From ba0f94458bf992bb1f34c75e36960811d77b5f55 Mon Sep 17 00:00:00 2001 From: Ron Yorston Date: Thu, 2 May 2024 13:08:14 +0100 Subject: ash: fix parsing of alias expansion + bash features An alias expansion immediately followed by '<' and a newline is parsed incorrectly: ~ $ alias x='echo yo' ~ $ x< yo ~ $ sh: syntax error: unexpected newline The echo is executed and an error is printed on the next command submission. In dash the echo isn't executed and the error is reported immediately: $ alias x='echo yo' $ x< dash: 3: Syntax error: newline unexpected $ The difference between BusyBox and dash is that BusyBox supports bash-style process substitution and output redirection. These require checking for '<(', '>(' and '&>' in readtoken1(). In the case above, when the end of the alias is found, the '<' and the following newline are both read to check for '<('. Since there's no match both characters are pushed back. The next input is obtained by reading the expansion of the alias. Once this string is exhausted the next call to __pgetc() calls preadbuffer() which pops the string, reverts to the previous input and recursively calls __pgetc(). This request is satisified from the pungetc buffer. But the first __pgetc() doesn't know this: it sees the character has come from preadbuffer() so it (incorrectly) updates the pungetc buffer. Resolve the issue by moving the code to pop the string and fetch the next character up from preadbuffer() into __pgetc(). function old new delta pgetc 28 589 +561 __pgetc 607 - -607 ------------------------------------------------------------------------------ (add/remove: 0/1 grow/shrink: 1/0 up/down: 561/-607) Total: -46 bytes Signed-off-by: Ron Yorston Signed-off-by: Denys Vlasenko --- shell/ash.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/shell/ash.c b/shell/ash.c index 4ca4c6c56..5df0ba625 100644 --- a/shell/ash.c +++ b/shell/ash.c @@ -10934,11 +10934,6 @@ preadbuffer(void) char *q; int more; - if (unlikely(g_parsefile->strpush)) { - popstring(); - return __pgetc(); - } - if (g_parsefile->buf == NULL) { pgetc_debug("preadbuffer PEOF1"); return PEOF; @@ -11053,8 +11048,13 @@ static int __pgetc(void) if (--g_parsefile->left_in_line >= 0) c = (unsigned char)*g_parsefile->next_to_pgetc++; - else + else { + if (unlikely(g_parsefile->strpush)) { + popstring(); + return __pgetc(); + } c = preadbuffer(); + } g_parsefile->lastc[1] = g_parsefile->lastc[0]; g_parsefile->lastc[0] = c; -- cgit v1.2.3-55-g6feb