Envz vectors are just argz vectors with additional constraints on the form of each element; as such, argz functions can also be used on them, where it makes sense.
Each element in an envz vector is a name-value pair, separated by a '='
character; if multiple '='
characters are present in an element, those
after the first are considered part of the value, and treated like all other
non-'\0'
characters.
If no '='
characters are present in an element, that element is
considered the name of a "null" entry, as distinct from an entry with an
empty value: envz_get
will return 0
if given the name of null
entry, whereas an entry with an empty value would result in a value of
""
; envz_entry
will still find such entries, however. Null
entries can be removed with envz_strip
function.
As with argz functions, envz functions that may allocate memory (and thus
fail) have a return type of error_t
, and return either 0
or
ENOMEM
.
These functions are declared in the standard include file `envz.h'.
envz_entry
function finds the entry in envz with the name
name, and returns a pointer to the whole entry--that is, the argz
element which begins with name followed by a '='
character. If
there is no entry with that name, 0
is returned.
envz_get
function finds the entry in envz with the name
name (like envz_entry
), and returns a pointer to the value
portion of that entry (following the '='
). If there is no entry with
that name (or only a null entry), 0
is returned.
envz_add
function adds an entry to *envz
(updating *envz
and *envz_len
) with the name
name, and value value. If an entry with the same name
already exists in envz, it is removed first. If value is
0
, then the new entry will the special null type of entry
(mentioned above).
envz_merge
function adds each entry in envz2 to envz,
as if with envz_add
, updating *envz
and
*envz_len
. If override is true, then values in envz2
will supersede those with the same name in envz, otherwise not.
Null entries are treated just like other entries in this respect, so a null entry in envz can prevent an entry of the same name in envz2 from being added to envz, if override is false.
envz_strip
function removes any null entries from envz,
updating *envz
and *envz_len
.
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