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/*
* C Implementation: cow
*
* Copy-on-write functions
*
* License: BSD-style license
* Copyright: Radek Podgorny <radek@podgorny.cz>,
* Bernd Schubert <bernd-schubert@gmx.de>
*/
#include <sys/types.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <locale.h>
#include <errno.h>
#include <stdio.h>
#include <dirent.h>
#include "opts.h"
#include "findbranch.h"
#include "general.h"
#include "cow.h"
#include "cow_utils.h"
#include "string.h"
#include "debug.h"
#include "usyslog.h"
/**
* Actually create the directory here.
*/
static int do_create(const char *path, int nbranch_ro, int nbranch_rw) {
DBG("%s\n", path);
char dirp[PATHLEN_MAX]; // dir path to create
sprintf(dirp, "%s%s", uopt.branches[nbranch_rw].path, path);
struct stat buf;
int res = stat(dirp, &buf);
if (res != -1) RETURN(0); // already exists
if (nbranch_ro == nbranch_rw) {
// special case nbranch_ro = nbranch_rw, this is if we a create
// unionfs meta directories, so not directly on cow operations
buf.st_mode = S_IRWXU | S_IRWXG;
} else {
// data from the ro-branch
char o_dirp[PATHLEN_MAX]; // the pathname we want to copy
sprintf(o_dirp, "%s%s", uopt.branches[nbranch_ro].path, path);
res = stat(o_dirp, &buf);
if (res == -1) RETURN(1); // lower level branch removed in the mean time?
}
res = mkdir(dirp, buf.st_mode);
if (res == -1) {
USYSLOG(LOG_DAEMON, "Creating %s failed: \n", dirp);
RETURN(1);
}
if (nbranch_ro == nbranch_rw) RETURN(0); // the special case again
if (setfile(dirp, &buf)) RETURN(1); // directory already removed by another process?
// TODO: time, but its values are modified by the next dir/file creation steps?
RETURN(0);
}
/**
* l_nbranch (lower nbranch than nbranch) is write protected, create the dir path on
* nbranch for an other COW operation.
*/
int path_create(const char *path, int nbranch_ro, int nbranch_rw) {
DBG("%s\n", path);
if (!uopt.cow_enabled) RETURN(0);
char p[PATHLEN_MAX];
if (BUILD_PATH(p, uopt.branches[nbranch_rw].path, path)) RETURN(-ENAMETOOLONG);
struct stat st;
if (!stat(p, &st)) {
// path does already exists, no need to create it
RETURN(0);
}
char *walk = (char *)path;
// first slashes, e.g. we have path = /dir1/dir2/, will set walk = dir1/dir2/
while (*walk != '\0' && *walk == '/') walk++;
do {
// walk over the directory name, walk will now be /dir2
while (*walk != '\0' && *walk != '/') walk++;
// +1 due to \0, which gets added automatically
snprintf(p, (walk - path) + 1, "%s", path); // walk - path = strlen(/dir1)
int res = do_create(p, nbranch_ro, nbranch_rw);
if (res) RETURN(res); // creating the directory failed
// as above the do loop, walk over the next slashes, walk = dir2/
while (*walk != '\0' && *walk == '/') walk++;
} while (*walk != '\0');
RETURN(0);
}
/**
* Same as path_create(), but ignore the last segment in path,
* i.e. it might be a filename.
*/
int path_create_cutlast(const char *path, int nbranch_ro, int nbranch_rw) {
DBG("%s\n", path);
char *dname = u_dirname(path);
if (dname == NULL)
RETURN(-ENOMEM);
int ret = path_create(dname, nbranch_ro, nbranch_rw);
free(dname);
RETURN(ret);
}
/**
* initiate the cow-copy action
*/
int cow_cp(const char *path, int branch_ro, int branch_rw) {
DBG("%s\n", path);
// create the path to the file
path_create_cutlast(path, branch_ro, branch_rw);
char from[PATHLEN_MAX], to[PATHLEN_MAX];
if (BUILD_PATH(from, uopt.branches[branch_ro].path, path))
RETURN(-ENAMETOOLONG);
if (BUILD_PATH(to, uopt.branches[branch_rw].path, path))
RETURN(-ENAMETOOLONG);
setlocale(LC_ALL, "");
struct cow cow;
cow.uid = getuid();
// Copy the umask for explicit mode setting.
cow.umask = umask(0);
umask(cow.umask);
cow.from_path = from;
cow.to_path = to;
struct stat buf;
lstat(cow.from_path, &buf);
cow.stat = &buf;
int res;
switch (buf.st_mode & S_IFMT) {
case S_IFLNK:
res = copy_link(&cow);
break;
case S_IFDIR:
res = copy_directory(path, branch_ro, branch_rw);
break;
case S_IFBLK:
case S_IFCHR:
res = copy_special(&cow);
break;
case S_IFIFO:
res = copy_fifo(&cow);
break;
case S_IFSOCK:
USYSLOG(LOG_WARNING, "COW of sockets not supported: %s\n", cow.from_path);
RETURN(1);
default:
res = copy_file(&cow);
}
RETURN(res);
}
/**
* copy a directory between branches (includes all contents of the directory)
*/
int copy_directory(const char *path, int branch_ro, int branch_rw) {
DBG("%s\n", path);
/* create the directory on the destination branch */
int res = path_create(path, branch_ro, branch_rw);
if (res != 0) {
RETURN(res);
}
/* determine path to source directory on read-only branch */
char from[PATHLEN_MAX];
if (BUILD_PATH(from, uopt.branches[branch_ro].path, path)) RETURN(1);
DIR *dp = opendir(from);
if (dp == NULL) RETURN(1);
struct dirent *de;
while ((de = readdir(dp)) != NULL) {
if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0) continue;
char member[PATHLEN_MAX];
if (BUILD_PATH(member, path, de->d_name)) RETURN(1);
res = cow_cp(member, branch_ro, branch_rw);
if (res != 0) RETURN(res);
}
closedir(dp);
RETURN(0);
}
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