[Bug libc/1890] New: strerror() unnecessarily non thread-safe

["stefan dot puiu at gmail dot com" <sourceware-bugzilla@sourceware.org>]

Because of some confusing information in the strerror() manual page, I decided
to check the glibc-2.3.6 source and see for myself, and was dissapointed to see
how strerror_r() (sysdeps/generic/_strerror.c) and strerror()
(string/strerror.c) are implemented. The only reason strerror() is not thread
safe is because it insists keeping a global buffer around, which it mallocs when
needed and then fills it in when it gets called with an invalid errno, with a
string like "Unknown error: <errno>". I would say this is a useless
complication, buys you nothing (you can examine the value without strerror()
supplying it back to you in a buffer), and forces people to use the non-POSIX
strerror_r() (which returns a char*), which only uses the supplied buffer when
the aforementioned situation occurs, further confusing people. 

I suggest changing strerror so that it simply returns "Unknown error" when an
invalid errno is supplied, and deprecating strerror_r. I can provide a patch if
needed. 

Note: both Solaris and HP-UX have thread-safe strerror() functions, so this will
ease the work of people developing applications for multiple Unices.

-- 
           Summary: strerror() unnecessarily non thread-safe
           Product: glibc
           Version: 2.3.6
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
        AssignedTo: drepper at redhat dot com
        ReportedBy: stefan dot puiu at gmail dot com
                CC: glibc-bugs at sources dot redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=1890

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