On Sun, Sep 02, 2018 at 10:15:50PM +0000, Martijn Dekker wrote:
> Commit 3cd538634f71538370f5af239f342aec48b7470b broke these:
>
> $ src/dash -c 'unset var; echo ${var+set}'
> set
> $ src/dash -c 'var=; echo ${var:+nonempty}'
> nonempty
Thanks for the report! I forgot to discard the result of the unused
expansion.
---8<---
Subject: expand: Discard result of unused expansion in evalvar
The commit 3cd538634f71538370f5af239f342aec48b7470b broke parameter
expansion where the nested expanded word needs to be discarded.
This is because the EXP_DISCARD flag wasn't set where it should
have been:
$ src/dash -c 'var=; echo ${var:+nonempty}'
nonempty
This patch fixes it by setting it where needed.
Reported-by: Martijn Dekker <[email protected]>
Fixes: 3cd538634f71 ("expand: Do not reprocess data when...")
Signed-off-by: Herbert Xu <[email protected]>
diff --git a/src/expand.c b/src/expand.c
index 14daa63..e890052 100644
--- a/src/expand.c
+++ b/src/expand.c
@@ -698,6 +698,7 @@ evalvar(char *p, int flag)
int patloc;
int startloc;
ssize_t varlen;
+ int discard;
int quoted;
varflags = *p++;
@@ -713,21 +714,24 @@ again:
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)
+ p = argstr(p, flag | EXP_TILDE | EXP_WORD |
+ (discard ^ EXP_DISCARD));
+ if (discard)
return p;
goto record;
case VSASSIGN:
case VSQUESTION:
- if (varlen >= 0)
+ if (!discard)
goto record;
p = subevalvar(p, var, 0, startloc, varflags,
@@ -740,7 +744,7 @@ again:
goto again;
}
- if (varlen < 0 && uflag)
+ if (discard && uflag)
varunset(p, var, 0, 0);
if (subtype == VSLENGTH) {
@@ -765,7 +769,7 @@ again:
}
#endif
- flag |= varlen < 0 ? EXP_DISCARD : 0;
+ flag |= discard;
if (!(flag & EXP_DISCARD)) {
/*
* Terminate the string and start recording the pattern
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
