The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/imgact_shell.c

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    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  * $FreeBSD$
   27  */
   28 
   29 #include <sys/param.h>
   30 #include <sys/systm.h>
   31 #include <sys/sysproto.h>
   32 #include <sys/exec.h>
   33 #include <sys/imgact.h>
   34 #include <sys/kernel.h>
   35 
   36 #if BYTE_ORDER == LITTLE_ENDIAN
   37 #define SHELLMAGIC      0x2123 /* #! */
   38 #else
   39 #define SHELLMAGIC      0x2321
   40 #endif
   41 
   42 #define MAXSHELLCMDLEN  64
   43 
   44 static int      exec_shell_imgact __P((struct image_params *imgp));
   45 
   46 /*
   47  * Shell interpreter image activator. A interpreter name beginning
   48  *      at imgp->stringbase is the minimal successful exit requirement.
   49  */
   50 static int
   51 exec_shell_imgact(imgp)
   52         struct image_params *imgp;
   53 {
   54         const char *image_header = imgp->image_header;
   55         const char *ihp, *line_endp;
   56         char *interp;
   57 
   58         /* a shell script? */
   59         if (((const short *) image_header)[0] != SHELLMAGIC)
   60                 return(-1);
   61 
   62         /*
   63          * Don't allow a shell script to be the shell for a shell
   64          *      script. :-)
   65          */
   66         if (imgp->interpreted)
   67                 return(ENOEXEC);
   68 
   69         imgp->interpreted = 1;
   70 
   71         /*
   72          * Copy shell name and arguments from image_header into string
   73          *      buffer.
   74          */
   75 
   76         /*
   77          * Find end of line; return if the line > MAXSHELLCMDLEN long.
   78          */
   79         for (ihp = &image_header[2]; *ihp != '\n' && *ihp != '#'; ++ihp) {
   80                 if (ihp >= &image_header[MAXSHELLCMDLEN])
   81                         return(ENOEXEC);
   82         }
   83         line_endp = ihp;
   84 
   85         /* reset for another pass */
   86         ihp = &image_header[2];
   87 
   88         /* Skip over leading spaces - until the interpreter name */
   89         while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
   90 
   91         /* copy the interpreter name */
   92         interp = imgp->interpreter_name;
   93         while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
   94                 *interp++ = *ihp++;
   95         *interp = '\0';
   96 
   97         /* Disallow a null interpreter filename */
   98         if (*imgp->interpreter_name == '\0')
   99                 return(ENOEXEC);
  100 
  101         /* reset for another pass */
  102         ihp = &image_header[2];
  103 
  104         /* copy the interpreter name and arguments */
  105         while (ihp < line_endp) {
  106                 /* Skip over leading spaces */
  107                 while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
  108 
  109                 if (ihp < line_endp) {
  110                         /*
  111                          * Copy to end of token. No need to watch stringspace
  112                          *      because this is at the front of the string buffer
  113                          *      and the maximum shell command length is tiny.
  114                          */
  115                         while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {
  116                                 *imgp->stringp++ = *ihp++;
  117                                 imgp->stringspace--;
  118                         }
  119 
  120                         *imgp->stringp++ = 0;
  121                         imgp->stringspace--;
  122 
  123                         imgp->argc++;
  124                 }
  125         }
  126 
  127         imgp->argv0 = imgp->uap->fname;
  128 
  129         return(0);
  130 }
  131 
  132 /*
  133  * Tell kern_execve.c about it, with a little help from the linker.
  134  * Since `const' objects end up in the text segment, TEXT_SET is the
  135  * correct directive to use.
  136  */
  137 static const struct execsw shell_execsw = { exec_shell_imgact, "#!" };
  138 EXEC_SET(shell, shell_execsw);

Cache object: a39ada819881fc27420e4c585792db06


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