Re: ttyname_r on Mac

[Bruno Haible]

Hi Simon,

> There appears to be a ttyname_r signature bug, see:
> http://autobuild.josefsson.org/gnulib/log-201004250717723515000.txt
> 
> g++ -DHAVE_CONFIG_H -I.  -DGNULIB_STRICT_CHECKING=1 -I. -I. -I.. -I./.. 
> -I../gllib -I./../gllib -I/opt/local/include   -MT test-fcntl-h-c++.o -MD -MP 
> -MF $depbase.Tpo -c -o test-fcntl-h-c++.o test-fcntl-h-c++.cc &&\
> mv -f $depbase.Tpo $depbase.Po
> ../gllib/unistd.h:1463: error: invalid conversion from 'char* (*)(int, char*, 
> size_t)' to 'int (*)(int, char*, size_t)'
> make[4]: *** [test-fcntl-h-c++.o] Error 1

Oh, indeed, it has a different return type. This problem was not known to us
before.

> /usr/include/unistd.h contains:
> 
> #if __DARWIN_UNIX03
> int      ttyname_r(int, char *, size_t) __DARWIN_ALIAS(ttyname_r);
> #else /* !__DARWIN_UNIX03 */
> char    *ttyname_r(int, char *, size_t);
> #endif /* __DARWIN_UNIX03 */
> 
> So it seems ttyname_r on older Mac OS X versions returned char*.

Yes. The attached patch fixes it for Solaris 10 and - presumably - also
on the MacOS X 10.4 that you are using.

> Should we define __DARWIN_UNIX03?  I'm not sure how well supported that
> is.

It has become the default in MacOS X 10.5. The fact that it's not enabled
by default in MacOS X 10.4 is a hint that it was not mature at that time.

> Maybe we want to define _APPLE_C_SOURCE?

I wouldn't do it, because
  - On MacOS X 10.3 this flag has no effect, and while MacOS X 10.3 is old
    some machine with it are likely still in use.
  - In MacOS X 10.5 this flag has been renamed to _DARWIN_C_SOURCE.

Bruno


2010-04-25  Bruno Haible  <address@hidden>

        ttyname_r: Make it work on MacOS X 10.4 and Solaris 10.
        * m4/ttyname_r.m4 (gl_FUNC_TTYNAME_R): Test whether the system function
        has the POSIX declaration. Set REPLACE_TTYNAME_R if not.
        * lib/ttyname_r.c: Include <limits.h>.
        (ttyname_r): Define using the system's ttyname_r function, if it exists
        and not on Solaris.
        * lib/unistd.in.h (ttyname_r): Replace function if REPLACE_TTYNAME_R is
        set.
        * m4/unistd_h.m4 (gl_UNISTD_H_DEFAULTS): Initialize REPLACE_TTYNAME_R.
        * modules/unistd (Makefile.am): Substitute REPLACE_TTYNAME_R.
        * doc/posix-functions/ttyname_r.texi: Mark the problem as fixed.
        Reported by Simon Josefsson.

--- doc/posix-functions/ttyname_r.texi.orig     Sun Apr 25 20:52:29 2010
+++ doc/posix-functions/ttyname_r.texi  Sun Apr 25 20:20:04 2010
@@ -11,11 +11,11 @@
 @item
 This function is missing on some platforms:
 NetBSD 3.0, mingw, BeOS.
address@hidden
+This function has an incompatible declaration on some platforms:
+MacOS X 10.4, Solaris 10 (when @code{_POSIX_PTHREAD_SEMANTICS} is not defined).
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
address@hidden
-This function has an incompatible declaration on some platforms:
-MacOS X 10.4, Solaris 10 (when @code{_POSIX_PTHREAD_SEMANTICS} is not defined).
 @end itemize
--- lib/ttyname_r.c.orig        Sun Apr 25 20:52:29 2010
+++ lib/ttyname_r.c     Sun Apr 25 20:50:26 2010
@@ -22,12 +22,30 @@
 #include <unistd.h>
 
 #include <errno.h>
+#include <limits.h>
 #include <string.h>
 
 int
 ttyname_r (int fd, char *buf, size_t buflen)
+#undef ttyname_r
 {
-#if HAVE_TTYNAME
+  /* When ttyname_r exists and works, use it.
+     But on Solaris 10, ttyname_r is broken: it returns NULL in situations
+     when ttyname finds the result.  */
+#if HAVE_TTYNAME_R && !defined __sun
+  /* This code is multithread-safe.  */
+  char *name = ttyname_r (fd, buf, buflen <= INT_MAX ? buflen : INT_MAX);
+  if (name == NULL)
+    return errno;
+  if (name != buf)
+    {
+      size_t namelen = strlen (name) + 1;
+      if (namelen > buflen)
+        return ERANGE;
+      memmove (buf, name, namelen);
+    }
+  return 0;
+#elif HAVE_TTYNAME
   /* Note: This is not multithread-safe.  */
   char *name;
   size_t namelen;
--- lib/unistd.in.h.orig        Sun Apr 25 20:52:29 2010
+++ lib/unistd.in.h     Sun Apr 25 19:09:07 2010
@@ -1164,12 +1164,23 @@
 #if @GNULIB_TTYNAME_R@
 /* Store at most BUFLEN characters of the pathname of the terminal FD is
    open on in BUF.  Return 0 on success, otherwise an error number.  */
-# if address@hidden@
+# if @REPLACE_TTYNAME_R@
+#  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
+#   undef ttyname_r
+#   define ttyname_r rpl_ttyname_r
+#  endif
+_GL_FUNCDECL_RPL (ttyname_r, int,
+                  (int fd, char *buf, size_t buflen) _GL_ARG_NONNULL ((2)));
+_GL_CXXALIAS_RPL (ttyname_r, int,
+                  (int fd, char *buf, size_t buflen));
+# else
+#  if address@hidden@
 _GL_FUNCDECL_SYS (ttyname_r, int,
                   (int fd, char *buf, size_t buflen) _GL_ARG_NONNULL ((2)));
-# endif
+#  endif
 _GL_CXXALIAS_SYS (ttyname_r, int,
                   (int fd, char *buf, size_t buflen));
+# endif
 _GL_CXXALIASWARN (ttyname_r);
 #elif defined GNULIB_POSIXCHECK
 # undef ttyname_r
--- m4/ttyname_r.m4.orig        Sun Apr 25 20:52:29 2010
+++ m4/ttyname_r.m4     Sun Apr 25 20:22:44 2010
@@ -1,4 +1,4 @@
-# ttyname_r.m4 serial 1
+# ttyname_r.m4 serial 2
 dnl Copyright (C) 2010 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -11,6 +11,24 @@
   AC_CHECK_FUNCS([ttyname_r])
   if test $ac_cv_func_ttyname_r = no; then
     HAVE_TTYNAME_R=0
+  else
+    dnl On MacOS X 10.4 and Solaris 10 the return type is 'char *', not 'int'.
+    AC_CACHE_CHECK([whether ttyname_r is compatible with its POSIX signature],
+      [gl_cv_func_ttyname_r_posix],
+      [AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [[#include <stddef.h>
+              #include <unistd.h>]],
+            [[*ttyname_r (0, NULL, 0);]])
+         ],
+         [gl_cv_func_ttyname_r_posix=no],
+         [gl_cv_func_ttyname_r_posix=yes])
+      ])
+    if test $gl_cv_func_ttyname_r_posix = no; then
+      REPLACE_TTYNAME_R=1
+    fi
+  fi
+  if test $HAVE_TTYNAME_R = 0 || test $REPLACE_TTYNAME_R = 1; then
     AC_LIBOBJ([ttyname_r])
     gl_PREREQ_TTYNAME_R
   fi
--- m4/unistd_h.m4.orig Sun Apr 25 20:52:29 2010
+++ m4/unistd_h.m4      Sun Apr 25 19:10:18 2010
@@ -1,4 +1,4 @@
-# unistd_h.m4 serial 45
+# unistd_h.m4 serial 46
 dnl Copyright (C) 2006-2010 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -144,6 +144,7 @@
   REPLACE_RMDIR=0;        AC_SUBST([REPLACE_RMDIR])
   REPLACE_SLEEP=0;        AC_SUBST([REPLACE_SLEEP])
   REPLACE_SYMLINK=0;      AC_SUBST([REPLACE_SYMLINK])
+  REPLACE_TTYNAME_R=0;    AC_SUBST([REPLACE_TTYNAME_R])
   REPLACE_UNLINK=0;       AC_SUBST([REPLACE_UNLINK])
   REPLACE_UNLINKAT=0;     AC_SUBST([REPLACE_UNLINKAT])
   REPLACE_USLEEP=0;       AC_SUBST([REPLACE_USLEEP])
--- modules/unistd.orig Sun Apr 25 20:52:29 2010
+++ modules/unistd      Sun Apr 25 19:09:47 2010
@@ -118,6 +118,7 @@
              -e 's|@''REPLACE_RMDIR''@|$(REPLACE_RMDIR)|g' \
              -e 's|@''REPLACE_SLEEP''@|$(REPLACE_SLEEP)|g' \
              -e 's|@''REPLACE_SYMLINK''@|$(REPLACE_SYMLINK)|g' \
+             -e 's|@''REPLACE_TTYNAME_R''@|$(REPLACE_TTYNAME_R)|g' \
              -e 's|@''REPLACE_UNLINK''@|$(REPLACE_UNLINK)|g' \
              -e 's|@''REPLACE_UNLINKAT''@|$(REPLACE_UNLINKAT)|g' \
              -e 's|@''REPLACE_USLEEP''@|$(REPLACE_USLEEP)|g' \