1 /* 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $FreeBSD: src/sys/kern/imgact_shell.c,v 1.21.2.2 2001/12/22 01:21:39 jwd Exp $ 27 * $DragonFly: src/sys/kern/imgact_shell.c,v 1.6 2005/02/28 05:44:52 dillon Exp $ 28 */ 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/sysproto.h> 33 #include <sys/exec.h> 34 #include <sys/imgact.h> 35 #include <sys/kernel.h> 36 37 #if BYTE_ORDER == LITTLE_ENDIAN 38 #define SHELLMAGIC 0x2123 /* #! */ 39 #else 40 #define SHELLMAGIC 0x2321 41 #endif 42 43 /* 44 * Shell interpreter image activator. A interpreter name beginning 45 * at imgp->args->begin_argv is the minimal successful exit requirement. 46 */ 47 int 48 exec_shell_imgact(struct image_params *imgp) 49 { 50 const char *image_header = imgp->image_header; 51 const char *ihp; 52 size_t length, offset; 53 int error; 54 55 /* a shell script? */ 56 if (((const short *) image_header)[0] != SHELLMAGIC) 57 return(-1); 58 59 /* 60 * Don't allow a shell script to be the shell for a shell 61 * script. :-) 62 */ 63 if (imgp->interpreted) 64 return(ENOEXEC); 65 66 imgp->interpreted = 1; 67 68 /* 69 * Figure out the number of bytes that need to be reserved in the 70 * argument string to copy the contents of the interpreter's command 71 * line into the argument string. 72 */ 73 ihp = &image_header[2]; 74 offset = 0; 75 while (ihp < &image_header[PAGE_SIZE]) { 76 /* Skip any whitespace */ 77 if (*ihp == ' ' || *ihp == '\t') { 78 ++ihp; 79 continue; 80 } 81 82 /* End of line? */ 83 if (*ihp == '\n' || *ihp == '#' || *ihp == '\0') 84 break; 85 86 /* Found a token */ 87 do { 88 ++offset; 89 ++ihp; 90 } while (ihp < &image_header[PAGE_SIZE] && 91 *ihp != ' ' && *ihp != '\t' && 92 *ihp != '\n' && *ihp != '#' && *ihp != '\0'); 93 94 /* Take into account the \0 that will terminate the token */ 95 ++offset; 96 } 97 98 /* If the script gives a null line as the interpreter, we bail */ 99 if (offset == 0) 100 return (ENOEXEC); 101 102 /* It should not be possible for offset to exceed PAGE_SIZE */ 103 KKASSERT(offset <= PAGE_SIZE); 104 105 /* Check that we aren't too big */ 106 if (ihp == &image_header[PAGE_SIZE]) 107 return (ENAMETOOLONG); 108 109 /* 110 * The full path name of the original script file must be tagged 111 * onto the end, adjust the offset to deal with it. 112 * 113 * The original argv0 is being replaced, set 'length' to the number 114 * of bytes being removed. So 'offset' is the number of bytes being 115 * added and 'length' is the number of bytes being removed. 116 */ 117 offset += strlen(imgp->args->fname) + 1; /* add fname */ 118 length = strlen(imgp->args->begin_argv) + 1; /* bytes to delete */ 119 120 if (offset > imgp->args->space + length) 121 return (E2BIG); 122 123 bcopy(imgp->args->begin_argv + length, imgp->args->begin_argv + offset, 124 imgp->args->endp - (imgp->args->begin_argv + length)); 125 126 offset -= length; /* calculate actual adjustment */ 127 imgp->args->begin_envv += offset; 128 imgp->args->endp += offset; 129 imgp->args->space -= offset; 130 /* decr argc remove old argv[0], incr argc for fname add, net 0 */ 131 132 /* 133 * Loop through the interpreter name yet again, copying as 134 * we go. 135 */ 136 ihp = &image_header[2]; 137 offset = 0; 138 while (ihp < &image_header[PAGE_SIZE]) { 139 /* Skip whitespace */ 140 if (*ihp == ' ' || *ihp == '\t') { 141 ++ihp; 142 continue; 143 } 144 145 /* End of line? */ 146 if (*ihp == '\n' || *ihp == '#' || *ihp == '\0') 147 break; 148 149 /* Found a token, copy it */ 150 do { 151 imgp->args->begin_argv[offset] = *ihp; 152 ++ihp; 153 ++offset; 154 } while (ihp < &image_header[PAGE_SIZE] && 155 *ihp != ' ' && *ihp != '\t' && 156 *ihp != '\n' && *ihp != '#' && *ihp != '\0'); 157 158 /* And terminate the argument */ 159 imgp->args->begin_argv[offset] = '\0'; 160 imgp->args->argc++; 161 ++offset; 162 } 163 164 /* 165 * Finally, add the filename onto the end for the interpreter to 166 * use and copy the interpreter's name to imgp->interpreter_name 167 * for exec to use. 168 */ 169 error = copystr(imgp->args->fname, imgp->args->buf + offset, 170 imgp->args->space, &length); 171 172 if (error == 0) { 173 error = copystr(imgp->args->begin_argv, imgp->interpreter_name, 174 MAXSHELLCMDLEN, &length); 175 } 176 return (error); 177 } 178 179 /* 180 * Tell kern_execve.c about it, with a little help from the linker. 181 */ 182 static struct execsw shell_execsw = { exec_shell_imgact, "#!" }; 183 EXEC_SET(shell, shell_execsw); 184