dd4cb2b31
Denis Vlasenko
2007-05-05
Subject
hush: stop generating extra empty pipes in parse stage.
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shell/hush.c+15 -13
| @@ -2685,8 +2685,8 @@ static int done_command(struct p_context *ctx) | |
| && child->argv == NULL | |
| && child->redirects == NULL | |
| ) { | |
| - | debug_printf_parse("done_command: skipping null command\n"); |
| - | return 0; |
| + | debug_printf_parse("done_command: skipping null cmd, num_progs=%d\n", pi->num_progs); |
| + | return pi->num_progs; |
| } | |
| pi->num_progs++; | |
| debug_printf_parse("done_command: ++num_progs=%d\n", pi->num_progs); | |
| @@ -2712,26 +2712,28 @@ static int done_command(struct p_context *ctx) | |
| ctx->child = child; | |
| /* but ctx->pipe and ctx->list_head remain unchanged */ | |
| - | return 0; |
| + | return pi->num_progs; /* used only for 0/nonzero check */ |
| } | |
| static int done_pipe(struct p_context *ctx, pipe_style type) | |
| { | |
| struct pipe *new_p; | |
| + | int not_null; |
| debug_printf_parse("done_pipe entered, followup %d\n", type); | |
| - | done_command(ctx); /* implicit closure of previous command */ |
| + | not_null = done_command(ctx); /* implicit closure of previous command */ |
| ctx->pipe->followup = type; | |
| ctx->pipe->r_mode = ctx->res_w; | |
| - | new_p = new_pipe(); |
| - | ctx->pipe->next = new_p; |
| - | ctx->pipe = new_p; |
| - | ctx->child = NULL; |
| - | // TODO: even just <enter> on command line basically generates |
| - | // tree of three NOPs (!). |
| - | // Can we detect that previous done_command have seen "skipping null command" |
| - | // condition and NOT create new pipe here? |
| - | done_command(ctx); /* set up new pipe to accept commands */ |
| + | /* Without this check, even just <enter> on command line generates |
| + | * tree of three NOPs (!). Which is harmless but annoying. |
| + | * IOW: it is safe to do it unconditionally. */ |
| + | if (not_null) { |
| + | new_p = new_pipe(); |
| + | ctx->pipe->next = new_p; |
| + | ctx->pipe = new_p; |
| + | ctx->child = NULL; |
| + | done_command(ctx); /* set up new pipe to accept commands */ |
| + | } |
| debug_printf_parse("done_pipe return 0\n"); | |
| return 0; | |
| } | |