1 /* 2 * Copyright 2000 Massachusetts Institute of Technology 3 * 4 * Permission to use, copy, modify, and distribute this software and 5 * its documentation for any purpose and without fee is hereby 6 * granted, provided that both the above copyright notice and this 7 * permission notice appear in all copies, that both the above 8 * copyright notice and this permission notice appear in all 9 * supporting documentation, and that the name of M.I.T. not be used 10 * in advertising or publicity pertaining to distribution of the 11 * software without specific, written prior permission. M.I.T. makes 12 * no representations about the suitability of this software for any 13 * purpose. It is provided "as is" without express or implied 14 * warranty. 15 * 16 * THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS 17 * ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE, 18 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT 20 * SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 23 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 25 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 26 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 * 29 * $FreeBSD: src/lib/libc/gen/posixshm.c,v 1.2.2.1 2000/08/22 01:48:12 jhb Exp $ 30 */ 31 32 #include "namespace.h" 33 #include <sys/types.h> 34 #include <sys/param.h> 35 #include <sys/fcntl.h> 36 #include <sys/mman.h> 37 #include <sys/stat.h> 38 39 #include <errno.h> 40 #include <unistd.h> 41 #include <string.h> 42 #include "un-namespace.h" 43 44 static int mkintermediatedirs(int dfd, const char *path); 45 46 int 47 shm_open(const char *path, int flags, mode_t mode) 48 { 49 int dfd; 50 int fd; 51 struct stat stab; 52 53 if ((flags & O_ACCMODE) == O_WRONLY) { 54 errno = EINVAL; 55 return (-1); 56 } 57 58 while (*path == '/') 59 ++path; 60 61 /* 62 * Expect a tmpfs filesystem for our shm base. If for some reason 63 * it does not exist (it really should), fall-back to /tmp. 64 */ 65 dfd = _open("/var/run/shm", O_RDONLY|O_DIRECTORY); 66 if (dfd < 0) 67 dfd = _open("/tmp", O_RDONLY|O_DIRECTORY); 68 69 if (dfd >= 0) { 70 fd = _openat(dfd, path, flags, mode); 71 if (fd < 0 && errno == ENOENT && 72 mkintermediatedirs(dfd, path) == 0) 73 { 74 fd = _openat(dfd, path, flags, mode); 75 } 76 _close(dfd); 77 } else { 78 fd = -1; 79 } 80 81 if (fd != -1) { 82 if (_fstat(fd, &stab) != 0 || !S_ISREG(stab.st_mode)) { 83 _close(fd); 84 errno = EINVAL; 85 return (-1); 86 } 87 88 if (_fcntl(fd, F_SETFD, FD_CLOEXEC) != 0 || 89 _fcntl(fd, F_SETFL, (int)FPOSIXSHM) != 0) { 90 _close(fd); 91 return (-1); 92 } 93 } 94 return (fd); 95 } 96 97 int 98 shm_unlink(const char *path) 99 { 100 int res; 101 int dfd; 102 103 while (*path == '/') 104 ++path; 105 106 /* 107 * Expect a tmpfs filesystem for our shm base. If for some reason 108 * it does not exist (it really should), fall-back to /tmp. 109 */ 110 dfd = _open("/var/run/shm", O_RDONLY|O_DIRECTORY); 111 if (dfd < 0) 112 dfd = _open("/tmp", O_RDONLY|O_DIRECTORY); 113 114 if (dfd >= 0) { 115 res = _unlinkat(dfd, path, 0); 116 _close(dfd); 117 } else { 118 res = -1; 119 } 120 return res; 121 } 122 123 /* 124 * Create any missing intermediate directories, modes 1777 125 */ 126 static int 127 mkintermediatedirs(int dfd, const char *path) 128 { 129 const char *eptr; 130 char buf[PATH_MAX+1]; 131 size_t len; 132 int res = 0; 133 134 eptr = path - 1; 135 while ((eptr = strchr(eptr + 1, '/')) != NULL) { 136 len = eptr - path; 137 if (len > PATH_MAX) { 138 errno = EINVAL; 139 return -1; 140 } 141 bcopy(path, buf, len); 142 buf[len] = 0; 143 res = _mkdirat(dfd, buf, 01777); 144 if (res < 0 && errno != EEXIST) 145 break; 146 } 147 return res; 148 } 149