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ENVZ_ADD(3) Linux Programmer's Manual ENVZ_ADD(3)

NAME

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

SYNOPSIS

     #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);

DESCRIPTION

     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.

RETURN VALUE

     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
     occurs.

ATTRIBUTES

     For   an   explanation   of   the  terms  used  in  this  section,  see
     attributes(7).

     allbox; lbw27 lb lb l l l.   Interface Attribute Value  T{  envz_add(),
     envz_entry(),
     envz_get(), envz_merge(),
     envz_remove(), envz_strip() T}   Thread safety  MT-Safe

CONFORMING TO

     These functions are a GNU extension.  Handle with care.

EXAMPLE

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

     int 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);
         exit(EXIT_SUCCESS); }