mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-05 11:11:04 +00:00
ec6275c0b7
1999-09-10 Andreas Schwab <schwab@suse.de> * sysdeps/generic/getenv.c (getenv): Fix lookup for single character variable on bigendian platforms without unaligned memory access.
101 lines
3.0 KiB
C
101 lines
3.0 KiB
C
/* Copyright (C) 1991, 92, 94, 96, 98, 99 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 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., 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>
|
|
|
|
#ifndef HAVE_GNU_LD
|
|
#define __environ environ
|
|
#endif
|
|
|
|
/* 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;
|
|
}
|