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env.c (2261B)

      1 /* env.c, envread.c, env.h: environ library
      2 Daniel J. Bernstein, djb@silverton.berkeley.edu.
      3 Depends on str.h, alloc.h.
      4 Requires environ.
      5 19960113: rewrite. warning: interface is different.
      6 No known patent problems.
      7 */
      8 
      9 #include "env.h"
     10 
     11 #include "str.h"
     12 #include "alloc.h"
     13 
     14 #include <string.h>
     15 
     16 int env_isinit = 0; /* if env_isinit: */
     17 static int ea; /* environ is a pointer to ea+1 char*'s. */
     18 static int en; /* the first en of those are ALLOCATED. environ[en] is 0. */
     19 
     20 static void env_goodbye(i) int i;
     21 {
     22  alloc_free(environ[i]);
     23  environ[i] = environ[--en];
     24  environ[en] = 0;
     25 }
     26 
     27 static char *null = 0;
     28 
     29 void env_clear()
     30 {
     31  if (env_isinit) while (en) env_goodbye(0);
     32  else environ = &null;
     33 }
     34 
     35 static void env_unsetlen(s,len) char *s; int len;
     36 {
     37  int i;
     38  for (i = en - 1;i >= 0;--i)
     39    if (!str_diffn(s,environ[i],len))
     40      if (environ[i][len] == '=')
     41        env_goodbye(i);
     42 }
     43 
     44 int env_unset(s) char *s;
     45 {
     46  if (!env_isinit) if (!env_init()) return 0;
     47  env_unsetlen(s,str_len(s));
     48  return 1;
     49 }
     50 
     51 static int env_add(s) char *s;
     52 {
     53  char *t;
     54  t = env_findeq(s);
     55  if (t) env_unsetlen(s,t - s);
     56  if (en == ea)
     57   {
     58    char **nenv;
     59    ea += 30;
     60    nenv = realloc(environ, (ea + 1) * sizeof(char *));
     61    if (nenv == NULL)
     62     { ea = en; return 0; }
     63    environ = nenv;
     64   }
     65  environ[en++] = s;
     66  environ[en] = 0;
     67  return 1;
     68 }
     69 
     70 int env_put(s) char *s;
     71 {
     72  char *u;
     73  if (!env_isinit) if (!env_init()) return 0;
     74  u = strdup(s);
     75  if (!u) return 0;
     76  if (!env_add(u)) { alloc_free(u); return 0; }
     77  return 1;
     78 }
     79 
     80 int env_put2(s,t) char *s; char *t;
     81 {
     82  char *u;
     83  int slen;
     84  if (!env_isinit) if (!env_init()) return 0;
     85  slen = str_len(s);
     86  u = alloc(slen + str_len(t) + 2);
     87  if (!u) return 0;
     88  str_copy(u,s);
     89  u[slen] = '=';
     90  str_copy(u + slen + 1,t);
     91  if (!env_add(u)) { alloc_free(u); return 0; }
     92  return 1;
     93 }
     94 
     95 int env_init()
     96 {
     97  char **newenviron;
     98  int i;
     99  for (en = 0;environ[en];++en) ;
    100  ea = en + 10;
    101  newenviron = (char **) alloc((ea + 1) * sizeof(char *));
    102  if (!newenviron) return 0;
    103  for (en = 0;environ[en];++en)
    104   {
    105    newenviron[en] = strdup(environ[en]);
    106    if (!newenviron[en])
    107     {
    108      for (i = 0;i < en;++i) alloc_free(newenviron[i]);
    109      alloc_free(newenviron);
    110      return 0;
    111     }
    112   }
    113  newenviron[en] = 0;
    114  environ = newenviron;
    115  env_isinit = 1;
    116  return 1;
    117 }