1 /* $NetBSD: posix_spawnp.c,v 1.5 2024/11/11 06:49:31 martin Exp $ */ 2 3 /*- 4 * Copyright (c) 2011 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Martin Husemann <martin@NetBSD.org>. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 __RCSID("$NetBSD: posix_spawnp.c,v 1.5 2024/11/11 06:49:31 martin Exp $"); 35 #endif /* LIBC_SCCS and not lint */ 36 37 #include "namespace.h" 38 39 #include <assert.h> 40 #include <errno.h> 41 #include <paths.h> 42 #include <spawn.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <unistd.h> 47 48 49 int posix_spawnp(pid_t * __restrict pid, const char * __restrict file, 50 const posix_spawn_file_actions_t *fa, 51 const posix_spawnattr_t * __restrict sa, 52 char * const *__restrict cav, char * const *__restrict env) 53 { 54 char fpath[FILENAME_MAX]; 55 const char *path, *p; 56 size_t lp, ln; 57 int err; 58 59 _DIAGASSERT(file != NULL); 60 61 /* "" is not a valid filename; check this before traversing PATH. */ 62 if (file[0] == '\0') 63 return ENOENT; 64 65 /* 66 * If there is a / in the name, fall straight through to posix_spawn(). 67 */ 68 if (strchr(file, '/') != NULL) 69 return posix_spawn(pid, file, fa, sa, cav, env); 70 71 /* Get the path we're searching. */ 72 if ((path = getenv("PATH")) == NULL) 73 path = _PATH_DEFPATH; 74 75 /* 76 * Find an executable image with the given name in the PATH 77 */ 78 79 ln = strlen(file); 80 err = 0; 81 do { 82 /* Find the end of this path element. */ 83 for (p = path; *path != 0 && *path != ':'; path++) 84 continue; 85 /* 86 * It's a SHELL path -- double, leading and trailing colons 87 * mean the current directory. 88 */ 89 if (p == path) { 90 p = "."; 91 lp = 1; 92 } else 93 lp = (size_t)(path - p); 94 95 /* 96 * Once we gain chdir/fchdir file actions, this will need 97 * serious work, as we must treat "." relative to the 98 * target of the (final) chdir performed. 99 * 100 * Fortunately, that day is yet to come. 101 */ 102 103 /* 104 * If the path is too long complain. This is a possible 105 * security issue; given a way to make the path too long 106 * the user may execute the wrong program. 107 */ 108 if (lp + ln + 2 > sizeof(fpath)) { 109 (void)write(STDERR_FILENO, "posix_spawnp: ", 14); 110 (void)write(STDERR_FILENO, p, lp); 111 (void)write(STDERR_FILENO, ": path too long\n", 16); 112 continue; 113 } 114 memcpy(fpath, p, lp); 115 fpath[lp] = '/'; 116 memcpy(fpath + lp + 1, file, ln); 117 fpath[lp + ln + 1] = '\0'; 118 119 /* 120 * It would be nice (much better) to try posix_spawn() 121 * here, using the current fpath as the filename, but 122 * there's no guarantee that it is safe to execute it 123 * twice (the file actions may screw us) so that we 124 * cannot do. This test is weak, barely even adequate. 125 * but unless we are forced into making posix_spawmp() 126 * become a system call (with PATH as an arg, or an array 127 * of possible paths to try, based upon PATH and file) 128 * we really have no better method. 129 */ 130 if (access(fpath, X_OK) == 0) 131 break; 132 133 if (err == 0) 134 err = errno; 135 136 fpath[0] = '\0'; 137 138 139 } while (*path++ == ':'); /* Otherwise, *path was NUL */ 140 141 if (fpath[0] == '\0') 142 return err; 143 144 /* 145 * Use posix_spawn() with the found binary 146 */ 147 return posix_spawn(pid, fpath, fa, sa, cav, env); 148 } 149