Control: forwarded 337013 https://sourceware.org/bugzilla/show_bug.cgi?id=2363 Control: tags 337013 patch
Hello. Please consider the attached patch. Thanks.
Description: Document that EOPNOTSUPP and ENOTSUP are equal, not distinct Bug-Debian: https://bugs.debian.org/337013 Forwarded: https://sourceware.org/bugzilla/show_bug.cgi?id=2363 Author: Nicolas Boulenguez <nico...@debian.org> --- a/manual_errno.texi +++ b/manual_errno.texi @@ -84,11 +84,16 @@ reserved names. @xref{Reserved Names}. The error code values are all positive integers and are all distinct, -with one exception: @code{EWOULDBLOCK} and @code{EAGAIN} are the same. -Since the values are distinct, you can use them as labels in a -@code{switch} statement; just don't use both @code{EWOULDBLOCK} and -@code{EAGAIN}. Your program should not make any other assumptions about +so they can be used as labels in a @code{switch} statement. +Your program should not make any other assumptions about the specific values of these symbolic constants. +Moreover, @theglibc{} does two exceptions: +@itemize @bullet +@item @code{AGAIN} and @code{EWOULDBLOCK} are the same, and +@item @code{ENOTSUP} and @code{EOPNOTSUPP} are the same. +@end itemize +To make your program portable, you should check for both codes and +treat them the same. The value of @code{errno} doesn't necessarily have to correspond to any of these macros, since some library functions might return other error @@ -383,8 +388,7 @@ @standards{POSIX.1, errno.h} @errno{EAGAIN, 35, Resource temporarily unavailable} The call might work if you try again -later. The macro @code{EWOULDBLOCK} is another name for @code{EAGAIN}; -they are always the same in @theglibc{}. +later. This error can happen in a few different situations: @@ -395,12 +399,6 @@ until some external condition makes it possible to read, write, or connect (whatever the operation). You can use @code{select} to find out when the operation will be possible; @pxref{Waiting for I/O}. - -@strong{Portability Note:} In many older Unix systems, this condition -was indicated by @code{EWOULDBLOCK}, which was a distinct error code -different from @code{EAGAIN}. To make your program portable, you should -check for both codes and treat them the same. - @item A temporary resource shortage made an operation impossible. @code{fork} can return this error. It indicates that the shortage is expected to @@ -411,16 +409,16 @@ so usually an interactive program should report the error to the user and return to its command loop. @end itemize + +@strong{Portability Note:} In @theglibc{}, +@code{EAGAIN} and @code{EWOULDBLOCK} are equal. +Portable code should check for both errors and treat them the same. @end deftypevr @deftypevr Macro int EWOULDBLOCK @standards{BSD, errno.h} @errno{EWOULDBLOCK, EAGAIN, Operation would block} In @theglibc{}, this is another name for @code{EAGAIN} (above). -The values are always the same, on every operating system. - -C libraries in many older Unix systems have @code{EWOULDBLOCK} as a -separate error code. @end deftypevr @deftypevr Macro int EINPROGRESS @@ -492,6 +490,10 @@ error can happen for many calls when the object does not support the particular operation; it is a generic indication that the server knows nothing to do for that call. + +@strong{Portability Note:} In @theglibc{}, +@code{EOPNOTSUPP} and @code{ENOTSUP} are equal. +Portable code should check for both errors and treat them the same. @end deftypevr @deftypevr Macro int EPFNOSUPPORT @@ -764,6 +766,10 @@ If the entire function is not available at all in the implementation, it returns @code{ENOSYS} instead. + +@strong{Portability Note:} In @theglibc{}, +@code{EOPNOTSUPP} and @code{ENOTSUP} are equal. +Portable code should check for both errors and treat them the same. @end deftypevr @deftypevr Macro int EILSEQ
