API_xar_attr_get

Table of Contents API Documentation const char *xar_attr_get(xar_file_t f, const char *prop, const char *key) Description Example

API Documentation

const char *xar_attr_get(xar_file_t f, const char *prop, const char *key)

Add or set an attribute

Description

XAR attributes map to XML attributes. The XAR attribute "bar" with value "baz" on (empty) property "foo" would serialize to XML as:

<foo bar="baz"/>

xar_attr_get() can be used to get attributes on files or properties within a file.

To get the attribute on a file, pass a NULL value for the second argument (the property). Here is an example of a call and what value it is retrieving: const char *value = xar_attr_get(f, NULL, "foo"); printf("Attribute foo of the file is: %s\n", value);

Attribute foo of the file is: bar

<file foo="bar">

Similarly, to modify an attribute of a property within a file: const char *value = xar_attr_get(f, "name", "foo"); printf("Attribute "foo" of property "name" of the file is: %s\n", value);

Attribute "foo" of property "name" of the file is: bar

<file>
	<name foo="bar">filename</name>
</file>

Returns a pointer to the value of the attribute, if it exists. NULL is returned if the attribute does not exist. No attribute may have a NULL value.

Example

#include <xar/xar.h>

int main(int argc, char *argv[]) {
	xar_t x;
	xar_file_t f;
	const char *value;

	x = xar_open(argv[1], WRITE);
	if( x == NULL ) {
		fprintf(stderr, "Error opening xarchive: %s\n", argv[1]);
		exit(1);
	}

	if( (f = xar_add(x, "/path/to/file")) == NULL ) {
		fprintf(stderr, "Error adding /path/to/file to the xarchive\n");
		exit(2);
	}

	value = xar_attr_get(f, NULL, "id");
	if( value == NULL ) {
		fprintf(stderr, "Error getting the id of the file\n");
		exit(3);
	}

	printf("/path/to/file's id is: %s\n", value);

	...

	xar_close(x);
	
	...

}