bug-gnulib
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Bug-gnulib] Re: Bug in getloadavg


From: Paul Eggert
Subject: Re: [Bug-gnulib] Re: Bug in getloadavg
Date: Tue, 30 Mar 2004 11:32:07 -0800
User-agent: Gnus/5.1006 (Gnus v5.10.6) Emacs/21.3 (gnu/linux)

Bruno Haible <address@hidden> writes:

> Since setlocale can return NULL (or, at least, the replacement stub for
> absent setlocale is NULL) and xstrdup (NULL) is invalid, I would rewrite
> this

Thanks for catching that: I installed the fix.

> I have a problem with functions returning 'bool' and errno. Namely,
> the calling convention is just the opposite of so many Unix
> functions, like close(), shmdt() etc.

It's a valid point.

I do prefer 'bool' for functions that don't set errno on failure.
And once one takes this approach, it's a short distance to having
functions return bool for every function that returns a failure
indication, regardless of what other things the function does.

However, there's a good consistency argument that functions that are
"like" Unix system calls (in particular, functions that return a
failure flag and set errno on failure) should use the Unix convention,
so perhaps I went overboard here.

Jim Meyering <address@hidden> writes:

> I sometimes have to re-read code that does this:
>   if (stat (...)) { /* handle failure */ ... }

Yes, and I prefer this:

    if (stat (...) != 0) { /* handle failure */ ... }

particularly if some routines return bool for failure, as it makes it
clearer that 'stat' uses the Unix convention.

Anyway, here's a proposed patch to gnulib.  If it's OK with people
I'll send a separate patch for this for coreutils, since coreutils
needs some other changes in this area too (for the Emacs changes, and
to accommodate the change to cloexec.h).

2004-03-30  Paul Eggert  <address@hidden>

        * lib/cloexec.h, lib/cloexec.c (set_cloexec_flag): Return int
        not bool, to be more consistent with Unix conventions.
        Suggested by Bruno Haible.

Index: lib/cloexec.h
===================================================================
RCS file: /cvsroot/gnulib/gnulib/lib/cloexec.h,v
retrieving revision 1.1
diff -p -u -r1.1 cloexec.h
--- lib/cloexec.h       29 Mar 2004 23:57:36 -0000      1.1
+++ lib/cloexec.h       30 Mar 2004 19:26:51 -0000
@@ -1,2 +1,2 @@
 #include <stdbool.h>
-bool set_cloexec_flag (int desc, bool value);
+int set_cloexec_flag (int desc, bool value);
Index: lib/cloexec.c
===================================================================
RCS file: /cvsroot/gnulib/gnulib/lib/cloexec.c,v
retrieving revision 1.1
diff -p -u -r1.1 cloexec.c
--- lib/cloexec.c       29 Mar 2004 23:57:36 -0000      1.1
+++ lib/cloexec.c       30 Mar 2004 19:26:51 -0000
@@ -37,27 +37,29 @@
 
 /* Set the `FD_CLOEXEC' flag of DESC if VALUE is true,
    or clear the flag if VALUE is false.
-   Return true on success, or false on error with `errno' set. */
+   Return 0 on success, or -1 on error with `errno' set. */
 
-bool
+int
 set_cloexec_flag (int desc, bool value)
 {
 #if defined F_GETFD && defined F_SETFD
 
   int flags = fcntl (desc, F_GETFD, 0);
-  int newflags;
 
-  if (flags < 0)
-    return false;
+  if (0 <= flags)
+    {
+      int newflags = (value ? flags | FD_CLOEXEC : flags & ~FD_CLOEXEC);
+
+      if (flags == newflags
+         || fcntl (desc, F_SETFD, newflags) != -1)
+       return 0;
+    }
 
-  newflags = (value ? flags | FD_CLOEXEC : flags & ~FD_CLOEXEC);
-
-  return (flags == newflags
-         || fcntl (desc, F_SETFD, newflags) != -1);
+  return -1;
 
 #else
 
-  return true;
+  return 0;
 
 #endif
 }




reply via email to

[Prev in Thread] Current Thread [Next in Thread]