ash: expand: Fix multiple issues with EXP_DISCARD in evalvar
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>
diff --git a/shell/ash.c b/shell/ash.c
index 425da6b..d0d99f6 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -7454,6 +7454,7 @@
int patloc;
int startloc;
ssize_t varlen;
+ int discard;
int quoted;
varflags = (unsigned char) *p++;
@@ -7469,33 +7470,31 @@
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 @@
if (flag & EXP_DISCARD)
return p;
cvtnum(varlen > 0 ? varlen : 0, flag);
- goto record;
+ goto really_record;
}
if (subtype == VSNORMAL)
@@ -7528,7 +7527,7 @@
}
#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 @@
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)
