emo/busybox
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

ash: expand: Do not quote backslashes in unquoted parameter expansion

Browse Source 
Upstream commit:

    Date: Wed, 28 Mar 2018 18:37:51 +0800
    expand: Do not quote backslashes in unquoted parameter expansion

    Here is a better example:

        a="/*/\nullx" b="/*/\null"; printf "%s\n" $a $b

    dash currently prints

        /*/\nullx
        /*/\null

    bash prints

        /*/\nullx
        /dev/null

    You may argue the bash behaviour is inconsistent but it actually
    makes sense.  What happens is that quote removal only applies to
    the original token as seen by the shell.  It is never applied to
    the result of parameter expansion.

    Now you may ask why on earth does the second line say "/dev/null"
    instead of "/dev/\null".  Well that's because it is not the quote
    removal step that removed the backslash, but the pathname expansion.

    The fact that the /de\v does not become /dev even though it exists
    is just the result of the optimisation to avoid unnecessarily
        calling stat(2).  I have checked POSIX and I don't see anything
    that forbids this behaviour.

    So going back to dash yes I think we should adopt the bash behaviour
    for pathname expansion and keep the existing case semantics.

    This patch does exactly that.  Note that this patch does not work
    unless you have already applied

        https://patchwork.kernel.org/patch/10306507/

    because otherwise the optimisation mentioned above does not get
    detected correctly and we will end up doing quote removal twice.

    This patch also updates expmeta to handle naked backslashes at
    the end of the pattern which is now possible.

    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

function                                             old     new   delta
expmeta                                              618     653     +35
memtodest                                            146     147      +1

Tested to work with both ASH_INTERNAL_GLOB on and off.

hush does not handle this correctly.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2018-08-07 18:54:52 +02:00
parent 77c18491b8
commit eb54ca8be0
5 changed files with 32 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
shell/ash.c
View File

@ -6236,9 +6236,7 @@ memtodest(const char *p, size_t len, int syntax, int quotes)
if (quotes & QUOTES_ESC) {
int n = SIT(c, syntax);
if (n == CCTL
|| (((quotes & EXP_FULL) || syntax != BASESYNTAX)
&& n == CBACK
)
|| (syntax != BASESYNTAX && n == CBACK)
) {
USTPUTC(CTLESC, q);
}
@ -7639,7 +7637,7 @@ expmeta(exp_t *exp, char *name, unsigned name_len, unsigned expdir_len)
}
}
} else {
if (*p == '\\')
if (*p == '\\' && p[1])
esc++;
if (p[esc] == '/') {
if (metaflag)
@ -7653,7 +7651,7 @@ expmeta(exp_t *exp, char *name, unsigned name_len, unsigned expdir_len)
return;
p = name;
do {
if (*p == '\\')
if (*p == '\\' && p[1])
p++;
*enddir++ = *p;
} while (*p++);
@ -7665,7 +7663,7 @@ expmeta(exp_t *exp, char *name, unsigned name_len, unsigned expdir_len)
if (name < start) {
p = name;
do {
if (*p == '\\')
if (*p == '\\' && p[1])
p++;
*enddir++ = *p++;
} while (p < start);

4
shell/ash_test/ash-glob/glob_bkslash_in_var.right Normal file
View File

@ -0,0 +1,4 @@
Unquoted non-matching glob in var:'test*.TMP/\name_doesnt_exist'
Unquoted matching glob in var: 'testdir.TMP/name'
Quoted non-matching glob in var: 'test*.TMP/\name_doesnt_exist'
Quoted matching glob in var: 'test*.TMP/\name'

10
shell/ash_test/ash-glob/glob_bkslash_in_var.tests Executable file
View File

@ -0,0 +1,10 @@
mkdir testdir.TMP
>testdir.TMP/name
a="test*.TMP/\name_doesnt_exist"
b="test*.TMP/\name"
printf "Unquoted non-matching glob in var:'%s'\n" $a
printf "Unquoted matching glob in var: '%s'\n" $b
printf "Quoted non-matching glob in var: '%s'\n" "$a"
printf "Quoted matching glob in var: '%s'\n" "$b"
rm -f testdir.TMP/name
rmdir testdir.TMP

4
shell/hush_test/hush-glob/glob_bkslash_in_var.right Normal file
View File

@ -0,0 +1,4 @@
Unquoted non-matching glob in var:'test*.TMP/\name_doesnt_exist'
Unquoted matching glob in var: 'testdir.TMP/name'
Quoted non-matching glob in var: 'test*.TMP/\name_doesnt_exist'
Quoted matching glob in var: 'test*.TMP/\name'

10
shell/hush_test/hush-glob/glob_bkslash_in_var.tests Executable file
View File

@ -0,0 +1,10 @@
mkdir testdir.TMP
>testdir.TMP/name
a="test*.TMP/\name_doesnt_exist"
b="test*.TMP/\name"
printf "Unquoted non-matching glob in var:'%s'\n" $a
printf "Unquoted matching glob in var: '%s'\n" $b
printf "Quoted non-matching glob in var: '%s'\n" "$a"
printf "Quoted matching glob in var: '%s'\n" "$b"
rm -f testdir.TMP/name
rmdir testdir.TMP