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-rw-r--r--bin/pax/file_subs.c1055
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diff --git a/bin/pax/file_subs.c b/bin/pax/file_subs.c
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+/*-
+ * 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. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. 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.
+ */
+
+#ifndef lint
+static char sccsid[] = "@(#)file_subs.c 8.1 (Berkeley) 5/31/93";
+#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"
+
+static int
+mk_link __P((register char *,register struct stat *,register char *, int));
+
+/*
+ * routines that deal with file operations such as: creating, removing;
+ * and setting access modes, uid/gid and times of files
+ */
+
+#define FILEBITS (S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO)
+#define SETBITS (S_ISUID | S_ISGID)
+#define ABITS (FILEBITS | SETBITS)
+
+/*
+ * file_creat()
+ * Create and open a file.
+ * Return:
+ * file descriptor or -1 for failure
+ */
+
+#if __STDC__
+int
+file_creat(register ARCHD *arcn)
+#else
+int
+file_creat(arcn)
+ register ARCHD *arcn;
+#endif
+{
+ int fd = -1;
+ mode_t file_mode;
+ int oerrno;
+
+ /*
+ * assume file doesn't exist, so just try to create it, most times this
+ * works. We have to take special handling when the file does exist. To
+ * detect this, we use O_EXCL. For example when trying to create a
+ * file and a character device or fifo exists with the same name, we
+ * can accidently open the device by mistake (or block waiting to open)
+ * If we find that the open has failed, then figure spend the effore to
+ * figure out why. This strategy was found to have better average
+ * performance in common use than checking the file (and the path)
+ * first with lstat.
+ */
+ file_mode = arcn->sb.st_mode & FILEBITS;
+ if ((fd = open(arcn->name, O_WRONLY | O_CREAT | O_TRUNC | O_EXCL,
+ file_mode)) >= 0)
+ return(fd);
+
+ /*
+ * the file seems to exist. First we try to get rid of it (found to be
+ * the second most common failure when traced). If this fails, only
+ * then we go to the expense to check and create the path to the file
+ */
+ if (unlnk_exist(arcn->name, arcn->type) != 0)
+ return(-1);
+
+ for (;;) {
+ /*
+ * try to open it again, if this fails, check all the nodes in
+ * the path and give it a final try. if chk_path() finds that
+ * it cannot fix anything, we will skip the last attempt
+ */
+ if ((fd = open(arcn->name, O_WRONLY | O_CREAT | O_TRUNC,
+ file_mode)) >= 0)
+ break;
+ oerrno = errno;
+ if (chk_path(arcn->name,arcn->sb.st_uid,arcn->sb.st_gid) < 0) {
+ syswarn(1, oerrno, "Unable to create %s", arcn->name);
+ 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
+ */
+
+#if __STDC__
+void
+file_close(register ARCHD *arcn, int fd)
+#else
+void
+file_close(arcn, fd)
+ register ARCHD *arcn;
+ int fd;
+#endif
+{
+ int res = 0;
+
+ if (fd < 0)
+ return;
+ if (close(fd) < 0)
+ syswarn(0, errno, "Unable to close file descriptor on %s",
+ arcn->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(arcn->name, arcn->sb.st_uid, arcn->sb.st_gid);
+
+ /*
+ * IMPORTANT SECURITY NOTE:
+ * if not preserving mode or we cannot set uid/gid, then PROHIBIT
+ * set uid/gid bits
+ */
+ if (!pmode || res)
+ arcn->sb.st_mode &= ~(SETBITS);
+ if (pmode)
+ set_pmode(arcn->name, arcn->sb.st_mode);
+ if (patime || pmtime)
+ set_ftime(arcn->name, arcn->sb.st_mtime, arcn->sb.st_atime, 0);
+}
+
+/*
+ * lnk_creat()
+ * Create a hard link to arcn->ln_name from arcn->name. arcn->ln_name
+ * must exist;
+ * Return:
+ * 0 if ok, -1 otherwise
+ */
+
+#if __STDC__
+int
+lnk_creat(register ARCHD *arcn)
+#else
+int
+lnk_creat(arcn)
+ register ARCHD *arcn;
+#endif
+{
+ struct stat sb;
+
+ /*
+ * we may be running as root, so we have to be sure that link target
+ * is not a directory, so we lstat and check
+ */
+ if (lstat(arcn->ln_name, &sb) < 0) {
+ syswarn(1,errno,"Unable to link to %s from %s", arcn->ln_name,
+ arcn->name);
+ return(-1);
+ }
+
+ if (S_ISDIR(sb.st_mode)) {
+ 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).
+ */
+
+#if __STDC__
+int
+cross_lnk(register ARCHD *arcn)
+#else
+int
+cross_lnk(arcn)
+ register ARCHD *arcn;
+#endif
+{
+ /*
+ * try to make a link to orginal 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
+ */
+
+#if __STDC__
+int
+chk_same(register ARCHD *arcn)
+#else
+int
+chk_same(arcn)
+ register ARCHD *arcn;
+#endif
+{
+ 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)) {
+ 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.
+ */
+
+#if __STDC__
+static int
+mk_link(register char *to, register struct stat *to_sb, register char *from,
+ int ign)
+#else
+static int
+mk_link(to, to_sb, from, ign)
+ register char *to;
+ register struct stat *to_sb;
+ register char *from;
+ int ign;
+#endif
+{
+ 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)) {
+ warn(1, "Unable to 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)) {
+ if (rmdir(from) < 0) {
+ syswarn(1, errno, "Unable to remove %s", from);
+ return(-1);
+ }
+ } else if (unlink(from) < 0) {
+ if (!ign) {
+ syswarn(1, errno, "Unable to 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, "Could not 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
+ */
+
+#if __STDC__
+int
+node_creat(register ARCHD *arcn)
+#else
+int
+node_creat(arcn)
+ register ARCHD *arcn;
+#endif
+{
+ register int res;
+ register int ign = 0;
+ register int oerrno;
+ register int pass = 0;
+ mode_t file_mode;
+ struct stat sb;
+
+ /*
+ * 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;
+
+ for (;;) {
+ switch(arcn->type) {
+ case PAX_DIR:
+ res = mkdir(arcn->name, file_mode);
+ if (ign)
+ res = 0;
+ break;
+ case PAX_CHR:
+ file_mode |= S_IFCHR;
+ res = mknod(arcn->name, file_mode, arcn->sb.st_rdev);
+ break;
+ case PAX_BLK:
+ file_mode |= S_IFBLK;
+ res = mknod(arcn->name, file_mode, arcn->sb.st_rdev);
+ break;
+ case PAX_FIF:
+ res = mkfifo(arcn->name, file_mode);
+ break;
+ case PAX_SCK:
+ /*
+ * Skip sockets, operation has no meaning under BSD
+ */
+ warn(0,
+ "%s skipped. Sockets cannot be copied or extracted",
+ arcn->name);
+ return(-1);
+ case PAX_SLK:
+ if ((res = symlink(arcn->ln_name, arcn->name)) == 0)
+ return(0);
+ break;
+ case PAX_CTG:
+ case PAX_HLK:
+ case PAX_HRG:
+ case PAX_REG:
+ default:
+ /*
+ * we should never get here
+ */
+ warn(0, "%s has an unknown file type, skipping",
+ arcn->name);
+ 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;
+ if ((ign = unlnk_exist(arcn->name, arcn->type)) < 0)
+ return(-1);
+
+ if (++pass <= 1)
+ continue;
+
+ if (chk_path(arcn->name,arcn->sb.st_uid,arcn->sb.st_gid) < 0) {
+ syswarn(1, oerrno, "Could not create: %s", arcn->name);
+ return(-1);
+ }
+ }
+
+ /*
+ * we were able to create the node. set uid/gid, modes and times
+ */
+ if (pids)
+ res = set_ids(arcn->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 any
+ * set uid/gid bits
+ */
+ if (!pmode || res)
+ arcn->sb.st_mode &= ~(SETBITS);
+ if (pmode)
+ set_pmode(arcn->name, arcn->sb.st_mode);
+
+ if (arcn->type == PAX_DIR) {
+ /*
+ * 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(arcn->name, R_OK | W_OK | X_OK) < 0) {
+ if (lstat(arcn->name, &sb) < 0) {
+ syswarn(0, errno,"Could not access %s (stat)",
+ arcn->name);
+ set_pmode(arcn->name,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(arcn->name,
+ ((sb.st_mode & FILEBITS) | 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(arcn->name, arcn->nlen, &(arcn->sb), 1);
+ } else if (pmode || patime || pmtime)
+ add_dir(arcn->name, arcn->nlen, &(arcn->sb), 0);
+ }
+
+ if (patime || pmtime)
+ set_ftime(arcn->name, arcn->sb.st_mtime, arcn->sb.st_atime, 0);
+ 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.
+ */
+
+#if __STDC__
+int
+unlnk_exist(register char *name, register int type)
+#else
+int
+unlnk_exist(name, type)
+ register char *name;
+ register int type;
+#endif
+{
+ 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)
+ */
+ if (rmdir(name) < 0) {
+ if (type == PAX_DIR)
+ return(1);
+ syswarn(1,errno,"Unable to remove directory %s", name);
+ return(-1);
+ }
+ return(0);
+ }
+
+ /*
+ * try to get rid of all non-directory type nodes
+ */
+ if (unlink(name) < 0) {
+ syswarn(1, errno, "Could not 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
+ * writeable. 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
+ */
+
+#if __STDC__
+int
+chk_path( register char *name, uid_t st_uid, gid_t st_gid)
+#else
+int
+chk_path(name, st_uid, st_gid)
+ register char *name;
+ uid_t st_uid;
+ gid_t st_gid;
+#endif
+{
+ register 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 foward 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 (mkdir(name, S_IRWXU | S_IRWXG | S_IRWXO) < 0) {
+ *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 doen'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) | S_IRWXU));
+ add_dir(name, spt - name, &sb, 1);
+ }
+ *(spt++) = '/';
+ continue;
+ }
+ 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 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.
+ */
+
+#if __STDC__
+void
+set_ftime(char *fnm, time_t mtime, time_t atime, int frc)
+#else
+void
+set_ftime(fnm, mtime, atime, frc)
+ char *fnm;
+ time_t mtime;
+ time_t atime;
+ int frc;
+#endif
+{
+ static struct timeval tv[2] = {{0L, 0L}, {0L, 0L}};
+ struct stat sb;
+
+ tv[0].tv_sec = (long)atime;
+ tv[1].tv_sec = (long)mtime;
+ 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 (!patime)
+ tv[0].tv_sec = (long)sb.st_atime;
+ if (!pmtime)
+ tv[1].tv_sec = (long)sb.st_mtime;
+ } else
+ syswarn(0,errno,"Unable to obtain file stats %s", fnm);
+ }
+
+ /*
+ * set the times
+ */
+ if (utimes(fnm, tv) < 0)
+ syswarn(1, errno, "Access/modification time set failed on: %s",
+ fnm);
+ return;
+}
+
+/*
+ * set_ids()
+ * set the uid and gid of a file system node
+ * Return:
+ * 0 when set, -1 on failure
+ */
+
+#if __STDC__
+int
+set_ids(char *fnm, uid_t uid, gid_t gid)
+#else
+int
+set_ids(fnm, uid, gid)
+ char *fnm;
+ uid_t uid;
+ gid_t gid;
+#endif
+{
+ if (chown(fnm, uid, gid) < 0) {
+ syswarn(1, errno, "Unable to set file uid/gid of %s", fnm);
+ return(-1);
+ }
+ return(0);
+}
+
+/*
+ * set_pmode()
+ * Set file access mode
+ */
+
+#if __STDC__
+void
+set_pmode(char *fnm, mode_t mode)
+#else
+void
+set_pmode(fnm, mode)
+ char *fnm;
+ mode_t mode;
+#endif
+{
+ mode &= ABITS;
+ if (chmod(fnm, mode) < 0)
+ syswarn(1, errno, "Could not set permissions on %s", fnm);
+ 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 boundries. 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 boundries 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.
+ */
+
+#if __STDC__
+int
+file_write(int fd, char *str, register int cnt, int *rem, int *isempt, int sz,
+ char *name)
+#else
+int
+file_write(fd, str, cnt, rem, isempt, sz, name)
+ int fd;
+ char *str;
+ register int cnt;
+ int *rem;
+ int *isempt;
+ int sz;
+ char *name;
+#endif
+{
+ register char *pt;
+ register char *end;
+ register int wcnt;
+ register char *st = str;
+
+ /*
+ * 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 (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
+ */
+ if (write(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).
+ */
+
+#if __STDC__
+void
+file_flush(int fd, char *fname, int isempt)
+#else
+void
+file_flush(fd, fname, isempt)
+ int fd;
+ char *fname;
+ int isempt;
+#endif
+{
+ 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(fd, blnk, 1) < 0)
+ syswarn(1, errno, "Failed write to file %s", fname);
+ return;
+}
+
+/*
+ * rdfile_close()
+ * close a file we have beed reading (to copy or archive). If we have to
+ * reset access time (tflag) do so (the times are stored in arcn).
+ */
+
+#if __STDC__
+void
+rdfile_close(register ARCHD *arcn, register int *fd)
+#else
+void
+rdfile_close(arcn, fd)
+ register ARCHD *arcn;
+ register int *fd;
+#endif
+{
+ /*
+ * 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);
+ 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
+ */
+
+#if __STDC__
+int
+set_crc(register ARCHD *arcn, register int fd)
+#else
+int
+set_crc(arcn, fd)
+ register ARCHD *arcn;
+ register int fd;
+#endif
+{
+ register int i;
+ register 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 inconsistant archive copies.
+ */
+ if (cpcnt != arcn->sb.st_size)
+ 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)
+ 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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