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 1.4 2003/11/16 02:37:39 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[MAXSHELLCMDLEN]) { 75 /* Skip any whitespace */ 76 while ((*ihp == ' ') || (*ihp == '\t')) { 77 ihp++; 78 continue; 79 } 80 81 /* End of line? */ 82 if ((*ihp == '\n') || (*ihp == '#')) 83 break; 84 85 /* Found a token */ 86 while ((*ihp != ' ') && (*ihp != '\t') && (*ihp != '\n') && 87 (*ihp != '#')) { 88 offset++; 89 ihp++; 90 } 91 /* Include terminating nulls in the offset */ 92 offset++; 93 } 94 95 /* If the script gives a null line as the interpreter, we bail */ 96 if (offset == 0) 97 return (ENOEXEC); 98 99 /* Check that we aren't too big */ 100 if (offset > MAXSHELLCMDLEN) 101 return (ENAMETOOLONG); 102 103 /* 104 * The full path name of the original script file must be tagged 105 * onto the end, adjust the offset to deal with it. 106 * 107 * The original argv0 is being replaced, set 'length' to the number 108 * of bytes being removed. So 'offset' is the number of bytes being 109 * added and 'length' is the number of bytes being removed. 110 */ 111 offset += strlen(imgp->args->fname) + 1; /* add fname */ 112 length = strlen(imgp->args->begin_argv) + 1; /* bytes to delete */ 113 114 if (offset - length > imgp->args->space) 115 return (E2BIG); 116 117 bcopy(imgp->args->begin_argv + length, imgp->args->begin_argv + offset, 118 imgp->args->endp - (imgp->args->begin_argv + length)); 119 120 offset -= length; /* calculate actual adjustment */ 121 imgp->args->begin_envv += offset; 122 imgp->args->endp += offset; 123 imgp->args->space -= offset; 124 /* decr argc remove old argv[0], incr argc for fname add, net 0 */ 125 126 /* 127 * Loop through the interpreter name yet again, copying as 128 * we go. 129 */ 130 ihp = &image_header[2]; 131 offset = 0; 132 while (ihp < &image_header[MAXSHELLCMDLEN]) { 133 /* Skip whitespace */ 134 while ((*ihp == ' ' || *ihp == '\t')) { 135 ihp++; 136 continue; 137 } 138 139 /* End of line? */ 140 if ((*ihp == '\n') || (*ihp == '#')) 141 break; 142 143 /* Found a token, copy it */ 144 while ((*ihp != ' ') && (*ihp != '\t') && 145 (*ihp != '\n') && (*ihp != '#')) { 146 imgp->args->begin_argv[offset++] = *ihp++; 147 } 148 imgp->args->begin_argv[offset++] = '\0'; 149 imgp->args->argc++; 150 } 151 152 /* 153 * Finally, add the filename onto the end for the interpreter to 154 * use and copy the interpreter's name to imgp->interpreter_name 155 * for exec to use. 156 */ 157 error = copystr(imgp->args->fname, imgp->args->buf + offset, 158 imgp->args->space, &length); 159 160 if (error == 0) { 161 error = copystr(imgp->args->begin_argv, imgp->interpreter_name, 162 MAXSHELLCMDLEN, &length); 163 } 164 return (error); 165 } 166 167 /* 168 * Tell kern_execve.c about it, with a little help from the linker. 169 */ 170 static struct execsw shell_execsw = { exec_shell_imgact, "#!" }; 171 EXEC_SET(shell, shell_execsw); 172