| 1 | /* $Id: kLdr.c 2830 2006-10-23 20:53:11Z bird $ */
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| 2 | /** @file
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| 3 | *
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| 4 | * kLdr - The Dynamic Loader.
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| 5 | *
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| 6 | * Copyright (c) 2006 knut st. osmundsen <bird@anduin.net>
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| 7 | *
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| 8 | *
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| 9 | * This file is part of kLdr.
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| 10 | *
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| 11 | * kLdr is free software; you can redistribute it and/or modify
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| 12 | * it under the terms of the GNU General Public License as published by
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| 13 | * the Free Software Foundation; either version 2 of the License, or
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| 14 | * (at your option) any later version.
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| 15 | *
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| 16 | * kLdr is distributed in the hope that it will be useful,
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| 17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 19 | * GNU General Public License for more details.
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| 20 | *
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| 21 | * You should have received a copy of the GNU General Public License
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| 22 | * along with kLdr; if not, write to the Free Software
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| 23 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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| 24 | *
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| 25 | */
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| 26 |
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| 27 | /** @pg pg_kLdr kLdr - The Dynamic Loader
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| 28 | *
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| 29 | * The purpose of kLdr is to provide a generic interface for querying
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| 30 | * information about and loading executable image modules.
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| 31 | *
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| 32 | * kLdr defines the term executable image to include all kinds of files that contains
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| 33 | * binary code that can be executed on a CPU - linker objects (OBJs/Os), shared
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| 34 | * objects (SOs), dynamic link libraries (DLLs), executables (EXEs), and all kinds
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| 35 | * of kernel modules / device drivers (SYSs).
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| 36 | *
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| 37 | * kLdr provides two types of services:
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| 38 | * -# Inspect or/and load individual modules (kLdrMod).
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| 39 | * -# Work as a dynamic loader - construct and maintain an address space (kLdrDy).
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| 40 | *
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| 41 | * The kLdrMod API works on KLDRMOD structures where all the internals are exposed, while
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| 42 | * the kLdrDy API works opque KLDRDY structures. KLDRDY are in reality simple wrappers
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| 43 | * around KLDRMOD with some extra linking and attributes.
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| 44 | *
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| 45 | */
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| 46 |
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| 47 |
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| 48 | #include "kLdr.h"
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| 49 | #include "kLdrHlp.h"
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| 50 |
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| 51 |
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| 52 | /*******************************************************************************
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| 53 | * Header Files *
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| 54 | *******************************************************************************/
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| 55 | /** Flag indicating whether we've initialized the loader or not.
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| 56 | *
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| 57 | * 0 if not initialized.
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| 58 | * -1 if we're initializing or terminating.
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| 59 | * 1 if we've successfully initialized it.
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| 60 | * -2 if initialization failed.
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| 61 | */
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| 62 | static int volatile g_fInitialized;
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| 63 |
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| 64 |
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| 65 |
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| 66 | /**
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| 67 | * Initializes the loader.
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| 68 | * @returns 0 on success, non-zero OS status code on failure.
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| 69 | */
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| 70 | int kldrInit(void)
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| 71 | {
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| 72 | int rc;
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| 73 |
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| 74 | /* check we're already good. */
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| 75 | if (g_fInitialized == 1)
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| 76 | return 0;
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| 77 |
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| 78 | /* a tiny serialization effort. */
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| 79 | for (;;)
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| 80 | {
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| 81 | if (g_fInitialized == 1)
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| 82 | return 0;
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| 83 | if (g_fInitialized == -2)
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| 84 | return -1;
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| 85 | /** @todo atomic test and set if we care. */
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| 86 | if (g_fInitialized == 0)
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| 87 | {
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| 88 | g_fInitialized = -1;
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| 89 | break;
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| 90 | }
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| 91 | kldrHlpSleep(1);
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| 92 | }
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| 93 |
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| 94 | /*
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| 95 | * Do the initialization.
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| 96 | */
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| 97 | rc = kldrHlpHeapInit();
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| 98 | if (!rc)
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| 99 | {
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| 100 | rc = kldrHlpSemInit();
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| 101 | if (!rc)
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| 102 | {
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| 103 | g_fInitialized = 1;
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| 104 | return 0;
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| 105 | }
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| 106 | kldrHlpHeapTerm();
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| 107 | }
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| 108 | g_fInitialized = -2;
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| 109 | return rc;
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| 110 | }
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| 111 |
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| 112 |
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| 113 | /**
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| 114 | * Terminates the loader.
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| 115 | */
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| 116 | void kldrTerm(void)
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| 117 | {
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| 118 | /* can't terminate unless it's initialized. */
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| 119 | if (g_fInitialized != 1)
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| 120 | return;
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| 121 | g_fInitialized = -1;
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| 122 |
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| 123 | /*
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| 124 | * Do the termination.
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| 125 | */
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| 126 | kldrHlpSemTerm();
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| 127 | kldrHlpHeapTerm();
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| 128 |
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| 129 | /* done */
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| 130 | g_fInitialized = 0;
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| 131 | }
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| 132 |
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