external/ibm-public/postfix/dist/src/util/environ.c

   1 /*      $NetBSD$        */
   2
   3  /*
   4   * From: TCP Wrapper.
   5   *
   6   * Many systems have putenv() but no setenv(). Other systems have setenv() but
   7   * no putenv() (MIPS). Still other systems have neither (NeXT). This is a
   8   * re-implementation that hopefully ends all problems.
   9   *
  10   * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
  11   */
  12 #include "sys_defs.h"
  13
  14 #ifdef MISSING_SETENV_PUTENV
  15
  16 #include <stdio.h>
  17 #include <string.h>
  18 #include <stdlib.h>
  19
  20 extern char **environ;
  21
  22 static int addenv(char *);              /* append entry to environment */
  23 static int allocated = 0;               /* environ is, or is not, allocated */
  24
  25 #define DO_CLOBBER      1
  26
  27 /* namelength - determine length of name in "name=whatever" */
  28
  29 static ssize_t namelength(const char *name)
  30 {
  31     char   *equal;
  32
  33     equal = strchr(name, '=');
  34     return ((equal == 0) ? strlen(name) : (equal - name));
  35 }
  36
  37 /* findenv - given name, locate name=value */
  38
  39 static char **findenv(const char *name, ssize_t len)
  40 {
  41     char  **envp;
  42
  43     for (envp = environ; envp && *envp; envp++)
  44         if (strncmp(name, *envp, len) == 0 && (*envp)[len] == '=')
  45             return (envp);
  46     return (0);
  47 }
  48
  49 #if 0
  50
  51 /* getenv - given name, locate value */
  52
  53 char   *getenv(const char *name)
  54 {
  55     ssize_t len = namelength(name);
  56     char  **envp = findenv(name, len);
  57
  58     return (envp ? *envp + len + 1 : 0);
  59 }
  60
  61 /* putenv - update or append environment (name,value) pair */
  62
  63 int     putenv(const char *nameval)
  64 {
  65     char   *equal = strchr(nameval, '=');
  66     char   *value = (equal ? equal : "");
  67
  68     return (setenv(nameval, value, DO_CLOBBER));
  69 }
  70
  71 /* unsetenv - remove variable from environment */
  72
  73 void    unsetenv(const char *name)
  74 {
  75     char  **envp;
  76
  77     while ((envp = findenv(name, namelength(name))) != 0)
  78         while (envp[0] = envp[1])
  79             envp++;
  80 }
  81
  82 #endif
  83
  84 /* setenv - update or append environment (name,value) pair */
  85
  86 int     setenv(const char *name, const char *value, int clobber)
  87 {
  88     char   *destination;
  89     char  **envp;
  90     ssize_t l_name;                     /* length of name part */
  91     unsigned int l_nameval;             /* length of name=value */
  92
  93     /* Permit name= and =value. */
  94
  95     l_name = namelength(name);
  96     envp = findenv(name, l_name);
  97     if (envp != 0 && clobber == 0)
  98         return (0);
  99     if (*value == '=')
 100         value++;
 101     l_nameval = l_name + strlen(value) + 1;
 102
 103     /*
 104      * Use available memory if the old value is long enough. Never free an
 105      * old name=value entry because it may not be allocated.
 106      */
 107
 108     destination = (envp != 0 && strlen(*envp) >= l_nameval) ?
 109         *envp : malloc(l_nameval + 1);
 110     if (destination == 0)
 111         return (-1);
 112     strncpy(destination, name, l_name);
 113     destination[l_name] = '=';
 114     strcpy(destination + l_name + 1, value);
 115     return ((envp == 0) ? addenv(destination) : (*envp = destination, 0));
 116 }
 117
 118 /* cmalloc - malloc and copy block of memory */
 119
 120 static char *cmalloc(ssize_t new_len, char *old, ssize_t old_len)
 121 {
 122     char   *new = malloc(new_len);
 123
 124     if (new != 0)
 125         memcpy(new, old, old_len);
 126     return (new);
 127 }
 128
 129 /* addenv - append environment entry */
 130
 131 static int addenv(char *nameval)
 132 {
 133     char  **envp;
 134     ssize_t n_used;                     /* number of environment entries */
 135     ssize_t l_used;                     /* bytes used excl. terminator */
 136     ssize_t l_need;                     /* bytes needed incl. terminator */
 137
 138     for (envp = environ; envp && *envp; envp++)
 139          /* void */ ;
 140     n_used = envp - environ;
 141     l_used = n_used * sizeof(*envp);
 142     l_need = l_used + 2 * sizeof(*envp);
 143
 144     envp = allocated ?
 145         (char **) realloc((char *) environ, l_need) :
 146         (char **) cmalloc(l_need, (char *) environ, l_used);
 147     if (envp == 0) {
 148         return (-1);
 149     } else {
 150         allocated = 1;
 151         environ = envp;
 152         environ[n_used++] = nameval;            /* add new entry */
 153         environ[n_used] = 0;                    /* terminate list */
 154         return (0);
 155     }
 156 }
 157
 158 #endif