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/*
* From: TCP Wrapper.
*
* Many systems have putenv() but no setenv(). Other systems have setenv() but
* no putenv() (MIPS). Still other systems have neither (NeXT). This is a
* re-implementation that hopefully ends all problems.
*
* Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
*/
#include "sys_defs.h"
#ifdef MISSING_SETENV_PUTENV
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
extern char **environ;
static int addenv(char *); /* append entry to environment */
static int allocated = 0; /* environ is, or is not, allocated */
#define DO_CLOBBER 1
/* namelength - determine length of name in "name=whatever" */
static ssize_t namelength(const char *name)
{
char *equal;
equal = strchr(name, '=');
return ((equal == 0) ? strlen(name) : (equal - name));
}
/* findenv - given name, locate name=value */
static char **findenv(const char *name, ssize_t len)
{
char **envp;
for (envp = environ; envp && *envp; envp++)
if (strncmp(name, *envp, len) == 0 && (*envp)[len] == '=')
return (envp);
return (0);
}
#if 0
/* getenv - given name, locate value */
char *getenv(const char *name)
{
ssize_t len = namelength(name);
char **envp = findenv(name, len);
return (envp ? *envp + len + 1 : 0);
}
/* putenv - update or append environment (name,value) pair */
int putenv(const char *nameval)
{
char *equal = strchr(nameval, '=');
char *value = (equal ? equal : "");
return (setenv(nameval, value, DO_CLOBBER));
}
/* unsetenv - remove variable from environment */
void unsetenv(const char *name)
{
char **envp;
while ((envp = findenv(name, namelength(name))) != 0)
while (envp[0] = envp[1])
envp++;
}
#endif
/* setenv - update or append environment (name,value) pair */
int setenv(const char *name, const char *value, int clobber)
{
char *destination;
char **envp;
ssize_t l_name; /* length of name part */
unsigned int l_nameval; /* length of name=value */
/* Permit name= and =value. */
l_name = namelength(name);
envp = findenv(name, l_name);
if (envp != 0 && clobber == 0)
return (0);
if (*value == '=')
value++;
l_nameval = l_name + strlen(value) + 1;
/*
* Use available memory if the old value is long enough. Never free an
* old name=value entry because it may not be allocated.
*/
destination = (envp != 0 && strlen(*envp) >= l_nameval) ?
*envp : malloc(l_nameval + 1);
if (destination == 0)
return (-1);
strncpy(destination, name, l_name);
destination[l_name] = '=';
strcpy(destination + l_name + 1, value);
return ((envp == 0) ? addenv(destination) : (*envp = destination, 0));
}
/* cmalloc - malloc and copy block of memory */
static char *cmalloc(ssize_t new_len, char *old, ssize_t old_len)
{
char *new = malloc(new_len);
if (new != 0)
memcpy(new, old, old_len);
return (new);
}
/* addenv - append environment entry */
static int addenv(char *nameval)
{
char **envp;
ssize_t n_used; /* number of environment entries */
ssize_t l_used; /* bytes used excl. terminator */
ssize_t l_need; /* bytes needed incl. terminator */
for (envp = environ; envp && *envp; envp++)
/* void */ ;
n_used = envp - environ;
l_used = n_used * sizeof(*envp);
l_need = l_used + 2 * sizeof(*envp);
envp = allocated ?
(char **) realloc((char *) environ, l_need) :
(char **) cmalloc(l_need, (char *) environ, l_used);
if (envp == 0) {
return (-1);
} else {
allocated = 1;
environ = envp;
environ[n_used++] = nameval; /* add new entry */
environ[n_used] = 0; /* terminate list */
return (0);
}
}
#endif
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