strerror: enforce POSIX ruling on strerror(0)

[gnulib.git] / doc / posix-functions / strerror.texi

diff --git a/doc/posix-functions/strerror.texi b/doc/posix-functions/strerror.texi
index 68a98da..6f9519a 100644 (file)
--- a/doc/posix-functions/strerror.texi
+++ b/doc/posix-functions/strerror.texi
@@ -13,11 +13,18 @@ This function does not support the error values that are specified by POSIX
 but not defined by the system, on some platforms:
 OpenBSD 4.0, OSF/1 5.1, NonStop Kernel, Cygwin 1.5.x, mingw.
 @item
+This function reports failure (by setting @code{errno}) for
+@code{strerror(0)}, although POSIX requires this to leave @code{errno}
+unchanged and report success, on some platforms:
+FreeBSD 8.2
+@item
 This function fails to return a string for out-of-range integers on
 some platforms:
 HP-UX 11, IRIX 6.5, Solaris 8.
-(This is not a POSIX violation, but can still cause bugs because most programs
-call @code{strerror} without setting and testing @code{errno}.)
+(Some return NULL which is a POSIX violation, others return the empty
+string which is valid but not as useful); this can still cause bugs
+because most programs call @code{strerror} without setting and testing
+@code{errno}.)
 @end itemize
 
 Portability problems not fixed by Gnulib: