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hwdb: port to flink_tmpfile()
And modernize heavily while doing so. Fixes: #21787 (Strictly speaking, this leaves a race window open: the the system is powered off in the short interval when we linked in the prepared hwdb file into the dir under a temporary name and are about to rename it to the final name, then the file might be left over after all. But this minimizes the window so much that this shouldn't be an issue in real-life. Key after all is that with this change we'll build up the hwdb file under O_TMPFILE, and thus are robust to power loss during the slow operation)
This commit is contained in:
Lennart Poettering
parent
23e208e742
commit
acbab8697e
@ -274,7 +274,6 @@ static int trie_insert(struct trie *trie, struct trie_node *node, const char *se
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}
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struct trie_f {
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FILE *f;
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struct trie *trie;
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uint64_t strings_off;
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@ -295,15 +294,14 @@ static void trie_store_nodes_size(struct trie_f *trie, struct trie_node *node, b
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trie->strings_off += compat ? sizeof(struct trie_value_entry_f) : sizeof(struct trie_value_entry2_f);
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}
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static int64_t trie_store_nodes(struct trie_f *trie, struct trie_node *node, bool compat) {
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struct trie_node_f n = {
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.prefix_off = htole64(trie->strings_off + node->prefix_off),
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.children_count = node->children_count,
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.values_count = htole64(node->values_count),
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};
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static int64_t trie_store_nodes(struct trie_f *trie, FILE *f, struct trie_node *node, bool compat) {
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_cleanup_free_ struct trie_child_entry_f *children = NULL;
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int64_t node_off;
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assert(trie);
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assert(f);
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assert(node);
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if (node->children_count) {
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children = new(struct trie_child_entry_f, node->children_count);
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if (!children)
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@ -314,7 +312,7 @@ static int64_t trie_store_nodes(struct trie_f *trie, struct trie_node *node, boo
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for (uint64_t i = 0; i < node->children_count; i++) {
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int64_t child_off;
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child_off = trie_store_nodes(trie, node->children[i].child, compat);
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child_off = trie_store_nodes(trie, f, node->children[i].child, compat);
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if (child_off < 0)
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return child_off;
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@ -324,14 +322,20 @@ static int64_t trie_store_nodes(struct trie_f *trie, struct trie_node *node, boo
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};
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}
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struct trie_node_f n = {
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.prefix_off = htole64(trie->strings_off + node->prefix_off),
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.children_count = node->children_count,
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.values_count = htole64(node->values_count),
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};
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/* write node */
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node_off = ftello(trie->f);
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fwrite(&n, sizeof(struct trie_node_f), 1, trie->f);
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node_off = ftello(f);
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fwrite(&n, sizeof(struct trie_node_f), 1, f);
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trie->nodes_count++;
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/* append children array */
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if (node->children_count) {
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fwrite(children, sizeof(struct trie_child_entry_f), node->children_count, trie->f);
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fwrite(children, sizeof(struct trie_child_entry_f), node->children_count, f);
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trie->children_count += node->children_count;
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}
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@ -345,7 +349,7 @@ static int64_t trie_store_nodes(struct trie_f *trie, struct trie_node *node, boo
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.file_priority = htole16(node->values[i].file_priority),
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};
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fwrite(&v, compat ? sizeof(struct trie_value_entry_f) : sizeof(struct trie_value_entry2_f), 1, trie->f);
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fwrite(&v, compat ? sizeof(struct trie_value_entry_f) : sizeof(struct trie_value_entry2_f), 1, f);
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}
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trie->values_count += node->values_count;
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@ -355,11 +359,26 @@ static int64_t trie_store_nodes(struct trie_f *trie, struct trie_node *node, boo
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static int trie_store(struct trie *trie, const char *filename, bool compat) {
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struct trie_f t = {
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.trie = trie,
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.strings_off = sizeof(struct trie_header_f),
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};
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_cleanup_free_ char *filename_tmp = NULL;
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int64_t pos;
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int64_t root_off;
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int64_t size;
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_cleanup_(unlink_and_freep) char *filename_tmp = NULL;
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_cleanup_fclose_ FILE *f = NULL;
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int64_t pos, root_off, size;
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int r;
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assert(trie);
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assert(filename);
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/* calculate size of header, nodes, children entries, value entries */
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trie_store_nodes_size(&t, trie->root, compat);
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r = fopen_tmpfile_linkable(filename, O_WRONLY|O_CLOEXEC, &filename_tmp, &f);
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if (r < 0)
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return r;
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if (fchmod(fileno(f), 0444) < 0)
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return -errno;
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struct trie_header_f h = {
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.signature = HWDB_SIG,
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.tool_version = htole64(PROJECT_VERSION),
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@ -368,48 +387,32 @@ static int trie_store(struct trie *trie, const char *filename, bool compat) {
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.child_entry_size = htole64(sizeof(struct trie_child_entry_f)),
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.value_entry_size = htole64(compat ? sizeof(struct trie_value_entry_f) : sizeof(struct trie_value_entry2_f)),
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};
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int r;
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/* calculate size of header, nodes, children entries, value entries */
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t.strings_off = sizeof(struct trie_header_f);
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trie_store_nodes_size(&t, trie->root, compat);
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r = fopen_temporary(filename, &t.f, &filename_tmp);
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if (r < 0)
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return r;
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(void) fchmod(fileno(t.f), 0444);
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/* write nodes */
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if (fseeko(t.f, sizeof(struct trie_header_f), SEEK_SET) < 0)
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goto error_fclose;
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if (fseeko(f, sizeof(struct trie_header_f), SEEK_SET) < 0)
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return -errno;
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root_off = trie_store_nodes(&t, trie->root, compat);
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root_off = trie_store_nodes(&t, f, trie->root, compat);
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h.nodes_root_off = htole64(root_off);
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pos = ftello(t.f);
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pos = ftello(f);
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h.nodes_len = htole64(pos - sizeof(struct trie_header_f));
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/* write string buffer */
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fwrite(trie->strings->buf, trie->strings->len, 1, t.f);
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fwrite(trie->strings->buf, trie->strings->len, 1, f);
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h.strings_len = htole64(trie->strings->len);
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/* write header */
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size = ftello(t.f);
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size = ftello(f);
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h.file_size = htole64(size);
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if (fseeko(t.f, 0, SEEK_SET) < 0)
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goto error_fclose;
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fwrite(&h, sizeof(struct trie_header_f), 1, t.f);
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if (fseeko(f, 0, SEEK_SET) < 0)
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return -errno;
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fwrite(&h, sizeof(struct trie_header_f), 1, f);
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if (ferror(t.f))
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goto error_fclose;
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if (fflush(t.f) < 0)
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goto error_fclose;
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if (fsync(fileno(t.f)) < 0)
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goto error_fclose;
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if (rename(filename_tmp, filename) < 0)
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goto error_fclose;
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r = flink_tmpfile(f, filename_tmp, filename, /* replace= */ true);
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if (r < 0)
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return r;
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/* write succeeded */
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fclose(t.f);
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log_debug("=== trie on-disk ===");
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log_debug("size: %8"PRIi64" bytes", size);
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@ -423,12 +426,6 @@ static int trie_store(struct trie *trie, const char *filename, bool compat) {
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log_debug("string store: %8zu bytes", trie->strings->len);
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log_debug("strings start: %8"PRIu64, t.strings_off);
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return 0;
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error_fclose:
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r = -errno;
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fclose(t.f);
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(void) unlink(filename_tmp);
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return r;
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}
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static int insert_data(struct trie *trie, char **match_list, char *line, const char *filename,
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