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<section id='main' class="content"><pre class="line-numbers"><span id="1"> 1</span>
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</pre><pre class="rust ">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">os</span>::<span class="ident">raw</span>::<span class="ident">c_void</span>;
<span class="doccomment">/// Inspects the current call-stack, passing all active frames into the closure</span>
<span class="doccomment">/// provided to calculate a stack trace.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This function is the workhorse of this library in calculating the stack</span>
<span class="doccomment">/// traces for a program. The given closure `cb` is yielded instances of a</span>
<span class="doccomment">/// `Frame` which represent information about that call frame on the stack. The</span>
<span class="doccomment">/// closure is yielded frames in a top-down fashion (most recently called</span>
<span class="doccomment">/// functions first).</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The closure's return value is an indication of whether the backtrace should</span>
<span class="doccomment">/// continue. A return value of `false` will terminate the backtrace and return</span>
<span class="doccomment">/// immediately.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Once a `Frame` is acquired you will likely want to call `backtrace::resolve`</span>
<span class="doccomment">/// to convert the `ip` (instruction pointer) or symbol address to a `Symbol`</span>
<span class="doccomment">/// through which the name and/or filename/line number can be learned.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Note that this is a relatively low-level function and if you'd like to, for</span>
<span class="doccomment">/// example, capture a backtrace to be inspected later, then the `Backtrace`</span>
<span class="doccomment">/// type may be more appropriate.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Example</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// extern crate backtrace;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// fn main() {</span>
<span class="doccomment">/// backtrace::trace(|frame| {</span>
<span class="doccomment">/// // ...</span>
<span class="doccomment">///</span>
<span class="doccomment">/// true // continue the backtrace</span>
<span class="doccomment">/// });</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>(<span class="ident">never</span>)]</span> <span class="comment">// if this is never inlined then the first frame can be known</span>
<span class="comment">// to be skipped</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">trace</span><span class="op"><</span><span class="ident">F</span>: <span class="ident">FnMut</span>(<span class="kw-2">&</span><span class="ident">Frame</span>) <span class="op">-></span> <span class="ident">bool</span><span class="op">></span>(<span class="kw-2">mut</span> <span class="ident">cb</span>: <span class="ident">F</span>) {
<span class="ident">trace_imp</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">cb</span>)
}
<span class="doccomment">/// A trait representing one frame of a backtrace, yielded to the `trace`</span>
<span class="doccomment">/// function of this crate.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The tracing function's closure will be yielded frames, and the frame is</span>
<span class="doccomment">/// virtually dispatched as the underlying implementation is not always known</span>
<span class="doccomment">/// until runtime.</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Frame</span> {
<span class="ident">inner</span>: <span class="ident">FrameImp</span>,
}
<span class="kw">impl</span> <span class="ident">Frame</span> {
<span class="doccomment">/// Returns the current instruction pointer of this frame.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is normally the next instruction to execute in the frame, but not</span>
<span class="doccomment">/// all implementations list this with 100% accuracy (but it's generally</span>
<span class="doccomment">/// pretty close).</span>
<span class="doccomment">///</span>
<span class="doccomment">/// It is recommended to pass this value to `backtrace::resolve` to turn it</span>
<span class="doccomment">/// into a symbol name.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">ip</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">c_void</span> {
<span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">ip</span>()
}
<span class="doccomment">/// Returns the starting symbol address of the frame of this function.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This will attempt to rewind the instruction pointer returned by `ip` to</span>
<span class="doccomment">/// the start of the function, returning that value. In some cases, however,</span>
<span class="doccomment">/// backends will just return `ip` from this function.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The returned value can sometimes be used if `backtrace::resolve` failed</span>
<span class="doccomment">/// on the `ip` given above.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">symbol_address</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">c_void</span> {
<span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">symbol_address</span>()
}
}
<span class="kw">impl</span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Frame</span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"Frame"</span>)
.<span class="ident">field</span>(<span class="string">"ip"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">ip</span>())
.<span class="ident">field</span>(<span class="string">"symbol_address"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">symbol_address</span>())
.<span class="ident">finish</span>()
}
}
<span class="macro">cfg_if</span><span class="macro">!</span> {
<span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>(<span class="ident">unix</span>,
<span class="ident">not</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"emscripten"</span>),
<span class="ident">not</span>(<span class="ident">all</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"ios"</span>, <span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"arm"</span>)),
<span class="ident">feature</span> <span class="op">=</span> <span class="string">"libunwind"</span>))]</span> {
<span class="kw">mod</span> <span class="ident">libunwind</span>;
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">libunwind</span>::<span class="ident">trace</span> <span class="kw">as</span> <span class="ident">trace_imp</span>;
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">libunwind</span>::<span class="ident">Frame</span> <span class="kw">as</span> <span class="ident">FrameImp</span>;
} <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>(<span class="ident">unix</span>,
<span class="ident">not</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"emscripten"</span>),
<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unix-backtrace"</span>))]</span> {
<span class="kw">mod</span> <span class="ident">unix_backtrace</span>;
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">unix_backtrace</span>::<span class="ident">trace</span> <span class="kw">as</span> <span class="ident">trace_imp</span>;
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">unix_backtrace</span>::<span class="ident">Frame</span> <span class="kw">as</span> <span class="ident">FrameImp</span>;
} <span class="kw">else</span> <span class="kw">if</span> <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>(<span class="ident">windows</span>, <span class="ident">feature</span> <span class="op">=</span> <span class="string">"dbghelp"</span>))]</span> {
<span class="kw">mod</span> <span class="ident">dbghelp</span>;
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">dbghelp</span>::<span class="ident">trace</span> <span class="kw">as</span> <span class="ident">trace_imp</span>;
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">dbghelp</span>::<span class="ident">Frame</span> <span class="kw">as</span> <span class="ident">FrameImp</span>;
} <span class="kw">else</span> {
<span class="kw">mod</span> <span class="ident">noop</span>;
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">noop</span>::<span class="ident">trace</span> <span class="kw">as</span> <span class="ident">trace_imp</span>;
<span class="kw">use</span> <span class="self">self</span>::<span class="ident">noop</span>::<span class="ident">Frame</span> <span class="kw">as</span> <span class="ident">FrameImp</span>;
}
}
</pre>
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