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Diffstat (limited to 'src/common/storagedir.c')
| -rw-r--r-- | src/common/storagedir.c | 586 |
1 files changed, 586 insertions, 0 deletions
diff --git a/src/common/storagedir.c b/src/common/storagedir.c new file mode 100644 index 0000000000..c471ea911f --- /dev/null +++ b/src/common/storagedir.c @@ -0,0 +1,586 @@ +/* Copyright (c) 2017, The Tor Project, Inc. */ +/* See LICENSE for licensing information */ + +#include "container.h" +#include "compat.h" +#include "confline.h" +#include "memarea.h" +#include "sandbox.h" +#include "storagedir.h" +#include "torlog.h" +#include "util.h" + +#ifdef HAVE_SYS_TYPES_H +#include <sys/types.h> +#endif +#ifdef HAVE_SYS_STAT_H +#include <sys/stat.h> +#endif +#ifdef HAVE_UNISTD_H +#include <unistd.h> +#endif + +#define FNAME_MIN_NUM 1000 + +/** A storage_dir_t represents a directory full of similar cached + * files. Filenames are decimal integers. Files can be cleaned as needed + * to limit total disk usage. */ +struct storage_dir_t { + /** Directory holding the files for this storagedir. */ + char *directory; + /** Either NULL, or a directory listing of the directory (as a smartlist + * of strings */ + smartlist_t *contents; + /** The largest number of non-temporary files we'll place in the + * directory. */ + int max_files; + /** If true, then 'usage' has been computed. */ + int usage_known; + /** The total number of bytes used in this directory */ + uint64_t usage; +}; + +/** Create or open a new storage directory at <b>dirname</b>, with + * capacity for up to <b>max_files</b> files. + */ +storage_dir_t * +storage_dir_new(const char *dirname, int max_files) +{ + if (check_private_dir(dirname, CPD_CREATE, NULL) < 0) + return NULL; + + storage_dir_t *d = tor_malloc_zero(sizeof(storage_dir_t)); + d->directory = tor_strdup(dirname); + d->max_files = max_files; + return d; +} + +/** + * Drop all in-RAM storage for <b>d</b>. Does not delete any files. + */ +void +storage_dir_free(storage_dir_t *d) +{ + if (d == NULL) + return; + tor_free(d->directory); + if (d->contents) { + SMARTLIST_FOREACH(d->contents, char *, cp, tor_free(cp)); + smartlist_free(d->contents); + } + tor_free(d); +} + +/** + * Tell the sandbox (if any) configured by <b>cfg</b> to allow the + * operations that <b>d</b> will need. + * + * The presence of this function is why we need an upper limit on the + * number of files in a storage_dir_t: we need to approve file operations + * one by one. + */ +int +storage_dir_register_with_sandbox(storage_dir_t *d, sandbox_cfg_t **cfg) +{ + int problems = 0; + int idx; + for (idx = FNAME_MIN_NUM; idx < FNAME_MIN_NUM + d->max_files; ++idx) { + char *path = NULL, *tmppath = NULL; + tor_asprintf(&path, "%s/%d", d->directory, idx); + tor_asprintf(&tmppath, "%s/%d.tmp", d->directory, idx); + + problems += sandbox_cfg_allow_open_filename(cfg, tor_strdup(path)); + problems += sandbox_cfg_allow_open_filename(cfg, tor_strdup(tmppath)); + problems += sandbox_cfg_allow_stat_filename(cfg, tor_strdup(path)); + problems += sandbox_cfg_allow_stat_filename(cfg, tor_strdup(tmppath)); + problems += sandbox_cfg_allow_rename(cfg, + tor_strdup(tmppath), tor_strdup(path)); + + tor_free(path); + tor_free(tmppath); + } + + return problems ? -1 : 0; +} + +/** + * Remove all files in <b>d</b> whose names end with ".tmp". + * + * Requires that the contents field of <b>d</b> is set. + */ +static void +storage_dir_clean_tmpfiles(storage_dir_t *d) +{ + if (!d->contents) + return; + SMARTLIST_FOREACH_BEGIN(d->contents, char *, fname) { + if (strcmpend(fname, ".tmp")) + continue; + char *path = NULL; + tor_asprintf(&path, "%s/%s", d->directory, fname); + if (unlink(sandbox_intern_string(path))) { + log_warn(LD_FS, "Unable to unlink %s while cleaning " + "temporary files: %s", escaped(path), strerror(errno)); + tor_free(path); + continue; + } + tor_free(path); + SMARTLIST_DEL_CURRENT(d->contents, fname); + tor_free(fname); + } SMARTLIST_FOREACH_END(fname); + + d->usage_known = 0; +} + +/** + * Re-scan the directory <b>d</b> to learn its contents. + */ +static int +storage_dir_rescan(storage_dir_t *d) +{ + if (d->contents) { + SMARTLIST_FOREACH(d->contents, char *, cp, tor_free(cp)); + smartlist_free(d->contents); + } + d->usage = 0; + d->usage_known = 0; + if (NULL == (d->contents = tor_listdir(d->directory))) { + return -1; + } + storage_dir_clean_tmpfiles(d); + return 0; +} + +/** + * Return a smartlist containing the filenames within <b>d</b>. + */ +const smartlist_t * +storage_dir_list(storage_dir_t *d) +{ + if (! d->contents) + storage_dir_rescan(d); + return d->contents; +} + +/** + * Return the total number of bytes used for storage in <b>d</b>. + */ +uint64_t +storage_dir_get_usage(storage_dir_t *d) +{ + if (d->usage_known) + return d->usage; + + uint64_t total = 0; + SMARTLIST_FOREACH_BEGIN(storage_dir_list(d), const char *, cp) { + char *path = NULL; + struct stat st; + tor_asprintf(&path, "%s/%s", d->directory, cp); + if (stat(sandbox_intern_string(path), &st) == 0) { + total += st.st_size; + } + tor_free(path); + } SMARTLIST_FOREACH_END(cp); + + d->usage = total; + d->usage_known = 1; + return d->usage; +} + +/** Mmap a specified file within <b>d</b>. + * + * On failure, return NULL and set errno as for tor_mmap_file(). */ +tor_mmap_t * +storage_dir_map(storage_dir_t *d, const char *fname) +{ + char *path = NULL; + tor_asprintf(&path, "%s/%s", d->directory, fname); + tor_mmap_t *result = tor_mmap_file(path); + int errval = errno; + tor_free(path); + if (result == NULL) + errno = errval; + return result; +} + +/** Read a file within <b>d</b> into a newly allocated buffer. Set + * *<b>sz_out</b> to its size. */ +uint8_t * +storage_dir_read(storage_dir_t *d, const char *fname, int bin, size_t *sz_out) +{ + const int flags = bin ? RFTS_BIN : 0; + + char *path = NULL; + tor_asprintf(&path, "%s/%s", d->directory, fname); + struct stat st; + char *contents = read_file_to_str(path, flags, &st); + if (contents && sz_out) { + // it fits in RAM, so we know its size is less than SIZE_MAX +#if UINT64_MAX > SIZE_MAX + tor_assert((uint64_t)st.st_size <= SIZE_MAX); +#endif + *sz_out = (size_t) st.st_size; + } + + tor_free(path); + return (uint8_t *) contents; +} + +/** Helper: Find an unused filename within the directory */ +static char * +find_unused_fname(storage_dir_t *d) +{ + if (!d->contents) { + if (storage_dir_rescan(d) < 0) + return NULL; + } + + char buf[16]; + int i; + /* Yuck; this is quadratic. Fortunately, that shouldn't matter much, + * since disk writes are more expensive by a lot. */ + for (i = FNAME_MIN_NUM; i < FNAME_MIN_NUM + d->max_files; ++i) { + tor_snprintf(buf, sizeof(buf), "%d", i); + if (!smartlist_contains_string(d->contents, buf)) { + return tor_strdup(buf); + } + } + 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 + * -1. */ +int +storage_dir_save_bytes_to_file(storage_dir_t *d, + const uint8_t *data, + size_t length, + int binary, + char **fname_out) +{ + 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; +} + +/** + * As storage_dir_save_bytes_to_file, but saves a NUL-terminated string + * <b>str</b>. + */ +int +storage_dir_save_string_to_file(storage_dir_t *d, + const char *str, + int binary, + char **fname_out) +{ + return storage_dir_save_bytes_to_file(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_to_file(). On + * failure, return NULL. On success, write a set of newly allocated labels + * into *<b>labels_out</b>, a pointer to the data into *<b>data_out</b>, and + * the data's size 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. + * + * On failure, set errno as for tor_mmap_file() if the file was missing or + * empty, and set errno to EINVAL if the file was not in the labeled + * format expected. + */ +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); + int errval; + if (! m) { + errval = errno; + goto err; + } + const char *nulp = memchr(m->data, '\0', m->size); + if (! nulp) { + errval = EINVAL; + goto err; + } + if (labels_out && config_get_lines(m->data, labels_out, 0) < 0) { + errval = EINVAL; + 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); + errno = errval; + 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; +} + +/* Reduce the cached usage amount in <b>d</b> by <b>removed_file_size</b>. + * This function is a no-op if <b>d->usage_known</b> is 0. */ +static void +storage_dir_reduce_usage(storage_dir_t *d, uint64_t removed_file_size) +{ + if (d->usage_known) { + if (! BUG(d->usage < removed_file_size)) { + /* This bug can also be triggered if an external process resized a file + * between the call to storage_dir_get_usage() that last checked + * actual usage (rather than relaying on cached usage), and the call to + * this function. */ + d->usage -= removed_file_size; + } else { + /* If we underflowed the cached directory size, re-check the sizes of all + * the files in the directory. This makes storage_dir_shrink() quadratic, + * but only if a process is continually changing file sizes in the + * storage directory (in which case, we have bigger issues). + * + * We can't just reset usage_known, because storage_dir_shrink() relies + * on knowing the usage. */ + storage_dir_rescan(d); + (void)storage_dir_get_usage(d); + } + } +} + +/** + * Remove the file called <b>fname</b> from <b>d</b>. + */ +void +storage_dir_remove_file(storage_dir_t *d, + const char *fname) +{ + char *path = NULL; + tor_asprintf(&path, "%s/%s", d->directory, fname); + const char *ipath = sandbox_intern_string(path); + + uint64_t size = 0; + if (d->usage_known) { + struct stat st; + if (stat(ipath, &st) == 0) { + size = st.st_size; + } + } + if (unlink(ipath) == 0) { + storage_dir_reduce_usage(d, size); + } else { + log_warn(LD_FS, "Unable to unlink %s while removing file: %s", + escaped(path), strerror(errno)); + tor_free(path); + return; + } + if (d->contents) { + smartlist_string_remove(d->contents, fname); + } + + tor_free(path); +} + +/** Helper type: used to sort the members of storage directory by mtime. */ +typedef struct shrinking_dir_entry_t { + time_t mtime; + uint64_t size; + char *path; +} shrinking_dir_entry_t; + +/** Helper: use with qsort to sort shrinking_dir_entry_t structs. */ +static int +shrinking_dir_entry_compare(const void *a_, const void *b_) +{ + const shrinking_dir_entry_t *a = a_; + const shrinking_dir_entry_t *b = b_; + + if (a->mtime < b->mtime) + return -1; + else if (a->mtime > b->mtime) + return 1; + else + return 0; +} + +/** + * Try to free space by removing the oldest files in <b>d</b>. Delete + * until no more than <b>target_size</b> bytes are left, and at least + * <b>min_to_remove</b> files have been removed... or until there is + * nothing left to remove. + * + * Return 0 on success; -1 on failure. + */ +int +storage_dir_shrink(storage_dir_t *d, + uint64_t target_size, + int min_to_remove) +{ + if (d->usage_known && d->usage <= target_size && !min_to_remove) { + /* Already small enough. */ + return 0; + } + + if (storage_dir_rescan(d) < 0) + return -1; + + const uint64_t orig_usage = storage_dir_get_usage(d); + if (orig_usage <= target_size && !min_to_remove) { + /* Okay, small enough after rescan! */ + return 0; + } + + const int n = smartlist_len(d->contents); + shrinking_dir_entry_t *ents = tor_calloc(n, sizeof(shrinking_dir_entry_t)); + SMARTLIST_FOREACH_BEGIN(d->contents, const char *, fname) { + shrinking_dir_entry_t *ent = &ents[fname_sl_idx]; + struct stat st; + tor_asprintf(&ent->path, "%s/%s", d->directory, fname); + if (stat(sandbox_intern_string(ent->path), &st) == 0) { + ent->mtime = st.st_mtime; + ent->size = st.st_size; + } + } SMARTLIST_FOREACH_END(fname); + + qsort(ents, n, sizeof(shrinking_dir_entry_t), shrinking_dir_entry_compare); + + int idx = 0; + while ((d->usage > target_size || min_to_remove > 0) && idx < n) { + if (unlink(sandbox_intern_string(ents[idx].path)) == 0) { + storage_dir_reduce_usage(d, ents[idx].size); + --min_to_remove; + } + ++idx; + } + + for (idx = 0; idx < n; ++idx) { + tor_free(ents[idx].path); + } + tor_free(ents); + + storage_dir_rescan(d); + + return 0; +} + +/** Remove all files in <b>d</b>. */ +int +storage_dir_remove_all(storage_dir_t *d) +{ + return storage_dir_shrink(d, 0, d->max_files); +} + +/** + * Return the largest number of non-temporary files we're willing to + * store in <b>d</b>. + */ +int +storage_dir_get_max_files(storage_dir_t *d) +{ + return d->max_files; +} + |