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/* $NetBSD: file_subs.c,v 1.63 2013/07/29 17:46:36 christos Exp $ */
/*-
* Copyright (c) 1992 Keith Muller.
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Keith Muller of the University of California, San Diego.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif
#include <sys/cdefs.h>
#if !defined(lint)
#if 0
static char sccsid[] = "@(#)file_subs.c 8.1 (Berkeley) 5/31/93";
#else
__RCSID("$NetBSD: file_subs.c,v 1.63 2013/07/29 17:46:36 christos Exp $");
#endif
#endif /* not lint */
#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/param.h>
#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#include <sys/uio.h>
#include <stdlib.h>
#include "pax.h"
#include "extern.h"
#include "options.h"
char *xtmp_name;
static int
mk_link(char *,struct stat *,char *, int);
static int warn_broken;
/*
* routines that deal with file operations such as: creating, removing;
* and setting access modes, uid/gid and times of files
*/
#define SET_BITS (S_ISUID | S_ISGID)
#define FILE_BITS (S_IRWXU | S_IRWXG | S_IRWXO)
#define A_BITS (FILE_BITS | SET_BITS | S_ISVTX)
/*
* The S_ISVTX (sticky bit) can be set by non-superuser on directories
* but not other kinds of files.
*/
#define FILEBITS(dir) ((dir) ? (FILE_BITS | S_ISVTX) : FILE_BITS)
#define SETBITS(dir) ((dir) ? SET_BITS : (SET_BITS | S_ISVTX))
static mode_t
apply_umask(mode_t mode)
{
static mode_t cached_umask;
static int cached_umask_valid;
if (!cached_umask_valid) {
cached_umask = umask(0);
umask(cached_umask);
cached_umask_valid = 1;
}
return mode & ~cached_umask;
}
/*
* file_creat()
* Create and open a file.
* Return:
* file descriptor or -1 for failure
*/
int
file_creat(ARCHD *arcn, int write_to_hardlink)
{
int fd = -1;
int oerrno;
/*
* Some horribly busted tar implementations, have directory nodes
* that end in a /, but they mark as files. Compensate for that
* by not creating a directory node at this point, but a file node,
* and not creating the temp file.
*/
if (arcn->nlen != 0 && arcn->name[arcn->nlen - 1] == '/') {
if (!warn_broken) {
tty_warn(0, "Archive was created with a broken tar;"
" file `%s' is a directory, but marked as plain.",
arcn->name);
warn_broken = 1;
}
return -1;
}
/*
* In "cpio" archives it's usually the last record of a set of
* hardlinks which includes the contents of the file. We cannot
* use a tempory file in that case because we couldn't link it
* with the existing other hardlinks after restoring the contents
* to it. And it's also useless to create the hardlink under a
* temporary name because the other hardlinks would have partial
* contents while restoring.
*/
if (write_to_hardlink)
return (open(arcn->name, O_TRUNC | O_EXCL | O_RDWR, 0));
/*
* Create a temporary file name so that the file doesn't have partial
* contents while restoring.
*/
arcn->tmp_name = malloc(arcn->nlen + 8);
if (arcn->tmp_name == NULL) {
syswarn(1, errno, "Cannot malloc %d bytes", arcn->nlen + 8);
return -1;
}
if (xtmp_name != NULL)
abort();
xtmp_name = arcn->tmp_name;
for (;;) {
/*
* try to create the temporary file we use to restore the
* contents info. if this fails, keep checking all the nodes
* in the path until chk_path() finds that it cannot fix
* anything further. if that happens we just give up.
*/
(void)snprintf(arcn->tmp_name, arcn->nlen + 8, "%s.XXXXXX",
arcn->name);
fd = mkstemp(arcn->tmp_name);
if (fd >= 0)
break;
oerrno = errno;
if (nodirs || chk_path(arcn->name,arcn->sb.st_uid,arcn->sb.st_gid) < 0) {
(void)fflush(listf);
syswarn(1, oerrno, "Cannot create %s", arcn->tmp_name);
xtmp_name = NULL;
free(arcn->tmp_name);
arcn->tmp_name = NULL;
return -1;
}
}
return fd;
}
/*
* file_close()
* Close file descriptor to a file just created by pax. Sets modes,
* ownership and times as required.
* Return:
* 0 for success, -1 for failure
*/
void
file_close(ARCHD *arcn, int fd)
{
char *tmp_name;
int res;
if (fd < 0)
return;
tmp_name = (arcn->tmp_name != NULL) ? arcn->tmp_name : arcn->name;
if (close(fd) < 0)
syswarn(0, errno, "Cannot close file descriptor on %s",
tmp_name);
/*
* set owner/groups first as this may strip off mode bits we want
* then set file permission modes. Then set file access and
* modification times.
*/
if (pids)
res = set_ids(tmp_name, arcn->sb.st_uid, arcn->sb.st_gid);
else
res = 0;
/*
* IMPORTANT SECURITY NOTE:
* if not preserving mode or we cannot set uid/gid, then PROHIBIT
* set uid/gid bits but restore the file modes (since mkstemp doesn't).
*/
if (!pmode || res)
arcn->sb.st_mode &= ~SETBITS(0);
if (pmode)
set_pmode(tmp_name, arcn->sb.st_mode);
else
set_pmode(tmp_name,
apply_umask((arcn->sb.st_mode & FILEBITS(0))));
if (patime || pmtime)
set_ftime(tmp_name, arcn->sb.st_mtime,
arcn->sb.st_atime, 0, 0);
/* Did we write directly to the target file? */
if (arcn->tmp_name == NULL)
return;
/*
* Finally, now the temp file is fully instantiated rename it to
* the desired file name.
*/
if (rename(tmp_name, arcn->name) < 0) {
syswarn(0, errno, "Cannot rename %s to %s",
tmp_name, arcn->name);
(void)unlink(tmp_name);
}
#if HAVE_STRUCT_STAT_ST_FLAGS
if (pfflags && arcn->type != PAX_SLK)
set_chflags(arcn->name, arcn->sb.st_flags);
#endif
free(arcn->tmp_name);
arcn->tmp_name = NULL;
xtmp_name = NULL;
}
/*
* lnk_creat()
* Create a hard link to arcn->ln_name from arcn->name. arcn->ln_name
* must exist;
* Return:
* 0 if ok, -1 otherwise
*/
int
lnk_creat(ARCHD *arcn, int *payload)
{
struct stat sb;
/*
* Check if this hardlink carries the "payload". In "cpio" archives
* it's usually the last record of a set of hardlinks which includes
* the contents of the file.
*
*/
*payload = S_ISREG(arcn->sb.st_mode) &&
(arcn->sb.st_size > 0) && (arcn->sb.st_size <= arcn->skip);
/*
* We may be running as root, so we have to be sure that link target
* is not a directory, so we lstat and check. XXX: This is still racy.
*/
if (lstat(arcn->ln_name, &sb) != -1 && S_ISDIR(sb.st_mode)) {
tty_warn(1, "A hard link to the directory %s is not allowed",
arcn->ln_name);
return -1;
}
return mk_link(arcn->ln_name, &sb, arcn->name, 0);
}
/*
* cross_lnk()
* Create a hard link to arcn->org_name from arcn->name. Only used in copy
* with the -l flag. No warning or error if this does not succeed (we will
* then just create the file)
* Return:
* 1 if copy() should try to create this file node
* 0 if cross_lnk() ok, -1 for fatal flaw (like linking to self).
*/
int
cross_lnk(ARCHD *arcn)
{
/*
* try to make a link to original file (-l flag in copy mode). make
* sure we do not try to link to directories in case we are running as
* root (and it might succeed).
*/
if (arcn->type == PAX_DIR)
return 1;
return mk_link(arcn->org_name, &(arcn->sb), arcn->name, 1);
}
/*
* chk_same()
* In copy mode if we are not trying to make hard links between the src
* and destinations, make sure we are not going to overwrite ourselves by
* accident. This slows things down a little, but we have to protect all
* those people who make typing errors.
* Return:
* 1 the target does not exist, go ahead and copy
* 0 skip it file exists (-k) or may be the same as source file
*/
int
chk_same(ARCHD *arcn)
{
struct stat sb;
/*
* if file does not exist, return. if file exists and -k, skip it
* quietly
*/
if (lstat(arcn->name, &sb) < 0)
return 1;
if (kflag)
return 0;
/*
* better make sure the user does not have src == dest by mistake
*/
if ((arcn->sb.st_dev == sb.st_dev) && (arcn->sb.st_ino == sb.st_ino)) {
tty_warn(1, "Unable to copy %s, file would overwrite itself",
arcn->name);
return 0;
}
return 1;
}
/*
* mk_link()
* try to make a hard link between two files. if ign set, we do not
* complain.
* Return:
* 0 if successful (or we are done with this file but no error, such as
* finding the from file exists and the user has set -k).
* 1 when ign was set to indicates we could not make the link but we
* should try to copy/extract the file as that might work (and is an
* allowed option). -1 an error occurred.
*/
static int
mk_link(char *to, struct stat *to_sb, char *from, int ign)
{
struct stat sb;
int oerrno;
/*
* if from file exists, it has to be unlinked to make the link. If the
* file exists and -k is set, skip it quietly
*/
if (lstat(from, &sb) == 0) {
if (kflag)
return 0;
/*
* make sure it is not the same file, protect the user
*/
if ((to_sb->st_dev==sb.st_dev)&&(to_sb->st_ino == sb.st_ino)) {
tty_warn(1, "Cannot link file %s to itself", to);
return -1;
}
/*
* try to get rid of the file, based on the type
*/
if (S_ISDIR(sb.st_mode) && strcmp(from, ".") != 0) {
if (rmdir(from) < 0) {
syswarn(1, errno, "Cannot remove %s", from);
return -1;
}
} else if (unlink(from) < 0) {
if (!ign) {
syswarn(1, errno, "Cannot remove %s", from);
return -1;
}
return 1;
}
}
/*
* from file is gone (or did not exist), try to make the hard link.
* if it fails, check the path and try it again (if chk_path() says to
* try again)
*/
for (;;) {
if (link(to, from) == 0)
break;
oerrno = errno;
if (chk_path(from, to_sb->st_uid, to_sb->st_gid) == 0)
continue;
if (!ign) {
syswarn(1, oerrno, "Cannot link to %s from %s", to,
from);
return -1;
}
return 1;
}
/*
* all right the link was made
*/
return 0;
}
/*
* node_creat()
* create an entry in the file system (other than a file or hard link).
* If successful, sets uid/gid modes and times as required.
* Return:
* 0 if ok, -1 otherwise
*/
int
node_creat(ARCHD *arcn)
{
int res;
int ign = 0;
int oerrno;
int pass = 0;
mode_t file_mode;
struct stat sb;
char target[MAXPATHLEN];
char *nm = arcn->name;
int len;
/*
* create node based on type, if that fails try to unlink the node and
* try again. finally check the path and try again. As noted in the
* file and link creation routines, this method seems to exhibit the
* best performance in general use workloads.
*/
file_mode = arcn->sb.st_mode & FILEBITS(arcn->type == PAX_DIR);
for (;;) {
switch (arcn->type) {
case PAX_DIR:
/*
* If -h (or -L) was given in tar-mode, follow the
* potential symlink chain before trying to create the
* directory.
*/
if (strcmp(NM_TAR, argv0) == 0 && Lflag) {
while (lstat(nm, &sb) == 0 &&
S_ISLNK(sb.st_mode)) {
len = readlink(nm, target,
sizeof target - 1);
if (len == -1) {
syswarn(0, errno,
"cannot follow symlink %s "
"in chain for %s",
nm, arcn->name);
res = -1;
goto badlink;
}
target[len] = '\0';
nm = target;
}
}
res = domkdir(nm, file_mode);
badlink:
if (ign)
res = 0;
break;
case PAX_CHR:
file_mode |= S_IFCHR;
res = mknod(nm, file_mode, arcn->sb.st_rdev);
break;
case PAX_BLK:
file_mode |= S_IFBLK;
res = mknod(nm, file_mode, arcn->sb.st_rdev);
break;
case PAX_FIF:
res = mkfifo(nm, file_mode);
break;
case PAX_SCK:
/*
* Skip sockets, operation has no meaning under BSD
*/
tty_warn(0,
"%s skipped. Sockets cannot be copied or extracted",
nm);
return (-1);
case PAX_SLK:
res = symlink(arcn->ln_name, nm);
break;
case PAX_CTG:
case PAX_HLK:
case PAX_HRG:
case PAX_REG:
default:
/*
* we should never get here
*/
tty_warn(0, "%s has an unknown file type, skipping",
nm);
return (-1);
}
/*
* if we were able to create the node break out of the loop,
* otherwise try to unlink the node and try again. if that
* fails check the full path and try a final time.
*/
if (res == 0)
break;
/*
* we failed to make the node
*/
oerrno = errno;
switch (pass++) {
case 0:
if ((ign = unlnk_exist(nm, arcn->type)) < 0)
return (-1);
continue;
case 1:
if (nodirs ||
chk_path(nm, arcn->sb.st_uid,
arcn->sb.st_gid) < 0) {
syswarn(1, oerrno, "Cannot create %s", nm);
return (-1);
}
continue;
}
/*
* it must be a file that exists but we can't create or
* remove, but we must avoid the infinite loop.
*/
break;
}
/*
* we were able to create the node. set uid/gid, modes and times
*/
if (pids)
res = set_ids(nm, arcn->sb.st_uid, arcn->sb.st_gid);
else
res = 0;
/*
* IMPORTANT SECURITY NOTE:
* if not preserving mode or we cannot set uid/gid, then PROHIBIT any
* set uid/gid bits
*/
if (!pmode || res)
arcn->sb.st_mode &= ~SETBITS(arcn->type == PAX_DIR);
if (pmode)
set_pmode(arcn->name, arcn->sb.st_mode);
if (arcn->type == PAX_DIR && strcmp(NM_CPIO, argv0) != 0) {
/*
* Dirs must be processed again at end of extract to set times
* and modes to agree with those stored in the archive. However
* to allow extract to continue, we may have to also set owner
* rights. This allows nodes in the archive that are children
* of this directory to be extracted without failure. Both time
* and modes will be fixed after the entire archive is read and
* before pax exits.
*/
if (access(nm, R_OK | W_OK | X_OK) < 0) {
if (lstat(nm, &sb) < 0) {
syswarn(0, errno,"Cannot access %s (stat)",
arcn->name);
set_pmode(nm,file_mode | S_IRWXU);
} else {
/*
* We have to add rights to the dir, so we make
* sure to restore the mode. The mode must be
* restored AS CREATED and not as stored if
* pmode is not set.
*/
set_pmode(nm, ((sb.st_mode &
FILEBITS(arcn->type == PAX_DIR)) |
S_IRWXU));
if (!pmode)
arcn->sb.st_mode = sb.st_mode;
}
/*
* we have to force the mode to what was set here,
* since we changed it from the default as created.
*/
add_dir(nm, arcn->nlen, &(arcn->sb), 1);
} else if (pmode || patime || pmtime)
add_dir(nm, arcn->nlen, &(arcn->sb), 0);
}
if (patime || pmtime)
set_ftime(arcn->name, arcn->sb.st_mtime,
arcn->sb.st_atime, 0, (arcn->type == PAX_SLK) ? 1 : 0);
#if HAVE_STRUCT_STAT_ST_FLAGS
if (pfflags && arcn->type != PAX_SLK)
set_chflags(arcn->name, arcn->sb.st_flags);
#endif
return 0;
}
/*
* unlnk_exist()
* Remove node from file system with the specified name. We pass the type
* of the node that is going to replace it. When we try to create a
* directory and find that it already exists, we allow processing to
* continue as proper modes etc will always be set for it later on.
* Return:
* 0 is ok to proceed, no file with the specified name exists
* -1 we were unable to remove the node, or we should not remove it (-k)
* 1 we found a directory and we were going to create a directory.
*/
int
unlnk_exist(char *name, int type)
{
struct stat sb;
/*
* the file does not exist, or -k we are done
*/
if (lstat(name, &sb) < 0)
return 0;
if (kflag)
return -1;
if (S_ISDIR(sb.st_mode)) {
/*
* try to remove a directory, if it fails and we were going to
* create a directory anyway, tell the caller (return a 1).
*
* don't try to remove the directory if the name is "."
* otherwise later file/directory creation fails.
*/
if (strcmp(name, ".") == 0)
return 1;
if (rmdir(name) < 0) {
if (type == PAX_DIR)
return 1;
syswarn(1, errno, "Cannot remove directory %s", name);
return -1;
}
return 0;
}
/*
* try to get rid of all non-directory type nodes
*/
if (unlink(name) < 0) {
(void)fflush(listf);
syswarn(1, errno, "Cannot unlink %s", name);
return -1;
}
return 0;
}
/*
* chk_path()
* We were trying to create some kind of node in the file system and it
* failed. chk_path() makes sure the path up to the node exists and is
* writable. When we have to create a directory that is missing along the
* path somewhere, the directory we create will be set to the same
* uid/gid as the file has (when uid and gid are being preserved).
* NOTE: this routine is a real performance loss. It is only used as a
* last resort when trying to create entries in the file system.
* Return:
* -1 when it could find nothing it is allowed to fix.
* 0 otherwise
*/
int
chk_path(char *name, uid_t st_uid, gid_t st_gid)
{
char *spt = name;
struct stat sb;
int retval = -1;
/*
* watch out for paths with nodes stored directly in / (e.g. /bozo)
*/
if (*spt == '/')
++spt;
for(;;) {
/*
* work forward from the first / and check each part of
* the path
*/
spt = strchr(spt, '/');
if (spt == NULL)
break;
*spt = '\0';
/*
* if it exists we assume it is a directory, it is not within
* the spec (at least it seems to read that way) to alter the
* file system for nodes NOT EXPLICITLY stored on the archive.
* If that assumption is changed, you would test the node here
* and figure out how to get rid of it (probably like some
* recursive unlink()) or fix up the directory permissions if
* required (do an access()).
*/
if (lstat(name, &sb) == 0) {
*(spt++) = '/';
continue;
}
/*
* the path fails at this point, see if we can create the
* needed directory and continue on
*/
if (domkdir(name, S_IRWXU | S_IRWXG | S_IRWXO) == -1) {
*spt = '/';
retval = -1;
break;
}
/*
* we were able to create the directory. We will tell the
* caller that we found something to fix, and it is ok to try
* and create the node again.
*/
retval = 0;
if (pids)
(void)set_ids(name, st_uid, st_gid);
/*
* make sure the user doesn't have some strange umask that
* causes this newly created directory to be unusable. We fix
* the modes and restore them back to the creation default at
* the end of pax
*/
if ((access(name, R_OK | W_OK | X_OK) < 0) &&
(lstat(name, &sb) == 0)) {
set_pmode(name, ((sb.st_mode & FILEBITS(0)) |
S_IRWXU));
add_dir(name, spt - name, &sb, 1);
}
*(spt++) = '/';
continue;
}
/*
* We perform one final check here, because if someone else
* created the directory in parallel with us, we might return
* the wrong error code, even if the directory exists now.
*/
if (retval == -1 && stat(name, &sb) == 0 && S_ISDIR(sb.st_mode))
retval = 0;
return retval;
}
/*
* set_ftime()
* Set the access time and modification time for a named file. If frc
* is non-zero we force these times to be set even if the user did not
* request access and/or modification time preservation (this is also
* used by -t to reset access times).
* When ign is zero, only those times the user has asked for are set, the
* other ones are left alone. We do not assume the un-documented feature
* of many utimes() implementations that consider a 0 time value as a do
* not set request.
*
* Unfortunately, there are systems where lutimes() is present but does
* not work on some filesystem types, which cannot be detected at
* compile time. This requires passing down symlink knowledge into
* this function to obtain correct operation. Linux with XFS is one
* example of such a system.
*/
void
set_ftime(char *fnm, time_t mtime, time_t atime, int frc, int slk)
{
struct timeval tv[2];
struct stat sb;
tv[0].tv_sec = atime;
tv[0].tv_usec = 0;
tv[1].tv_sec = mtime;
tv[1].tv_usec = 0;
if (!frc && (!patime || !pmtime)) {
/*
* if we are not forcing, only set those times the user wants
* set. We get the current values of the times if we need them.
*/
if (lstat(fnm, &sb) == 0) {
#if BSD4_4 && !HAVE_NBTOOL_CONFIG_H
if (!patime)
TIMESPEC_TO_TIMEVAL(&tv[0], &sb.st_atimespec);
if (!pmtime)
TIMESPEC_TO_TIMEVAL(&tv[1], &sb.st_mtimespec);
#else
if (!patime)
tv[0].tv_sec = sb.st_atime;
if (!pmtime)
tv[1].tv_sec = sb.st_mtime;
#endif
} else
syswarn(0, errno, "Cannot obtain file stats %s", fnm);
}
/*
* set the times
*/
#if HAVE_LUTIMES
if (lutimes(fnm, tv) == 0)
return;
if (errno != ENOSYS) /* XXX linux: lutimes is per-FS */
goto bad;
#endif
if (slk)
return;
if (utimes(fnm, tv) == -1)
goto bad;
return;
bad:
syswarn(1, errno, "Access/modification time set failed on: %s", fnm);
}
/*
* set_ids()
* set the uid and gid of a file system node
* Return:
* 0 when set, -1 on failure
*/
int
set_ids(char *fnm, uid_t uid, gid_t gid)
{
if (geteuid() == 0)
if (lchown(fnm, uid, gid)) {
(void)fflush(listf);
syswarn(1, errno, "Cannot set file uid/gid of %s",
fnm);
return -1;
}
return 0;
}
/*
* set_pmode()
* Set file access mode
*/
void
set_pmode(char *fnm, mode_t mode)
{
mode &= A_BITS;
if (lchmod(fnm, mode)) {
(void)fflush(listf);
syswarn(1, errno, "Cannot set permissions on %s", fnm);
}
return;
}
/*
* set_chflags()
* Set 4.4BSD file flags
*/
void
set_chflags(char *fnm, u_int32_t flags)
{
#if 0
if (chflags(fnm, flags) < 0 && errno != EOPNOTSUPP)
syswarn(1, errno, "Cannot set file flags on %s", fnm);
#endif
return;
}
/*
* file_write()
* Write/copy a file (during copy or archive extract). This routine knows
* how to copy files with lseek holes in it. (Which are read as file
* blocks containing all 0's but do not have any file blocks associated
* with the data). Typical examples of these are files created by dbm
* variants (.pag files). While the file size of these files are huge, the
* actual storage is quite small (the files are sparse). The problem is
* the holes read as all zeros so are probably stored on the archive that
* way (there is no way to determine if the file block is really a hole,
* we only know that a file block of all zero's can be a hole).
* At this writing, no major archive format knows how to archive files
* with holes. However, on extraction (or during copy, -rw) we have to
* deal with these files. Without detecting the holes, the files can
* consume a lot of file space if just written to disk. This replacement
* for write when passed the basic allocation size of a file system block,
* uses lseek whenever it detects the input data is all 0 within that
* file block. In more detail, the strategy is as follows:
* While the input is all zero keep doing an lseek. Keep track of when we
* pass over file block boundaries. Only write when we hit a non zero
* input. once we have written a file block, we continue to write it to
* the end (we stop looking at the input). When we reach the start of the
* next file block, start checking for zero blocks again. Working on file
* block boundaries significantly reduces the overhead when copying files
* that are NOT very sparse. This overhead (when compared to a write) is
* almost below the measurement resolution on many systems. Without it,
* files with holes cannot be safely copied. It does has a side effect as
* it can put holes into files that did not have them before, but that is
* not a problem since the file contents are unchanged (in fact it saves
* file space). (Except on paging files for diskless clients. But since we
* cannot determine one of those file from here, we ignore them). If this
* ever ends up on a system where CTG files are supported and the holes
* are not desired, just do a conditional test in those routines that
* call file_write() and have it call write() instead. BEFORE CLOSING THE
* FILE, make sure to call file_flush() when the last write finishes with
* an empty block. A lot of file systems will not create an lseek hole at
* the end. In this case we drop a single 0 at the end to force the
* trailing 0's in the file.
* ---Parameters---
* rem: how many bytes left in this file system block
* isempt: have we written to the file block yet (is it empty)
* sz: basic file block allocation size
* cnt: number of bytes on this write
* str: buffer to write
* Return:
* number of bytes written, -1 on write (or lseek) error.
*/
int
file_write(int fd, char *str, int cnt, int *rem, int *isempt, int sz,
char *name)
{
char *pt;
char *end;
int wcnt;
char *st = str;
char **strp;
size_t *lenp;
/*
* while we have data to process
*/
while (cnt) {
if (!*rem) {
/*
* We are now at the start of file system block again
* (or what we think one is...). start looking for
* empty blocks again
*/
*isempt = 1;
*rem = sz;
}
/*
* only examine up to the end of the current file block or
* remaining characters to write, whatever is smaller
*/
wcnt = MIN(cnt, *rem);
cnt -= wcnt;
*rem -= wcnt;
if (*isempt) {
/*
* have not written to this block yet, so we keep
* looking for zero's
*/
pt = st;
end = st + wcnt;
/*
* look for a zero filled buffer
*/
while ((pt < end) && (*pt == '\0'))
++pt;
if (pt == end) {
/*
* skip, buf is empty so far
*/
if (fd > -1 &&
lseek(fd, (off_t)wcnt, SEEK_CUR) < 0) {
syswarn(1, errno, "File seek on %s",
name);
return -1;
}
st = pt;
continue;
}
/*
* drat, the buf is not zero filled
*/
*isempt = 0;
}
/*
* have non-zero data in this file system block, have to write
*/
switch (fd) {
case -PAX_GLF:
strp = &gnu_name_string;
lenp = &gnu_name_length;
break;
case -PAX_GLL:
strp = &gnu_link_string;
lenp = &gnu_link_length;
break;
default:
strp = NULL;
lenp = NULL;
break;
}
if (strp) {
char *nstr = *strp ? realloc(*strp, *lenp + wcnt + 1) :
malloc(wcnt + 1);
if (nstr == NULL) {
tty_warn(1, "Out of memory");
return -1;
}
(void)strlcpy(&nstr[*lenp], st, wcnt + 1);
*strp = nstr;
*lenp += wcnt;
} else if (xwrite(fd, st, wcnt) != wcnt) {
syswarn(1, errno, "Failed write to file %s", name);
return -1;
}
st += wcnt;
}
return st - str;
}
/*
* file_flush()
* when the last file block in a file is zero, many file systems will not
* let us create a hole at the end. To get the last block with zeros, we
* write the last BYTE with a zero (back up one byte and write a zero).
*/
void
file_flush(int fd, char *fname, int isempt)
{
static char blnk[] = "\0";
/*
* silly test, but make sure we are only called when the last block is
* filled with all zeros.
*/
if (!isempt)
return;
/*
* move back one byte and write a zero
*/
if (lseek(fd, (off_t)-1, SEEK_CUR) < 0) {
syswarn(1, errno, "Failed seek on file %s", fname);
return;
}
if (write_with_restart(fd, blnk, 1) < 0)
syswarn(1, errno, "Failed write to file %s", fname);
return;
}
/*
* rdfile_close()
* close a file we have been reading (to copy or archive). If we have to
* reset access time (tflag) do so (the times are stored in arcn).
*/
void
rdfile_close(ARCHD *arcn, int *fd)
{
/*
* make sure the file is open
*/
if (*fd < 0)
return;
(void)close(*fd);
*fd = -1;
if (!tflag)
return;
/*
* user wants last access time reset
*/
set_ftime(arcn->org_name, arcn->sb.st_mtime, arcn->sb.st_atime, 1, 0);
return;
}
/*
* set_crc()
* read a file to calculate its crc. This is a real drag. Archive formats
* that have this, end up reading the file twice (we have to write the
* header WITH the crc before writing the file contents. Oh well...
* Return:
* 0 if was able to calculate the crc, -1 otherwise
*/
int
set_crc(ARCHD *arcn, int fd)
{
int i;
int res;
off_t cpcnt = 0L;
u_long size;
unsigned long crc = 0L;
char tbuf[FILEBLK];
struct stat sb;
if (fd < 0) {
/*
* hmm, no fd, should never happen. well no crc then.
*/
arcn->crc = 0L;
return 0;
}
if ((size = (u_long)arcn->sb.st_blksize) > (u_long)sizeof(tbuf))
size = (u_long)sizeof(tbuf);
/*
* read all the bytes we think that there are in the file. If the user
* is trying to archive an active file, forget this file.
*/
for(;;) {
if ((res = read(fd, tbuf, size)) <= 0)
break;
cpcnt += res;
for (i = 0; i < res; ++i)
crc += (tbuf[i] & 0xff);
}
/*
* safety check. we want to avoid archiving files that are active as
* they can create inconsistent archive copies.
*/
if (cpcnt != arcn->sb.st_size)
tty_warn(1, "File changed size %s", arcn->org_name);
else if (fstat(fd, &sb) < 0)
syswarn(1, errno, "Failed stat on %s", arcn->org_name);
else if (arcn->sb.st_mtime != sb.st_mtime)
tty_warn(1, "File %s was modified during read", arcn->org_name);
else if (lseek(fd, (off_t)0L, SEEK_SET) < 0)
syswarn(1, errno, "File rewind failed on: %s", arcn->org_name);
else {
arcn->crc = crc;
return 0;
}
return -1;
}
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