Erroneous use of getcwd on lib/nspath.c

[Andreas Ericsson]

Good thing I read the mail before I submitted my previous code.

This looks good. Thanks.

On 10/26/2012 05:23 PM, Ricardo Jose Maraschini wrote:
> * Ricardo Jose Maraschini (ricardo.maraschini at opservices.com.br) wrote:
>> * Ricardo Jose Maraschini (ricardo.maraschini at opservices.com.br) wrote:
>>>
>>> Accordingly to manpages and some home made tests, getcwd returns NULL
>>> when an error occurs, not a value < 0.
>>>
>>> Following, on openbsd MAX_PATH is 1024 bytes while in linux it is 4096
>>> bytes, so i thought it would be ok to include <limits.h> and use macro
>>> MAX_PATH, not a fixed size of 4096.
>>>
>>> Also we don't need to make sizeof(path) - 1 when calling getcwd.
>>> Quoting manpage:
>>>
>>> "The size argument is the size, in bytes, of the array referenced by
>>> buf."
>>>
>>> Is it sounds resonable?
>>> Comments?
>>
>> I keep trolling nagios and discovered that it segfaults, or, as the code
>> states "256 components will fail hard" with a configuration path with
>> more than 256 directories.
>>
>> I know that a configuration with more than 256 directories is, above
>> all, stupid, but i do prefer to have it working even if the
>> administrator isn't so much clever.
>>
>> So, the previous patch may be ignored cause it's included on this.
>>
> 
> Sorry, wrong patch, here goes the right one.
> 
> ===================================================================
> --- lib/nspath.c	(revision 2409)
> +++ lib/nspath.c	(working copy)
> @@ -5,6 +5,7 @@
>   #include <string.h>
>   #include <sys/types.h>
>   #include <stdio.h>
> +#include <limits.h>
>   #include "nspath.h"
>   
>   #ifndef PATH_MAX
> @@ -64,7 +65,7 @@
>    */
>   char *nspath_normalize(const char *orig_path)
>   {
> -	struct pcomp pcomp[256]; /* >256 components will fail hard */
> +	struct pcomp *pcomp = NULL;
>   	int comps, i = 0, m, depth = 0;
>   	char *path, *rpath, *p, *slash;
>   
> @@ -73,7 +74,10 @@
>   
>   	rpath = strdup(orig_path);
>   	comps = path_components(rpath);
> -	memset(pcomp, 0, sizeof(pcomp));
> +	pcomp = calloc(comps,sizeof(struct pcomp));
> +	if (pcomp == NULL)
> +		return NULL;
> +
>   	p = pcomp[0].str = rpath;
>   	for (; p; p = slash, i++) {
>   		slash = strchr(p, '/');
> @@ -114,12 +118,13 @@
>   
>   	path = pcomp_construct(pcomp, comps);
>   	free(rpath);
> +	free(pcomp);
>   	return path;
>   }
>   
>   char *nspath_absolute(const char *rel_path, const char *base)
>   {
> -	char cwd[4096];
> +	char cwd[PATH_MAX];
>   	int len;
>   	char *path = NULL, *normpath;
>   
> @@ -127,7 +132,7 @@
>   		return nspath_normalize(rel_path);
>   
>   	if (!base) {
> -		if (getcwd(cwd, sizeof(cwd) - 1) < 0)
> +		if (getcwd(cwd, sizeof(cwd)) == NULL)
>   			return NULL;
>   		base = cwd;
>   	}
> 
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-- 
Andreas Ericsson                   andreas.ericsson at op5.se
OP5 AB                             www.op5.se
Tel: +46 8-230225                  Fax: +46 8-230231

Considering the successes of the wars on alcohol, poverty, drugs and
terror, I think we should give some serious thought to declaring war
on peace.

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