Originální popis anglicky:
envz_add, envz_entry, envz_get, envz_merge, envz_remove, envz_strip -
environment string support
Návod, kniha: Library Functions Manual
#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 occurs.
#include <stdio.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);
return 0;
}
These functions are a GNU extension. Handle with care.
argz(3)
