1 /* ----------------------------------------------------------------------- *
2 *
3 * Copyright 2010 Gert Hulselmans - All Rights Reserved
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
8 * Boston MA 02110-1301, USA; either version 2 of the License, or
9 * (at your option) any later version; incorporated herein by reference.
10 *
11 * ----------------------------------------------------------------------- */
12
13 /*
14 * ifplop.c
15 *
16 * This COM32 module detects if the PLoP Boot Manager was used to boot a CDROM
17 * drive or USB drive, by checking for the presence of the PLoP INT13h hook.
18 *
19 * Usage: ifplop.c32 [<plop_detected>] -- [<plop_not_detected>]
20 * Examples: ifplop.c32 menu.c32 another.cfg -- plpbt hiddenusb usb1=2
21 * You need to remove the ".bin" extension of the plpbt.bin file
22 * if you use it this way.
23 * ifplop.c32 plop_detected -- plop_not_detected
24 *
25 * A possible config file could be:
26 *
27 * ===========================================================================
28 * DEFAULT plopcheck
29 *
30 * # Check for the presence of PLoP (run by default)
31 * # When PLoP INT13h hook is found, run the first command (plop_detected)
32 * # When PLoP INT13h hook isn't found, run the second command (plop_not_detected)
33 * LABEL plopcheck
34 * COM32 ifplop.c32
35 * APPEND plop_detected -- plop_not_detected
36 *
37 * # When PLoP INT13h hook was found, boot the menu system.
38 * # PLoP can have added USB 2.0 speed, so the entries we want to boot
39 * # will be read from disk much faster (supposing that we have a BIOS
40 * # that only supports USB 1.1 speed, but a mobo with USB 2.0 controllers).
41 * LABEL plop_detected
42 * COM32 menu.c32
43 * APPEND another.cfg
44 *
45 * # PLoP INT13h hook wasn't found, so we boot PLoP, so it can add USB 2.0 support
46 * # When using "LINUX plpbt.bin", you don't need to remove the .bin extension.
47 * LABEL plop_not_detected
48 * LINUX plpbt.bin
49 * APPEND hiddenusb usb1=2
50 *
51 * ===========================================================================
52 *
53 * Why is/can this module be useful?
54 *
55 * You may want to boot PLoP by default from Syslinux when you boot from your
56 * USB stick/drive:
57 * 1. PLoP can upgrade USB 1.1 speed offered by the BIOS to USB 2.0 speed
58 * if you have USB 2.0 controllers on your mobo.
59 * 2. Some BIOSes only can access the first 128GiB (137GB) on USB drives, while
60 * internal hard drives don't necessarily suffer from this 128GiB problem.
61 * Using PLoPs USB capabilities, you can access the whole drive.
62 *
63 * When you select the "USB" entry in PLoP, it will boot your USB stick/drive
64 * again and it will boot PLoP again when you have set booting PLoP as DEFAULT
65 * boot option in your Syslinux configuration file.
66 *
67 * By using ifplop.c32 you can specify which action you want to do the second
68 * time your USB stick/drive is booted. So you can load another config file or
69 * boot a large hard disk image or whatever you want.
70 *
71 * PLoP Boot Manager website: http://www.plop.at/en/bootmanager.html
72 */
73
74 #include <com32.h>
75 #include <stdlib.h>
76 #include <stdio.h>
77 #include <string.h>
78 #include <alloca.h>
79 #include <console.h>
80 #include <syslinux/boot.h>
81
plop_INT13h_check(void)82 static bool plop_INT13h_check(void)
83 {
84 com32sys_t inregs, outregs;
85
86 /* Prepare the register set */
87 memset(&inregs, 0, sizeof inregs);
88
89 /*
90 * Check if PLoP already has booted a CDROM or USB drive by checking
91 * for the presence of the PLoP INT13h hook.
92 *
93 * The following assembly code (NASM) can detect the PLoP INT13h hook:
94 *
95 * mov eax,'PoLP' ; Reverse of 'PLoP'
96 * mov ebp,'DKHC' ; Reverse of 'CHKD'
97 * int 13h
98 * cmp eax,' sey' ; Reverse of 'yes '
99 * jz plop_INT13h_active
100 */
101
102 inregs.eax.l = 0x504c6f50; /* "PLoP" */
103 inregs.ebp.l = 0x43484b44; /* "CHKD" */
104
105 __intcall(0x13, &inregs, &outregs);
106
107 /* eax will contain "yes " if PLoP INT13h hook is available */
108 if (outregs.eax.l == 0x79657320)
109 return true;
110
111 return false;
112 }
113
114 /* XXX: this really should be librarized */
boot_args(char ** args)115 static void boot_args(char **args)
116 {
117 int len = 0, a = 0;
118 char **pp;
119 const char *p;
120 char c, *q, *str;
121
122 for (pp = args; *pp; pp++)
123 len += strlen(*pp) + 1;
124
125 q = str = alloca(len);
126 for (pp = args; *pp; pp++) {
127 p = *pp;
128 while ((c = *p++))
129 *q++ = c;
130 *q++ = ' ';
131 a = 1;
132 }
133 q -= a;
134 *q = '\0';
135
136 if (!str[0])
137 syslinux_run_default();
138 else
139 syslinux_run_command(str);
140 }
141
main(int argc,char * argv[])142 int main(int argc, char *argv[])
143 {
144 char **args[2];
145 int arg = 0;
146
147 if (argc)
148 arg++;
149 args[0] = &argv[arg];
150 args[1] = NULL;
151 while (arg < argc) {
152 if (!strcmp(argv[arg], "--")) {
153 argv[arg] = NULL;
154 args[1] = &argv[arg + 1];
155 break;
156 }
157 arg++;
158 }
159 if (args[1] != NULL) {
160 boot_args(plop_INT13h_check()? args[0] : args[1]);
161 } else {
162 fprintf(stderr,
163 "Usage: ifplop.c32 [<plop_detected>] -- [<plop_not_detected>]\n"
164 "Example: ifplop.c32 menu.c32 another.cfg -- plpbt hiddenusb usb1=2\n");
165 }
166
167 return 0;
168 }
169