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Annotation of src/usr.bin/rsync/copy.c, Revision 1.2.4.1

1.2.4.1 ! bluhm       1: /*     $OpenBSD: copy.c,v 1.2 2021/10/24 21:24:17 deraadt Exp $ */
1.1       claudio     2: /*
                      3:  * Copyright (c) 2021 Claudio Jeker <claudio@openbsd.org>
                      4:  *
                      5:  * Permission to use, copy, modify, and distribute this software for any
                      6:  * purpose with or without fee is hereby granted, provided that the above
                      7:  * copyright notice and this permission notice appear in all copies.
                      8:  *
                      9:  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
                     10:  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
                     11:  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
                     12:  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
                     13:  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
                     14:  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
                     15:  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
                     16:  */
                     17:
                     18: #include <sys/param.h> /* MAXBSIZE */
                     19:
                     20: #include <err.h>
                     21: #include <fcntl.h>
                     22: #include <unistd.h>
                     23:
                     24: #include "extern.h"
                     25:
                     26: /*
                     27:  * Return true if all bytes in buffer are zero.
                     28:  * A buffer of zero lenght is also considered a zero buffer.
                     29:  */
                     30: static int
                     31: iszero(const void *b, size_t len)
                     32: {
                     33:        const unsigned char *c = b;
                     34:
                     35:        for (; len > 0; len--) {
                     36:                if (*c++ != '\0')
                     37:                        return 0;
                     38:        }
                     39:        return 1;
                     40: }
                     41:
                     42: static int
                     43: copy_internal(int fromfd, int tofd)
                     44: {
                     45:        char buf[MAXBSIZE];
                     46:        ssize_t r, w;
                     47:
                     48:        while ((r = read(fromfd, buf, sizeof(buf))) > 0) {
                     49:                if (iszero(buf, sizeof(buf))) {
                     50:                        if (lseek(tofd, r, SEEK_CUR) == -1)
                     51:                                return -1;
                     52:                } else {
                     53:                        w = write(tofd, buf, r);
                     54:                        if (r != w || w == -1)
                     55:                                return -1;
                     56:                }
                     57:        }
                     58:        if (r == -1)
                     59:                return -1;
                     60:        if (ftruncate(tofd, lseek(tofd, 0, SEEK_CUR)) == -1)
                     61:                return -1;
                     62:        return 0;
                     63: }
                     64:
                     65: void
                     66: copy_file(int rootfd, const char *basedir, const struct flist *f)
                     67: {
                     68:        int fromfd, tofd, dfd;
                     69:
1.2       deraadt    70:        dfd = openat(rootfd, basedir, O_RDONLY | O_DIRECTORY);
1.1       claudio    71:        if (dfd == -1)
                     72:                err(ERR_FILE_IO, "%s: openat", basedir);
                     73:
1.2       deraadt    74:        fromfd = openat(dfd, f->path, O_RDONLY | O_NOFOLLOW);
1.1       claudio    75:        if (fromfd == -1)
                     76:                err(ERR_FILE_IO, "%s/%s: openat", basedir, f->path);
                     77:        close(dfd);
                     78:
                     79:        tofd = openat(rootfd, f->path,
                     80:            O_WRONLY | O_NOFOLLOW | O_TRUNC | O_CREAT | O_EXCL,
                     81:            0600);
                     82:        if (tofd == -1)
                     83:                err(ERR_FILE_IO, "%s: openat", f->path);
                     84:
                     85:        if (copy_internal(fromfd, tofd) == -1)
                     86:                err(ERR_FILE_IO, "%s: copy file", f->path);
                     87:
                     88:        close(fromfd);
                     89:        close(tofd);
                     90: }