env.c revision 3f54fd611f536639ec30dd53c48e5ec1897cc7d9
/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1982-2011 AT&T Intellectual Property *
* and is licensed under the *
* Eclipse Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.eclipse.org/org/documents/epl-v10.html *
* (with md5 checksum b35adb5213ca9657e911e9befb180842) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* David Korn <dgk@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
#include <ast.h>
#include <cdt.h>
#define env_change() (++ast.env_serial)
typedef struct _venv_ Evar_t;
struct _venv_
{
union
{
Evar_t *next;
char *ptr;
} un;
Dtlink_t link;
int index;
};
typedef struct _env_
{
Dt_t *dt;
Evar_t *freelist;
char **env;
int count;
int extra;
int max;
int flags;
} Env_t;
#define _BLD_env 1
#include <env.h>
#define ENV_VALID 2 /* set if env is valid */
#define ENV_PMALLOC 1 /* set if Evar_t->un.ptr *s malloced */
#define ENV_VMALLOC 2 /* set of Evar_t was malloced */
#define ENV_BITS 3
/*
* Compares the name portion of name=... only.
*/
static int compare(Dt_t *dt, Void_t* key1, Void_t* key2, Dtdisc_t* disc)
{
register int c,d;
const unsigned char *s1=(unsigned const char*)key1;
const unsigned char *s2=(unsigned const char*)key2;
while((c= *s1++) && c!='=' && c==*s2)
s2++;
if(c=='=')
c = 0;
if((d=*s2)=='=')
d = 0;
return(c-d);
}
static Dtdisc_t env_disc =
{
0, -1,
sizeof(char*),
0,
0,
compare
};
/*
* return a pointer to the environment in sorted order
* NULL is returned if there if there is nospace
*/
char **env_get(Env_t* ep)
{
register Evar_t *vp;
register int n=ep->extra;
if(ep->flags&ENV_VALID)
return(ep->env+n);
if(ep->count > ep->max)
{
if(ep->flags&ENV_MALLOCED)
free((void*)ep->env);
if(!(ep->env = (char**)malloc(sizeof(char*)*(ep->count+1))))
return(0);
ep->flags |= ENV_MALLOCED;
ep->max = ep->count;
}
for(vp=(Evar_t*)dtfirst(ep->dt);vp; vp=(Evar_t*)dtnext(ep->dt,vp))
{
vp->index = (n<<ENV_BITS) | (vp->index&((1<<ENV_BITS)-1));
ep->env[n++] = vp->un.ptr;
}
ep->env[n] = 0;
ep->flags |= ENV_VALID;
environ = ep->env+ep->extra;
return(ep->env+ep->extra);
}
/*
* add name=value pair given by <str> to <ep>
* if malloced is set, the variable will be freed when reassigned
* The environment list may become invalidated
* Returns 1 for success, 0 for failure
*/
int env_add(Env_t *ep, const char *str, int flags)
{
Evar_t *vp = (Evar_t*)dtmatch(ep->dt,(void*)str);
if(vp && strcmp(str,vp->un.ptr)==0)
return(1);
if(flags&ENV_STRDUP)
str = strdup(str);
if(vp)
{
if(vp->index&ENV_PMALLOC)
free((void*)vp->un.ptr);
vp->un.ptr = (char*)str;
if(ep->env && (ep->flags&ENV_VALID))
ep->env[vp->index>>ENV_BITS] = vp->un.ptr;
}
else
{
ep->flags &= ~ENV_VALID;
if(vp = ep->freelist)
ep->freelist = vp->un.next;
else if(vp = newof((Evar_t*)0,Evar_t,2,0))
{
vp->index = ENV_VMALLOC;
ep->freelist = (vp+1);
ep->freelist->un.next = 0;
}
else
return(0);
vp->un.ptr = (void*)str;
if(!(vp=dtinsert(ep->dt,vp)))
return(0);
ep->count++;
}
if(flags)
vp->index |= ENV_PMALLOC;
else
vp->index &= ~ENV_PMALLOC;
env_change();
return(1);
}
/*
* delete name from <ep>
* The environment list may become invalidated
* Returns 1 for success, 0 for if name is not present
*/
int env_delete(Env_t *ep, const char *str)
{
Evar_t *vp = (Evar_t*)dtmatch(ep->dt,(void*)str);
if(!vp)
return(0);
ep->flags &= ~ENV_VALID;
if(vp->index&ENV_PMALLOC)
free((void*)vp->un.ptr);
dtdelete(ep->dt,vp);
vp->un.next = ep->freelist;
ep->freelist = vp;
env_change();
return(1);
}
/*
* open up a structure to support environment variables
* initialize with environment give by <envp>
* If <extra> > 0, <extra> slots will be left at beginning of
* environment list when env_get() is involed.
* If <extra>==ENV_USABLE, then the original environ can be
* used and returned. Otherwise, a new one will be returned
*/
Env_t *env_open(char **envp, int extra)
{
char **env;
Env_t *ep;
Evar_t *vp;
int n=2;
if(!(ep = newof((Env_t*)0,Env_t,1,0)))
return(0);
if(!(ep->dt = dtopen(&env_disc,Dtoset)))
return(0);
if(env=envp)
{
while(*env++);
n = (env+2)-envp;
}
if(extra==ENV_STABLE)
{
ep->env = envp;
ep->max = n-1;
}
else
ep->count = ep->extra = extra;
ep->freelist = vp = newof((Evar_t*)0,Evar_t,n,0);
vp->index = ENV_VMALLOC;
while(--n>0)
{
vp->un.next = (vp+1);
vp++;
}
vp->un.next = 0;
if(env)
{
for(env=envp; *env; env++)
env_add(ep,*env,0);
}
return(ep);
}
/*
* close <ep> and free up all space used by it
*/
void env_close(Env_t *ep)
{
Evar_t *vp, *vpnext,*top;
if(ep->env && (ep->flags&ENV_MALLOCED))
free((void*)ep->env);
for(vp=(Evar_t*)dtfirst(ep->dt);vp; vp=vpnext)
{
vpnext = (Evar_t*)dtnext(ep->dt,vp);
env_delete(ep,vp->un.ptr);
}
for(top=0,vp = ep->freelist; vp; vp = vpnext)
{
vpnext = vp->un.next;
if(vp->index&ENV_VMALLOC)
{
vp->un.next = top;
top = vp;
}
}
for(vp=top; vp; vp = vpnext)
{
vpnext = vp->un.next;
free((void*)vp);
}
dtclose(ep->dt);
}