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Diffstat (limited to 'bin/pax/file_subs.c')
| -rw-r--r-- | bin/pax/file_subs.c | 1106 |
1 files changed, 1106 insertions, 0 deletions
diff --git a/bin/pax/file_subs.c b/bin/pax/file_subs.c new file mode 100644 index 0000000..2c0994f --- /dev/null +++ b/bin/pax/file_subs.c @@ -0,0 +1,1106 @@ +/* $OpenBSD: file_subs.c,v 1.55 2020/03/23 20:04:19 espie Exp $ */ +/* $NetBSD: file_subs.c,v 1.4 1995/03/21 09:07:18 cgd 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. + */ + +#include <sys/stat.h> +#include <sys/time.h> +#include <sys/types.h> +#include <err.h> +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include "pax.h" +#include "extern.h" + +static int +mk_link(char *, struct stat *, char *, int); + +/* + * routines that deal with file operations such as: creating, removing; + * and setting access modes, uid/gid and times of files + */ + +/* + * file_creat() + * Create and open a file. + * Return: + * file descriptor or -1 for failure + */ + +int +file_creat(ARCHD *arcn) +{ + 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 spend the effort 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_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 (nodirs || chk_path(arcn->name,arcn->sb.st_uid,arcn->sb.st_gid, 0) < 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 + */ + +void +file_close(ARCHD *arcn, int fd) +{ + int res = 0; + + if (fd < 0) + return; + + /* + * 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 = fset_ids(arcn->name, fd, 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) + fset_pmode(arcn->name, fd, arcn->sb.st_mode); + if (patime || pmtime) + fset_ftime(arcn->name, fd, &arcn->sb.st_mtim, + &arcn->sb.st_atim, 0); + if (close(fd) == -1) + syswarn(0, errno, "Unable to close file descriptor on %s", + arcn->name); +} + +/* + * 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) +{ + struct stat sb; + int res; + + /* + * 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) == -1) { + syswarn(1,errno,"Unable to link to %s from %s", arcn->ln_name, + arcn->name); + return(-1); + } + + if (S_ISDIR(sb.st_mode)) { + paxwarn(1, "A hard link to the directory %s is not allowed", + arcn->ln_name); + return(-1); + } + + res = mk_link(arcn->ln_name, &sb, arcn->name, 0); + if (res == 0) { + /* check for a hardlink to a placeholder symlink */ + res = sltab_add_link(arcn->name, &sb); + + if (res < 0) { + /* arrgh, it failed, clean up */ + unlink(arcn->name); + } + } + + return (res); +} + +/* + * 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) == -1) + 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)) { + paxwarn(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)) { + paxwarn(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) == -1) { + syswarn(1, errno, "Unable to remove %s", from); + return(-1); + } + delete_dir(sb.st_dev, sb.st_ino); + } else if (unlink(from) == -1) { + 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 (linkat(AT_FDCWD, to, AT_FDCWD, from, 0) == 0) + break; + oerrno = errno; + if (!nodirs && chk_path(from, to_sb->st_uid, to_sb->st_gid, ign) == 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 + */ + +int +node_creat(ARCHD *arcn) +{ + int res; + int ign = 0; + int oerrno; + int pass = 0; + mode_t file_mode; + struct stat sb; + char target[PATH_MAX]; + char *nm = arcn->name; + int len, defer_pmode = 0; + + /* + * 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: + /* + * If -h (or -L) was given in tar-mode, follow the + * potential symlink chain before trying to create the + * directory. + */ + if (op_mode == OP_TAR && 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 = mkdir(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 + */ + paxwarn(0, + "%s skipped. Sockets cannot be copied or extracted", + nm); + return(-1); + case PAX_SLK: + if (arcn->ln_name[0] != '/' && + !has_dotdot(arcn->ln_name)) + res = symlink(arcn->ln_name, nm); + else { + /* + * absolute symlinks and symlinks with ".." + * have to be deferred to prevent the archive + * from bootstrapping itself to outside the + * working directory. + */ + res = sltab_add_sym(nm, arcn->ln_name, + arcn->sb.st_mode); + if (res == 0) + defer_pmode = 1; + } + break; + case PAX_CTG: + case PAX_HLK: + case PAX_HRG: + case PAX_REG: + default: + /* + * we should never get here + */ + paxwarn(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; + if ((ign = unlnk_exist(nm, arcn->type)) < 0) + return(-1); + + if (++pass <= 1) + continue; + + if (nodirs || chk_path(nm,arcn->sb.st_uid,arcn->sb.st_gid, 0) < 0) { + syswarn(1, oerrno, "Could not create: %s", nm); + return(-1); + } + } + + /* + * 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); + if (pmode && !defer_pmode) + set_pmode(nm, arcn->sb.st_mode); + + if (arcn->type == PAX_DIR && op_mode != OP_CPIO) { + /* + * 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. To do that safely, we want the dev+ino + * of the directory we created. + */ + if (lstat(nm, &sb) == -1) { + syswarn(0, errno,"Could not access %s (stat)", nm); + } else if (access(nm, R_OK | W_OK | X_OK) == -1) { + /* + * 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) | 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. + */ + arcn->sb.st_dev = sb.st_dev; + arcn->sb.st_ino = sb.st_ino; + add_dir(nm, &(arcn->sb), 1); + } else if (pmode || patime || pmtime) { + arcn->sb.st_dev = sb.st_dev; + arcn->sb.st_ino = sb.st_ino; + add_dir(nm, &(arcn->sb), 0); + } + } else if (patime || pmtime) + set_ftime(nm, &arcn->sb.st_mtim, &arcn->sb.st_atim, 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. + */ + +int +unlnk_exist(char *name, int type) +{ + struct stat sb; + + /* + * the file does not exist, or -k we are done + */ + if (lstat(name, &sb) == -1) + 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) == -1) { + if (type == PAX_DIR) + return(1); + syswarn(1,errno,"Unable to remove directory %s", name); + return(-1); + } + delete_dir(sb.st_dev, sb.st_ino); + return(0); + } + + /* + * try to get rid of all non-directory type nodes + */ + if (unlink(name) == -1) { + 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 + */ + +int +chk_path(char *name, uid_t st_uid, gid_t st_gid, int ign) +{ + char *spt = name; + char *next; + struct stat sb; + int retval = -1; + + /* + * watch out for paths with nodes stored directly in / (e.g. /bozo) + */ + while (*spt == '/') + ++spt; + + for (;;) { + /* + * work forward from the first / and check each part of the path + */ + spt = strchr(spt, '/'); + if (spt == NULL) + break; + + /* + * skip over duplicate slashes; stop if there're only + * trailing slashes left + */ + next = spt + 1; + while (*next == '/') + next++; + if (*next == '\0') + 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 = '/'; + spt = next; + 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) == -1) { + if (!ign) + syswarn(1, errno, "Unable to mkdir %s", name); + *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) == -1) && + (lstat(name, &sb) == 0)) { + set_pmode(name, ((sb.st_mode & FILEBITS) | S_IRWXU)); + add_dir(name, &sb, 1); + } + *spt = '/'; + spt = next; + 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 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. + */ + +void +set_ftime(const char *fnm, const struct timespec *mtimp, + const struct timespec *atimp, int frc) +{ + struct timespec tv[2]; + + tv[0] = *atimp; + tv[1] = *mtimp; + + if (!frc) { + /* + * if we are not forcing, only set those times the user wants + * set. + */ + if (!patime) + tv[0].tv_nsec = UTIME_OMIT; + if (!pmtime) + tv[1].tv_nsec = UTIME_OMIT; + } + + /* + * set the times + */ + if (utimensat(AT_FDCWD, fnm, tv, AT_SYMLINK_NOFOLLOW) < 0) + syswarn(1, errno, "Access/modification time set failed on: %s", + fnm); +} + +void +fset_ftime(const char *fnm, int fd, const struct timespec *mtimp, + const struct timespec *atimp, int frc) +{ + struct timespec tv[2]; + + + tv[0] = *atimp; + tv[1] = *mtimp; + + if (!frc) { + /* + * if we are not forcing, only set those times the user wants + * set. + */ + if (!patime) + tv[0].tv_nsec = UTIME_OMIT; + if (!pmtime) + tv[1].tv_nsec = UTIME_OMIT; + } + /* + * set the times + */ + if (futimens(fd, tv) == -1) + 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 (fchownat(AT_FDCWD, fnm, uid, gid, AT_SYMLINK_NOFOLLOW) == -1) { + /* + * ignore EPERM unless in verbose mode or being run by root. + * if running as pax, POSIX requires a warning. + */ + if (op_mode == OP_PAX || errno != EPERM || vflag || + geteuid() == 0) + syswarn(1, errno, "Unable to set file uid/gid of %s", + fnm); + return(-1); + } + return(0); +} + +int +fset_ids(char *fnm, int fd, uid_t uid, gid_t gid) +{ + if (fchown(fd, uid, gid) == -1) { + /* + * ignore EPERM unless in verbose mode or being run by root. + * if running as pax, POSIX requires a warning. + */ + if (op_mode == OP_PAX || errno != EPERM || vflag || + geteuid() == 0) + syswarn(1, errno, "Unable to 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 &= ABITS; + if (fchmodat(AT_FDCWD, fnm, mode, AT_SYMLINK_NOFOLLOW) == -1 && errno != EOPNOTSUPP) + syswarn(1, errno, "Could not set permissions on %s", fnm); +} + +void +fset_pmode(char *fnm, int fd, mode_t mode) +{ + mode &= ABITS; + if (fchmod(fd, mode) == -1) + syswarn(1, errno, "Could not set permissions on %s", fnm); +} + +/* + * set_attr() + * Given a DIRDATA, restore the mode and times as indicated, but + * only after verifying that it's the directory that we wanted. + */ +int +set_attr(const struct file_times *ft, int force_times, mode_t mode, + int do_mode, int in_sig) +{ + struct stat sb; + int fd, r; + + if (!do_mode && !force_times && !patime && !pmtime) + return (0); + + /* + * We could legitimately go through a symlink here, + * so do *not* use O_NOFOLLOW. The dev+ino check will + * protect us from evil. + */ + fd = open(ft->ft_name, O_RDONLY | O_DIRECTORY); + if (fd == -1) { + if (!in_sig) + syswarn(1, errno, "Unable to restore mode and times" + " for directory: %s", ft->ft_name); + return (-1); + } + + if (fstat(fd, &sb) == -1) { + if (!in_sig) + syswarn(1, errno, "Unable to stat directory: %s", + ft->ft_name); + r = -1; + } else if (ft->ft_ino != sb.st_ino || ft->ft_dev != sb.st_dev) { + if (!in_sig) + paxwarn(1, "Directory vanished before restoring" + " mode and times: %s", ft->ft_name); + r = -1; + } else { + /* Whew, it's a match! Is there anything to change? */ + if (do_mode && (mode & ABITS) != (sb.st_mode & ABITS)) + fset_pmode(ft->ft_name, fd, mode); + if (((force_times || patime) && + timespeccmp(&ft->ft_atim, &sb.st_atim, !=)) || + ((force_times || pmtime) && + timespeccmp(&ft->ft_mtim, &sb.st_mtim, !=))) + fset_ftime(ft->ft_name, fd, &ft->ft_mtim, + &ft->ft_atim, force_times); + r = 0; + } + close(fd); + + return (r); +} + + +/* + * 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; + + /* + * 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 = MINIMUM(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, 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). + */ + +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, -1, SEEK_CUR) < 0) { + syswarn(1, errno, "Failed seek on file %s", fname); + return; + } + + if (write(fd, blnk, 1) == -1) + syswarn(1, errno, "Failed write to file %s", fname); +} + +/* + * 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; + + /* + * user wants last access time reset + */ + if (tflag) + fset_ftime(arcn->org_name, *fd, &arcn->sb.st_mtim, + &arcn->sb.st_atim, 1); + + (void)close(*fd); + *fd = -1; +} + +/* + * 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 = 0; + size_t size; + u_int32_t crc = 0; + char tbuf[FILEBLK]; + struct stat sb; + + if (fd < 0) { + /* + * hmm, no fd, should never happen. well no crc then. + */ + arcn->crc = 0; + return(0); + } + + if ((size = arcn->sb.st_blksize) > sizeof(tbuf)) + size = 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) + paxwarn(1, "File changed size %s", arcn->org_name); + else if (fstat(fd, &sb) == -1) + syswarn(1, errno, "Failed stat on %s", arcn->org_name); + else if (timespeccmp(&arcn->sb.st_mtim, &sb.st_mtim, !=)) + paxwarn(1, "File %s was modified during read", arcn->org_name); + else if (lseek(fd, 0, SEEK_SET) < 0) + syswarn(1, errno, "File rewind failed on: %s", arcn->org_name); + else { + arcn->crc = crc; + return(0); + } + return(-1); +} |