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Annotation of mandoc/compat_mkstemps.c, Revision 1.1

1.1     ! schwarze    1: /* $Id$ */
        !             2: /*
        !             3:  * Copyright (c) 2015, 2021 Ingo Schwarze <schwarze@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:  * Parts of the algorithm of this function are inspired by OpenBSD
        !            18:  * mkdtemp(3) by Theo de Raadt and Todd Miller, but the code differs.
        !            19:  */
        !            20: #include "config.h"
        !            21:
        !            22: #include <sys/stat.h>
        !            23: #include <errno.h>
        !            24: #include <fcntl.h>
        !            25: #include <limits.h>
        !            26: #include <stdlib.h>
        !            27: #include <string.h>
        !            28:
        !            29: int
        !            30: mkstemps(char *path, int suffixlen)
        !            31: {
        !            32:        char    *start, *end, *cp;
        !            33:        int      fd, tries;
        !            34:        char     backup;
        !            35:
        !            36:        end = strchr(path, '\0');
        !            37:        if (suffixlen < 0 || suffixlen > end - path - 6) {
        !            38:                errno = EINVAL;
        !            39:                return -1;
        !            40:        }
        !            41:        end -= suffixlen;
        !            42:        for (start = end; start > path; start--)
        !            43:                if (start[-1] != 'X')
        !            44:                        break;
        !            45:
        !            46:        backup = *end;
        !            47:        for (tries = INT_MAX; tries; tries--) {
        !            48:                *end = '\0';
        !            49:                cp = mktemp(path);
        !            50:                *end = backup;
        !            51:                if (cp == NULL)
        !            52:                        return -1;
        !            53:                fd = open(path, O_CREAT | O_EXCL | O_RDWR, S_IRUSR | S_IWUSR);
        !            54:                if (fd != -1)
        !            55:                        return fd;
        !            56:                for (cp = start; cp < end; cp++)
        !            57:                        *cp = 'X';
        !            58:                if (errno != EEXIST)
        !            59:                        return -1;
        !            60:        }
        !            61:        errno = EEXIST;
        !            62:        return -1;
        !            63: }