1 files changed, 127 insertions, 0 deletions
diff --git a/lib/unsetenv.c b/lib/unsetenv.c
new file mode 100644
index 0000000..766df35
--- /dev/null
+++ b/lib/unsetenv.c
@@ -0,0 +1,127 @@
+/* Copyright (C) 1992, 1995-2002, 2005-2020 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   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
+   (at your option) 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 <https://www.gnu.org/licenses/>.  */
+
+/* Don't use __attribute__ __nonnull__ in this compilation unit.  Otherwise gcc
+   optimizes away the name == NULL test below.  */
+#define _GL_ARG_NONNULL(params)
+
+#include <config.h>
+
+/* Specification.  */
+#include <stdlib.h>
+
+#include <errno.h>
+#if !_LIBC
+# define __set_errno(ev) ((errno) = (ev))
+#endif
+
+#include <string.h>
+#include <unistd.h>
+
+#if !_LIBC
+# define __environ      environ
+#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
+
+/* In the GNU C library we must keep the namespace clean.  */
+#ifdef _LIBC
+# define unsetenv __unsetenv
+#endif
+
+#if _LIBC || !HAVE_UNSETENV
+
+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;
+}
+
+#ifdef _LIBC
+# undef unsetenv
+weak_alias (__unsetenv, unsetenv)
+#endif
+
+#else /* HAVE_UNSETENV */
+
+# undef unsetenv
+# if !HAVE_DECL_UNSETENV
+#  if VOID_UNSETENV
+extern void unsetenv (const char *);
+#  else
+extern int unsetenv (const char *);
+#  endif
+# endif
+
+/* Call the underlying unsetenv, in case there is hidden bookkeeping
+   that needs updating beyond just modifying environ.  */
+int
+rpl_unsetenv (const char *name)
+{
+  int result = 0;
+  if (!name || !*name || strchr (name, '='))
+    {
+      errno = EINVAL;
+      return -1;
+    }
+  while (getenv (name))
+# if !VOID_UNSETENV
+    result =
+# endif
+      unsetenv (name);
+  return result;
+}
+
+#endif /* HAVE_UNSETENV */