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 int error, length, offset; 53 54 /* a shell script? */ 55 if (((const short *) image_header)[0] != SHELLMAGIC) 56 return(-1); 57 58 /* 59 * Don't allow a shell script to be the shell for a shell 60 * script. :-) 61 */ 62 if (imgp->interpreted) 63 return(ENOEXEC); 64 65 imgp->interpreted = 1; 66 67 /* 68 * Figure out the number of bytes that need to be reserved in the 69 * argument string to copy the contents of the interpreter's command 70 * line into the argument string. 71 */ 72 ihp = &image_header[2]; 73 offset = 0; 74 while (ihp < &image_header[PAGE_SIZE]) { 75 /* Skip any whitespace */ 76 if (*ihp == ' ' || *ihp == '\t') { 77 ++ihp; 78 continue; 79 } 80 81 /* End of line? */ 82 if (*ihp == '\n' || *ihp == '#' || *ihp == '\0') 83 break; 84 85 /* Found a token */ 86 do { 87 ++offset; 88 ++ihp; 89 } while (ihp < &image_header[PAGE_SIZE] && 90 *ihp != ' ' && *ihp != '\t' && 91 *ihp != '\n' && *ihp != '#' && *ihp != '\0'); 92 93 /* Take into account the \0 that will terminate the token */ 94 ++offset; 95 } 96 97 /* If the script gives a null line as the interpreter, we bail */ 98 if (offset == 0) 99 return (ENOEXEC); 100 101 /* It should not be possible for offset to exceed PAGE_SIZE */ 102 KKASSERT(offset <= PAGE_SIZE); 103 104 /* Check that we aren't too big */ 105 if (ihp == &image_header[PAGE_SIZE]) 106 return (ENAMETOOLONG); 107 108 /* 109 * The full path name of the original script file must be tagged 110 * onto the end, adjust the offset to deal with it. 111 * 112 * The original argv0 is being replaced, set 'length' to the number 113 * of bytes being removed. So 'offset' is the number of bytes being 114 * added and 'length' is the number of bytes being removed. 115 */ 116 offset += strlen(imgp->args->fname) + 1; /* add fname */ 117 length = strlen(imgp->args->begin_argv) + 1; /* bytes to delete */ 118 119 if (offset - length > imgp->args->space) 120 return (E2BIG); 121 122 bcopy(imgp->args->begin_argv + length, imgp->args->begin_argv + offset, 123 imgp->args->endp - (imgp->args->begin_argv + length)); 124 125 offset -= length; /* calculate actual adjustment */ 126 imgp->args->begin_envv += offset; 127 imgp->args->endp += offset; 128 imgp->args->space -= offset; 129 /* decr argc remove old argv[0], incr argc for fname add, net 0 */ 130 131 /* 132 * Loop through the interpreter name yet again, copying as 133 * we go. 134 */ 135 ihp = &image_header[2]; 136 offset = 0; 137 while (ihp < &image_header[PAGE_SIZE]) { 138 /* Skip whitespace */ 139 if (*ihp == ' ' || *ihp == '\t') { 140 ++ihp; 141 continue; 142 } 143 144 /* End of line? */ 145 if (*ihp == '\n' || *ihp == '#' || *ihp == '\0') 146 break; 147 148 /* Found a token, copy it */ 149 do { 150 imgp->args->begin_argv[offset] = *ihp; 151 ++ihp; 152 ++offset; 153 } while (ihp < &image_header[PAGE_SIZE] && 154 *ihp != ' ' && *ihp != '\t' && 155 *ihp != '\n' && *ihp != '#' && *ihp != '\0'); 156 157 /* And terminate the argument */ 158 imgp->args->begin_argv[offset] = '\0'; 159 imgp->args->argc++; 160 ++offset; 161 } 162 163 /* 164 * Finally, add the filename onto the end for the interpreter to 165 * use and copy the interpreter's name to imgp->interpreter_name 166 * for exec to use. 167 */ 168 error = copystr(imgp->args->fname, imgp->args->buf + offset, 169 imgp->args->space, &length); 170 171 if (error == 0) { 172 error = copystr(imgp->args->begin_argv, imgp->interpreter_name, 173 MAXSHELLCMDLEN, &length); 174 } 175 return (error); 176 } 177 178 /* 179 * Tell kern_execve.c about it, with a little help from the linker. 180 */ 181 static struct execsw shell_execsw = { exec_shell_imgact, "#!" }; 182 EXEC_SET(shell, shell_execsw); 183