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/* var.c
*
* Variable expansion and maintenance.
*
* All variables are stored as enviroment variables.
*/
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <stdio.h>
#include "lafe.h"
extern char **environ;
static void printvar() {
int i;
for (i=0;environ[i];i++) {
printf("%s\n",environ[i]);
}
}
char *getvar(char *name) {
char *v;
v = getenv(name);
if (v) return strdup(v);
else return NULL;
}
void putvar(char *name,char *val) {
setenv(name,val,1);
}
void clearvar(char *name) {
unsetenv(name);
}
/* variable expansion, return a malloced line */
char *expand_variables(char *line) {
char *oldline;
int size;
int src,dst,i;
char *var,*val;
/* exit fast if no $ in line */
/* if (!strchr(line,'$')) return line; */
oldline=line;
size=256;
line=malloc(size);
if (!line) {
perror("malloc");
return oldline;
}
for (src=dst=0;oldline[src];) {
/* begining of a variable */
if (oldline[src] == '$') {
/* allocate var to be the variable name */
/* a general {} variable */
if (oldline[++src]=='{') {
for (i=(++src);oldline[i] && oldline[i]!='}';i++) ;
var=malloc(i-src+1);
strncpy(var,oldline+src,i-src);
var[i-src]=0;
src=i+1;
/* a simple alphanumeric variable */
} else if (isalnum(oldline[src])) {
for (i=src;isalnum(oldline[i]);i++) ;
var=malloc(i-src+1);
strncpy(var,oldline+src,i-src);
var[i-src]=0;
src=i;
/* single character variable */
} else {
var=malloc(2);
var[0]=oldline[src];
var[1]=0;
src++;
}
/* get value and copy into line at point dst */
val=getvar(var);
if (!val) {
if (verbose) fprintf(stderr,"%s not defined\n",var);
} else {
for (;*val;val++) {
line[dst++] = *val;
if (dst>=size-1) {
line=realloc(line,size*=2);
}
}
}
free(var);
/* everything between '' is returned verbatim, without the quotes.
* needed to define aliases with runtime variables */
} else if (oldline[src]=='\'') {
for (src++;oldline[src] && oldline[src]!='\'';src++) {
line[dst++]=oldline[src];
if (dst>=size-1) {
line=realloc(line,size*=2);
}
}
if (oldline[src]) src++;
/* copy character from src to dst */
} else {
line[dst++]=oldline[src++];
if (dst>=size-1) {
line=realloc(line,size*=2);
}
}
}
/* terminate string */
line[dst]=0;
free(oldline);
return line;
}
/* local commands to affect variables */
void setvar(char *line) {
int i,j;
for (i=0;line[i] && !isspace(line[i]);i++) ;
if (!line[i]) { printvar(); return; }
for (j=i;line[j] && isspace(line[j]);j++) ;
line[i]=0;
if (line[j]) putvar(line,line+j); else clearvar(line);
}
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