Add some "labeled storagedir" abstractions.

These add a tiny bit of structure on top of the regular storagedir
abstractions in order to store key-value lists at the head of each
document.
This commit is contained in:
Nick Mathewson 2017-03-29 12:55:09 +02:00
parent b6f22524ee
commit 37bb3b31fa
2 changed files with 155 additions and 20 deletions

View File

@ -3,6 +3,8 @@
#include "container.h"
#include "compat.h"
#include "confline.h"
#include "memarea.h"
#include "sandbox.h"
#include "storagedir.h"
#include "torlog.h"
@ -237,6 +239,40 @@ find_unused_fname(storage_dir_t *d)
return NULL;
}
/** Helper: As storage_dir_save_bytes_to_file, but store a smartlist of
* sized_chunk_t rather than a single byte array. */
static int
storage_dir_save_chunks_to_file(storage_dir_t *d,
const smartlist_t *chunks,
int binary,
char **fname_out)
{
uint64_t total_length = 0;
char *fname = find_unused_fname(d);
if (!fname)
return -1;
SMARTLIST_FOREACH(chunks, const sized_chunk_t *, ch,
total_length += ch->len);
char *path = NULL;
tor_asprintf(&path, "%s/%s", d->directory, fname);
int r = write_chunks_to_file(path, chunks, binary, 0);
if (r == 0) {
if (d->usage_known)
d->usage += total_length;
if (fname_out) {
*fname_out = tor_strdup(fname);
}
if (d->contents)
smartlist_add(d->contents, tor_strdup(fname));
}
tor_free(fname);
tor_free(path);
return r;
}
/** Try to write the <b>length</b> bytes at <b>data</b> into a new file
* in <b>d</b>. On success, return 0 and set *<b>fname_out</b> to a
* newly allocated string containing the filename. On failure, return
@ -248,25 +284,11 @@ storage_dir_save_bytes_to_file(storage_dir_t *d,
int binary,
char **fname_out)
{
char *fname = find_unused_fname(d);
if (!fname)
return -1;
char *path = NULL;
tor_asprintf(&path, "%s/%s", d->directory, fname);
int r = write_bytes_to_file(path, (const char *)data, length, binary);
if (r == 0) {
if (d->usage_known)
d->usage += length;
if (fname_out) {
*fname_out = tor_strdup(fname);
}
if (d->contents)
smartlist_add(d->contents, tor_strdup(fname));
}
tor_free(fname);
tor_free(path);
smartlist_t *chunks = smartlist_new();
sized_chunk_t chunk = { (const char *)data, length };
smartlist_add(chunks, &chunk);
int r = storage_dir_save_chunks_to_file(d, chunks, binary, fname_out);
smartlist_free(chunks);
return r;
}
@ -284,6 +306,106 @@ storage_dir_save_string_to_file(storage_dir_t *d,
(const uint8_t*)str, strlen(str), binary, fname_out);
}
/**
* As storage_dir_save_bytes_to_file, but associates the data with the
* key-value pairs in <b>labels</b>. Files
* stored in this format can be recovered with storage_dir_map_labeled
* or storage_dir_read_labeled().
*/
int
storage_dir_save_labeled_to_file(storage_dir_t *d,
const config_line_t *labels,
const uint8_t *data,
size_t length,
char **fname_out)
{
/*
* The storage format is to prefix the data with the key-value pairs in
* <b>labels</b>, and a single NUL separator. But code outside this module
* MUST NOT rely on that format.
*/
smartlist_t *chunks = smartlist_new();
memarea_t *area = memarea_new();
const config_line_t *line;
for (line = labels; line; line = line->next) {
sized_chunk_t *sz = memarea_alloc(area, sizeof(sized_chunk_t));
sz->len = strlen(line->key) + 1 + strlen(line->value) + 1;
const size_t allocated = sz->len + 1;
char *bytes = memarea_alloc(area, allocated);
tor_snprintf(bytes, allocated, "%s %s\n", line->key, line->value);
sz->bytes = bytes;
smartlist_add(chunks, sz);
}
sized_chunk_t *nul = memarea_alloc(area, sizeof(sized_chunk_t));
nul->len = 1;
nul->bytes = "\0";
smartlist_add(chunks, nul);
sized_chunk_t *datachunk = memarea_alloc(area, sizeof(sized_chunk_t));
datachunk->bytes = (const char *)data;
datachunk->len = length;
smartlist_add(chunks, datachunk);
int r = storage_dir_save_chunks_to_file(d, chunks, 1, fname_out);
smartlist_free(chunks);
memarea_drop_all(area);
return r;
}
/**
* Map a file that was created with storage_dir_save_labeled(). On failure,
* return NULL. On success, write a set of newly allocated labels into to
* *<b>labels_out</b>, a pointer to the into *<b>data_out</b>, and the data's
* into *<b>sz_out</b>. On success, also return a tor_mmap_t object whose
* contents should not be used -- it needs to be kept around, though, for as
* long as <b>data_out</b> is going to be valid.
*/
tor_mmap_t *
storage_dir_map_labeled(storage_dir_t *dir,
const char *fname,
config_line_t **labels_out,
const uint8_t **data_out,
size_t *sz_out)
{
tor_mmap_t *m = storage_dir_map(dir, fname);
if (! m)
goto err;
const char *nulp = memchr(m->data, '\0', m->size);
if (! nulp)
goto err;
if (labels_out && config_get_lines(m->data, labels_out, 0) < 0)
goto err;
size_t offset = nulp - m->data + 1;
tor_assert(offset <= m->size);
*data_out = (const uint8_t *)(m->data + offset);
*sz_out = m->size - offset;
return m;
err:
tor_munmap_file(m);
return NULL;
}
/** As storage_dir_map_labeled, but return a new byte array containing the
* data. */
uint8_t *
storage_dir_read_labeled(storage_dir_t *dir,
const char *fname,
config_line_t **labels_out,
size_t *sz_out)
{
const uint8_t *data = NULL;
tor_mmap_t *m = storage_dir_map_labeled(dir, fname, labels_out,
&data, sz_out);
if (m == NULL)
return NULL;
uint8_t *result = tor_memdup(data, *sz_out);
tor_munmap_file(m);
return result;
}
/**
* Remove the file called <b>fname</b> from <b>d</b>.
*/

View File

@ -5,7 +5,7 @@
#define TOR_STORAGEDIR_H
typedef struct storage_dir_t storage_dir_t;
struct config_line_t;
struct sandbox_cfg_elem;
storage_dir_t * storage_dir_new(const char *dirname, int n_files);
@ -26,6 +26,19 @@ int storage_dir_save_string_to_file(storage_dir_t *d,
const char *data,
int binary,
char **fname_out);
int storage_dir_save_labeled_to_file(storage_dir_t *d,
const struct config_line_t *labels,
const uint8_t *data,
size_t length,
char **fname_out);
tor_mmap_t *storage_dir_map_labeled(storage_dir_t *dir,
const char *fname,
struct config_line_t **labels_out,
const uint8_t **data_out,
size_t *size_out);
uint8_t *storage_dir_read_labeled(storage_dir_t *d, const char *fname,
struct config_line_t **labels_out,
size_t *sz_out);
void storage_dir_remove_file(storage_dir_t *d,
const char *fname);
int storage_dir_shrink(storage_dir_t *d,