[Bug libc/3426] New: canonicalize_file_name's behavior differs from documentation

[Bug libc/3426] New: canonicalize_file_name's behavior differs from documentation

[lemke_juergen at yahoo dot de]

In GNU libc 2.3.5, the header file /usr/lib/stdlib.h reads:

#ifdef  __USE_GNU                                                               
/* Return a malloc'd string containing the canonical absolute name of the       
   named file.  The last file name component need not exist, and may be a       
   symlink to a nonexistent file.  */                                           
extern char *canonicalize_file_name (__const char *__name)                      
     __THROW __nonnull ((1));                                                   
#endif                            


However, canonicalize_file_name() returns NULL when passed a path where the last
component does not exist.

// file: can-test.c

#define _GNU_SOURCE                                                             
#include <stdlib.h>                                                             
#include <stdio.h>                                                              

int main(void)                                                                  
{                                                                               
   char *p = canonicalize_file_name("no-such-file");                            
                                                                                
   if (!p)                                                                      
     perror(NULL);                                                              
                                                                                
   return 0;                                                                    
}

The same applies to realpath() and its description. As of version 2.3.5, either
the documentation or the implementation is wrong.

Best

Juergen Lemke

-- 
           Summary: canonicalize_file_name's behavior differs from
                    documentation
           Product: glibc
           Version: 2.3.5
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: lemke_juergen at yahoo dot de
                CC: glibc-bugs at sources dot redhat dot com,lemke_juergen
                    at yahoo dot de


http://sourceware.org/bugzilla/show_bug.cgi?id=3426

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[Bug libc/3426] canonicalize_file_name's behavior differs from documentation

[jakub at redhat dot com]

------- Additional Comments From jakub at redhat dot com  2006-10-26 07:13 -------
__nonnull ((1)) means that the first argument must not be NULL, not that
the function can't return NULL.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |INVALID


http://sourceware.org/bugzilla/show_bug.cgi?id=3426

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[Bug libc/3426] canonicalize_file_name's behavior differs from documentation

[lemke_juergen at yahoo dot de]

------- Additional Comments From lemke_juergen at yahoo dot de  2006-10-26 20:13 -------
Hello,

jakub at redhat dot com wrote:

> __nonnull ((1)) means that the first argument must
> not be NULL, not that
> the function can't return NULL.

That is not what I was referring to. Just above the declaration of
canonicalize_file_name() you can read:

"The last file name component need not exist [...]"

However, as of GNU libc 2.3.5, this function always fails (returning NULL) when
passed a path to a inexistent file.

Best,

Juergen

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|INVALID                     |


http://sourceware.org/bugzilla/show_bug.cgi?id=3426

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[Bug libc/3426] canonicalize_file_name's behavior differs from documentation

[ldv at altlinux dot org]

------- Additional Comments From ldv at altlinux dot org  2006-10-26 21:16 -------
As of glibc HEAD, stdlib/stdlib.h really contains wrong comments about
canonicalize_file_name() and realpath().  The comment in stdlib/canonicalize.c
is correct, though.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=3426

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[Bug libc/3426] canonicalize_file_name's behavior differs from documentation

[drepper at redhat dot com]

------- Additional Comments From drepper at redhat dot com  2006-10-27 18:47 -------
I adjusted the comment.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |FIXED


http://sourceware.org/bugzilla/show_bug.cgi?id=3426

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