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ash: expand: Fix multiple issues with EXP_DISCARD in evalvar

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Upstream commit:

    Date: Wed, 12 Sep 2018 14:27:16 +0800
    expand: Fix multiple issues with EXP_DISCARD in evalvar

    The commit 3cd538634f71538370f5af239f342aec48b7470b broke parameter
    expansion in multiple ways because the EXP_DISCARD flag wasn't set
    or tested for various cases:

            $ src/dash -c 'var=; echo ${var:+nonempty}'
            nonempty
            $ src/dash -u -c 'unset foo bar; echo ${foo+${bar}}'
            dash: 1: bar: parameter not set
            $ src/dash -c 'foo=bar; echo ${foo=BUG}; echo $foo'
            barBUG
            bar
            $

    This patch fixes them by introducing a new discard variable that
    tracks whether the extra word should be discarded or not when it
    is parsed.

    Reported-by: Martijn Dekker <martijn@inlv.org>
    Fixes: 3cd538634f71 ("expand: Do not reprocess data when...")
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
    Reported-by: Martijn Dekker <martijn@inlv.org>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2020-02-22 19:38:40 +01:00
parent 823318822c
commit 1555895b4a
1 changed files with 15 additions and 15 deletions
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30
shell/ash.c
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@ -7454,6 +7454,7 @@ evalvar(char *p, int flag)
int patloc;
int startloc;
ssize_t varlen;
int discard;
int quoted;
varflags = (unsigned char) *p++;
@ -7469,33 +7470,31 @@ evalvar(char *p, int flag)
if (varflags & VSNUL)
varlen--;
discard = varlen < 0 ? EXP_DISCARD : 0;
switch (subtype) {
case VSPLUS:
varlen = -1 - varlen;
discard ^= EXP_DISCARD;
/* fall through */
case 0:
case VSMINUS:
p = argstr(p, flag | EXP_TILDE | EXP_WORD);
if (varlen < 0)
return p;
p = argstr(p, flag | EXP_TILDE | EXP_WORD | (discard ^ EXP_DISCARD));
goto record;
case VSASSIGN:
case VSQUESTION:
if (varlen >= 0)
p = subevalvar(p, var, 0, startloc, varflags,
(flag & ~QUOTES_ESC) | (discard ^ EXP_DISCARD));
if ((flag | ~discard) & EXP_DISCARD)
goto record;
p = subevalvar(p, var, 0, startloc, varflags,
flag & ~QUOTES_ESC);
if (flag & EXP_DISCARD)
return p;
varflags &= ~VSNUL;
subtype = VSNORMAL;
goto again;
}
if (varlen < 0 && uflag)
if ((discard & ~flag) && uflag)
varunset(p, var, 0, 0);
if (subtype == VSLENGTH) {
@ -7503,7 +7502,7 @@ evalvar(char *p, int flag)
if (flag & EXP_DISCARD)
return p;
cvtnum(varlen > 0 ? varlen : 0, flag);
goto record;
goto really_record;
}
if (subtype == VSNORMAL)
@ -7528,7 +7527,7 @@ evalvar(char *p, int flag)
}
#endif
flag |= varlen < 0 ? EXP_DISCARD : 0;
flag |= discard;
if (!(flag & EXP_DISCARD)) {
/*
* Terminate the string and start recording the pattern
@ -7541,9 +7540,10 @@ evalvar(char *p, int flag)
p = subevalvar(p, NULL, patloc, startloc, varflags, flag);
record:
if (flag & EXP_DISCARD)
if ((flag | discard) & EXP_DISCARD)
return p;
really_record:
if (quoted) {
quoted = *var == '@' && shellparam.nparam;
if (!quoted)