| Current Path : /usr/src/lib/libc/stdlib/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //usr/src/lib/libc/stdlib/getenv.c |
/*-
* 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: release/9.1.0/lib/libc/stdlib/getenv.c 200198 2009-12-07 00:22:10Z scf $");
#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 = realloc(intEnviron, sizeof (*intEnviron) *
(tmpEnvironSize + 1));
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 = realloc(envVars, sizeof (*envVars) *
newEnvVarsSize);
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(1, sizeof (*envVars) * envVarsSize);
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 = stpcpy(envVars[envNdx].name, name);
if ((envVars[envNdx].name)[nameLen] != '=')
env = stpcpy(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;
/* 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. */
envNdx = envVarsTotal - 1;
if (__findenv(name, nameLen, &envNdx, true) != NULL) {
envVars[envNdx].active = false;
if (envVars[envNdx].putenv)
__remove_putenv(envNdx);
__rebuild_environ(envActive - 1);
}
return (0);
}