diff options
Diffstat (limited to 'html/001help.cc.html')
| -rw-r--r-- | html/001help.cc.html | 85 |
1 files changed, 75 insertions, 10 deletions
diff --git a/html/001help.cc.html b/html/001help.cc.html index c25cbf2f..d6b21301 100644 --- a/html/001help.cc.html +++ b/html/001help.cc.html @@ -21,6 +21,7 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color .Identifier { color: #fcb165; } .Normal { color: #eeeeee; background-color: #080808; padding-bottom: 1px; } .PreProc { color: #800080; } +.CommentedCode { color: #6c6c6c; } --> </style> @@ -129,10 +130,71 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color <span class="Comment">//: up in than integer overflow.</span> <span class="Delimiter">:(before "End Includes")</span> <span class="PreProc">#define SIZE(X) (assert((X)</span><span class="Delimiter">.</span><span class="PreProc">size() < (</span><span class="Constant">1LL</span><span class="PreProc"><<(</span><span class="Normal">sizeof</span><span class="PreProc">(</span><span class="Normal">int</span><span class="PreProc">)*</span><span class="Constant">8</span><span class="PreProc">-</span><span class="Constant">2</span><span class="PreProc">)))</span><span class="Delimiter">,</span><span class="PreProc"> </span><span class="Normal">static_cast</span><span class="PreProc"><</span><span class="Normal">int</span><span class="PreProc">>((X)</span><span class="Delimiter">.</span><span class="PreProc">size()))</span> -<span class="Comment">//:</span> -<span class="Comment">//: 5. Integer overflow is still impossible to guard against. Maybe after</span> -<span class="Comment">//: reading <a href="http://www.cs.utah.edu/~regehr/papers/overflow12.pdf">http://www.cs.utah.edu/~regehr/papers/overflow12.pdf</a></span> -<span class="Comment">//:</span> + +<span class="Comment">//: 5. Integer overflow is guarded against at runtime using the -ftrapv flag</span> +<span class="Comment">//: to the compiler, supported by Clang (GCC version only works sometimes:</span> +<span class="Comment">//: <a href="http://stackoverflow.com/questions/20851061/how-to-make-gcc-ftrapv-work).">http://stackoverflow.com/questions/20851061/how-to-make-gcc-ftrapv-work).</a></span> +<span class="Delimiter">:(before "atexit(teardown)")</span> +initialize_signal_handlers<span class="Delimiter">();</span> <span class="Comment">// not always necessary, but doesn't hurt</span> +<span class="CommentedCode">//? cerr << INT_MAX+1 << '\n'; // test overflow</span> +<span class="CommentedCode">//? assert(false); // test SIGABRT</span> +<span class="Delimiter">:(code)</span> +<span class="Comment">// based on <a href="https://spin.atomicobject.com/2013/01/13/exceptions-stack-traces-c">https://spin.atomicobject.com/2013/01/13/exceptions-stack-traces-c</a></span> +<span class="Normal">void</span> initialize_signal_handlers<span class="Delimiter">()</span> <span class="Delimiter">{</span> + <span class="Normal">struct</span> sigaction action<span class="Delimiter">;</span> + bzero<span class="Delimiter">(</span>&action<span class="Delimiter">,</span> <span class="Normal">sizeof</span><span class="Delimiter">(</span>action<span class="Delimiter">));</span> + action<span class="Delimiter">.</span>sa_sigaction = dump_and_exit<span class="Delimiter">;</span> + sigemptyset<span class="Delimiter">(</span>&action<span class="Delimiter">.</span>sa_mask<span class="Delimiter">);</span> + sigaction<span class="Delimiter">(</span><span class="Constant">SIGABRT</span><span class="Delimiter">,</span> &action<span class="Delimiter">,</span> <span class="Constant">NULL</span><span class="Delimiter">);</span> <span class="Comment">// assert() failure or integer overflow on linux (with -ftrapv)</span> + sigaction<span class="Delimiter">(</span><span class="Constant">SIGILL</span><span class="Delimiter">,</span> &action<span class="Delimiter">,</span> <span class="Constant">NULL</span><span class="Delimiter">);</span> <span class="Comment">// integer overflow on OS X (with -ftrapv)</span> +<span class="Delimiter">}</span> +<span class="Normal">void</span> dump_and_exit<span class="Delimiter">(</span><span class="Normal">int</span> sig<span class="Delimiter">,</span> unused siginfo_t* dummy1<span class="Delimiter">,</span> unused <span class="Normal">void</span>* dummy2<span class="Delimiter">)</span> <span class="Delimiter">{</span> + <span class="Normal">switch</span> <span class="Delimiter">(</span>sig<span class="Delimiter">)</span> <span class="Delimiter">{</span> + <span class="Normal">case</span> <span class="Constant">SIGABRT</span>: +<span class="PreProc"> #ifndef __APPLE__</span> + cerr << <span class="Constant">"SIGABRT: might be an integer overflow if it wasn't an assert() failure</span><span class="cSpecial">\n</span><span class="Constant">"</span><span class="Delimiter">;</span> + _Exit<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span> +<span class="PreProc"> #endif</span> + <span class="Identifier">break</span><span class="Delimiter">;</span> + <span class="Normal">case</span> <span class="Constant">SIGILL</span>: +<span class="PreProc"> #ifdef __APPLE__</span> + cerr << <span class="Constant">"SIGILL: most likely caused by integer overflow</span><span class="cSpecial">\n</span><span class="Constant">"</span><span class="Delimiter">;</span> + _Exit<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span> +<span class="PreProc"> #endif</span> + <span class="Identifier">break</span><span class="Delimiter">;</span> + <span class="Normal">default</span>: + <span class="Identifier">break</span><span class="Delimiter">;</span> + <span class="Delimiter">}</span> +<span class="Delimiter">}</span> +<span class="Delimiter">:(before "End Includes")</span> +<span class="PreProc">#include </span><span class="Constant"><signal.h></span> + +<span class="Comment">//: For good measure we'll also enable SIGFPE.</span> +<span class="Delimiter">:(before "atexit(teardown)")</span> +feenableexcept<span class="Delimiter">(</span>FE_OVERFLOW | FE_UNDERFLOW<span class="Delimiter">);</span> +<span class="CommentedCode">//? assert(sizeof(int) == 4 && sizeof(float) == 4);</span> +<span class="CommentedCode">//? // | exp | mantissa</span> +<span class="CommentedCode">//? int smallest_subnormal = 0b00000000000000000000000000000001;</span> +<span class="CommentedCode">//? float smallest_subnormal_f = *reinterpret_cast<int*>(&smallest_subnormal);</span> +<span class="CommentedCode">//? cerr << "ε/2: " << smallest_subnormal_f/2 << " (underflow)\n"; // test SIGFPE</span> +<span class="Delimiter">:(before "End Includes")</span> +<span class="PreProc">#include </span><span class="Constant"><fenv.h></span> +<span class="Delimiter">:(code)</span> +<span class="PreProc">#ifdef __APPLE__</span> +<span class="Comment">// Public domain polyfill for feenableexcept on OS X</span> +<span class="Comment">// <a href="http://www-personal.umich.edu/~williams/archive/computation/fe-handling-example.c">http://www-personal.umich.edu/~williams/archive/computation/fe-handling-example.c</a></span> +<span class="Normal">inline</span> <span class="Normal">int</span> feenableexcept <span class="Delimiter">(</span><span class="Normal">unsigned</span> <span class="Normal">int</span> excepts<span class="Delimiter">)</span> <span class="Delimiter">{</span> + <span class="Normal">static</span> fenv_t fenv<span class="Delimiter">;</span> + <span class="Normal">unsigned</span> <span class="Normal">int</span> new_excepts = excepts & FE_ALL_EXCEPT<span class="Delimiter">;</span> + <span class="Normal">unsigned</span> <span class="Normal">int</span> old_excepts<span class="Delimiter">;</span> + <span class="Normal">if</span> <span class="Delimiter">(</span>fegetenv<span class="Delimiter">(</span>&fenv<span class="Delimiter">))</span> <span class="Identifier">return</span> -<span class="Constant">1</span><span class="Delimiter">;</span> + old_excepts = fenv<span class="Delimiter">.</span>__control & FE_ALL_EXCEPT<span class="Delimiter">;</span> + fenv<span class="Delimiter">.</span>__control &= ~new_excepts<span class="Delimiter">;</span> + fenv<span class="Delimiter">.</span>__mxcsr &= ~<span class="Delimiter">(</span>new_excepts << <span class="Constant">7</span><span class="Delimiter">);</span> + <span class="Identifier">return</span> fesetenv<span class="Delimiter">(</span>&fenv<span class="Delimiter">)</span> ? -<span class="Constant">1</span> : old_excepts<span class="Delimiter">;</span> +<span class="Delimiter">}</span> +<span class="PreProc">#endif</span> + <span class="Comment">//: 6. Map's operator[] being non-const is fucking evil.</span> <span class="Delimiter">:(before "Globals")</span> <span class="Comment">// can't generate prototypes for these</span> <span class="Comment">// from <a href="http://stackoverflow.com/questions/152643/idiomatic-c-for-reading-from-a-const-map">http://stackoverflow.com/questions/152643/idiomatic-c-for-reading-from-a-const-map</a></span> @@ -158,29 +220,32 @@ body { font-size: 12pt; font-family: monospace; color: #eeeeee; background-color <span class="Delimiter">}</span> <span class="Comment">//: The contract: any container that relies on get_or_insert should never call</span> <span class="Comment">//: contains_key.</span> -<span class="Comment">//:</span> + <span class="Comment">//: 7. istreams are a royal pain in the arse. You have to be careful about</span> <span class="Comment">//: what subclass you try to putback into. You have to watch out for the pesky</span> <span class="Comment">//: failbit and badbit. Just avoid eof() and use this helper instead.</span> +<span class="Delimiter">:(code)</span> <span class="Normal">bool</span> has_data<span class="Delimiter">(</span>istream& in<span class="Delimiter">)</span> <span class="Delimiter">{</span> <span class="Identifier">return</span> in && !in<span class="Delimiter">.</span>eof<span class="Delimiter">();</span> <span class="Delimiter">}</span> <span class="Delimiter">:(before "End Includes")</span> -<span class="PreProc">#include</span><span class="Constant"><assert.h></span> +<span class="PreProc">#include </span><span class="Constant"><assert.h></span> -<span class="PreProc">#include</span><span class="Constant"><iostream></span> +<span class="PreProc">#include </span><span class="Constant"><iostream></span> <span class="Normal">using</span> std::istream<span class="Delimiter">;</span> <span class="Normal">using</span> std::ostream<span class="Delimiter">;</span> <span class="Normal">using</span> std::iostream<span class="Delimiter">;</span> <span class="Normal">using</span> std::cin<span class="Delimiter">;</span> <span class="Normal">using</span> std::cout<span class="Delimiter">;</span> <span class="Normal">using</span> std::cerr<span class="Delimiter">;</span> -<span class="PreProc">#include</span><span class="Constant"><iomanip></span> +<span class="PreProc">#include </span><span class="Constant"><iomanip></span> -<span class="PreProc">#include</span><span class="Constant"><cstring></span> -<span class="PreProc">#include</span><span class="Constant"><string></span> +<span class="PreProc">#include </span><span class="Constant"><cstring></span> +<span class="PreProc">#include </span><span class="Constant"><string></span> <span class="Normal">using</span> std::string<span class="Delimiter">;</span> + +<span class="PreProc">#define unused __attribute__((unused))</span> </pre> </body> </html> |