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ash: prevent error in backquotes in PS1 from exiting shell

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Setting PS1 to:

   PS1='`xxx(`'

causes the shell to terminate with the error:

   sh: syntax error: unexpected end of file (expecting ")")

This happens because old-style backquotes require the input to be reread
and thus call setinputstring() a second time.  Prevent the problem by
unwinding all recently opened files in expandstr().

function                                             old     new   delta
unwindfiles                                            -      22     +22
expandstr                                            247     262     +15
forkchild                                            631     625      -6
evalcommand                                         1694    1685      -9
ash_main                                            1346    1336     -10
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/3 up/down: 37/-25)             Total: 12 bytes

Signed-off-by: Ron Yorston <rmy@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Ron Yorston 2019-04-18 09:48:13 +01:00 committed by Denys Vlasenko
parent 32c8ce4def
commit 48645b8350
1 changed files with 3 additions and 1 deletions
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4
shell/ash.c
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@ -13042,6 +13042,7 @@ expandstr(const char *ps, int syntax_type)
{
union node n;
int saveprompt;
struct parsefile *file_stop = g_parsefile;
/* XXX Fix (char *) cast. */
setinputstring((char *)ps);
@ -13068,7 +13069,8 @@ expandstr(const char *ps, int syntax_type)
doprompt = saveprompt;
popfile();
/* Try: PS1='`xxx(`' */
unwindfiles(file_stop);
n.narg.type = NARG;
n.narg.next = NULL;