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       envz_add,  envz_entry,  envz_get, envz_merge, envz_remove, envz_strip -
       environment string support


       #include <envz.h>

       error_t envz_add(char **envz, size_t *envz_len,
                    const char *name, const char *value);

       char *envz_entry(const char *envz, size_t *envz_len, const char *name);

       char *envz_get(const char *envz, size_t *envz_len, const char *name);

       error_t envz_merge(char **envz, size_t *envz_len,
                    const char *envz2, size_t envz2_len, int override);

       void envz_remove(char **envz, size_t *envz_len, const char *name);

       void envz_strip(char **envz, size_t *envz_len);


       These functions are glibc-specific.

       An argz vector is a pointer to  a  character  buffer  together  with  a
       length,  see  argz_add(3).   An  envz  vector is a special argz vector,
       namely one where the strings have the  form  "name=value".   Everything
       after the first '=' is considered to be the value.  If there is no '=',
       the value is taken to be NULL.  (While the value in case of a  trailing
       '=' is the empty string "".)

       These functions are for handling envz vectors.

       envz_add()  adds the string "name=value" (in case value is non-NULL) or
       "name" (in case value is NULL) to the  envz  vector  (*envz, *envz_len)
       and  updates  *envz  and  *envz_len.   If  an  entry with the same name
       existed, it is removed.

       envz_entry() looks for name in the  envz  vector  (envz, envz_len)  and
       returns the entry if found, or NULL if not.

       envz_get()  looks  for  name  in  the  envz vector (envz, envz_len) and
       returns the value if found, or NULL if not.  (Note that the  value  can
       also be NULL, namely when there is an entry for name without '=' sign.)

       envz_merge() adds each entry in envz2 to *envz, as if with  envz_add().
       If override is true, then values in envz2 will supersede those with the
       same name in *envz, otherwise not.

       envz_remove() removes the entry for  name  from  (*envz, *envz_len)  if
       there was one.

       envz_strip() removes all entries with value NULL.


       All  envz  functions  that  do  memory allocation have a return type of
       error_t, and return 0 for success, and ENOMEM if  an  allocation  error


       These functions are a GNU extension.  Handle with care.


       #include <stdio.h>
       #include <stdlib.h>
       #include <envz.h>

       main(int argc, char *argv[], char *envp[])
           int i, e_len = 0;
           char *str;

           for (i = 0; envp[i] != NULL; i++)
               e_len += strlen(envp[i]) + 1;

           str = envz_entry(*envp, e_len, "HOME");
           printf("%s\n", str);
           str = envz_get(*envp, e_len, "HOME");
           printf("%s\n", str);




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