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Annotation of src/usr.bin/rsync/symlinks.c, Revision 1.1

1.1     ! benno       1: /*     $Id$ */
        !             2: /*
        !             3:  * Copyright (c) 2019 Kristaps Dzonsons <kristaps@bsd.lv>
        !             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: #include <sys/param.h>
        !            18:
        !            19: #include <assert.h>
        !            20: #include <stdint.h>
        !            21: #include <stdlib.h>
        !            22: #include <unistd.h>
        !            23:
        !            24: #include "extern.h"
        !            25:
        !            26: /*
        !            27:  * Allocate space for a readlink(2) invocation.
        !            28:  * Returns NULL on failure or a buffer otherwise.
        !            29:  * The buffer must be passed to free() by the caller.
        !            30:  */
        !            31: char *
        !            32: symlink_read(struct sess *sess, const char *path)
        !            33: {
        !            34:        char    *buf = NULL;
        !            35:        size_t   sz;
        !            36:        ssize_t  nsz = 0;
        !            37:        void    *pp;
        !            38:
        !            39:        for (sz = MAXPATHLEN; ; sz *= 2) {
        !            40:                if (NULL == (pp = realloc(buf, sz + 1))) {
        !            41:                        ERR(sess, "realloc");
        !            42:                        free(buf);
        !            43:                        return NULL;
        !            44:                }
        !            45:                buf = pp;
        !            46:
        !            47:                if (-1 == (nsz = readlink(path, buf, sz))) {
        !            48:                        ERR(sess, "%s: readlink", path);
        !            49:                        free(buf);
        !            50:                        return NULL;
        !            51:                } else if (0 == nsz) {
        !            52:                        ERRX(sess, "%s: empty link", path);
        !            53:                        free(buf);
        !            54:                        return NULL;
        !            55:                } else if ((size_t)nsz < sz)
        !            56:                        break;
        !            57:        }
        !            58:
        !            59:        assert(NULL != buf);
        !            60:        assert(nsz > 0);
        !            61:        buf[nsz] = '\0';
        !            62:        return buf;
        !            63: }
        !            64:
        !            65: /*
        !            66:  * Allocate space for a readlinkat(2) invocation.
        !            67:  * Returns NULL on failure or a buffer otherwise.
        !            68:  * The buffer must be passed to free() by the caller.
        !            69:  */
        !            70: char *
        !            71: symlinkat_read(struct sess *sess, int fd, const char *path)
        !            72: {
        !            73:        char    *buf = NULL;
        !            74:        size_t   sz;
        !            75:        ssize_t  nsz = 0;
        !            76:        void    *pp;
        !            77:
        !            78:        for (sz = MAXPATHLEN; ; sz *= 2) {
        !            79:                if (NULL == (pp = realloc(buf, sz + 1))) {
        !            80:                        ERR(sess, "realloc");
        !            81:                        free(buf);
        !            82:                        return NULL;
        !            83:                }
        !            84:                buf = pp;
        !            85:
        !            86:                if (-1 == (nsz = readlinkat(fd, path, buf, sz))) {
        !            87:                        ERR(sess, "%s: readlinkat", path);
        !            88:                        free(buf);
        !            89:                        return NULL;
        !            90:                } else if (0 == nsz) {
        !            91:                        ERRX(sess, "%s: empty link", path);
        !            92:                        free(buf);
        !            93:                        return NULL;
        !            94:                } else if ((size_t)nsz < sz)
        !            95:                        break;
        !            96:        }
        !            97:
        !            98:        assert(NULL != buf);
        !            99:        assert(nsz > 0);
        !           100:        buf[nsz] = '\0';
        !           101:        return buf;
        !           102: }