* Re: Wrong PWD with chasedots
[not found] ` <141111193532.ZM31133@torch.brasslantern.com>
@ 2014-11-13 18:46 ` Marc Finet
2014-11-13 19:44 ` Peter Stephenson
0 siblings, 1 reply; 3+ messages in thread
From: Marc Finet @ 2014-11-13 18:46 UTC (permalink / raw)
To: Bart Schaefer; +Cc: zsh-workers
On Tue, Nov 11, 2014 at 07:35:32PM -0800, Bart Schaefer wrote:
> On Nov 11, 11:35am, Marc Finet wrote:
> } Subject: Wrong PWD with chasedots
> }
> } With chasedots activated:
> } # setopt chasedots
> } # cd bar
> } # cd ..
> } # pwd
> } /alt
> } # echo $PWD
> } /
>
> I have some vague recollection of this having been mentioned before.
> I can reproduce it exactly once: the first time I go through those
> steps in any new shell. Thereafter it works as expected, i.e., $PWD
> has the same value as $(pwd).
I did not experienced the same behavior. I always have the problem.
> I've gotten as far as discovering that builtin.c:cd_new_pwd() produces
> different results on the first call as opposed to any later call (that
> is, the first call after "setopt chasedots") but have run out of time
> to keep looking.
I had some time to investigate and the problem lies in the
utils.c::xsymlinks() where there is a discrepancy between the content of
the global variable xbuf and the local value xbuflen:
- in the case a symlink is found, xsymlinks() is called,
- xbuf is updated but not xbuflen in the calling function
- later, when ".." is found, it is trimmed but uses xbuf + xbuflen as
starting point, not xbuf + its length. This leads to lose the data
set by xsymlinks(), i.e. the name of the sub-directories.
This wrong behavior has been introduced by commit 3e06aeabd8a9e8384ebaa
"32294: prevent buffer overflow when scanning very long directory paths
for symbolic links".
So I have two patches. The first one forces the xbuflen synchronization:
--8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<--
diff --git a/Src/utils.c b/Src/utils.c
index e6eb8e6..4a13eb9 100644
--- a/Src/utils.c
+++ b/Src/utils.c
@@ -762,9 +762,13 @@ xsymlinks(char *s)
strcpy(xbuf, "");
if (xsymlinks(xbuf3 + 1) < 0)
ret = -1;
+ else
+ xbuflen = strlen(xbuf);
} else
if (xsymlinks(xbuf3) < 0)
ret = -1;
+ else
+ xbuflen = strlen(xbuf);
}
}
freearray(opp);
--8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<--
The second patch changes local xbuflen into a global to follow xbuf
"localization":
--8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<--
diff --git a/Src/utils.c b/Src/utils.c
index e6eb8e6..5d67781 100644
--- a/Src/utils.c
+++ b/Src/utils.c
@@ -684,6 +684,7 @@ ispwd(char *s)
}
static char xbuf[PATH_MAX*2];
+static zulong xbuflen;
/**/
static char **
@@ -724,7 +725,6 @@ xsymlinks(char *s)
char **pp, **opp;
char xbuf2[PATH_MAX*3], xbuf3[PATH_MAX*2];
int t0, ret = 0;
- zulong xbuflen = strlen(xbuf);
opp = pp = slashsplit(s);
for (; xbuflen < sizeof(xbuf) && *pp; pp++) {
@@ -783,6 +783,7 @@ xsymlink(char *s)
if (*s != '/')
return NULL;
*xbuf = '\0';
+ xbuflen = 0;
if (xsymlinks(s + 1) < 0)
zwarn("path expansion failed, using root directory");
if (!*xbuf)
@@ -796,6 +797,7 @@ print_if_link(char *s)
{
if (*s == '/') {
*xbuf = '\0';
+ xbuflen = 0;
if (xsymlinks(s + 1) > 0)
printf(" -> "), zputs(*xbuf ? xbuf : "/", stdout);
}
--8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<--
I do not know which one do you prefer.
While reading the xsymlinks() function I think that a (ret >= 0)
condition should be added in the for() loop to exit early. Or a break
should be added after setting ret to -1 in the case of error after
symlink is found. Anyway, it's not homogeneous, but I do not know which
method is 'cleaner'.
--8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<--
diff --git a/Src/utils.c b/Src/utils.c
index e6eb8e6..c66b7ae 100644
--- a/Src/utils.c
+++ b/Src/utils.c
@@ -727,7 +727,7 @@ xsymlinks(char *s)
zulong xbuflen = strlen(xbuf);
opp = pp = slashsplit(s);
- for (; xbuflen < sizeof(xbuf) && *pp; pp++) {
+ for (; xbuflen < sizeof(xbuf) && *pp && ret >= 0; pp++) {
if (!strcmp(*pp, "."))
continue;
if (!strcmp(*pp, "..")) {
--8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<-8<--
Marc.
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