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Add some basic signal support.

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It only works for sending a signal to a process that's in userspace code.

We implement reception by synthesizing a PUSHA+PUSHF in the receiving process
(operating on values in the TSS.)
The TSS CS:EIP is then rerouted to the signal handler and a tiny return
trampoline is constructed in a dedicated region in the receiving process.

Also hacked up /bin/kill to be able to send arbitrary signals (kill -N PID)
This commit is contained in:
Andreas Kling 2018-11-06 10:46:40 +01:00
parent 52d502e11f
commit 153ea704af
13 changed files with 240 additions and 30 deletions
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39
Userland/kill.cpp
View file

@ -1,6 +1,7 @@
#include <LibC/unistd.h>
#include <LibC/stdio.h>
#include <LibC/signal.h>
#include <unistd.h>
#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <AK/String.h>
static unsigned parseUInt(const String& str, bool& ok)
@ -18,20 +19,36 @@ static unsigned parseUInt(const String& str, bool& ok)
return value;
}
static void print_usage_and_exit()
{
printf("usage: kill [-signal] <PID>\n");
exit(1);
}
int main(int argc, char** argv)
{
if (argc < 2) {
printf("usage: kill <PID>\n");
return 1;
}
if (argc != 2 && argc != 3)
print_usage_and_exit();
bool ok;
unsigned value = parseUInt(argv[1], ok);
unsigned signum = SIGTERM;
int pid_argi = 1;
if (argc == 3) {
pid_argi = 2;
if (argv[1][0] != '-')
print_usage_and_exit();
signum = parseUInt(&argv[1][1], ok);
if (!ok) {
printf("%s is not a valid signal number\n", &argv[1][1]);
return 2;
}
}
unsigned pid = parseUInt(argv[pid_argi], ok);
if (!ok) {
printf("%s is not a valid PID\n", argv[1]);
return 2;
printf("%s is not a valid PID\n", argv[pid_argi]);
return 3;
}
kill((pid_t)value, SIGKILL);
kill((pid_t)pid, signum);
return 0;
}