package main
import "os"
// getEnv will check if the the key exists, if it does then it'll
// return the value otherwise it will return fallback string.
func getEnv(key, fallback string) string {
// We use os.LookupEnv instead of using os.GetEnv and checking
// if the length equals 0 because environment variable can be
// set and be of length 0. User could've set key="" which
// means the variable was set but the length is 0. There is no
// reason why user would want to do this over here though.
value, exists := os.LookupEnv(key)
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<a href='https://github.com/akkartik/mu/blob/master/306files.subx'>https://github.com/akkartik/mu/blob/master/306files.subx</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># Methods for constructing buffered-file objects.</span>
<span id="L2" class="LineNr"> 2 </span><span class="subxComment">#</span>
<span id="L3" class="LineNr"> 3 </span><span class="subxComment"># TODO: There are hard-coded parameters here for buffer sizes. When they</span>
<span id="L4" class="LineNr"> 4 </span><span class="subxComment"># overflow, tracking down what's going on can get hairy.</span>
<span id="L5" class="LineNr"> 5 </span><span class="subxComment">#</span>
<span id="L6" class="LineNr"> 6 </span><span class="subxComment"># HACK: buffered-file stores naked addrs. This is safe because buffered-file</span>
<span id="L7" class="LineNr"> 7 </span><span class="subxComment"># objects are opaque. But still sub-optimal; they'll be harder to reclaim when</span>
<span id="L8" class="LineNr"> 8 </span><span class="subxComment"># we get around to that.</span>
<span id="L9" class="LineNr"> 9 </span>
<span id="L10" class="LineNr"> 10 </span>== code
<span id="L11" class="LineNr"> 11 </span>
<span id="L12" class="LineNr"> 12 </span><span class="subxFunction">open</span>: <span class="subxComment"># filename: (addr array byte), write?: boolean, out: (addr handle buffered-file)</span>
<span id="L13" class="LineNr"> 13 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L14" class="LineNr"> 14 </span> 55/push-ebp
<span id="L15" class="LineNr"> 15 </span> 89/<- %ebp 4/r32/esp
<span id="L16" class="LineNr"> 16 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L17" class="LineNr"> 17 </span> 50/push-eax
<span id="L18" class="LineNr"> 18 </span> 51/push-ecx
<span id="L19" class="LineNr"> 19 </span> <span class="subxComment"># var new-fd/ecx: fd</span>
<span id="L20" class="LineNr"> 20 </span> (<a href='306files.subx.html#L43'>open-fd</a> *(ebp+8) *(ebp+0xc)) <span class="subxComment"># => eax</span>
<span id="L21" class="LineNr"> 21 </span> 89/<- %ecx 0/r32/eax
<span id="L22" class="LineNr"> 22 </span> <span class="subxComment"># if fd < 0 return</span>
<span id="L23" class="LineNr"> 23 </span> 3d/compare-eax-with 0/imm32
<span id="L24" class="LineNr"> 24 </span> 7c/jump-if-< $open:end/disp8
<span id="L25" class="LineNr"> 25 </span> <span class="subxComment"># allocate a buffered-file</span>
<span id="L26" class="LineNr"> 26 </span> (<a href='120allocate.subx.html#L66'>allocate</a> <span class="SpecialChar"><a href='120allocate.subx.html#L27'>Heap</a></span> 0x1010 *(ebp+0x10)) <span class="subxComment"># file-buffer-size + 16 for other fields</span>
<span id="L27" class="LineNr"> 27 </span> <span class="subxComment"># var out-addr/eax: (addr buffered-file)</span>
<span id="L28" class="LineNr"> 28 </span> 8b/-> *(ebp+0x10) 0/r32/eax
<span id="L29" class="LineNr"> 29 </span> (<a href='120allocate.subx.html#L256'>lookup</a> *eax *(eax+4)) <span class="subxComment"># => eax</span>
<span id="L30" class="LineNr"> 30 </span> <span class="subxComment"># out-addr->size = 4KB</span>
<span id="L31" class="LineNr"> 31 </span> c7 0/subop/copy *(eax+0xc) 0x1000/imm32/file-buffer-size <span class="subxComment"># Stream-size + 4 for fd</span>
<span id="L32" class="LineNr"> 32 </span> <span class="subxComment"># out-addr->fd = fd</span>
<span id="L33" class="LineNr"> 33 </span> 89/<- *eax 1/r32/ecx
<span id="L34" class="LineNr"> 34 </span><span class="Constant">$open:end</span>:
<span id="L35" class="LineNr"> 35 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L36" class="LineNr"> 36 </span> 59/pop-to-ecx
<span id="L37" class="LineNr"> 37 </span> 58/pop-to-eax
<span id="L38" class="LineNr"> 38 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L39" class="LineNr"> 39 </span> 89/<- %esp 5/r32/ebp
<span id="L40" class="LineNr"> 40 </span> 5d/pop-to-ebp
<span id="L41" class="LineNr"> 41 </span> c3/return
<span id="L42" class="LineNr"> 42 </span>
<span id="L43" class="LineNr"> 43 </span><span class="subxFunction">open-fd</span>: <span class="subxComment"># filename: (addr array byte), write?: boolean -> result/eax: fd</span>
<span id="L44" class="LineNr"> 44 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L45" class="LineNr"> 45 </span> 55/push-ebp
<span id="L46" class="LineNr"> 46 </span> 89/<- %ebp 4/r32/esp
<span id="L47" class="LineNr"> 47 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L48" class="LineNr"> 48 </span> 51/push-ecx
<span id="L49" class="LineNr"> 49 </span> 52/push-edx
<span id="L50" class="LineNr"> 50 </span> 53/push-ebx
<span id="L51" class="LineNr"> 51 </span> 56/push-esi
<span id="L52" class="LineNr"> 52 </span> <span class="subxComment"># ecx = filename</span>
<span id="L53" class="LineNr"> 53 </span> 8b/-> *(ebp+8) 1/r32/ecx
<span id="L54" class="LineNr"> 54 </span> <span class="subxComment"># var size/edx: int = filename->length + 1 for the trailing null character</span>
<span id="L55" class="LineNr"> 55 </span> 8b/-> *ecx 2/r32/edx
<span id="L56" class="LineNr"> 56 </span> 42/increment-edx
<span id="L57" class="LineNr"> 57 </span> <span class="subxComment"># var s/esi: (stream size)</span>
<span id="L58" class="LineNr"> 58 </span> 29/subtract-from %esp 2/r32/edx
<span id="L59" class="LineNr"> 59 </span> 52/push-edx <span class="subxComment"># size</span>
<span id="L60" class="LineNr"> 60 </span> 68/push 0/imm32/read
<span id="L61" class="LineNr"> 61 </span> 68/push 0/imm32/write
<span id="L62" class="LineNr"> 62 </span> 89/<- %esi 4/r32/esp
<span id="L63" class="LineNr"> 63 </span> <span class="subxComment"># copy filename and a final null character</span>
<span id="L64" class="LineNr"> 64 </span> (<a href='106stream.subx.html#L17'>clear-stream</a> %esi)
<span id="L65" class="LineNr"> 65 </span> (<a href='108write.subx.html#L24'>write</a> %esi %ecx)
<span id="L66" class="LineNr"> 66 </span> <span class="subxComment"># spill edx</span>
<span id="L67" class="LineNr"> 67 </span> 52/push-edx
<span id="L68" class="LineNr"> 68 </span> <span class="subxComment"># var fd/eax: fd = open(filename)</span>
<span id="L69" class="LineNr"> 69 </span> 8d/copy-address *(esi+0xc) 3/r32/ebx
<span id="L70" class="LineNr"> 70 </span> 8b/-> *(ebp+0xc) 1/r32/ecx/flags
<span id="L71" class="LineNr"> 71 </span> ba/copy-to-edx 0x180/imm32/permissions
<span id="L72" class="LineNr"> 72 </span> e8/call syscall_open/disp32
<span id="L73" class="LineNr"> 73 </span> <span class="subxComment"># restore edx</span>
<span id="L74" class="LineNr"> 74 </span> 5a/pop-to-edx
<span id="L75" class="LineNr"> 75 </span><span class="Constant">$open-fd:end</span>:
<span id="L76" class="LineNr"> 76 </span> <span class="subxS1Comment"># . reclaim locals</span>
<span id="L77" class="LineNr"> 77 </span> 01/add-to %esp 2/r32/edx
<span id="L78" class="LineNr"> 78 </span> 81 0/subop/add %esp 0xc/imm32
<span id="L79" class="LineNr"> 79 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L80" class="LineNr"> 80 </span> 5e/pop-to-esi
<span id="L81" class="LineNr"> 81 </span> 5b/pop-to-ebx
<span id="L82" class="LineNr"> 82 </span> 5a/pop-to-edx
<span id="L83" class="LineNr"> 83 </span> 59/pop-to-ecx
<span id="L84" class="LineNr"> 84 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L85" class="LineNr"> 85 </span> 89/<- %esp 5/r32/ebp
<span id="L86" class="LineNr"> 86 </span> 5d/pop-to-ebp
<span id="L87" class="LineNr"> 87 </span> c3/return
<span id="L88" class="LineNr"> 88 </span>
<span id="L89" class="LineNr"> 89 </span><span class="subxFunction">populate-buffered-file-containing</span>: <span class="subxComment"># contents: (addr array byte), out: (addr handle buffered-file)</span>
<span id="L90" class="LineNr"> 90 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L91" class="LineNr"> 91 </span> 55/push-ebp
<span id="L92" class="LineNr"> 92 </span> 89/<- %ebp 4/r32/esp
<span id="L93" class="LineNr"> 93 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L94" class="LineNr"> 94 </span> 50/push-eax
<span id="L95" class="LineNr"> 95 </span> 51/push-ecx
<span id="L96" class="LineNr"> 96 </span> 56/push-esi
<span id="L97" class="LineNr"> 97 </span> 57/push-edi
<span id="L98" class="LineNr"> 98 </span> <span class="subxComment"># esi = contents</span>
<span id="L99" class="LineNr"> 99 </span> 8b/-> *(ebp+8) 6/r32/esi
<span id="L100" class="LineNr">100 </span> <span class="subxComment"># var n/ecx: int = len(contents)</span>
<span id="L101" class="LineNr">101 </span> 8b/-> *esi 1/r32/ecx
<span id="L102" class="LineNr">102 </span> <span class="subxComment"># var stream/edi: (handle stream byte)</span>
<span id="L103" class="LineNr">103 </span> 68/push 0/imm32
<span id="L104" class="LineNr">104 </span> 68/push 0/imm32
<span id="L105" class="LineNr">105 </span> 89/<- %edi 4/r32/esp
<span id="L106" class="LineNr">106 </span> <span class="subxComment"># allocate stream</span>
<span id="L107" class="LineNr">107 </span> (<a href='121new-stream.subx.html#L8'>new-stream</a> <span class="SpecialChar"><a href='120allocate.subx.html#L27'>Heap</a></span> %ecx 1 %edi)
<span id="L108" class="LineNr">108 </span> <span class="subxComment"># var stream-addr/edi: (addr stream byte) = lookup(stream)</span>
<span id="L109" class="LineNr">109 </span> (<a href='120allocate.subx.html#L256'>lookup</a> *edi *(edi+4)) <span class="subxComment"># => eax</span>
<span id="L110" class="LineNr">110 </span> 89/<- %edi 0/r32/eax
<span id="L111" class="LineNr">111 </span> <span class="subxComment"># write contents to stream</span>
<span id="L112" class="LineNr">112 </span> (<a href='108write.subx.html#L24'>write</a> %edi %esi)
<span id="L113" class="LineNr">113 </span> <span class="subxComment"># allocate buffered-file</span>
<span id="L114" class="LineNr">114 </span> (<a href='120allocate.subx.html#L66'>allocate</a> <span class="SpecialChar"><a href='120allocate.subx.html#L27'>Heap</a></span> 0x110 *(ebp+0xc))
<span id="L115" class="LineNr">115 </span> <span class="subxComment"># var out-addr/eax: (addr buffered-file)</span>
<span id="L116" class="LineNr">116 </span> 8b/-> *(ebp+0xc) 0/r32/eax
<span id="L117" class="LineNr">117 </span> (<a href='120allocate.subx.html#L256'>lookup</a> *eax *(eax+4)) <span class="subxComment"># => eax</span>
<span id="L118" class="LineNr">118 </span> <span class="subxComment"># out-addr->size = 256 bytes</span>
<span id="L119" class="LineNr">119 </span> c7 0/subop/copy *(eax+0xc) 0x100/imm32/file-buffer-size
<span id="L120" class="LineNr">120 </span> <span class="subxComment"># out-addr->fd = stream</span>
<span id="L121" class="LineNr">121 </span> 89/<- *eax 7/r32/edi
<span id="L122" class="LineNr">122 </span><span class="Constant">$populate-buffered-file-containing:end</span>:
<span id="L123" class="LineNr">123 </span> <span class="subxS1Comment"># . reclaim locals</span>
<span id="L124" class="LineNr">124 </span> 81 0/subop/add %esp 8/imm32
<span id="L125" class="LineNr">125 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L126" class="LineNr">126 </span> 5f/pop-to-edi
<span id="L127" class="LineNr">127 </span> 5e/pop-to-esi
<span id="L128" class="LineNr">128 </span> 59/pop-to-ecx
<span id="L129" class="LineNr">129 </span> 58/pop-to-eax
<span id="L130" class="LineNr">130 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L131" class="LineNr">131 </span> 89/<- %esp 5/r32/ebp
<span id="L132" class="LineNr">132 </span> 5d/pop-to-ebp
<span id="L133" class="LineNr">133 </span> c3/return
<span id="L134" class="LineNr">134 </span>
<span id="L135" class="LineNr">135 </span><span class="subxFunction">new-buffered-file</span>: <span class="subxComment"># out: (addr handle buffered-file)</span>
<span id="L136" class="LineNr">136 </span> <span class="subxS1Comment"># . prologue</span>
<span id="L137" class="LineNr">137 </span> 55/push-ebp
<span id="L138" class="LineNr">138 </span> 89/<- %ebp 4/r32/esp
<span id="L139" class="LineNr">139 </span> <span class="subxS1Comment"># . save registers</span>
<span id="L140" class="LineNr">140 </span> 50/push-eax
<span id="L141" class="LineNr">141 </span> 51/push-ecx
<span id="L142" class="LineNr">142 </span> <span class="subxComment"># var stream/ecx: (handle stream byte)</span>
<span id="L143" class="LineNr">143 </span> 68/push 0/imm32
<span id="L144" class="LineNr">144 </span> 68/push 0/imm32
<span id="L145" class="LineNr">145 </span> 89/<- %ecx 4/r32/esp
<span id="L146" class="LineNr">146 </span> <span class="subxComment"># allocate stream</span>
<span id="L147" class="LineNr">147 </span> (<a href='121new-stream.subx.html#L8'>new-stream</a> <span class="SpecialChar"><a href='120allocate.subx.html#L27'>Heap</a></span> 0x100 1 %ecx)
<span id="L148" class="LineNr">148 </span> <span class="subxComment"># var stream-addr/ecx: (addr stream byte) = lookup(stream)</span>
<span id="L149" class="LineNr">149 </span> (<a href='120allocate.subx.html#L256'>lookup</a> *ecx *(ecx+4)) <span class="subxComment"># => eax</span>
<span id="L150" class="LineNr">150 </span> 89/<- %ecx 0/r32/eax
<span id="L151" class="LineNr">151 </span> <span class="subxComment"># allocate buffered-file</span>
<span id="L152" class="LineNr">152 </span> (<a href='120allocate.subx.html#L66'>allocate</a> <span class="SpecialChar"><a href='120allocate.subx.html#L27'>Heap</a></span> 0x110 *(ebp+8))
<span id="L153" class="LineNr">153 </span> <span class="subxComment"># var out-addr/eax: (addr buffered-file)</span>
<span id="L154" class="LineNr">154 </span> 8b/-> *(ebp+8) 0/r32/eax
<span id="L155" class="LineNr">155 </span> (<a href='120allocate.subx.html#L256'>lookup</a> *eax *(eax+4)) <span class="subxComment"># => eax</span>
<span id="L156" class="LineNr">156 </span> <span class="subxComment"># out-addr->size = 256 bytes</span>
<span id="L157" class="LineNr">157 </span> c7 0/subop/copy *(eax+0xc) 0x100/imm32/file-buffer-size
<span id="L158" class="LineNr">158 </span> <span class="subxComment"># out-addr->fd = stream</span>
<span id="L159" class="LineNr">159 </span> 89/<- *eax 1/r32/ecx
<span id="L160" class="LineNr">160 </span><span class="Constant">$new-buffered-file:end</span>:
<span id="L161" class="LineNr">161 </span> <span class="subxS1Comment"># . reclaim locals</span>
<span id="L162" class="LineNr">162 </span> 81 0/subop/add %esp 8/imm32
<span id="L163" class="LineNr">163 </span> <span class="subxS1Comment"># . restore registers</span>
<span id="L164" class="LineNr">164 </span> 59/pop-to-ecx
<span id="L165" class="LineNr">165 </span> 58/pop-to-eax
<span id="L166" class="LineNr">166 </span> <span class="subxS1Comment"># . epilogue</span>
<span id="L167" class="LineNr">167 </span> 89/<- %esp 5/r32/ebp
<span id="L168" class="LineNr">168 </span> 5d/pop-to-ebp
<span id="L169" class="LineNr">169 </span> c3/return
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