[PATCH, UDEV] change no_trailing_slash() to remove all trailing slashes

[PATCH, UDEV] change no_trailing_slash() to remove all trailing slashes

[Michael Buesch]

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Hi,

This changes no_trailing_slash() to remove all trailing slashes
and not just the last one.
This protects against crazy users which do:
export SYSFS_PATH="/sys//"
or something similiar.

-- 
Regards Michael Buesch  [ http://www.tuxsoft.de.vu ]



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===== udev_utils.c 1.25 vs edited =====
--- 1.25/udev_utils.c	2004-12-20 22:10:57 +01:00
+++ edited/udev_utils.c	2005-02-05 18:13:46 +01:00
@@ -200,11 +200,11 @@
 
 void no_trailing_slash(char *path)
 {
-	int len;
+	size_t len;
 
 	len = strlen(path);
-	if (len > 0 && path[len-1] == '/')
-		path[len-1] = '\0';
+	while (len > 0 && path[len-1] == '/')
+		path[--len] = '\0';
 }
 
 struct files {

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Re: [PATCH, UDEV] change no_trailing_slash() to remove all

[Kay Sievers]

On Sat, 2005-02-05 at 18:18 +0100, Michael Buesch wrote:
> This changes no_trailing_slash() to remove all trailing slashes
> and not just the last one.
> This protects against crazy users which do:
> export SYSFS_PATH="/sys//"
> or something similiar.

Applied.

Thanks,
Kay



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Re: [PATCH, UDEV] change no_trailing_slash() to remove all trailing

[Paul Jackson]

Michael wrote:
> 	while (len > 0 && path[len-1] = '/')

I think you'd better make that:

	while (len > 1 && path[len-1] = '/')

or else you can eat your last slash.

The call no_trailing_slash("/") should produce "/", not "".

Not that anyone is likely to call no_trailing_slash("////")
very often ;).

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.650.933.1373, 1.925.600.0401


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Re: [PATCH, UDEV] change no_trailing_slash() to remove all trailing slashes

[Michael Buesch]

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Quoting Paul Jackson <pj@sgi.com>:
> Michael wrote:
> > 	while (len > 0 && path[len-1] == '/')
> 
> I think you'd better make that:
> 
> 	while (len > 1 && path[len-1] == '/')
> 
> or else you can eat your last slash.
> 
> The call no_trailing_slash("/") should produce "/", not "".

Well, I would call that expected behaviour.
Consider the following:
char buf[SIZE];
strcpy(buf, "///");
no_trailing_slash(buf);
strcat(buf, "/foo/bar");

I would expect that to expand to "/foo/bar" and _not_
to "//foo/bar" as you suggest.

> Not that anyone is likely to call no_trailing_slash("////")
> very often ;).
> 

-- 
Regards Michael Buesch  [ http://www.tuxsoft.de.vu ]



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Re: [PATCH, UDEV] change no_trailing_slash() to remove all trailing

[Paul Jackson]

What if someone does:

    strcpy(buf, "/");
    no_trailing_slash(buf);
    strcat(buf, "foo");

Would you expect "foo", or "/foo" ?

Actually, I did not expect this to be called in the middle
of a construction, after only explicit constant strings
had been added.

I would have expected it to be called after the final
construction, following the concatenation of a variable
string.

And I would have expected it to scrupulously avoid changing
the meaning of the path - just cosmetic trimming.

But apparently my expectations are confused.  Feel free to
dismiss my comments.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.650.933.1373, 1.925.600.0401


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Re: [PATCH, UDEV] change no_trailing_slash() to remove all trailing slashes

[Michael Buesch]

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Quoting Paul Jackson <pj@sgi.com>:
> What if someone does:
> 
>     strcpy(buf, "/");
>     no_trailing_slash(buf);
>     strcat(buf, "foo");
> 
> Would you expect "foo", or "/foo" ?

I would expect "foo".
It's the function semantics:
no_trailing_slash means (at least for me) clearly,
that there will be "no trailing slash" under any circumstances in
the string.
It should be the caller's job to ensure, that we have a
valid path after cutting of all trailing slashes.

	strcpy(buf, "/");
	no_trailing_slash(buf);
	if (buf[0] == '\0')
		strcat(buf, "/");
	strcat(buf, "foo");

But having saied this all, I can't find where this
actually happens in the udev code. I did a very quick
search even before I submitted the code, but I could only
find places like this, which will always result
in a valid path:

	no_trailing_slash(buf);
	strcat(buf, "/foo");

> Actually, I did not expect this to be called in the middle
> of a construction, after only explicit constant strings
> had been added.
> 
> I would have expected it to be called after the final
> construction, following the concatenation of a variable
> string.
> 
> And I would have expected it to scrupulously avoid changing
> the meaning of the path - just cosmetic trimming.
> 
> But apparently my expectations are confused.  Feel free to
> dismiss my comments.
> 

-- 
Regards Michael Buesch  [ http://www.tuxsoft.de.vu ]



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