port 'forkpty' to all Unix platforms

[Bruno Haible]

Here, finally, comes the port of forkpty() to all Unix platforms.
Again, it was easy to adapt the glibc source code.


2010-03-21  Bruno Haible  <address@hidden>

        forkpty: Provide replacement on AIX, HP-UX, IRIX, Solaris.
        * lib/forkpty.c (forkpty): New replacement function, from glibc with
        modifications.
        * lib/pty.in.h (forkpty): Update declaration. Add comments.
        * m4/pty.m4 (gl_FORKPTY): If forkpty is not declared, arrange to
        provide the replacement.
        * modules/forkpty (Depends-on): Add openpty, login_tty.
        * m4/pty_h.m4 (gl_PTY_H_DEFAULTS): Initialize HAVE_FORKPTY.
        * modules/pty (Makefile.am): Substitute HAVE_FORKPTY.
        * doc/glibc-functions/forkpty.texi: More supported platforms.
        * config/srclist.txt: Add forkpty.c (commented).

--- lib/forkpty.c.orig  Mon Mar 22 02:40:38 2010
+++ lib/forkpty.c       Mon Mar 22 02:25:02 2010
@@ -1,4 +1,4 @@
-/* Fork a child attached to a pseudo-terminal descriptor.
+/* Fork a child process attached to the slave of a pseudo-terminal.
    Copyright (C) 2010 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
@@ -19,7 +19,9 @@
 /* Specification.  */
 #include <pty.h>
 
-#if HAVE_DECL_FORKPTY
+#if HAVE_FORKPTY
+
+/* Provider a wrapper with the precise POSIX prototype.  */
 # undef forkpty
 int
 rpl_forkpty (int *amaster, char *name, struct termios const *termp,
@@ -29,7 +31,43 @@
   return forkpty (amaster, name, (struct termios *) termp,
                   (struct winsize *) winp);
 }
-#else
-# error forkpty has not been ported to your system; \
-  report this to address@hidden for help
+
+#else /* AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 10, mingw */
+
+# include <pty.h>
+# include <unistd.h>
+
+extern int login_tty (int slave_fd);
+
+int
+forkpty (int *amaster, char *name,
+         const struct termios *termp, const struct winsize *winp)
+{
+  int master, slave, pid;
+
+  if (openpty (&master, &slave, name, termp, winp) == -1)
+    return -1;
+
+  switch (pid = fork ())
+    {
+    case -1:
+      close (master);
+      close (slave);
+      return -1;
+
+    case 0:
+      /* Child.  */
+      close (master);
+      if (login_tty (slave))
+        _exit (1);
+      return 0;
+
+    default:
+      /* Parent.  */
+      *amaster = master;
+      close (slave);
+      return pid;
+    }
+}
+
 #endif
--- lib/pty.in.h.orig   Mon Mar 22 02:40:38 2010
+++ lib/pty.in.h        Mon Mar 22 02:07:10 2010
@@ -48,21 +48,25 @@
 /* Declare overridden functions.  */
 
 #if @GNULIB_FORKPTY@
+/* Create pseudo tty master slave pair and set terminal attributes
+   according to TERMP and WINP.  Fork a child process attached to the
+   slave end.  Return a handle for the master end in *AMASTER, and
+   return the name of the slave end in NAME.  */
 # if @REPLACE_FORKPTY@
 #  if !(defined __cplusplus && defined GNULIB_NAMESPACE)
 #   undef forkpty
 #   define forkpty rpl_forkpty
 #  endif
 _GL_FUNCDECL_RPL (forkpty, int,
-                  (int *, char *, struct termios const *,
-                   struct winsize const *));
+                  (int *amaster, char *name,
+                   struct termios const *termp, struct winsize const *winp));
 _GL_CXXALIAS_RPL (forkpty, int,
-                  (int *, char *, struct termios const *,
-                   struct winsize const *));
+                  (int *amaster, char *name,
+                   struct termios const *termp, struct winsize const *winp));
 # else
 _GL_CXXALIAS_SYS (forkpty, int,
-                  (int *, char *, struct termios const *,
-                   struct winsize const *));
+                  (int *amaster, char *name,
+                   struct termios const *termp, struct winsize const *winp));
 # endif
 _GL_CXXALIASWARN (forkpty);
 #elif defined GNULIB_POSIXCHECK
--- m4/pty.m4.orig      Mon Mar 22 02:40:38 2010
+++ m4/pty.m4   Mon Mar 22 02:31:55 2010
@@ -1,4 +1,4 @@
-# pty.m4 serial 4
+# pty.m4 serial 5
 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,
@@ -25,6 +25,8 @@
   AC_REQUIRE([gl_PTY_LIB])
   AC_REQUIRE([gl_PTY_H])
 
+  dnl We assume that forkpty exists (possibly in libc, possibly in libutil)
+  dnl if and only if it is declared.
   AC_CHECK_DECLS([forkpty],,, [[
 #if HAVE_PTY_H
 # include <pty.h>
@@ -36,15 +38,13 @@
 # include <libutil.h>
 #endif
 ]])
-  if test $ac_cv_have_decl_forkpty = no; then
-    AC_MSG_WARN([[Cannot find forkpty, build will likely fail]])
-  fi
-
-  dnl Prefer glibc's const-safe prototype, if available.
-  AC_CACHE_CHECK([for const-safe forkpty signature],
-    [gl_cv_func_forkpty_const],
-    [AC_COMPILE_IFELSE(
-      [AC_LANG_PROGRAM([[
+  if test $ac_cv_have_decl_forkpty = yes; then
+    dnl The system has forkpty.
+    dnl Prefer glibc's const-safe prototype, if available.
+    AC_CACHE_CHECK([for const-safe forkpty signature],
+      [gl_cv_func_forkpty_const],
+      [AC_COMPILE_IFELSE(
+        [AC_LANG_PROGRAM([[
 #if HAVE_PTY_H
 # include <pty.h>
 #endif
@@ -54,13 +54,20 @@
 #if HAVE_LIBUTIL_H
 # include <libutil.h>
 #endif
-      ]], [[
-        int forkpty (int *, char *, struct termios const *,
-                     struct winsize const *);
-      ]])],
-      [gl_cv_func_forkpty_const=yes], [gl_cv_func_forkpty_const=no])])
-  if test $gl_cv_func_forkpty_const != yes; then
-    REPLACE_FORKPTY=1
+          ]], [[
+            int forkpty (int *, char *, struct termios const *,
+                         struct winsize const *);
+          ]])
+        ],
+        [gl_cv_func_forkpty_const=yes], [gl_cv_func_forkpty_const=no])
+      ])
+    if test $gl_cv_func_forkpty_const != yes; then
+      REPLACE_FORKPTY=1
+      AC_LIBOBJ([forkpty])
+    fi
+  else
+    dnl The system does not have forkpty.
+    HAVE_FORKPTY=0
     AC_LIBOBJ([forkpty])
   fi
 ])
--- modules/forkpty.orig        Mon Mar 22 02:40:38 2010
+++ modules/forkpty     Mon Mar 22 02:33:05 2010
@@ -1,5 +1,6 @@
 Description:
-Provide the forkpty() function.
+forkpty() function: Open a pseudo-terminal, fork, and connect the child process
+to the pseudo-terminal's slave.
 
 Files:
 lib/forkpty.c
@@ -7,6 +8,8 @@
 
 Depends-on:
 pty
+openpty
+login_tty
 
 configure.ac:
 gl_FORKPTY
--- m4/pty_h.m4.orig    Mon Mar 22 02:40:38 2010
+++ m4/pty_h.m4 Mon Mar 22 02:32:21 2010
@@ -1,4 +1,4 @@
-# pty_h.m4 serial 7
+# pty_h.m4 serial 8
 dnl Copyright (C) 2009, 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,
@@ -60,6 +60,7 @@
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_UTIL_H=0;        AC_SUBST([HAVE_UTIL_H])
   HAVE_LIBUTIL_H=0;     AC_SUBST([HAVE_LIBUTIL_H])
+  HAVE_FORKPTY=1;       AC_SUBST([HAVE_FORKPTY])
   HAVE_OPENPTY=1;       AC_SUBST([HAVE_OPENPTY])
   REPLACE_FORKPTY=0;    AC_SUBST([REPLACE_FORKPTY])
   REPLACE_OPENPTY=0;    AC_SUBST([REPLACE_OPENPTY])
--- modules/pty.orig    Mon Mar 22 02:40:38 2010
+++ modules/pty Mon Mar 22 02:33:45 2010
@@ -29,6 +29,7 @@
              -e 's|@''GNULIB_OPENPTY''@|$(GNULIB_OPENPTY)|g' \
              -e 's|@''HAVE_UTIL_H''@|$(HAVE_UTIL_H)|g' \
              -e 's|@''HAVE_LIBUTIL_H''@|$(HAVE_LIBUTIL_H)|g' \
+             -e 's|@''HAVE_FORKPTY''@|$(HAVE_FORKPTY)|g' \
              -e 's|@''HAVE_OPENPTY''@|$(HAVE_OPENPTY)|g' \
              -e 's|@''REPLACE_FORKPTY''@|$(REPLACE_FORKPTY)|g' \
              -e 's|@''REPLACE_OPENPTY''@|$(REPLACE_OPENPTY)|g' \
--- doc/glibc-functions/forkpty.texi.orig       Mon Mar 22 02:40:38 2010
+++ doc/glibc-functions/forkpty.texi    Mon Mar 22 02:27:49 2010
@@ -7,6 +7,9 @@
 Portability problems fixed by Gnulib:
 @itemize
 @item
+This function is missing on some platforms:
+AIX 5.1, HP-UX 11, IRIX 6.5, Solaris 10, mingw.
address@hidden
 One some systems (at least including Cygwin, Interix, OSF/1 4 and 5,
 and Mac OS X) linking with @code{-lutil} is not required.
 @item
@@ -24,6 +27,4 @@
 
 Portability problems not fixed by Gnulib:
 @itemize
-On some systems (at least including Solaris and HP-UX) the function is
-missing.
 @end itemize
--- config/srclist.txt.orig     Mon Mar 22 02:40:38 2010
+++ config/srclist.txt  Mon Mar 22 02:40:24 2010
@@ -174,6 +174,7 @@
 #$LIBCSRC/locale/programs/xmalloc.c    lib gpl
 #$LIBCSRC/locale/programs/xstrdup.c    lib gpl
 #
+#$LIBCSRC/login/forkpty.c              lib gpl
 #$LIBCSRC/login/programs/pt_chown.c    lib gpl
 #
 # http://sources.redhat.com/bugzilla/show_bug.cgi?id=321