src/image/script.c

   1 /*
   2  * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17  */
  18
  19 FILE_LICENCE ( GPL2_OR_LATER );
  20
  21 /**
  22  * @file
  23  *
  24  * gPXE scripts
  25  *
  26  */
  27
  28 #include <string.h>
  29 #include <stdlib.h>
  30 #include <ctype.h>
  31 #include <errno.h>
  32 #include <gpxe/image.h>
  33
  34 struct image_type script_image_type __image_type ( PROBE_NORMAL );
  35
  36 /**
  37  * Execute script
  38  *
  39  * @v image             Script
  40  * @ret rc              Return status code
  41  */
  42 static int script_exec ( struct image *image ) {
  43         size_t offset = 0;
  44         off_t eol;
  45         size_t len;
  46         int rc;
  47
  48         /* Temporarily de-register image, so that a "boot" command
  49          * doesn't throw us into an execution loop.
  50          */
  51         unregister_image ( image );
  52
  53         while ( offset < image->len ) {
  54
  55                 /* Find length of next line, excluding any terminating '\n' */
  56                 eol = memchr_user ( image->data, offset, '\n',
  57                                     ( image->len - offset ) );
  58                 if ( eol < 0 )
  59                         eol = image->len;
  60                 len = ( eol - offset );
  61
  62                 /* Copy line, terminate with NUL, and execute command */
  63                 {
  64                         char cmdbuf[ len + 1 ];
  65
  66                         copy_from_user ( cmdbuf, image->data, offset, len );
  67                         cmdbuf[len] = '\0';
  68                         DBG ( "$ %s\n", cmdbuf );
  69                         if ( ( rc = system ( cmdbuf ) ) != 0 ) {
  70                                 DBG ( "Command \"%s\" failed: %s\n",
  71                                       cmdbuf, strerror ( rc ) );
  72                                 goto done;
  73                         }
  74                 }
  75
  76                 /* Move to next line */
  77                 offset += ( len + 1 );
  78         }
  79
  80         rc = 0;
  81  done:
  82         /* Re-register image and return */
  83         register_image ( image );
  84         return rc;
  85 }
  86
  87 /**
  88  * Load script into memory
  89  *
  90  * @v image             Script
  91  * @ret rc              Return status code
  92  */
  93 static int script_load ( struct image *image ) {
  94         static const char magic[] = "#!gpxe";
  95         char test[ sizeof ( magic ) - 1 /* NUL */ + 1 /* terminating space */];
  96
  97         /* Sanity check */
  98         if ( image->len < sizeof ( test ) ) {
  99                 DBG ( "Too short to be a script\n" );
 100                 return -ENOEXEC;
 101         }
 102
 103         /* Check for magic signature */
 104         copy_from_user ( test, image->data, 0, sizeof ( test ) );
 105         if ( ( memcmp ( test, magic, ( sizeof ( test ) - 1 ) ) != 0 ) ||
 106              ! isspace ( test[ sizeof ( test ) - 1 ] ) ) {
 107                 DBG ( "Invalid magic signature\n" );
 108                 return -ENOEXEC;
 109         }
 110
 111         /* This is a script */
 112         image->type = &script_image_type;
 113
 114         /* We don't actually load it anywhere; we will pick the lines
 115          * out of the image as we need them.
 116          */
 117
 118         return 0;
 119 }
 120
 121 /** Script image type */
 122 struct image_type script_image_type __image_type ( PROBE_NORMAL ) = {
 123         .name = "script",
 124         .load = script_load,
 125         .exec = script_exec,
 126 };