deco/env.c at master · shodanium/deco · GitHub

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/*
 *      EnvInit (char **env)
 *              Initialixe Env packadge by environment vector.
 *
 *      char *EnvGet (char *name)
 *              Get variable from environment.
 *
 *      EnvPut (char *name, char *value)
 *              Change value of variable.
 *
 *      char **EnvVector
 *              Current environment vector.
 */
#include <stdlib.h>
#include <string.h>
#include "deco.h"

#define QUANT 10

char **EnvVector;

static int nenv;
static int last;

static char *nvmatch (char *s1, char *s2);
static char *findvar (char *name, char ***ptr);

void EnvInit (char **env)
{
	register char **p;
	register i;

	if (EnvVector) {
		for (p=EnvVector; *p; ++p)
			free (*p);
		free (EnvVector);
		EnvVector = 0;
		nenv = 0;
		last = nenv = 0;
	}
	if (! env)
		return;
	for (i=0, p=env; *p; ++p, ++i) {
		mcheck (EnvVector, char**, nenv, QUANT, i);
		EnvVector [i] = malloc (strlen (*p) + 1);
		strcpy (EnvVector [i], *p);
	}
	mcheck (EnvVector, char **, nenv, QUANT, i);
	last = i;
	EnvVector [last] = 0;
}

void EnvPut (char *name, char *value)
{
	register char *v;
	char **p;

	if (! name)
		return;
	if (! value)
		value = "";
	v = findvar (name, &p);
	if (v)
		free (*p);
	else {
		p = EnvVector + last;
		++last;
		mcheck (EnvVector, char **, nenv, QUANT, last);
		EnvVector [last] = 0;
	}
	*p = malloc (strlen (name) + 1 + strlen (value) + 1);
	strcpy (*p, name);
	strcat (*p, "=");
	strcat (*p, value);
}

void EnvDelete (char *name)
{
	register char *v;
	char **p;

	if (! name)
		return;
	v = findvar (name, &p);
	if (! v)
		return;
	free (*p);
	for (++p; *p; ++p)
		*(p-1) = *p;
	EnvVector [--last] = 0;
}

char *EnvGet (char *name)
{
	char **p;

	return (findvar (name, &p));
}

static char *findvar (char *name, char ***ptr)
{
	register char *v, **p;

	p = EnvVector;
	if (! p)
		return (0);
	for (; *p; ++p)
		if ((v = nvmatch (name, *p))) {
			*ptr = p;
			return (v);
		}
	return (0);
}

/*
 *	s1 is either name, or name=value
 *	s2 is name=value
 *	if names match, return value of s2, else NULL
 *	used for environment searching: see getenv
 */
static char *nvmatch (char *s1, char *s2)
{
	while (*s1 == *s2++)
		if (*s1++ == '=')
			return (s2);
	if (*s1 == '\0' && *(s2-1) == '=')
		return (s2);
	return (0);
}