metalink_parse_update - Man Page

Parse Metalink file and create metalink_t object.


#include <metalink/metalink.h>

metalink_error_t metalink_parse_update(metalink_parser_context_t *ctx, const char *buf, size_t len);
metalink_error_t metalink_parse_final(metalink_parser_context_t *ctx, const char *buf, size_t len, metalink_t **res);

metalink_parser_context_t* metalink_parser_context_new();
void metalink_parser_context_delete(metalink_parser_context_t *ctx);


These functions provide a push interface for parsing Metalink XML files.

Before calling metalink_parse_update() and metalink_parse_final(), metalink_parse_context_t has to be created by metalink_parser_context_new().

In each call of metalink_parse_update(), len bytes of buf are processed. At the last piece of data, call metalink_parse_final() to get metalink_t(3) structure as a result. Giving 0 as len is permitted.

metalink_parse_final() calls metalink_parser_context_delete() internally to deallocate the memory for passed metalink_parser_context_t. Therefore you don't have to call metlaink_parser_context_delete() if you call metalink_parse_final(). Otherwise call metalink_parser_context_delete() to free the allocated resource.

You don't have to allocate memory for metalink_t(3) structure. metalink_parse_final() takes the pointer of metalink_t(3) pointer and allocates memory for that pointer.

The caller must free the memory allocated for metalink_t(3) structure using metalink_delete(3) if it is no longer used.

Return Value

metalink_parse_update(), metalink_parse_final() return 0 for success. When error occurred, non-zero value error code is returned. If error occurred, metalink_parse_final() does not allocate memory for metalink_t. The error codes are described in metalink_error.h.

In case of success, metalink_parser_context_new() allocates memory for metalink_parser_context_t() and returns the pointer to it. In case of failure, metalink_parser_context_new() returns NULL.

metalink_parser_context_delete() returns no value.


#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <metalink/metalink.h>

int main(int argc, char** argv)
  metalink_error_t r;
  metalink_t* metalink;
  metalink_file_t* file;
  metalink_checksum_t** checksums;
  metalink_parser_context_t* context;
  int fd;
  char buf[BUFSIZ];
  ssize_t length;

  context = metalink_parser_context_new();

  if(context == NULL) {
            "ERROR: failed to create metalink_parser_context_t\n");

  fd = open("sample.metalink", O_RDONLY);
  if(fd == -1) {
    fprintf(stderr, "ERROR: open():%s\n", strerror(errno));
  while((length = TEMP_FAILURE_RETRY(read(fd, buf, sizeof(buf)))) != 0){
    r = metalink_parse_update(context, buf, length);
    if(r != 0) {
      fprintf(stderr, "ERROR: code=%d\n", r);
  if(length == -1) {
    fprintf(stderr, "ERROR: read():%s\n", strerror(errno));
  r = metalink_parse_final(context, NULL, 0, &metalink);

  if(r != 0) {
    fprintf(stderr, "ERROR: code=%d\n", r);

  file = metalink->files[0];
  printf("name: %s\n", file->name);
  printf("size: %lld\n", file->size);
  printf("os  : %s\n", file->os);

  if(file->checksums) {
    checksums = file->checksums;
    while(*checksums) {
      printf("hash: %s %s\n", (*checksums)->type, (*checksums)->hash);
  if(file->chunk_checksum) {
    size_t count = 0;
    metalink_piece_hash_t** piece_hashes;
    printf("chunk checksum: size=%d, type=%s\n",
    printf("first 5 piece hashes...\n");
    piece_hashes = file->chunk_checksum->piece_hashes;
    while(*piece_hashes && count < 5) {
      printf("piece=%d, hash=%s\n", (*piece_hashes)->piece,
  if(file->resources) {
    size_t count = 0;
    metalink_resource_t** resources;
    printf("first 5 resources...\n");
    resources = file->resources;
    while(*resources && count < 5) {
      printf("type=%s, location=%s, preference=%d, url=%s\n",
             (*resources)->type, (*resources)->location,
             (*resources)->preference, (*resources)->url);

  /* delete metalink_t */

  return EXIT_SUCCESS;

See Also

metalink_delete(3), metalink_parse_file(3), metalink_t(3)

Referenced By


The man pages metalink_parse_final(3), metalink_parser_context_delete(3) and metalink_parser_context_new(3) are aliases of metalink_parse_update(3).

July 2012 libmetalink 0.1.0 libmetalink Manual