[ITP] libfakesu 1.0

Christian Franke Christian.Franke@t-online.de
Sat Sep 13 11:15:00 GMT 2014

D. Boland wrote:
> Hi Christian,
> Christian Franke wrote:
>> ...
>> BTW: All these variables except root_uid/gid are not needed as static
>> globals:
>> my_uid is only used to pass the uid from uid_get/set() to get/set(e)uid().
>> my_pw and str255 are only needed because su_getpwnam() calls
>> getpwnam_r() instead of getpwnam().
> I did that to avoid writing into 'external' memory. Would calling getpwnam directly
> be thread-safe?

No and this cannot be fixed because the function interface itself uses 
on a static pwd buffer as return value (and TLS is not allowed). As a 
consequence, the su_getpwnam() is also not thread safe. Calling 
thread-safe su_getpwnam_r() with a static result buffer makes the result 

This would work without any extra buffers and is as thread-unsafe as the 
current version:

struct passwd *su_getpwnam(const char *name)
     struct passwd *pwd = getpwnam(name);
     if (!pwd)
         return NULL;
     if (pwd->pw_uid == root_uid)
         pwd->pw_uid = 0;
     if (pwd->pw_gid == root_gid)
         pwd->pw_gid = 0;
     return pwd;


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