[Bug libc/492] New: New setre*id functions broken on alpha

["mmazur at kernel dot pl" <sourceware-bugzilla at sources dot redhat dot com>]

Up to 2004-09-19 setreuid, setresuid, setregid and setresgid functions (and  
lots of others) on alpha where generated from a couple of macros, that due to  
the way function arguments are passed on alpha, generated stub functions  
(literally a couple of lines of asm code) that just issued a syscall without  
even touching the passed arguments. That worked fine. 
But on that day fulltime C functions where added (ci log: "Call callback to  
set IDs in all other threads as well.") which broke above functions on alpha. 
 
Stub functions aren't used any more, now C compiler has controll of the what's  
going on. Those functions take gid_t or uid_t as arguments and those types  
are defines as unsigned int (32 bit). Later they are casted to type long to  
put them into appropriate registers before making a syscall. The problem is  
that although those are unsigned ints we're using, the kernel expects to get  
a '-1' value in some cases (ask the designers what where they thinking). Now  
according to "Calling Standard for Alpha Systems"* when passing a 32bit  
signed to a function (that is putting it into a 64bit register) the signed  
stuff should get expanded to full 64bits (0xffffffff should become  
0xffffffffffffffff). But that doesn't happen, since those are unsigned ints  
the compiler is handling, so it doesn't expand the signed stuff, but just  
zeroes the first four bytes. So we're doing setreuid(-1, -1), but the kernel  
gets setreuid(4294967295, 4294967295) and doesn't treat that as -1. Casting  
that value to signed int before casting it to long fixes the problem. I'm attaching a 
patch. 
 
* 
http://www.cs.arizona.edu/computer.help/policy/DIGITAL_unix/AA-PY8AC-TET1_html/callCH4.html#BLOCK52

-- 
           Summary: New setre*id functions broken on alpha
           Product: glibc
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: gotom at debian dot or dot jp
        ReportedBy: mmazur at kernel dot pl
                CC: glibc-bugs at sources dot redhat dot com


http://sources.redhat.com/bugzilla/show_bug.cgi?id=492

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