Re: dash bug: double-quoted "\" breaks glob protection for next char
On 2/14/18 10:44 PM, Harald van Dijk wrote:
On 2/14/18 9:03 PM, Harald van Dijk wrote:
On 13/02/2018 14:53, Denys Vlasenko wrote:
$ >'\'
$ >'\'
$ dash -c 'echo "\*"'
\ \
[...]
Currently:
$ dash -c 'foo=a; echo "<${foo#[a\]]}>"'
<>
This is what I expect, and also what bash, ksh and posh do.
With your patch:
$ dash -c 'foo=a; echo "<${foo#[a\]]}>"'
Does the attached look right as an alternative? It treats a quoted
backslash the same way as if it were preceded by CTLESC in _rmescapes.
It passes your test case and mine, but I'll do more extensive testing.
It causes preglob's string to potentially grow larger than the original.
When called with RMESCAPE_ALLOC, that can be handled by increasing the
buffer size, but preglob also gets called without RMESCAPE_ALLOC to
modify a string in-place. That's never going to work with this approach.
Back to the drawing board...
Cheers,
Harald van Dijk
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Re: dash bug: double-quoted "\" breaks glob protection for next char
On 2/14/18 9:03 PM, Harald van Dijk wrote:
On 13/02/2018 14:53, Denys Vlasenko wrote:
$ >'\'
$ >'\'
$ dash -c 'echo "\*"'
\ \
[...]
Currently:
$ dash -c 'foo=a; echo "<${foo#[a\]]}>"'
<>
This is what I expect, and also what bash, ksh and posh do.
With your patch:
$ dash -c 'foo=a; echo "<${foo#[a\]]}>"'
Does the attached look right as an alternative? It treats a quoted
backslash the same way as if it were preceded by CTLESC in _rmescapes.
It passes your test case and mine, but I'll do more extensive testing.
Cheers,
Harald van Dijk
diff --git a/src/expand.c b/src/expand.c
index 2a50830..af88a69 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -1686,12 +1686,17 @@ _rmescapes(char *str, int flag)
}
if (*p == (char)CTLESC) {
p++;
- if (notescaped)
-*q++ = '\\';
- } else if (*p == '\\' && !inquotes) {
- /* naked back slash */
- notescaped = 0;
- goto copy;
+ goto escape;
+ } else if (*p == '\\') {
+ if (inquotes) {
+escape:
+if (notescaped)
+ *q++ = '\\';
+ } else {
+/* naked back slash */
+notescaped = 0;
+goto copy;
+ }
}
notescaped = globbing;
copy:
Re: dash bug: double-quoted "\" breaks glob protection for next char
On 13/02/2018 14:53, Denys Vlasenko wrote:
$ >'\'
$ >'\'
$ dash -c 'echo "\*"'
\ \
Nice catch.
The cause: uses "\\*" pattern instead of "\\\*".
The fix:
/* backslash */
case CBACK:
c = pgetc2();
if (c == PEOF) {
USTPUTC(CTLESC, out);
USTPUTC('\\', out);
pungetc();
} else if (c == '\n') {
nlprompt();
} else {
if (
dblquote &&
c != '\\' && c != '`' &&
c != '$' && (
c != '"' ||
eofmark != NULL
)
) {
USTPUTC(CTLESC, out); // add this line
USTPUTC('\\', out);
}
USTPUTC(CTLESC, out);
USTPUTC(c, out);
quotef++;
}
I don't think this is right. The bug was introduced in
Prior to that, the line USTPUTC(CTLESC, out); was there. The commit
message is saying that the logic for detecting whether \ should be taken
literally doesn't belong in the parser, that the parser will get it
wrong. The example in the commit message doesn't break with your patch,
but short modifications to that example do make it fail:
Currently:
$ dash -c 'foo=a; echo "<${foo#[a\]]}>"'
<>
This is what I expect, and also what bash, ksh and posh do.
With your patch:
$ dash -c 'foo=a; echo "<${foo#[a\]]}>"'
Cheers,
Harald van Dijk
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