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 * $Id: imgact_shell.c,v 1.11 1996/04/08 01:21:58 davidg Exp $ 27 */ 28 29 #include <sys/param.h> 30 #include <sys/systm.h> 31 #include <sys/sysproto.h> 32 #include <sys/resourcevar.h> 33 #include <sys/exec.h> 34 #include <sys/imgact.h> 35 #include <sys/kernel.h> 36 #include <machine/endian.h> 37 38 #if BYTE_ORDER == LITTLE_ENDIAN 39 #define SHELLMAGIC 0x2123 /* #! */ 40 #else 41 #define SHELLMAGIC 0x2321 42 #endif 43 44 #define MAXSHELLCMDLEN 64 45 46 static int exec_shell_imgact __P((struct image_params *imgp)); 47 48 /* 49 * Shell interpreter image activator. A interpreter name beginning 50 * at imgp->stringbase is the minimal successful exit requirement. 51 */ 52 static int 53 exec_shell_imgact(imgp) 54 struct image_params *imgp; 55 { 56 const char *image_header = imgp->image_header; 57 const char *ihp, *line_endp; 58 char *interp; 59 60 /* a shell script? */ 61 if (((const short *) image_header)[0] != SHELLMAGIC) 62 return(-1); 63 64 /* 65 * Don't allow a shell script to be the shell for a shell 66 * script. :-) 67 */ 68 if (imgp->interpreted) 69 return(ENOEXEC); 70 71 imgp->interpreted = 1; 72 73 /* 74 * Copy shell name and arguments from image_header into string 75 * buffer. 76 */ 77 78 /* 79 * Find end of line; return if the line > MAXSHELLCMDLEN long. 80 */ 81 for (ihp = &image_header[2]; *ihp != '\n'; ++ihp) { 82 if (ihp >= &image_header[MAXSHELLCMDLEN]) 83 return(ENOEXEC); 84 } 85 line_endp = ihp; 86 87 /* reset for another pass */ 88 ihp = &image_header[2]; 89 90 /* Skip over leading spaces - until the interpreter name */ 91 while ((*ihp == ' ') || (*ihp == '\t')) ihp++; 92 93 /* copy the interpreter name */ 94 interp = imgp->interpreter_name; 95 while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) 96 *interp++ = *ihp++; 97 *interp = '\0'; 98 99 /* Disallow a null interpreter filename */ 100 if (*imgp->interpreter_name == '\0') 101 return(ENOEXEC); 102 103 /* reset for another pass */ 104 ihp = &image_header[2]; 105 106 /* copy the interpreter name and arguments */ 107 while (ihp < line_endp) { 108 /* Skip over leading spaces */ 109 while ((*ihp == ' ') || (*ihp == '\t')) ihp++; 110 111 if (ihp < line_endp) { 112 /* 113 * Copy to end of token. No need to watch stringspace 114 * because this is at the front of the string buffer 115 * and the maximum shell command length is tiny. 116 */ 117 while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) { 118 *imgp->stringp++ = *ihp++; 119 imgp->stringspace--; 120 } 121 122 *imgp->stringp++ = 0; 123 imgp->stringspace--; 124 125 imgp->argc++; 126 } 127 } 128 129 /* set argv[0] to point to original file name */ 130 suword(imgp->uap->argv, (int)imgp->uap->fname); 131 132 return(0); 133 } 134 135 /* 136 * Tell kern_execve.c about it, with a little help from the linker. 137 * Since `const' objects end up in the text segment, TEXT_SET is the 138 * correct directive to use. 139 */ 140 static const struct execsw shell_execsw = { exec_shell_imgact, "#!" }; 141 TEXT_SET(execsw_set, shell_execsw); 142