applied sanders patch of my config - suckless/dwm - Unnamed repository; edit this file 'description' to name the repository.

diff options

author	Anselm R. Garbe <arg@suckless.org>	2007-01-16 11:12:34 +0100
committer	Anselm R. Garbe <arg@suckless.org>	2007-01-16 11:12:34 +0100
commit	3059c9c5070d225c1f6692ed127ed61ea4c9607b (patch)
tree	ffad0326c57c2568cb7a4f4cebd3f2f30265378c /util.c
parent	3b18f17d4d4f2d7502f52346cbd158b7120fd835 (diff)
download	dwm-3059c9c5070d225c1f6692ed127ed61ea4c9607b.tar.gz

applied sanders patch of my config

Diffstat (limited to 'util.c')

0 files changed, 0 insertions, 0 deletions

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Mu - 028translate.cc</title> <meta name="Generator" content="Vim/8.1"> <meta name="plugin-version" content="vim8.1_v1"> <meta name="syntax" content="cpp"> <meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy="> <meta name="colorscheme" content="minimal-light"> <style type="text/css">  </style> <script type='text/javascript'>  </script> </head> <body onload='JumpToLine();'> <a href='https://github.com/akkartik/mu/blob/master/028translate.cc'>https://github.com/akkartik/mu/blob/master/028translate.cc</a> <pre id='vimCodeElement'> 1 //: The bedrock level 1 of abstraction is now done, and we're going to start 2 //: building levels above it that make programming in x86 machine code a 3 //: little more ergonomic. 4 //: 5 //: All levels will be "pass through by default". Whatever they don't 6 //: understand they will silently pass through to lower levels. 7 //: 8 //: Since raw hex bytes of machine code are always possible to inject, SubX is 9 //: not a language, and we aren't building a compiler. This is something 10 //: deliberately leakier. Levels are more for improving auditing, checks and 11 //: error messages rather than for hiding low-level details. 12 13 //: Translator workflow: read 'source' file. Run a series of transforms on it, 14 //: each passing through what it doesn't understand. The final program should 15 //: be just machine code, suitable to write to an ELF binary. 16 //: 17 //: Higher levels usually transform code on the basis of metadata. 18 19 :(before "End Main") 20 if (<a href='001help.cc.html#L96'>is_equal</a>(argv[1], "translate")) { 21 // Outside of tests, traces must be explicitly requested. 22 if (<a href='003trace.cc.html#L446'>Trace_file</a>.is_open()) <a href='003trace.cc.html#L72'>Trace_stream</a> = new trace_stream; 23 <a href='000organization.cc.html#L148'>reset</a>(); 24 // Begin subx translate 25 program p; 26 string output_filename; 27 for (int i = /*skip 'subx translate'*/2; i < argc; ++i) { 28 if (<a href='001help.cc.html#L96'>is_equal</a>(argv[i], "-o")) { 29 ++i; 30 if (i >= argc) { 31 <a href='028translate.cc.html#L72'>print_translate_usage</a>(); 32 cerr << "'-o' must be followed by a filename to write results to\n"; 33 exit(1); 34 } 35 output_filename = argv[i]; 36 } 37 else { 38 <a href='003trace.cc.html#L96'>trace</a>(2, "parse") << argv[i] << end(); 39 ifstream fin(argv[i]); 40 if (!fin) { 41 cerr << "could not open " << argv[i] << '\n'; 42 return 1; 43 } 44 parse(fin, p); 45 if (<a href='003trace.cc.html#L262'>trace_contains_errors</a>()) return 1; 46 } 47 } 48 if (p.<a href='011run.cc.html#L107'>segments</a>.empty()) { 49 <a href='028translate.cc.html#L72'>print_translate_usage</a>(); 50 cerr << "nothing to do; must provide at least one file to read\n"; 51 exit(1); 52 } 53 if (output_filename.empty()) { 54 <a href='028translate.cc.html#L72'>print_translate_usage</a>(); 55 cerr << "must provide a filename to write to using '-o'\n"; 56 exit(1); 57 } 58 <a href='003trace.cc.html#L96'>trace</a>(2, "transform") << "begin" << end(); 59 transform(p); 60 if (<a href='003trace.cc.html#L262'>trace_contains_errors</a>()) return 1; 61 <a href='003trace.cc.html#L96'>trace</a>(2, "translate") << "begin" << end(); 62 save_elf(p, output_filename); 63 if (<a href='003trace.cc.html#L262'>trace_contains_errors</a>()) { 64 unlink(output_filename.c_str()); 65 return 1; 66 } 67 // End subx translate 68 return 0; 69 } 70 71 :(code) 72 void <a href='028translate.cc.html#L72'>print_translate_usage</a>() { 73 cerr << "Usage: subx translate file1 file2 ... -o output\n"; 74 } 75 76 // write out a program to a bare-bones ELF file 77 void save_elf(const program& p, const string& filename) { 78 ofstream out(filename.c_str(), ios::binary); 79 save_elf(p, out); 80 out.close(); 81 } 82 83 void save_elf(const program& p, ostream& out) { 84 // validation: stay consistent with the self-hosted translator 85 if (p.<a href='011run.cc.html#L106'>entry</a> == 0) { 86 <a href='003trace.cc.html#L226'>raise</a> << "no 'Entry' label found\n" << end(); 87 return; 88 } 89 if (find(p, "data") == NULL) { 90 <a href='003trace.cc.html#L226'>raise</a> << "must include a 'data' segment\n" << end(); 91 return; 92 } 93 // processing 94 <a href='028translate.cc.html#L99'>write_elf_header</a>(out, p); 95 for (size_t i = 0; i < p.<a href='011run.cc.html#L107'>segments</a>.size(); ++i) 96 <a href='028translate.cc.html#L195'>write_segment</a>(p.<a href='011run.cc.html#L107'>segments</a>.at(i), out); 97 } 98 99 void <a href='028translate.cc.html#L99'>write_elf_header</a>(ostream& out, const program& p) { 100 char c = '\0'; 101 #define O(X) c = (X); out.write(&c, sizeof(c)) 102 // host is required to be little-endian 103 #define emit(X) out.write(reinterpret_cast<const char*>(&X), sizeof(X)) 104 //// ehdr 105 // e_ident 106 O(0x7f); O(/*E*/0x45); O(/*L*/0x4c); O(/*F*/0x46); 107 O(0x1); // 32-bit format 108 O(0x1); // little-endian 109 O(0x1); O(0x0); 110 for (size_t i = 0; i < 8; ++i) { O(0x0); } 111 // e_type 112 O(0x02); O(0x00); 113 // e_machine 114 O(0x03); O(0x00); 115 // e_version 116 O(0x01); O(0x00); O(0x00); O(0x00); 117 // e_entry 118 uint32_t e_entry = p.<a href='011run.cc.html#L106'>entry</a>; 119 // Override e_entry 120 emit(e_entry); 121 // e_phoff -- immediately after ELF header 122 uint32_t e_phoff = 0x34; 123 emit(e_phoff); 124 // e_shoff; unused 125 uint32_t dummy32 = 0; 126 emit(dummy32); 127 // e_flags; unused 128 emit(dummy32); 129 // e_ehsize 130 uint16_t e_ehsize = 0x34; 131 emit(e_ehsize); 132 // e_phentsize 133 uint16_t e_phentsize = 0x20; 134 emit(e_phentsize); 135 // e_phnum 136 uint16_t e_phnum = <a href='001help.cc.html#L164'>SIZE</a>(p.<a href='011run.cc.html#L107'>segments</a>); 137 emit(e_phnum); 138 // e_shentsize 139 uint16_t dummy16 = 0x0; 140 emit(dummy16); 141 // e_shnum 142 emit(dummy16); 143 // e_shstrndx 144 emit(dummy16); 145 146 uint32_t p_offset = /*size of ehdr*/0x34 + <a href='001help.cc.html#L164'>SIZE</a>(p.<a href='011run.cc.html#L107'>segments</a>)*0x20/*size of each phdr*/; 147 for (int i = 0; i < <a href='001help.cc.html#L164'>SIZE</a>(p.<a href='011run.cc.html#L107'>segments</a>); ++i) { 148 const segment& curr = p.<a href='011run.cc.html#L107'>segments</a>.at(i); 149 //// phdr 150 // p_type 151 uint32_t p_type = 0x1; 152 emit(p_type); 153 // p_offset 154 emit(p_offset); 155 // p_vaddr 156 uint32_t p_start = curr.start; 157 emit(p_start); 158 // p_paddr 159 emit(p_start); 160 // p_filesz 161 uint32_t size = <a href='028translate.cc.html#L205'>num_words</a>(curr); 162 assert(p_offset + size < <a href='010---vm.cc.html#L95'>SEGMENT_ALIGNMENT</a>); 163 emit(size); 164 // p_memsz 165 emit(size); 166 // p_flags 167 uint32_t p_flags = (curr.<a href='011run.cc.html#L112'>name</a> == "code") ? /*r-x*/0x5 : /*rw-*/0x6; 168 emit(p_flags); 169 170 // p_align 171 // "As the system creates or augments a process image, it logically copies 172 // a file's segment to a virtual memory segment. When—and if— the system 173 // physically reads the file depends on the program's execution behavior, 174 // system load, and so on. A process does not require a physical page 175 // unless it references the logical page during execution, and processes 176 // commonly leave many pages unreferenced. Therefore delaying physical 177 // reads frequently obviates them, improving system performance. To obtain 178 // this efficiency in practice, executable and shared object files must 179 // have segment images whose file offsets and virtual addresses are 180 // congruent, modulo the page size." -- <a href="http://refspecs.linuxbase.org/elf/elf.pdf">http://refspecs.linuxbase.org/elf/elf.pdf</a> (page 95) 181 uint32_t p_align = 0x1000; // default page size on linux 182 emit(p_align); 183 if (p_offset % p_align != p_start % p_align) { 184 <a href='003trace.cc.html#L226'>raise</a> << "segment starting at 0x" << <a href='010---vm.cc.html#L401'>HEXWORD</a> << p_start << " is improperly aligned; alignment for p_offset " << p_offset << " should be " << (p_offset % p_align) << " but is " << (p_start % p_align) << '\n' << end(); 185 return; 186 } 187 188 // prepare for next segment 189 p_offset += size; 190 } 191 #undef O 192 #undef emit 193 } 194 195 void <a href='028translate.cc.html#L195'>write_segment</a>(const segment& s, ostream& out) { 196 for (int i = 0; i < <a href='001help.cc.html#L164'>SIZE</a>(s.<a href='011run.cc.html#L114'>lines</a>); ++i) { 197 const vector<word>& w = s.<a href='011run.cc.html#L114'>lines</a>.at(i).<a href='011run.cc.html#L123'>words</a>; 198 for (int j = 0; j < <a href='001help.cc.html#L164'>SIZE</a>(w); ++j) { 199 uint8_t x = <a href='011run.cc.html#L302'>hex_byte</a>(w.at(j).data); // we're done with metadata by this point 200 out.write(reinterpret_cast<const char*>(&x), /*sizeof(byte)*/1); 201 } 202 } 203 } 204 205 uint32_t <a href='028translate.cc.html#L205'>num_words</a>(const segment& s) { 206 uint32_t sum = 0; 207 for (int i = 0; i < <a href='001help.cc.html#L164'>SIZE</a>(s.<a href='011run.cc.html#L114'>lines</a>); ++i) 208 sum += <a href='001help.cc.html#L164'>SIZE</a>(s.<a href='011run.cc.html#L114'>lines</a>.at(i).<a href='011run.cc.html#L123'>words</a>); 209 return sum; 210 } 211 212 :(before "End Includes") 213 using std::ios; </pre> </body> </html>


context:
space:
mode: