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hush: stop generating extra empty pipes in parse stage.

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This commit is contained in:
Denis Vlasenko 2007-05-05 15:11:40 +00:00
parent a6c467f6d1
commit dd4cb2b31e
1 changed files with 15 additions and 13 deletions
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28
shell/hush.c
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@ -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;
}