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</pre><pre class="rust ">
<span class="comment">// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT</span>
<span class="comment">// file at the top-level directory of this distribution and at</span>
<span class="comment">// http://rust-lang.org/COPYRIGHT.</span>
<span class="comment">//</span>
<span class="comment">// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or</span>
<span class="comment">// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license</span>
<span class="comment">// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your</span>
<span class="comment">// option. This file may not be copied, modified, or distributed</span>
<span class="comment">// except according to those terms.</span>
<span class="attribute">#<span class="op">!</span>[<span class="ident">cfg_attr</span>(<span class="ident">test</span>, <span class="ident">allow</span>(<span class="ident">dead_code</span>))]</span>
<span class="kw">use</span> <span class="ident">libc</span>;
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">imp</span>::{<span class="ident">make_handler</span>, <span class="ident">drop_handler</span>};
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">imp</span>::<span class="ident">cleanup</span>;
<span class="kw">pub</span> <span class="kw">use</span> <span class="self">self</span>::<span class="ident">imp</span>::<span class="ident">init</span>;
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Handler</span> {
<span class="ident">_data</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">libc</span>::<span class="ident">c_void</span>
}
<span class="kw">impl</span> <span class="ident">Handler</span> {
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">new</span>() <span class="op">-></span> <span class="ident">Handler</span> {
<span class="ident">make_handler</span>()
}
}
<span class="kw">impl</span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Handler</span> {
<span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">unsafe</span> {
<span class="ident">drop_handler</span>(<span class="self">self</span>);
}
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"linux"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"macos"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"bitrig"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"dragonfly"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"freebsd"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"solaris"</span>,
<span class="ident">all</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"netbsd"</span>, <span class="ident">not</span>(<span class="ident">target_vendor</span> <span class="op">=</span> <span class="string">"rumprun"</span>)),
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"openbsd"</span>))]</span>
<span class="kw">mod</span> <span class="ident">imp</span> {
<span class="kw">use</span> <span class="kw">super</span>::<span class="ident">Handler</span>;
<span class="kw">use</span> <span class="ident">mem</span>;
<span class="kw">use</span> <span class="ident">ptr</span>;
<span class="kw">use</span> <span class="ident">libc</span>::{<span class="ident">sigaltstack</span>, <span class="ident">SIGSTKSZ</span>, <span class="ident">SS_DISABLE</span>};
<span class="kw">use</span> <span class="ident">libc</span>::{<span class="ident">sigaction</span>, <span class="ident">SIGBUS</span>, <span class="ident">SIG_DFL</span>,
<span class="ident">SA_SIGINFO</span>, <span class="ident">SA_ONSTACK</span>, <span class="ident">sighandler_t</span>};
<span class="kw">use</span> <span class="ident">libc</span>;
<span class="kw">use</span> <span class="ident">libc</span>::{<span class="ident">mmap</span>, <span class="ident">munmap</span>};
<span class="kw">use</span> <span class="ident">libc</span>::{<span class="ident">SIGSEGV</span>, <span class="ident">PROT_READ</span>, <span class="ident">PROT_WRITE</span>, <span class="ident">MAP_PRIVATE</span>, <span class="ident">MAP_ANON</span>};
<span class="kw">use</span> <span class="ident">libc</span>::<span class="ident">MAP_FAILED</span>;
<span class="kw">use</span> <span class="ident">sys_common</span>::<span class="ident">thread_info</span>;
<span class="comment">// This is initialized in init() and only read from after</span>
<span class="kw">static</span> <span class="kw-2">mut</span> <span class="ident">PAGE_SIZE</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="number">0</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"linux"</span>, <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"android"</span>))]</span>
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">siginfo_si_addr</span>(<span class="ident">info</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">libc</span>::<span class="ident">siginfo_t</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="attribute">#[<span class="ident">repr</span>(<span class="ident">C</span>)]</span>
<span class="kw">struct</span> <span class="ident">siginfo_t</span> {
<span class="ident">a</span>: [<span class="ident">libc</span>::<span class="ident">c_int</span>; <span class="number">3</span>], <span class="comment">// si_signo, si_errno, si_code</span>
<span class="ident">si_addr</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">libc</span>::<span class="ident">c_void</span>,
}
(<span class="kw-2">*</span>(<span class="ident">info</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">siginfo_t</span>)).<span class="ident">si_addr</span> <span class="kw">as</span> <span class="ident">usize</span>
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">not</span>(<span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"linux"</span>, <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"android"</span>)))]</span>
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">siginfo_si_addr</span>(<span class="ident">info</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">libc</span>::<span class="ident">siginfo_t</span>) <span class="op">-></span> <span class="ident">usize</span> {
(<span class="kw-2">*</span><span class="ident">info</span>).<span class="ident">si_addr</span> <span class="kw">as</span> <span class="ident">usize</span>
}
<span class="comment">// Signal handler for the SIGSEGV and SIGBUS handlers. We've got guard pages</span>
<span class="comment">// (unmapped pages) at the end of every thread's stack, so if a thread ends</span>
<span class="comment">// up running into the guard page it'll trigger this handler. We want to</span>
<span class="comment">// detect these cases and print out a helpful error saying that the stack</span>
<span class="comment">// has overflowed. All other signals, however, should go back to what they</span>
<span class="comment">// were originally supposed to do.</span>
<span class="comment">//</span>
<span class="comment">// This handler currently exists purely to print an informative message</span>
<span class="comment">// whenever a thread overflows its stack. We then abort to exit and</span>
<span class="comment">// indicate a crash, but to avoid a misleading SIGSEGV that might lead</span>
<span class="comment">// users to believe that unsafe code has accessed an invalid pointer; the</span>
<span class="comment">// SIGSEGV encountered when overflowing the stack is expected and</span>
<span class="comment">// well-defined.</span>
<span class="comment">//</span>
<span class="comment">// If this is not a stack overflow, the handler un-registers itself and</span>
<span class="comment">// then returns (to allow the original signal to be delivered again).</span>
<span class="comment">// Returning from this kind of signal handler is technically not defined</span>
<span class="comment">// to work when reading the POSIX spec strictly, but in practice it turns</span>
<span class="comment">// out many large systems and all implementations allow returning from a</span>
<span class="comment">// signal handler to work. For a more detailed explanation see the</span>
<span class="comment">// comments on #26458.</span>
<span class="kw">unsafe</span> <span class="kw">extern</span> <span class="kw">fn</span> <span class="ident">signal_handler</span>(<span class="ident">signum</span>: <span class="ident">libc</span>::<span class="ident">c_int</span>,
<span class="ident">info</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">libc</span>::<span class="ident">siginfo_t</span>,
<span class="ident">_data</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">libc</span>::<span class="ident">c_void</span>) {
<span class="kw">use</span> <span class="ident">sys_common</span>::<span class="ident">util</span>::<span class="ident">report_overflow</span>;
<span class="kw">let</span> <span class="ident">guard</span> <span class="op">=</span> <span class="ident">thread_info</span>::<span class="ident">stack_guard</span>().<span class="ident">unwrap_or</span>(<span class="number">0</span>);
<span class="kw">let</span> <span class="ident">addr</span> <span class="op">=</span> <span class="ident">siginfo_si_addr</span>(<span class="ident">info</span>);
<span class="comment">// If the faulting address is within the guard page, then we print a</span>
<span class="comment">// message saying so and abort.</span>
<span class="kw">if</span> <span class="ident">guard</span> <span class="op">!=</span> <span class="number">0</span> <span class="op">&&</span> <span class="ident">guard</span> <span class="op">-</span> <span class="ident">PAGE_SIZE</span> <span class="op"><=</span> <span class="ident">addr</span> <span class="op">&&</span> <span class="ident">addr</span> <span class="op"><</span> <span class="ident">guard</span> {
<span class="ident">report_overflow</span>();
<span class="macro">rtabort</span><span class="macro">!</span>(<span class="string">"stack overflow"</span>);
} <span class="kw">else</span> {
<span class="comment">// Unregister ourselves by reverting back to the default behavior.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">action</span>: <span class="ident">sigaction</span> <span class="op">=</span> <span class="ident">mem</span>::<span class="ident">zeroed</span>();
<span class="ident">action</span>.<span class="ident">sa_sigaction</span> <span class="op">=</span> <span class="ident">SIG_DFL</span>;
<span class="ident">sigaction</span>(<span class="ident">signum</span>, <span class="kw-2">&</span><span class="ident">action</span>, <span class="ident">ptr</span>::<span class="ident">null_mut</span>());
<span class="comment">// See comment above for why this function returns.</span>
}
}
<span class="kw">static</span> <span class="kw-2">mut</span> <span class="ident">MAIN_ALTSTACK</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">libc</span>::<span class="ident">c_void</span> <span class="op">=</span> <span class="ident">ptr</span>::<span class="ident">null_mut</span>();
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">init</span>() {
<span class="ident">PAGE_SIZE</span> <span class="op">=</span> ::<span class="ident">sys</span>::<span class="ident">os</span>::<span class="ident">page_size</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">action</span>: <span class="ident">sigaction</span> <span class="op">=</span> <span class="ident">mem</span>::<span class="ident">zeroed</span>();
<span class="ident">action</span>.<span class="ident">sa_flags</span> <span class="op">=</span> <span class="ident">SA_SIGINFO</span> <span class="op">|</span> <span class="ident">SA_ONSTACK</span>;
<span class="ident">action</span>.<span class="ident">sa_sigaction</span> <span class="op">=</span> <span class="ident">signal_handler</span> <span class="kw">as</span> <span class="ident">sighandler_t</span>;
<span class="ident">sigaction</span>(<span class="ident">SIGSEGV</span>, <span class="kw-2">&</span><span class="ident">action</span>, <span class="ident">ptr</span>::<span class="ident">null_mut</span>());
<span class="ident">sigaction</span>(<span class="ident">SIGBUS</span>, <span class="kw-2">&</span><span class="ident">action</span>, <span class="ident">ptr</span>::<span class="ident">null_mut</span>());
<span class="kw">let</span> <span class="ident">handler</span> <span class="op">=</span> <span class="ident">make_handler</span>();
<span class="ident">MAIN_ALTSTACK</span> <span class="op">=</span> <span class="ident">handler</span>.<span class="ident">_data</span>;
<span class="ident">mem</span>::<span class="ident">forget</span>(<span class="ident">handler</span>);
}
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">cleanup</span>() {
<span class="ident">Handler</span> { <span class="ident">_data</span>: <span class="ident">MAIN_ALTSTACK</span> };
}
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">get_stackp</span>() <span class="op">-></span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">libc</span>::<span class="ident">c_void</span> {
<span class="kw">let</span> <span class="ident">stackp</span> <span class="op">=</span> <span class="ident">mmap</span>(<span class="ident">ptr</span>::<span class="ident">null_mut</span>(),
<span class="ident">SIGSTKSZ</span>,
<span class="ident">PROT_READ</span> <span class="op">|</span> <span class="ident">PROT_WRITE</span>,
<span class="ident">MAP_PRIVATE</span> <span class="op">|</span> <span class="ident">MAP_ANON</span>,
<span class="op">-</span><span class="number">1</span>,
<span class="number">0</span>);
<span class="kw">if</span> <span class="ident">stackp</span> <span class="op">==</span> <span class="ident">MAP_FAILED</span> {
<span class="macro">panic</span><span class="macro">!</span>(<span class="string">"failed to allocate an alternative stack"</span>);
}
<span class="ident">stackp</span>
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"linux"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"macos"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"bitrig"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"netbsd"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"openbsd"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"solaris"</span>))]</span>
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">get_stack</span>() <span class="op">-></span> <span class="ident">libc</span>::<span class="ident">stack_t</span> {
<span class="ident">libc</span>::<span class="ident">stack_t</span> { <span class="ident">ss_sp</span>: <span class="ident">get_stackp</span>(), <span class="ident">ss_flags</span>: <span class="number">0</span>, <span class="ident">ss_size</span>: <span class="ident">SIGSTKSZ</span> }
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"freebsd"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"dragonfly"</span>))]</span>
<span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">get_stack</span>() <span class="op">-></span> <span class="ident">libc</span>::<span class="ident">stack_t</span> {
<span class="ident">libc</span>::<span class="ident">stack_t</span> { <span class="ident">ss_sp</span>: <span class="ident">get_stackp</span>() <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">i8</span>, <span class="ident">ss_flags</span>: <span class="number">0</span>, <span class="ident">ss_size</span>: <span class="ident">SIGSTKSZ</span> }
}
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">make_handler</span>() <span class="op">-></span> <span class="ident">Handler</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">stack</span> <span class="op">=</span> <span class="ident">mem</span>::<span class="ident">zeroed</span>();
<span class="ident">sigaltstack</span>(<span class="ident">ptr</span>::<span class="ident">null</span>(), <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">stack</span>);
<span class="comment">// Configure alternate signal stack, if one is not already set.</span>
<span class="kw">if</span> <span class="ident">stack</span>.<span class="ident">ss_flags</span> <span class="op">&</span> <span class="ident">SS_DISABLE</span> <span class="op">!=</span> <span class="number">0</span> {
<span class="ident">stack</span> <span class="op">=</span> <span class="ident">get_stack</span>();
<span class="ident">sigaltstack</span>(<span class="kw-2">&</span><span class="ident">stack</span>, <span class="ident">ptr</span>::<span class="ident">null_mut</span>());
<span class="ident">Handler</span> { <span class="ident">_data</span>: <span class="ident">stack</span>.<span class="ident">ss_sp</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">libc</span>::<span class="ident">c_void</span> }
} <span class="kw">else</span> {
<span class="ident">Handler</span> { <span class="ident">_data</span>: <span class="ident">ptr</span>::<span class="ident">null_mut</span>() }
}
}
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">drop_handler</span>(<span class="ident">handler</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Handler</span>) {
<span class="kw">if</span> <span class="op">!</span><span class="ident">handler</span>.<span class="ident">_data</span>.<span class="ident">is_null</span>() {
<span class="kw">let</span> <span class="ident">stack</span> <span class="op">=</span> <span class="ident">libc</span>::<span class="ident">stack_t</span> {
<span class="ident">ss_sp</span>: <span class="ident">ptr</span>::<span class="ident">null_mut</span>(),
<span class="ident">ss_flags</span>: <span class="ident">SS_DISABLE</span>,
<span class="comment">// Workaround for bug in macOS implementation of sigaltstack</span>
<span class="comment">// UNIX2003 which returns ENOMEM when disabling a stack while</span>
<span class="comment">// passing ss_size smaller than MINSIGSTKSZ. According to POSIX</span>
<span class="comment">// both ss_sp and ss_size should be ignored in this case.</span>
<span class="ident">ss_size</span>: <span class="ident">SIGSTKSZ</span>,
};
<span class="ident">sigaltstack</span>(<span class="kw-2">&</span><span class="ident">stack</span>, <span class="ident">ptr</span>::<span class="ident">null_mut</span>());
<span class="ident">munmap</span>(<span class="ident">handler</span>.<span class="ident">_data</span>, <span class="ident">SIGSTKSZ</span>);
}
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">not</span>(<span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"linux"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"macos"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"bitrig"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"dragonfly"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"freebsd"</span>,
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"solaris"</span>,
<span class="ident">all</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"netbsd"</span>, <span class="ident">not</span>(<span class="ident">target_vendor</span> <span class="op">=</span> <span class="string">"rumprun"</span>)),
<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"openbsd"</span>)))]</span>
<span class="kw">mod</span> <span class="ident">imp</span> {
<span class="kw">use</span> <span class="ident">ptr</span>;
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">init</span>() {
}
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">cleanup</span>() {
}
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">make_handler</span>() <span class="op">-></span> <span class="kw">super</span>::<span class="ident">Handler</span> {
<span class="kw">super</span>::<span class="ident">Handler</span> { <span class="ident">_data</span>: <span class="ident">ptr</span>::<span class="ident">null_mut</span>() }
}
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">drop_handler</span>(<span class="ident">_handler</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="kw">super</span>::<span class="ident">Handler</span>) {
}
}
</pre>
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