Prepare for radical source tree reorganization. zack/build-layout-experiment

All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).

1 files changed, 92 insertions, 0 deletions

diff --git a/REORG.TODO/stdlib/getenv.c b/REORG.TODO/stdlib/getenv.c
new file mode 100644
index 0000000000..b6fb1abeaa
--- /dev/null
+++ b/REORG.TODO/stdlib/getenv.c
@@ -0,0 +1,92 @@
+/* Copyright (C) 1991-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <endian.h>
+#include <errno.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+
+/* Return the value of the environment variable NAME.  This implementation
+   is tuned a bit in that it assumes no environment variable has an empty
+   name which of course should always be true.  We have a special case for
+   one character names so that for the general case we can assume at least
+   two characters which we can access.  By doing this we can avoid using the
+   `strncmp' most of the time.  */
+char *
+getenv (const char *name)
+{
+  size_t len = strlen (name);
+  char **ep;
+  uint16_t name_start;
+
+  if (__environ == NULL || name[0] == '\0')
+    return NULL;
+
+  if (name[1] == '\0')
+    {
+      /* The name of the variable consists of only one character.  Therefore
+	 the first two characters of the environment entry are this character
+	 and a '=' character.  */
+#if __BYTE_ORDER == __LITTLE_ENDIAN || !_STRING_ARCH_unaligned
+      name_start = ('=' << 8) | *(const unsigned char *) name;
+#else
+      name_start = '=' | ((*(const unsigned char *) name) << 8);
+#endif
+      for (ep = __environ; *ep != NULL; ++ep)
+	{
+#if _STRING_ARCH_unaligned
+	  uint16_t ep_start = *(uint16_t *) *ep;
+#else
+	  uint16_t ep_start = (((unsigned char *) *ep)[0]
+			       | (((unsigned char *) *ep)[1] << 8));
+#endif
+	  if (name_start == ep_start)
+	    return &(*ep)[2];
+	}
+    }
+  else
+    {
+#if _STRING_ARCH_unaligned
+      name_start = *(const uint16_t *) name;
+#else
+      name_start = (((const unsigned char *) name)[0]
+		    | (((const unsigned char *) name)[1] << 8));
+#endif
+      len -= 2;
+      name += 2;
+
+      for (ep = __environ; *ep != NULL; ++ep)
+	{
+#if _STRING_ARCH_unaligned
+	  uint16_t ep_start = *(uint16_t *) *ep;
+#else
+	  uint16_t ep_start = (((unsigned char *) *ep)[0]
+			       | (((unsigned char *) *ep)[1] << 8));
+#endif
+
+	  if (name_start == ep_start && !strncmp (*ep + 2, name, len)
+	      && (*ep)[len + 2] == '=')
+	    return &(*ep)[len + 3];
+	}
+    }
+
+  return NULL;
+}
+libc_hidden_def (getenv)