mirror of
https://github.com/RGBCube/serenity
synced 2025-05-22 19:45:08 +00:00
03a8357e84
This is dirty but pretty cool! If we have a pending, unmasked signal for a process that's blocked inside the kernel, we set up alternate stacks for that process and unblock it to execute the signal handler. A slightly different return trampoline is used here: since we need to get back into the kernel, a dedicated syscall is used (sys$sigreturn.) This restores the TSS contents of the process to the state it was in while we were originally blocking in the kernel. NOTE: There's currently only one "kernel resume TSS" so signal nesting definitely won't work.
47 lines
1 KiB
C++
47 lines
1 KiB
C++
#include <unistd.h>
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#include <stdio.h>
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#include <signal.h>
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#include <AK/String.h>
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static unsigned parseUInt(const String& str, bool& ok)
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{
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unsigned value = 0;
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for (size_t i = 0; i < str.length(); ++i) {
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if (str[i] < '0' || str[i] > '9') {
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ok = false;
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return 0;
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}
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value = value * 10;
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value += str[i] - '0';
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}
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ok = true;
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return value;
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}
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void handle_sigint(int)
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{
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}
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int main(int argc, char** argv)
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{
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if (argc != 2) {
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printf("usage: sleep <seconds>\n");
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return 1;
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}
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bool ok;
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unsigned secs = parseUInt(argv[1], ok);
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if (!ok) {
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fprintf(stderr, "Not a valid number of seconds: \"%s\"\n", argv[1]);
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return 1;
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}
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struct sigaction sa;
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memset(&sa, 0, sizeof(struct sigaction));
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sa.sa_handler = handle_sigint;
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sigaction(SIGINT, &sa, nullptr);
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unsigned remaining = sleep(secs);
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if (remaining) {
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printf("Sleep interrupted with %u seconds remaining.\n", remaining);
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}
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return 0;
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}
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