c-ipfs/importer/exporter.c

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#include <stdio.h>
#include <string.h>
#include "ipfs/cid/cid.h"
#include "ipfs/merkledag/merkledag.h"
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#include "ipfs/merkledag/node.h"
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#include "ipfs/repo/fsrepo/fs_repo.h"
/**
* pull objects from ipfs
*/
/**
* get a file by its hash, and write the data to a file
* @param hash the base58 multihash of the cid
* @param file_name the file name to write to
* @returns true(1) on success
*/
int ipfs_exporter_to_file(const unsigned char* hash, const char* file_name, const struct FSRepo* fs_repo) {
// convert hash to cid
struct Cid* cid = NULL;
if ( ipfs_cid_decode_hash_from_base58(hash, strlen((char*)hash), &cid) == 0) {
return 0;
}
// find block
struct Node* read_node = NULL;
if (ipfs_merkledag_get(cid, &read_node, fs_repo) == 0) {
ipfs_cid_free(cid);
return 0;
}
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// no longer need the cid
ipfs_cid_free(cid);
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// process blocks
FILE* file = fopen(file_name, "wb");
if (file == NULL) {
ipfs_node_free(read_node);
return 0;
}
size_t bytes_written = fwrite(read_node->data, 1, read_node->data_size, file);
if (bytes_written != read_node->data_size) {
fclose(file);
ipfs_node_free(read_node);
return 0;
}
struct NodeLink* link = read_node->head_link;
struct Node* link_node = NULL;
while (link != NULL) {
if ( ipfs_merkledag_get(link->cid, &link_node, fs_repo) == 0) {
fclose(file);
ipfs_node_free(read_node);
return 0;
}
bytes_written = fwrite(link_node->data, 1, link_node->data_size, file);
if (bytes_written != link_node->data_size) {
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ipfs_node_free(link_node);
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fclose(file);
ipfs_node_free(read_node);
return 0;
}
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ipfs_node_free(link_node);
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link = link->next;
}
fclose(file);
if (read_node != NULL)
ipfs_node_free(read_node);
return 1;
}