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 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: releng/5.2/sys/kern/imgact_shell.c 116182 2003-06-11 00:56:59Z obrien $");
   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. An interpreter name beginning
   45  *      at imgp->stringbase is the minimal successful exit requirement.
   46  */
   47 int
   48 exec_shell_imgact(imgp)
   49         struct image_params *imgp;
   50 {
   51         const char *image_header = imgp->image_header;
   52         const char *ihp, *line_endp;
   53         char *interp;
   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          * Copy shell name and arguments from image_header into string
   70          *      buffer.
   71          */
   72 
   73         /*
   74          * Find end of line; return if the line > MAXSHELLCMDLEN long.
   75          */
   76         for (ihp = &image_header[2]; *ihp != '\n' && *ihp != '#'; ++ihp) {
   77                 if (ihp >= &image_header[MAXSHELLCMDLEN])
   78                         return(ENAMETOOLONG);
   79         }
   80         line_endp = ihp;
   81 
   82         /* reset for another pass */
   83         ihp = &image_header[2];
   84 
   85         /* Skip over leading spaces - until the interpreter name */
   86         while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
   87 
   88         /* copy the interpreter name */
   89         interp = imgp->interpreter_name;
   90         while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t'))
   91                 *interp++ = *ihp++;
   92         *interp = '\0';
   93 
   94         /* Disallow a null interpreter filename */
   95         if (*imgp->interpreter_name == '\0')
   96                 return(ENOEXEC);
   97 
   98         /* reset for another pass */
   99         ihp = &image_header[2];
  100 
  101         /* copy the interpreter name and arguments */
  102         while (ihp < line_endp) {
  103                 /* Skip over leading spaces */
  104                 while ((*ihp == ' ') || (*ihp == '\t')) ihp++;
  105 
  106                 if (ihp < line_endp) {
  107                         /*
  108                          * Copy to end of token. No need to watch stringspace
  109                          *      because this is at the front of the string buffer
  110                          *      and the maximum shell command length is tiny.
  111                          */
  112                         while ((ihp < line_endp) && (*ihp != ' ') && (*ihp != '\t')) {
  113                                 *imgp->stringp++ = *ihp++;
  114                                 imgp->stringspace--;
  115                         }
  116 
  117                         *imgp->stringp++ = 0;
  118                         imgp->stringspace--;
  119 
  120                         imgp->argc++;
  121                 }
  122         }
  123 
  124         imgp->argv0 = imgp->fname;
  125 
  126         return(0);
  127 }
  128 
  129 /*
  130  * Tell kern_execve.c about it, with a little help from the linker.
  131  */
  132 static struct execsw shell_execsw = { exec_shell_imgact, "#!" };
  133 EXEC_SET(shell, shell_execsw);

Cache object: 33682eb7d91e31b828501e5b2d7ff82b


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