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| <h4 class="subsection">5.12.2 Envz Functions</h4> |
| |
| <p>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. |
| |
| <p>Each element in an envz vector is a name-value pair, separated by a <code>'='</code> |
| character; if multiple <code>'='</code> characters are present in an element, those |
| after the first are considered part of the value, and treated like all other |
| non-<code>'\0'</code> characters. |
| |
| <p>If <em>no</em> <code>'='</code> 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: <code>envz_get</code> will return <code>0</code> if given the name of null |
| entry, whereas an entry with an empty value would result in a value of |
| <code>""</code>; <code>envz_entry</code> will still find such entries, however. Null |
| entries can be removed with <code>envz_strip</code> function. |
| |
| <p>As with argz functions, envz functions that may allocate memory (and thus |
| fail) have a return type of <code>error_t</code>, and return either <code>0</code> or |
| <code>ENOMEM</code>. |
| |
| <p><a name="index-envz_002eh-604"></a>These functions are declared in the standard include file <samp><span class="file">envz.h</span></samp>. |
| |
| <!-- envz.h --> |
| <!-- GNU --> |
| <div class="defun"> |
| — Function: char * <b>envz_entry</b> (<var>const char *envz, size_t envz_len, const char *name</var>)<var><a name="index-envz_005fentry-605"></a></var><br> |
| <blockquote><p>The <code>envz_entry</code> function finds the entry in <var>envz</var> with the name |
| <var>name</var>, and returns a pointer to the whole entry—that is, the argz |
| element which begins with <var>name</var> followed by a <code>'='</code> character. If |
| there is no entry with that name, <code>0</code> is returned. |
| </p></blockquote></div> |
| |
| <!-- envz.h --> |
| <!-- GNU --> |
| <div class="defun"> |
| — Function: char * <b>envz_get</b> (<var>const char *envz, size_t envz_len, const char *name</var>)<var><a name="index-envz_005fget-606"></a></var><br> |
| <blockquote><p>The <code>envz_get</code> function finds the entry in <var>envz</var> with the name |
| <var>name</var> (like <code>envz_entry</code>), and returns a pointer to the value |
| portion of that entry (following the <code>'='</code>). If there is no entry with |
| that name (or only a null entry), <code>0</code> is returned. |
| </p></blockquote></div> |
| |
| <!-- envz.h --> |
| <!-- GNU --> |
| <div class="defun"> |
| — Function: error_t <b>envz_add</b> (<var>char **envz, size_t *envz_len, const char *name, const char *value</var>)<var><a name="index-envz_005fadd-607"></a></var><br> |
| <blockquote><p>The <code>envz_add</code> function adds an entry to <code>*</code><var>envz</var> |
| (updating <code>*</code><var>envz</var> and <code>*</code><var>envz_len</var>) with the name |
| <var>name</var>, and value <var>value</var>. If an entry with the same name |
| already exists in <var>envz</var>, it is removed first. If <var>value</var> is |
| <code>0</code>, then the new entry will the special null type of entry |
| (mentioned above). |
| </p></blockquote></div> |
| |
| <!-- envz.h --> |
| <!-- GNU --> |
| <div class="defun"> |
| — Function: error_t <b>envz_merge</b> (<var>char **envz, size_t *envz_len, const char *envz2, size_t envz2_len, int override</var>)<var><a name="index-envz_005fmerge-608"></a></var><br> |
| <blockquote><p>The <code>envz_merge</code> function adds each entry in <var>envz2</var> to <var>envz</var>, |
| as if with <code>envz_add</code>, updating <code>*</code><var>envz</var> and |
| <code>*</code><var>envz_len</var>. If <var>override</var> is true, then values in <var>envz2</var> |
| will supersede those with the same name in <var>envz</var>, otherwise not. |
| |
| <p>Null entries are treated just like other entries in this respect, so a null |
| entry in <var>envz</var> can prevent an entry of the same name in <var>envz2</var> from |
| being added to <var>envz</var>, if <var>override</var> is false. |
| </p></blockquote></div> |
| |
| <!-- envz.h --> |
| <!-- GNU --> |
| <div class="defun"> |
| — Function: void <b>envz_strip</b> (<var>char **envz, size_t *envz_len</var>)<var><a name="index-envz_005fstrip-609"></a></var><br> |
| <blockquote><p>The <code>envz_strip</code> function removes any null entries from <var>envz</var>, |
| updating <code>*</code><var>envz</var> and <code>*</code><var>envz_len</var>. |
| </p></blockquote></div> |
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