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113 lines
5.7 KiB
HTML
113 lines
5.7 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="content-type"
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content="text/html; charset=ISO-8859-1">
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<title>Kernel Javascript Support</title>
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</head>
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<body>
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<h1>Kernel Javascript support</h1>
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<br>
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This document details the kernel javascript debugging extension
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recently added to the reactos kernel.<br>
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<h2>Enabling</h2>
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The extension is enabled when KDBG := 1 is set in <span
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style="font-family: monospace;">config</span> in the reactos source
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tree.<br>
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<br>
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kdb presents the usual prompt when ReactOS starts, but the '<span
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style="font-family: monospace;">js</span>' command initializes the
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javascript system and allows the user to start working with the system
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in javascript. A welcome banner is displayed when the system is
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ready, along with the prompt <span style="font-family: monospace;">kjs:></span>.<br>
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<h2>Using</h2>
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You may type as many lines in each input as needed. To cancel
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some input, just enter '.' as the only character on an input
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line. To exit from the javascript interpreter, enter '.' on the
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first input line. In order to determine when the user is finished
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typing, the kernel javascript system uses the harmless ';;'
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sequence. Entering ';;' anywhere in the input terminates input
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and evaluates the current input buffer. The buffer is emptied
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afterward. Any javascript error messages or output are printed
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before the next prompt is displayed. Note that the interpreter
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does not automatically print the evaluation results, so it's useful to
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wrap simple evaluations with write().<br>
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<br>
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<h2>Sample Session</h2>
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<pre>kdb:> js<br>JS Registry Init Complete. Welcome to ReactOS kernel scripting<br>Kernel Debugger Script Interface (JavaScript :-)<br>Terminate input with ;; and end scripting with .<br>kjs:> write(System.getmodule(1));; <br>hal.dll,3225501696 <br>kjs:> write(System.getmodule(1)[1].toString(16));; <br>c0414000<br>kjs:> write(ebp().toString(16));;<br>cee8bf84<br><br>kjs:> function dump_sec(base) {<br>..... base2 = peekw(base + 0x3c) + base;<br>..... sec_off = 0xf8;<br>..... for( i = 0; peekl(base2 + sec_off + (40 * i)); i++ ) {<br>..... base_sec = base2 + sec_off + (40 * i);<br>..... write("Section: " + System.mread(0,base_sec) + "\n");<br>..... write("RVA: " + peekl(base_sec + 12).toString(16) + "\n");<br>..... }<br>..... }<br>..... ;;<br>kjs:> dump_sec(0xc0000000);;<br>Section: .text<br>RVA: 1000<br>Section: init<br>RVA: e6000<br>Section: .data<br>RVA: f4000<br>Section: .edata<br>RVA: 10d000<br>Section: .idata<br>RVA: 115000<br>Section: .rsrc<br>RVA: 116000<br>Section: .bss<br>RVA: 118000<br>Section: .reloc<br>RVA: 15a000<br><br>kjs:> var key = "\\registry\\machine\\system\\currentcontrolset\\services\\ne20001\\parameters\\tcpip";;<br>kjs:> write(regread(key,"defaultgateway"));;<br>10.0.0.1<br></pre>
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<h2>Builtin and initialized functions</h2>
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These functions are available after a successful javascript
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initialization:<br>
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<br style="font-weight: bold;">
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<span style="font-weight: bold;">System.getmodule(n) => (string,int)
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array</span><br>
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<br>
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Returns the name and base address of the nth module in the kernel
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module list.<br>
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<br style="font-weight: bold;">
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<span style="font-weight: bold;">System.mread(s,address) =>
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integer/string</span><br>
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<br>
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System.mread reads a value from memory and returns it. s
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determines what type of read is performed, and address specifies the
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starting address of the operation.<br>
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<br>
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Valid values of s are:<br>
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<br>
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0 -- Read a null-terminated ascii string<br>
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1 -- Read a byte<br>
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2 -- Read a word<br>
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4 -- Read a dword<br style="font-weight: bold;">
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<br style="font-weight: bold;">
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<span style="font-weight: bold;">System.mwrite(s,address,value) =>
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bool</span><br>
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<br>
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System.mwrite writes a value to a memory address. The operand
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size depends on s, 1 for byte, 2 for word, 4 for dword.<br>
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<br>
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<span style="font-weight: bold;">System.print(...) => undefined</span><br>
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<br>
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Uses DbgPrint to print the specified output. In javascript, every
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value is printable, so feel free to give any value type to print.<br>
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Use C style escapes for tabs and newlines: \t and \n.<br>
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<br>
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<span style="font-weight: bold;">System.regs(int) => int</span><br>
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<br>
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System.regs read the specified word value from the TRAP_FRAME given to
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kdb when it was started. This is useful for locating the stack,
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along with various other queries. The machine registers are also
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provided as named functions by javascript, for example ebp() and eax().<br>
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<br>
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<span style="font-weight: bold;">System.regread(key,value) =>
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string/undefined</span><br>
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<br>
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System.regread reads a string value from the registry (as a member of
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the specified registry key). If the read is successful, the
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string value contained in it is returned. If the value cannot be
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read, then undefined is returned.<br>
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<br>
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This method is used by the registry initializer to read the
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initialization strings.<br>
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<br>
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<span style="font-weight: bold;">ebp(), eip(), esp() ... vm86_gs()
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=> int</span><br>
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<br>
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Every register provided by the system trap frame is available as a
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global function of the same name. This makes reading specific
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registers easy.<br>
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<br>
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<span style="font-weight: bold;">peek,peekw,peekl(int addr) => int</span><br>
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<br>
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Aliases for System.mread([1,2,4],addr)<br>
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<br>
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<span style="font-weight: bold;">poke,pokew,pokel(int addr, int value)
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=> int</span><br>
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<br>
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Aliases for System.mwrite([1,2,4],addr,value)<br>
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<br>
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<span style="font-weight: bold;">write(...) => undefined</span><br>
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<br>
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Alias for System.print<br>
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</body>
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</html>
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