+++ /dev/null
-/*
- * Unix SMB/CIFS implementation.
- *
- * OneFS shadow copy implementation that utilizes the file system's native
- * snapshot support. This file does all of the heavy lifting.
- *
- * Copyright (C) Dave Richards, 2007
- * Copyright (C) Tim Prouty, 2009
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, see <http://www.gnu.org/licenses/>.
- */
-
-#include "smbd/smbd.h"
-#include <ifs/ifs_syscalls.h>
-#include <sys/types.h>
-#include <sys/isi_enc.h>
-#include <sys/module.h>
-#include <sys/stat.h>
-#include <sys/syscall.h>
-#include <sys/time.h>
-#include <dirent.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <limits.h>
-#include <search.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-
-#include "onefs_shadow_copy.h"
-
-/* Copied from ../include/proto.h */
-void become_root(void);
-void unbecome_root(void);
-
-#define SNAPSHOT_DIRECTORY ".snapshot"
-
-#define MAX_VERSIONS 64
-
-/**
- * A snapshot object.
- *
- * During snapshot enumeration, snapshots are represented by snapshot objects
- * and are stored in a snapshot set. The snapshot object represents one
- * snapshot within the set. An important thing to note about the set is that
- * the key of the snapshot object is the tv_sec component of the is_time
- * member. What this means is that we only store one snapshot for each
- * second. If multiple snapshots were created within the same second, we'll
- * keep the earliest one and ignore the rest. Thus, not all snapshots are
- * necessarily retained.
- */
-struct osc_snapshot {
- char * is_name;
- struct timespec is_time;
- struct osc_snapshot * is_next;
-};
-
-/**
- * A snapshot context object.
- *
- * Snapshot contexts are used to pass information throughout the snapshot
- * enumeration routines. As a result, snapshot contexts are stored on the
- * stack and are both created and destroyed within a single API function.
- */
-struct osc_snapshot_ctx {
- void * osc_set;
- struct timespec osc_mtime;
-};
-
-/**
- * A directory context.
- *
- * Directory contexts are the underlying data structured used to enumerate
- * snapshot versions. An opendir()-, readdir()- and closedir()-like interface
- * is provided that utilizes directory contexts. At the API level, directory
- * contexts are passed around as void pointers. Directory contexts are
- * allocated on the heap and their lifetime is dictated by the calling
- * routine.
- */
-struct osc_directory_ctx {
- size_t idc_pos;
- size_t idc_len;
- size_t idc_size;
- char ** idc_version;
-};
-
-/**
- * Return a file descriptor to the STF names directory.
- *
- * Opens the STF names directory and returns a file descriptor to it.
- * Subsequent calls return the same value (avoiding the need to re-open the
- * directory repeatedly). Caveat caller: don't close the file descriptor or
- * you will be shot!
- */
-static int
-osc_get_names_directory_fd(void)
-{
- static int fd = -1;
-
- if (fd == -1) {
- become_root();
- fd = pctl2_lin_open(STF_NAMES_LIN, HEAD_SNAPID, O_RDONLY);
- unbecome_root();
- }
-
- return fd;
-}
-
-/**
- * Compare two time values.
- *
- * Accepts two struct timespecs and compares the tv_sec components of these
- * values. It returns -1 if the first value preceeds the second, 0 if they
- * are equal and +1 if the first values succeeds the second.
- */
-static int
-osc_time_compare(const struct timespec *tsp1, const struct timespec *tsp2)
-{
- return (tsp1->tv_sec < tsp2->tv_sec) ? -1 :
- (tsp1->tv_sec > tsp2->tv_sec) ? +1 : 0;
-}
-
-/**
- * Compare two timespec values.
- *
- * Compares two timespec values. It returns -1 if the first value preceeds
- * the second, 0 if they are equal and +1 if the first values succeeds the
- * second.
- */
-static int
-osc_timespec_compare(const struct timespec *tsp1, const struct timespec *tsp2)
-{
- return (tsp1->tv_sec < tsp2->tv_sec) ? -1 :
- (tsp1->tv_sec > tsp2->tv_sec) ? +1 :
- (tsp1->tv_nsec < tsp2->tv_nsec) ? -1 :
- (tsp1->tv_nsec > tsp2->tv_nsec) ? +1 : 0;
-}
-
-/**
- * Determine whether a timespec value is zero.
- *
- * Return 1 if the struct timespec provided is zero and 0 otherwise.
- */
-static int
-osc_timespec_is_zero(const struct timespec *tsp)
-{
- return (tsp->tv_sec == 0) &&
- (tsp->tv_nsec == 0);
-}
-
-/**
- * Create a snapshot object.
- *
- * Allocates and initializes a new snapshot object. In addition to allocating
- * space for the snapshot object itself, space is allocated for the snapshot
- * name. Both the name and time are then copied to the new object.
- */
-static struct osc_snapshot *
-osc_snapshot_create(const char *name, const struct timespec *tsp)
-{
- struct osc_snapshot *isp;
-
- isp = malloc(sizeof *isp);
- if (isp == NULL)
- goto out;
-
- isp->is_name = malloc(strlen(name) + 1);
- if (isp->is_name == NULL) {
- free(isp);
- isp = NULL;
- goto out;
- }
-
- strcpy(isp->is_name, name);
- isp->is_time = *tsp;
- isp->is_next = NULL;
-
- out:
- return isp;
-}
-
-/**
- * Destroy a snapshot object.
- *
- * Frees both the name and the snapshot object itself. Appropriate NULL
- * checking is performed because counting on free to do so is immoral.
- */
-static void
-osc_snapshot_destroy(struct osc_snapshot *isp)
-{
- if (isp != NULL) {
- if (isp->is_name != NULL)
- free(isp->is_name);
- free(isp);
- }
-}
-
-/**
- * Destroy all snapshots in the snapshot list.
- *
- * Calls osc_snapshot_destroy() on each snapshot in the list.
- */
-static void
-osc_snapshot_destroy_list(struct osc_snapshot *isp)
-{
- struct osc_snapshot *tmp;
-
- while (isp != NULL) {
- tmp = isp;
- isp = isp->is_next;
- osc_snapshot_destroy(tmp);
- }
-}
-
-/**
- * Compare two snapshot objects.
- *
- * Compare two snapshot objects. It is really just a wrapper for
- * osc_time_compare(), which compare the time value of the two snapshots.
- * N.B. time value in this context refers only to the tv_sec component.
- */
-static int
-osc_snapshot_compare(const void *vp1, const void *vp2)
-{
- const struct osc_snapshot *isp1 = vp1;
- const struct osc_snapshot *isp2 = vp2;
-
- return -osc_time_compare(&isp1->is_time, &isp2->is_time);
-}
-
-/**
- * Insert a snapshot into the snapshot set.
- *
- * Inserts a new snapshot into the snapshot set. The key for snapshots is
- * their creation time (it's actually the seconds portion of the creation
- * time). If a duplicate snapshot is found in the set, the new snapshot is
- * added to a linked list of snapshots for that second.
- */
-static void
-osc_snapshot_insert(struct osc_snapshot_ctx *oscp, const char *name,
- const struct timespec *tsp, int *errorp)
-{
- struct osc_snapshot *isp1;
- struct osc_snapshot **ispp;
-
- isp1 = osc_snapshot_create(name, tsp);
- if (isp1 == NULL) {
- *errorp = 1;
- return;
- }
-
- ispp = tsearch(isp1, &oscp->osc_set, osc_snapshot_compare);
- if (ispp != NULL) {
- struct osc_snapshot *isp2 = *ispp;
-
- /* If this is the only snapshot for this second, we're done. */
- if (isp2 == isp1)
- return;
-
- /* Collision: add the new snapshot to the list. */
- isp1->is_next = isp2->is_next;
- isp2->is_next = isp1;
-
- } else
- *errorp = 1;
-
-}
-
-/**
- * Process the next snapshot.
- *
- * Called for (almost) every entry in a .snapshot directory, ("." and ".." are
- * ignored in osc_process_snapshot_directory()). All other entries are passed
- * to osc_process_snapshot(), however. These entries can fall into one of two
- * categories: snapshot names and snapshot aliases. We only care about
- * snapshot names (as aliases are just redundant entries). Once it verifies
- * that name represents a valid snapshot name, it calls fstat() to get the
- * creation time of the snapshot and then calls osc_snapshot_insert() to add
- * this entry to the snapshot set.
- */
-static void
-osc_process_snapshot(struct osc_snapshot_ctx *oscp, const char *name,
- int *errorp)
-{
- int fd;
- struct stf_stat stf_stat;
- struct stat stbuf;
-
- fd = osc_get_names_directory_fd();
- if (fd == -1)
- goto out;
-
- fd = enc_openat(fd, name, ENC_DEFAULT, O_RDONLY);
- if (fd == -1)
- goto out;
-
- memset(&stf_stat, 0, sizeof stf_stat);
- if (ifs_snap_stat(fd, &stf_stat) == -1)
- goto out;
-
- if (stf_stat.sf_type != SF_STF)
- goto out;
-
- if (fstat(fd, &stbuf) == -1)
- goto out;
-
- osc_snapshot_insert(oscp, name, &stbuf.st_birthtimespec, errorp);
-
- out:
- if (fd != -1)
- close(fd);
-}
-
-/**
- * Process a snapshot directory.
- *
- * Opens the snapshot directory and calls osc_process_snapshot() for each
- * entry. (Well ok, "." and ".." are ignored.) The goal here is to add all
- * snapshots in the directory to the snapshot set.
- */
-static void
-osc_process_snapshot_directory(struct osc_snapshot_ctx *oscp, int *errorp)
-{
- int fd;
- struct stat stbuf;
- DIR *dirp;
- struct dirent *dp;
-
- fd = osc_get_names_directory_fd();
- if (fd == -1)
- goto out;
-
- if (fstat(fd, &stbuf) == -1)
- goto out;
-
- dirp = opendir(SNAPSHOT_DIRECTORY);
- if (dirp == NULL)
- goto out;
-
- for (;;) {
- dp = readdir(dirp);
- if (dp == NULL)
- break;
-
- if (dp->d_name[0] == '.' && (dp->d_name[1] == '\0' ||
- (dp->d_name[1] == '.' && dp->d_name[2] == '\0')))
- continue;
-
- osc_process_snapshot(oscp, dp->d_name, errorp);
- if (*errorp)
- break;
- }
-
- closedir(dirp);
-
- if (!*errorp)
- oscp->osc_mtime = stbuf.st_mtimespec;
-
- out:
- return;
-}
-
-/**
- * Initialize a snapshot context object.
- *
- * Clears all members of the context object.
- */
-static void
-osc_snapshot_ctx_init(struct osc_snapshot_ctx *oscp)
-{
- memset(oscp, 0, sizeof *oscp);
-}
-
-/**
- * Desoy a snapshot context object.
- *
- * Frees all snapshots associated with the snapshot context and then calls
- * osc_snapshot_ctx_init() to re-initialize the context object.
- */
-static void
-osc_snapshot_ctx_clean(struct osc_snapshot_ctx *oscp)
-{
- struct osc_snapshot *tmp;
-
- while (oscp->osc_set != NULL) {
- tmp = *(void **)oscp->osc_set;
- tdelete(tmp, &oscp->osc_set, osc_snapshot_compare);
- osc_snapshot_destroy_list(tmp);
- }
-
- osc_snapshot_ctx_init(oscp);
-}
-
-/**
- * Return the "global" snapshot context.
- *
- * We maintain a single open snapshot context. Return a pointer to it.
- */
-static struct osc_snapshot_ctx *
-osc_get_snapshot_ctx(void)
-{
- static struct osc_snapshot_ctx osc = { 0, { 0, 0 } };
-
- return &osc;
-}
-
-/**
- * Determine whether a snapshot context is still valid.
- *
- * "Valid" in this context means "reusable". We can re-use a previous
- * snapshot context iff we successfully built a previous snapshot context
- * and no snapshots have been created or deleted since we did so.
- * A "names" directory exists within our snapshot
- * implementation in which all snapshot names are entered. Each time a
- * snapshot is created or deleted, an entry must be added or removed.
- * When this happens the modification time on the "names" directory
- * changes. Therefore, a snapshot context is valid iff the context
- * pointer is non-NULL, the cached modification time is non-zero
- * (zero means uninitialized), and the modification time of the "names"
- * directory matches the cached value.
- */
-static int
-osc_snapshot_ctx_is_valid(struct osc_snapshot_ctx *oscp)
-{
- int fd;
- struct stat stbuf;
-
- if (oscp == NULL)
- return 0;
-
- if (osc_timespec_is_zero(&oscp->osc_mtime))
- return 0;
-
- fd = osc_get_names_directory_fd();
- if (fd == -1)
- return 0;
-
- if (fstat(fd, &stbuf) == -1)
- return 0;
-
- if (osc_timespec_compare(&oscp->osc_mtime, &stbuf.st_mtimespec) != 0)
- return 0;
-
- return 1;
-}
-
-/**
- * Create and initialize a directory context.
- *
- * Allocates a directory context from the heap and initializes it.
- */
-static struct osc_directory_ctx *
-osc_directory_ctx_create(void)
-{
- struct osc_directory_ctx *idcp;
-
- idcp = malloc(sizeof *idcp);
- if (idcp != NULL)
- memset(idcp, 0, sizeof *idcp);
-
- return idcp;
-}
-
-/**
- * Destroy a directory context.
- *
- * Frees any versions associated with the directory context and then frees the
- * context itself.
- */
-static void
-osc_directory_ctx_destroy(struct osc_directory_ctx *idcp)
-{
- int i;
-
- if (idcp == NULL)
- return;
-
- for (i = 0; i < idcp->idc_len; i++)
- free(idcp->idc_version[i]);
-
- free(idcp);
-}
-
-/**
- * Expand the size of a directory context's version list.
- *
- * If osc_directory_ctx_append_version() detects that the version list is too
- * small to accomodate a new version string, it called
- * osc_directory_ctx_expand_version_list() to expand the version list.
- */
-static void
-osc_directory_ctx_expand_version_list(struct osc_snapshot_ctx *oscp,
- struct osc_directory_ctx *idcp, int *errorp)
-{
- size_t size;
- char **cpp;
-
- size = idcp->idc_size * 2 ?: 1;
-
- cpp = realloc(idcp->idc_version, size * sizeof (char *));
- if (cpp == NULL) {
- *errorp = 1;
- return;
- }
-
- idcp->idc_size = size;
- idcp->idc_version = cpp;
-}
-
-/**
- * Append a new version to a directory context.
- *
- * Appends a snapshot version to the
- * directory context's version list.
- */
-static void
-osc_directory_ctx_append_version(struct osc_snapshot_ctx *oscp,
- struct osc_directory_ctx *idcp, const struct timespec *tsp, int *errorp)
-{
- char *cp;
- struct tm *tmp;
- char text[64];
-
- if (idcp->idc_len >= MAX_VERSIONS)
- return;
-
- if (idcp->idc_len >= idcp->idc_size) {
- osc_directory_ctx_expand_version_list(oscp, idcp, errorp);
- if (*errorp)
- return;
- }
-
- tmp = gmtime(&tsp->tv_sec);
- if (tmp == NULL) {
- *errorp = 1;
- return;
- }
-
- snprintf(text, sizeof text,
- "@GMT-%04u.%02u.%02u-%02u.%02u.%02u",
- tmp->tm_year + 1900,
- tmp->tm_mon + 1,
- tmp->tm_mday,
- tmp->tm_hour,
- tmp->tm_min,
- tmp->tm_sec);
-
- cp = malloc(strlen(text) + 1);
- if (cp == NULL) {
- *errorp = 1;
- return;
- }
-
- strcpy(cp, text);
-
- idcp->idc_version[idcp->idc_len++] = cp;
-}
-
-/**
- * Make a directory context from a snapshot context.
- *
- * Once a snapshot context has been completely filled-in,
- * osc_make_directory_ctx() is used to build a directory context from it. The
- * idea here is to create version for each snapshot in the snapshot set.
- */
-static void
-osc_make_directory_ctx(struct osc_snapshot_ctx *oscp,
- struct osc_directory_ctx *idcp, int *errorp)
-{
- static void
- walk(const void *vp, VISIT v, int level)
- {
- const struct osc_snapshot *isp;
-
- if ((v != postorder && v != leaf) || *errorp)
- return;
-
- isp = *(const struct osc_snapshot **)(u_long)vp;
-
- osc_directory_ctx_append_version(oscp, idcp, &isp->is_time,
- errorp);
- }
-
- twalk(oscp->osc_set, walk);
-}
-
-/**
- * Open a version directory.
- *
- * Opens a version directory. What this really means is that
- * osc_version_opendir() returns a handle to a directory context, which can be
- * used to retrieve version strings.
- */
-void *
-osc_version_opendir(void)
-{
- int error = 0;
- struct osc_directory_ctx *idcp;
- struct osc_snapshot_ctx *oscp;
-
- idcp = osc_directory_ctx_create();
- if (idcp == NULL)
- goto error_out;
-
- oscp = osc_get_snapshot_ctx();
-
- if (!osc_snapshot_ctx_is_valid(oscp)) {
- osc_snapshot_ctx_clean(oscp);
- osc_process_snapshot_directory(oscp, &error);
- if (error)
- goto error_out;
- }
-
- osc_make_directory_ctx(oscp, idcp, &error);
- if (error)
- goto error_out;
-
- goto out;
-
- error_out:
- if (idcp != NULL) {
- osc_directory_ctx_destroy(idcp);
- idcp = NULL;
- }
-
- out:
- return (void *)idcp;
-}
-
-/**
- * Read the next version directory entry.
- *
- * Returns the name of the next version in the version directory, or NULL if
- * we're at the end of the directory. What this really does is return the
- * next version from the version list stored in the directory context.
- */
-char *
-osc_version_readdir(void *vp)
-{
- struct osc_directory_ctx *idcp = vp;
-
- if (idcp == NULL)
- return NULL;
-
- if (idcp->idc_pos >= idcp->idc_len)
- return NULL;
-
- return idcp->idc_version[idcp->idc_pos++];
-}
-
-/**
- * Close the version directory.
- *
- * Destroys the underlying directory context.
- */
-void
-osc_version_closedir(void *vp)
-{
- struct osc_directory_ctx *idcp = vp;
-
- if (idcp != NULL)
- osc_directory_ctx_destroy(idcp);
-}
-
-/**
- * Canonicalize a path.
- *
- * Converts paths of the form @GMT-.. to paths of the form ../.snapshot/..
- * It's not the prettiest routine I've ever written, but what the heck?
- */
-char *
-osc_canonicalize_path(const char *path, char *snap_component)
-{
- int error = 0;
- struct osc_snapshot_ctx *oscp;
- struct tm tm;
- int n;
- struct osc_snapshot is;
- struct osc_snapshot **ispp;
- struct osc_snapshot *isp;
- char *cpath = NULL;
- char *cpath2 = NULL;
- const char *snap_component_orig = snap_component;
- struct stat sb;
-
- oscp = osc_get_snapshot_ctx();
-
- if (!osc_snapshot_ctx_is_valid(oscp)) {
- osc_snapshot_ctx_clean(oscp);
- osc_process_snapshot_directory(oscp, &error);
- if (error)
- goto out;
- }
-
- memset(&tm, 0, sizeof tm);
- n = sscanf(snap_component,
- "@GMT-%4u.%2u.%2u-%2u.%2u.%2u",
- &tm.tm_year,
- &tm.tm_mon,
- &tm.tm_mday,
- &tm.tm_hour,
- &tm.tm_min,
- &tm.tm_sec);
- if (n != 6)
- goto out;
-
- tm.tm_year -= 1900;
- tm.tm_mon -= 1;
-
- is.is_name = NULL;
- is.is_time.tv_sec = timegm(&tm);
- is.is_time.tv_nsec = 0;
-
- ispp = tfind(&is, &oscp->osc_set, osc_snapshot_compare);
- if (ispp == NULL)
- goto out;
- isp = *ispp;
-
- /* Determine the path after "@GMT-..." */
- while (*snap_component != '/' && *snap_component != '\0')
- snap_component++;
-
- while (*snap_component == '/')
- snap_component++;
-
- cpath = malloc(strlen(SNAPSHOT_DIRECTORY) + strlen(isp->is_name) +
- strlen(path) + 3);
-
- if (cpath == NULL)
- goto out;
-
- /*
- * Use the first snapshot that has a successful stat for the requested
- * path.
- */
- while (true) {
-
- sprintf(cpath, "%s/%s", SNAPSHOT_DIRECTORY, isp->is_name);
-
- /* Append path before "@GMT-..." */
- if (snap_component_orig != path) {
- strcat(cpath, "/");
- strncat(cpath, path, snap_component_orig - path);
- }
-
- /* Append path after "@GMT-..." */
- if (*snap_component != '\0') {
- strcat(cpath, "/");
- strcat(cpath, snap_component);
- }
-
- /* If there is a valid snapshot for this file, we're done. */
- if (stat(cpath, &sb) == 0)
- break;
-
- /* Try the next snapshot. If this was the last one, give up. */
- isp = isp->is_next;
- if (isp == NULL)
- break;
-
- /* If the realloc fails, give up. */
- cpath2 = realloc(cpath, strlen(SNAPSHOT_DIRECTORY) +
- strlen(isp->is_name) + strlen(path) + 3);
- if (cpath2 == NULL)
- break;
- cpath = cpath2;
- }
-
- out:
- return cpath;
-}
git.samba.org / abartlet / samba-debian.git / blobdiff