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* Copyright (C) 2010 The Android Open Source Project
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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#include "linker_environ.h"
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/* Returns 1 if 'str' points to a valid environment variable definition.
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* For now, we check that:
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* - It is smaller than MAX_ENV_LEN (to detect non-zero terminated strings)
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* - It contains at least one equal sign that is not the first character
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_is_valid_definition(const char* str)
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int first_equal_pos = -1;
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/* According to its sources, the kernel uses 32*PAGE_SIZE by default
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* as the maximum size for an env. variable definition.
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const int MAX_ENV_LEN = 32*4096;
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/* Parse the string, looking for the first '=' there, and its size */
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if (str[pos] == '=' && first_equal_pos < 0)
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first_equal_pos = pos;
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} while (pos < MAX_ENV_LEN);
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if (pos >= MAX_ENV_LEN) /* Too large */
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if (first_equal_pos < 1) /* No equal sign, or it is the first character */
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linker_env_init(unsigned* vecs)
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/* Store environment pointer - can't be NULL */
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_envp = (char**) vecs;
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/* Skip over all definitions */
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/* The end of the environment block is marked by two NULL pointers */
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/* As a sanity check, we're going to remove all invalid variable
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* definitions from the environment array.
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char** writep = _envp;
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for ( ; readp[0] != NULL; readp++ ) {
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if (!_is_valid_definition(readp[0]))
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/* Return the address of the aux vectors table */
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/* Check if the environment variable definition at 'envstr'
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* starts with '<name>=', and if so return the address of the
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* first character after the equal sign. Otherwise return NULL.
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env_match(char* envstr, const char* name)
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while (envstr[cnt] == name[cnt] && name[cnt] != '\0')
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if (name[cnt] == '\0' && envstr[cnt] == '=')
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return envstr + cnt + 1;
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#define MAX_ENV_LEN (16*4096)
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linker_env_get(const char* name)
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char** readp = _envp;
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if (name == NULL || name[0] == '\0')
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for ( ; readp[0] != NULL; readp++ ) {
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char* val = env_match(readp[0], name);
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/* Return NULL for empty strings, or if it is too large */
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linker_env_unset(const char* name)
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char** readp = _envp;
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char** writep = readp;
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if (name == NULL || name[0] == '\0')
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for ( ; readp[0] != NULL; readp++ ) {
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if (env_match(readp[0], name))
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writep[0] = readp[0];
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/* end list with a NULL */
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/* Remove unsafe environment variables. This should be used when
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* running setuid programs. */
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linker_env_secure(void)
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/* The same list than GLibc at this point */
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static const char* const unsec_vars[] = {
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"LD_AOUT_LIBRARY_PATH",
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const char* const* cp = unsec_vars;
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const char* const* endp = cp + sizeof(unsec_vars)/sizeof(unsec_vars[0]);
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linker_env_unset(*cp);
added
removed
hybris/common/gingerbread/linker_environ.c
