freebsd-skq/lib/libc/stdlib/getenv.c
Pedro F. Giffuni d915a14ef0 libc: further adoption of SPDX licensing ID tags.
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using mis-identified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.
2017-11-25 17:12:48 +00:00

694 lines
17 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2007-2009 Sean C. Farley <scf@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer,
* without modification, immediately at the beginning of the file.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "namespace.h"
#include <sys/types.h>
#include <errno.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "un-namespace.h"
static const char CorruptEnvFindMsg[] = "environment corrupt; unable to find ";
static const char CorruptEnvValueMsg[] =
"environment corrupt; missing value for ";
/*
* Standard environ. environ variable is exposed to entire process.
*
* origEnviron: Upon cleanup on unloading of library or failure, this
* allows environ to return to as it was before.
* environSize: Number of variables environ can hold. Can only
* increase.
* intEnviron: Internally-built environ. Exposed via environ during
* (re)builds of the environment.
*/
extern char **environ;
static char **origEnviron;
static char **intEnviron = NULL;
static int environSize = 0;
/*
* Array of environment variables built from environ. Each element records:
* name: Pointer to name=value string
* name length: Length of name not counting '=' character
* value: Pointer to value within same string as name
* value size: Size (not length) of space for value not counting the
* nul character
* active state: true/false value to signify whether variable is active.
* Useful since multiple variables with the same name can
* co-exist. At most, one variable can be active at any
* one time.
* putenv: Created from putenv() call. This memory must not be
* reused.
*/
static struct envVars {
size_t nameLen;
size_t valueSize;
char *name;
char *value;
bool active;
bool putenv;
} *envVars = NULL;
/*
* Environment array information.
*
* envActive: Number of active variables in array.
* envVarsSize: Size of array.
* envVarsTotal: Number of total variables in array (active or not).
*/
static int envActive = 0;
static int envVarsSize = 0;
static int envVarsTotal = 0;
/* Deinitialization of new environment. */
static void __attribute__ ((destructor)) __clean_env_destructor(void);
/*
* A simple version of warnx() to avoid the bloat of including stdio in static
* binaries.
*/
static void
__env_warnx(const char *msg, const char *name, size_t nameLen)
{
static const char nl[] = "\n";
static const char progSep[] = ": ";
_write(STDERR_FILENO, _getprogname(), strlen(_getprogname()));
_write(STDERR_FILENO, progSep, sizeof(progSep) - 1);
_write(STDERR_FILENO, msg, strlen(msg));
_write(STDERR_FILENO, name, nameLen);
_write(STDERR_FILENO, nl, sizeof(nl) - 1);
return;
}
/*
* Inline strlen() for performance. Also, perform check for an equals sign.
* Cheaper here than peforming a strchr() later.
*/
static inline size_t
__strleneq(const char *str)
{
const char *s;
for (s = str; *s != '\0'; ++s)
if (*s == '=')
return (0);
return (s - str);
}
/*
* Comparison of an environment name=value to a name.
*/
static inline bool
strncmpeq(const char *nameValue, const char *name, size_t nameLen)
{
if (strncmp(nameValue, name, nameLen) == 0 && nameValue[nameLen] == '=')
return (true);
return (false);
}
/*
* Using environment, returns pointer to value associated with name, if any,
* else NULL. If the onlyActive flag is set to true, only variables that are
* active are returned else all are.
*/
static inline char *
__findenv(const char *name, size_t nameLen, int *envNdx, bool onlyActive)
{
int ndx;
/*
* Find environment variable from end of array (more likely to be
* active). A variable created by putenv is always active, or it is not
* tracked in the array.
*/
for (ndx = *envNdx; ndx >= 0; ndx--)
if (envVars[ndx].putenv) {
if (strncmpeq(envVars[ndx].name, name, nameLen)) {
*envNdx = ndx;
return (envVars[ndx].name + nameLen +
sizeof ("=") - 1);
}
} else if ((!onlyActive || envVars[ndx].active) &&
(envVars[ndx].nameLen == nameLen &&
strncmpeq(envVars[ndx].name, name, nameLen))) {
*envNdx = ndx;
return (envVars[ndx].value);
}
return (NULL);
}
/*
* Using environ, returns pointer to value associated with name, if any, else
* NULL. Used on the original environ passed into the program.
*/
static char *
__findenv_environ(const char *name, size_t nameLen)
{
int envNdx;
/* Find variable within environ. */
for (envNdx = 0; environ[envNdx] != NULL; envNdx++)
if (strncmpeq(environ[envNdx], name, nameLen))
return (&(environ[envNdx][nameLen + sizeof("=") - 1]));
return (NULL);
}
/*
* Remove variable added by putenv() from variable tracking array.
*/
static void
__remove_putenv(int envNdx)
{
envVarsTotal--;
if (envVarsTotal > envNdx)
memmove(&(envVars[envNdx]), &(envVars[envNdx + 1]),
(envVarsTotal - envNdx) * sizeof (*envVars));
memset(&(envVars[envVarsTotal]), 0, sizeof (*envVars));
return;
}
/*
* Deallocate the environment built from environ as well as environ then set
* both to NULL. Eases debugging of memory leaks.
*/
static void
__clean_env(bool freeVars)
{
int envNdx;
/* Deallocate environment and environ if created by *env(). */
if (envVars != NULL) {
for (envNdx = envVarsTotal - 1; envNdx >= 0; envNdx--)
/* Free variables or deactivate them. */
if (envVars[envNdx].putenv) {
if (!freeVars)
__remove_putenv(envNdx);
} else {
if (freeVars)
free(envVars[envNdx].name);
else
envVars[envNdx].active = false;
}
if (freeVars) {
free(envVars);
envVars = NULL;
} else
envActive = 0;
/* Restore original environ if it has not updated by program. */
if (origEnviron != NULL) {
if (environ == intEnviron)
environ = origEnviron;
free(intEnviron);
intEnviron = NULL;
environSize = 0;
}
}
return;
}
/*
* Using the environment, rebuild the environ array for use by other C library
* calls that depend upon it.
*/
static int
__rebuild_environ(int newEnvironSize)
{
char **tmpEnviron;
int envNdx;
int environNdx;
int tmpEnvironSize;
/* Resize environ. */
if (newEnvironSize > environSize) {
tmpEnvironSize = newEnvironSize * 2;
tmpEnviron = reallocarray(intEnviron, tmpEnvironSize + 1,
sizeof(*intEnviron));
if (tmpEnviron == NULL)
return (-1);
environSize = tmpEnvironSize;
intEnviron = tmpEnviron;
}
envActive = newEnvironSize;
/* Assign active variables to environ. */
for (envNdx = envVarsTotal - 1, environNdx = 0; envNdx >= 0; envNdx--)
if (envVars[envNdx].active)
intEnviron[environNdx++] = envVars[envNdx].name;
intEnviron[environNdx] = NULL;
/* Always set environ which may have been replaced by program. */
environ = intEnviron;
return (0);
}
/*
* Enlarge new environment.
*/
static inline bool
__enlarge_env(void)
{
int newEnvVarsSize;
struct envVars *tmpEnvVars;
envVarsTotal++;
if (envVarsTotal > envVarsSize) {
newEnvVarsSize = envVarsTotal * 2;
tmpEnvVars = reallocarray(envVars, newEnvVarsSize,
sizeof(*envVars));
if (tmpEnvVars == NULL) {
envVarsTotal--;
return (false);
}
envVarsSize = newEnvVarsSize;
envVars = tmpEnvVars;
}
return (true);
}
/*
* Using environ, build an environment for use by standard C library calls.
*/
static int
__build_env(void)
{
char **env;
int activeNdx;
int envNdx;
int savedErrno;
size_t nameLen;
/* Check for non-existant environment. */
if (environ == NULL || environ[0] == NULL)
return (0);
/* Count environment variables. */
for (env = environ, envVarsTotal = 0; *env != NULL; env++)
envVarsTotal++;
envVarsSize = envVarsTotal * 2;
/* Create new environment. */
envVars = calloc(envVarsSize, sizeof(*envVars));
if (envVars == NULL)
goto Failure;
/* Copy environ values and keep track of them. */
for (envNdx = envVarsTotal - 1; envNdx >= 0; envNdx--) {
envVars[envNdx].putenv = false;
envVars[envNdx].name =
strdup(environ[envVarsTotal - envNdx - 1]);
if (envVars[envNdx].name == NULL)
goto Failure;
envVars[envNdx].value = strchr(envVars[envNdx].name, '=');
if (envVars[envNdx].value != NULL) {
envVars[envNdx].value++;
envVars[envNdx].valueSize =
strlen(envVars[envNdx].value);
} else {
__env_warnx(CorruptEnvValueMsg, envVars[envNdx].name,
strlen(envVars[envNdx].name));
errno = EFAULT;
goto Failure;
}
/*
* Find most current version of variable to make active. This
* will prevent multiple active variables from being created
* during this initialization phase.
*/
nameLen = envVars[envNdx].value - envVars[envNdx].name - 1;
envVars[envNdx].nameLen = nameLen;
activeNdx = envVarsTotal - 1;
if (__findenv(envVars[envNdx].name, nameLen, &activeNdx,
false) == NULL) {
__env_warnx(CorruptEnvFindMsg, envVars[envNdx].name,
nameLen);
errno = EFAULT;
goto Failure;
}
envVars[activeNdx].active = true;
}
/* Create a new environ. */
origEnviron = environ;
environ = NULL;
if (__rebuild_environ(envVarsTotal) == 0)
return (0);
Failure:
savedErrno = errno;
__clean_env(true);
errno = savedErrno;
return (-1);
}
/*
* Destructor function with default argument to __clean_env().
*/
static void
__clean_env_destructor(void)
{
__clean_env(true);
return;
}
/*
* Returns the value of a variable or NULL if none are found.
*/
char *
getenv(const char *name)
{
int envNdx;
size_t nameLen;
/* Check for malformed name. */
if (name == NULL || (nameLen = __strleneq(name)) == 0) {
errno = EINVAL;
return (NULL);
}
/*
* Variable search order:
* 1. Check for an empty environ. This allows an application to clear
* the environment.
* 2. Search the external environ array.
* 3. Search the internal environment.
*
* Since malloc() depends upon getenv(), getenv() must never cause the
* internal environment storage to be generated.
*/
if (environ == NULL || environ[0] == NULL)
return (NULL);
else if (envVars == NULL || environ != intEnviron)
return (__findenv_environ(name, nameLen));
else {
envNdx = envVarsTotal - 1;
return (__findenv(name, nameLen, &envNdx, true));
}
}
/*
* Set the value of a variable. Older settings are labeled as inactive. If an
* older setting has enough room to store the new value, it will be reused. No
* previous variables are ever freed here to avoid causing a segmentation fault
* in a user's code.
*
* The variables nameLen and valueLen are passed into here to allow the caller
* to calculate the length by means besides just strlen().
*/
static int
__setenv(const char *name, size_t nameLen, const char *value, int overwrite)
{
bool reuse;
char *env;
int envNdx;
int newEnvActive;
size_t valueLen;
/* Find existing environment variable large enough to use. */
envNdx = envVarsTotal - 1;
newEnvActive = envActive;
valueLen = strlen(value);
reuse = false;
if (__findenv(name, nameLen, &envNdx, false) != NULL) {
/* Deactivate entry if overwrite is allowed. */
if (envVars[envNdx].active) {
if (overwrite == 0)
return (0);
envVars[envNdx].active = false;
newEnvActive--;
}
/* putenv() created variable cannot be reused. */
if (envVars[envNdx].putenv)
__remove_putenv(envNdx);
/* Entry is large enough to reuse. */
else if (envVars[envNdx].valueSize >= valueLen)
reuse = true;
}
/* Create new variable if none was found of sufficient size. */
if (! reuse) {
/* Enlarge environment. */
envNdx = envVarsTotal;
if (!__enlarge_env())
return (-1);
/* Create environment entry. */
envVars[envNdx].name = malloc(nameLen + sizeof ("=") +
valueLen);
if (envVars[envNdx].name == NULL) {
envVarsTotal--;
return (-1);
}
envVars[envNdx].nameLen = nameLen;
envVars[envNdx].valueSize = valueLen;
/* Save name of name/value pair. */
env = stpncpy(envVars[envNdx].name, name, nameLen);
*env++ = '=';
}
else
env = envVars[envNdx].value;
/* Save value of name/value pair. */
strcpy(env, value);
envVars[envNdx].value = env;
envVars[envNdx].active = true;
newEnvActive++;
/* No need to rebuild environ if an active variable was reused. */
if (reuse && newEnvActive == envActive)
return (0);
else
return (__rebuild_environ(newEnvActive));
}
/*
* If the program attempts to replace the array of environment variables
* (environ) environ or sets the first varible to NULL, then deactivate all
* variables and merge in the new list from environ.
*/
static int
__merge_environ(void)
{
char **env;
char *equals;
/*
* Internally-built environ has been replaced or cleared (detected by
* using the count of active variables against a NULL as the first value
* in environ). Clean up everything.
*/
if (intEnviron != NULL && (environ != intEnviron || (envActive > 0 &&
environ[0] == NULL))) {
/* Deactivate all environment variables. */
if (envActive > 0) {
origEnviron = NULL;
__clean_env(false);
}
/*
* Insert new environ into existing, yet deactivated,
* environment array.
*/
origEnviron = environ;
if (origEnviron != NULL)
for (env = origEnviron; *env != NULL; env++) {
if ((equals = strchr(*env, '=')) == NULL) {
__env_warnx(CorruptEnvValueMsg, *env,
strlen(*env));
errno = EFAULT;
return (-1);
}
if (__setenv(*env, equals - *env, equals + 1,
1) == -1)
return (-1);
}
}
return (0);
}
/*
* The exposed setenv() that peforms a few tests before calling the function
* (__setenv()) that does the actual work of inserting a variable into the
* environment.
*/
int
setenv(const char *name, const char *value, int overwrite)
{
size_t nameLen;
/* Check for malformed name. */
if (name == NULL || (nameLen = __strleneq(name)) == 0) {
errno = EINVAL;
return (-1);
}
/* Initialize environment. */
if (__merge_environ() == -1 || (envVars == NULL && __build_env() == -1))
return (-1);
return (__setenv(name, nameLen, value, overwrite));
}
/*
* Insert a "name=value" string into the environment. Special settings must be
* made to keep setenv() from reusing this memory block and unsetenv() from
* allowing it to be tracked.
*/
int
putenv(char *string)
{
char *equals;
int envNdx;
int newEnvActive;
size_t nameLen;
/* Check for malformed argument. */
if (string == NULL || (equals = strchr(string, '=')) == NULL ||
(nameLen = equals - string) == 0) {
errno = EINVAL;
return (-1);
}
/* Initialize environment. */
if (__merge_environ() == -1 || (envVars == NULL && __build_env() == -1))
return (-1);
/* Deactivate previous environment variable. */
envNdx = envVarsTotal - 1;
newEnvActive = envActive;
if (__findenv(string, nameLen, &envNdx, true) != NULL) {
/* Reuse previous putenv slot. */
if (envVars[envNdx].putenv) {
envVars[envNdx].name = string;
return (__rebuild_environ(envActive));
} else {
newEnvActive--;
envVars[envNdx].active = false;
}
}
/* Enlarge environment. */
envNdx = envVarsTotal;
if (!__enlarge_env())
return (-1);
/* Create environment entry. */
envVars[envNdx].name = string;
envVars[envNdx].nameLen = -1;
envVars[envNdx].value = NULL;
envVars[envNdx].valueSize = -1;
envVars[envNdx].putenv = true;
envVars[envNdx].active = true;
newEnvActive++;
return (__rebuild_environ(newEnvActive));
}
/*
* Unset variable with the same name by flagging it as inactive. No variable is
* ever freed.
*/
int
unsetenv(const char *name)
{
int envNdx;
size_t nameLen;
int newEnvActive;
/* Check for malformed name. */
if (name == NULL || (nameLen = __strleneq(name)) == 0) {
errno = EINVAL;
return (-1);
}
/* Initialize environment. */
if (__merge_environ() == -1 || (envVars == NULL && __build_env() == -1))
return (-1);
/* Deactivate specified variable. */
/* Remove all occurrences. */
envNdx = envVarsTotal - 1;
newEnvActive = envActive;
while (__findenv(name, nameLen, &envNdx, true) != NULL) {
envVars[envNdx].active = false;
if (envVars[envNdx].putenv)
__remove_putenv(envNdx);
envNdx--;
newEnvActive--;
}
if (newEnvActive != envActive)
__rebuild_environ(newEnvActive);
return (0);
}