Update.

[thirdparty/glibc.git] / sysdeps / generic / getenv.c

diff --git a/sysdeps/generic/getenv.c b/sysdeps/generic/getenv.c
index daf292743a21960c6dab2435cbad6892cddac6f8..b6f405df08078ec21f32063f38c8ba953dc24bd5 100644 (file)
--- a/sysdeps/generic/getenv.c
+++ b/sysdeps/generic/getenv.c
@@ -1,22 +1,24 @@
-/* Copyright (C) 1991, 1992, 1994, 1996 Free Software Foundation, Inc.
-This file is part of the GNU C Library.
+/* Copyright (C) 1991, 1992, 1994, 1996, 1998 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 Library General Public License as
-published by the Free Software Foundation; either version 2 of the
-License, or (at your option) any later version.
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 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
-Library General Public License for more details.
+   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
+   Library General Public License for more details.
 
-You should have received a copy of the GNU Library General Public
-License along with the GNU C Library; see the file COPYING.LIB.  If
-not, write to the Free Software Foundation, Inc., 675 Mass Ave,
-Cambridge, MA 02139, USA.  */
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  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>
@@ -25,31 +27,74 @@ Cambridge, MA 02139, USA.  */
 #define        __environ       environ
 #endif
 
-/* Return the value of the environment variable NAME.  */
+/* 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;
 {
   const size_t len = strlen (name);
   char **ep;
+  uint16_t name_start;
 
-  if (__environ == NULL)
+  if (__environ == NULL || name[0] == '\0')
     return NULL;
 
-  for (ep = __environ; *ep != NULL; ++ep)
-    if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
-      return &(*ep)[len + 1];
+  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
+      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;
 
-  return NULL;
-}
+      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];
+       }
+    }
 
-/* Some programs and especially the libc itself have to be careful
-   what values to accept from the environment.  This special version
-   checks for SUID or SGID first before doing any work.  */
-char *
-__secure_getenv (name)
-     const char *name;
-{
-  return __libc_enable_secure ? NULL : getenv (name);
+  return NULL;
 }