||" shall have equal precedence and shall be
+#evaluated with left associativity. For example, both of the following
+#commands write solely bar to standard output:
+#
+#    false && echo foo || echo bar
+#    true || echo foo && echo bar
+#
+#A ';' or <newline> terminator shall cause the preceding AND-OR list
+#to be executed sequentially; an '&' shall cause asynchronous execution
+#of the preceding AND-OR list.
+
+echo First && sleep 0.2 && echo Third &
+sleep 0.1
+echo Second
+wait
+echo Done