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 "str.h"

    10 #include "alloc.h"

    11 #include "env.h"

    12 

    13 int env_isinit = 0; /* if env_isinit: */

    14 static int ea; /* environ is a pointer to ea+1 char*'s. */

    15 static int en; /* the first en of those are ALLOCATED. environ[en] is 0. */

    16 

    17 static void env_goodbye(i) int i;

    18 {

    19  alloc_free(environ[i]);

    20  environ[i] = environ[--en];

    21  environ[en] = 0;

    22 }

    23 

    24 static char *null = 0;

    25 

    26 void env_clear()

    27 {

    28  if (env_isinit) while (en) env_goodbye(0);

    29  else environ = &null;

    30 }

    31 

    32 static void env_unsetlen(s,len) char *s; int len;

    33 {

    34  int i;

    35  for (i = en - 1;i >= 0;--i)

    36    if (!str_diffn(s,environ[i],len))

    37      if (environ[i][len] == '=')

    38        env_goodbye(i);

    39 }

    40 

    41 int env_unset(s) char *s;

    42 {

    43  if (!env_isinit) if (!env_init()) return 0;

    44  env_unsetlen(s,str_len(s));

    45  return 1;

    46 }

    47 

    48 static int env_add(s) char *s;

    49 {

    50  char *t;

    51  t = env_findeq(s);

    52  if (t) env_unsetlen(s,t - s);

    53  if (en == ea)

    54   {

    55    ea += 30;

    56    if (!alloc_re(&environ,(en + 1) * sizeof(char *),(ea + 1) * sizeof(char *)))

    57     { ea = en; return 0; }

    58   }

    59  environ[en++] = s;

    60  environ[en] = 0;

    61  return 1;

    62 }

    63 

    64 int env_put(s) char *s;

    65 {

    66  char *u;

    67  if (!env_isinit) if (!env_init()) return 0;

    68  u = alloc(str_len(s) + 1);

    69  if (!u) return 0;

    70  str_copy(u,s);

    71  if (!env_add(u)) { alloc_free(u); return 0; }

    72  return 1;

    73 }

    74 

    75 int env_put2(s,t) char *s; char *t;

    76 {

    77  char *u;

    78  int slen;

    79  if (!env_isinit) if (!env_init()) return 0;

    80  slen = str_len(s);

    81  u = alloc(slen + str_len(t) + 2);

    82  if (!u) return 0;

    83  str_copy(u,s);

    84  u[slen] = '=';

    85  str_copy(u + slen + 1,t);

    86  if (!env_add(u)) { alloc_free(u); return 0; }

    87  return 1;

    88 }

    89 

    90 int env_init()

    91 {

    92  char **newenviron;

    93  int i;

    94  for (en = 0;environ[en];++en) ;

    95  ea = en + 10;

    96  newenviron = (char **) alloc((ea + 1) * sizeof(char *));

    97  if (!newenviron) return 0;

    98  for (en = 0;environ[en];++en)

    99   {

   100    newenviron[en] = alloc(str_len(environ[en]) + 1);

   101    if (!newenviron[en])

   102     {

   103      for (i = 0;i < en;++i) alloc_free(newenviron[i]);

   104      alloc_free(newenviron);

   105      return 0;

   106     }

   107    str_copy(newenviron[en],environ[en]);

   108   }

   109  newenviron[en] = 0;

   110  environ = newenviron;

   111  env_isinit = 1;

   112  return 1;

   113 }