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POIs there a better way than parsing /proc/self/maps to figure out memory protection?
 

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    <p>On Linux (or Solaris) is there a better way than hand parsing <code>/proc/self/maps</code> repeatedly to figure out whether or not you can read, write or execute whatever is stored at one or more addresses in memory?</p> <p>For instance, in Windows you have <code>VirtualQuery</code>. </p> <p>In Linux, I can <code>mprotect</code> to change those values, but I can't read them back.</p> <p>Furthermore, is there any way to know when those permissions change (e.g. when someone uses <code>mmap</code> on a file behind my back) other than doing something terribly invasive and using <code>ptrace</code> on all threads in the process and intercepting any attempt to make a <code>syscall</code> that could affect the memory map?</p> <p><strong>Update:</strong></p> <p>Unfortunately, I'm using this inside of a JIT that has very little information about the code it is executing to get an approximation of what is constant. Yes, I realize I could have a constant map of mutable data, like the vsyscall page used by Linux. I <em>can</em> safely fall back on an assumption that anything that isn't included in the initial parse is mutable and dangerous, but I'm not entirely happy with that option.</p> <p>Right now what I do is I read <code>/proc/self/maps</code> and build a structure I can binary search through for a given address's protection. Any time I need to know something about a page that isn't in my structure I reread /proc/self/maps assuming it has been added in the meantime or I'd be about to segfault anyways.</p> <p>It just seems that parsing text to get at this information and not knowing when it changes is awfully crufty. (<code>/dev/inotify</code> doesn't work on pretty much anything in <code>/proc</code>)</p>
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