2.5-18.1

1 files changed, 98 insertions, 0 deletions

diff --git a/stdlib/getenv.c b/stdlib/getenv.c
new file mode 100644
index 0000000000..6cdfe2b266
--- /dev/null
+++ b/stdlib/getenv.c
@@ -0,0 +1,98 @@
+/* Copyright (C) 1991,92,94,96,98,99,2002,2005 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, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#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 (name)
+     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
+# if __BYTE_ORDER == __BIG_ENDIAN
+      name_start = '=' | ((*(const unsigned char *) name) << 8);
+# else
+ #error "Funny byte order."
+# endif
+#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)