Use putenv+unsetenv instead of modifying environ directly.

* admin/merge-gnulib (GNULIB_MODULES): Add putenv, unsetenv.
* lib/putenv.c, lib/unsetenv.c, m4/putenv.m4, m4/setenv.m4:
New files, copied automatically from gnulib.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* src/alloc.c (xputenv): New function.
* src/dbusbind.c (Fdbus_init_bus):
* src/emacs.c (main):
* src/xterm.c (x_term_init):
Use xputenv instead of setenv or putenv, to detect memory exhaustion.
* src/editfns.c (initial_tz): Move static var decl up.
(tzvalbuf_in_environ): New static var.
(init_editfns):	Initialize these two static vars.
(Fencode_time): Don't assume arbitrary limit on EMACS_INT width.
Save old TZ value on stack, if it's small.
(Fencode_time, set_time_zone_rule): Don't modify 'environ' directly;
instead, use xputenv+unsetenv to set and restore TZ.
(environbuf): Remove static var.  All uses removed.
(Fset_time_zone_rule): Do not save TZ and environ;
no longer needed here.
(set_time_zone_rule_tz1, set_time_zone_rule_tz2) [LOCALTIME_CACHE]:
Move to inside set_time_zone_rule; they don't need file scope any more.
(set_time_zone_rule): Maintain the TZ=value string separately.
(syms_of_editfns): Don't initialize initial_tz;
init_editfns now does it.
* src/emacs.c (dump_tz) [HAVE_TZSET]: Now const.
* src/lisp.h (xputenv): New decl.

Fixes: debbugs:13070

1 files changed, 134 insertions, 0 deletions

diff --git a/lib/putenv.c b/lib/putenv.c
new file mode 100644
index 00000000000..3c0f7ead330
--- /dev/null
+++ b/lib/putenv.c
@@ -0,0 +1,134 @@
+/* Copyright (C) 1991, 1994, 1997-1998, 2000, 2003-2012 Free Software
+   Foundation, Inc.
+
+   NOTE: The canonical source of this file is maintained with the GNU C
+   Library.  Bugs can be reported to bug-glibc@prep.ai.mit.edu.
+
+   This program is free software: you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by the
+   Free Software Foundation; either version 3 of the License, or any
+   later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+/* Specification.  */
+#include <stdlib.h>
+
+#include <stddef.h>
+
+/* Include errno.h *after* sys/types.h to work around header problems
+   on AIX 3.2.5.  */
+#include <errno.h>
+#ifndef __set_errno
+# define __set_errno(ev) ((errno) = (ev))
+#endif
+
+#include <string.h>
+#include <unistd.h>
+
+#if _LIBC
+# if HAVE_GNU_LD
+#  define environ __environ
+# else
+extern char **environ;
+# endif
+#endif
+
+#if _LIBC
+/* This lock protects against simultaneous modifications of 'environ'.  */
+# include <bits/libc-lock.h>
+__libc_lock_define_initialized (static, envlock)
+# define LOCK   __libc_lock_lock (envlock)
+# define UNLOCK __libc_lock_unlock (envlock)
+#else
+# define LOCK
+# define UNLOCK
+#endif
+
+static int
+_unsetenv (const char *name)
+{
+  size_t len;
+  char **ep;
+
+  if (name == NULL || *name == '\0' || strchr (name, '=') != NULL)
+    {
+      __set_errno (EINVAL);
+      return -1;
+    }
+
+  len = strlen (name);
+
+  LOCK;
+
+  ep = environ;
+  while (*ep != NULL)
+    if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
+      {
+        /* Found it.  Remove this pointer by moving later ones back.  */
+        char **dp = ep;
+
+        do
+          dp[0] = dp[1];
+        while (*dp++);
+        /* Continue the loop in case NAME appears again.  */
+      }
+    else
+      ++ep;
+
+  UNLOCK;
+
+  return 0;
+}
+
+
+/* Put STRING, which is of the form "NAME=VALUE", in the environment.
+   If STRING contains no '=', then remove STRING from the environment.  */
+int
+putenv (char *string)
+{
+  const char *const name_end = strchr (string, '=');
+  register size_t size;
+  register char **ep;
+
+  if (name_end == NULL)
+    {
+      /* Remove the variable from the environment.  */
+      return _unsetenv (string);
+    }
+
+  size = 0;
+  for (ep = environ; *ep != NULL; ++ep)
+    if (!strncmp (*ep, string, name_end - string) &&
+        (*ep)[name_end - string] == '=')
+      break;
+    else
+      ++size;
+
+  if (*ep == NULL)
+    {
+      static char **last_environ = NULL;
+      char **new_environ = (char **) malloc ((size + 2) * sizeof (char *));
+      if (new_environ == NULL)
+        return -1;
+      (void) memcpy ((void *) new_environ, (void *) environ,
+                     size * sizeof (char *));
+      new_environ[size] = (char *) string;
+      new_environ[size + 1] = NULL;
+      free (last_environ);
+      last_environ = new_environ;
+      environ = new_environ;
+    }
+  else
+    *ep = string;
+
+  return 0;
+}