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Implement raise() with getcontext() / setcontext()

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Justine Tunney 2023-11-05 17:52:30 -08:00
parent dd83db9567
commit 736fdb757a
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GPG key ID: BE714B4575D6E328
12 changed files with 73 additions and 97 deletions
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91
libc/calls/sig.c
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@ -34,6 +34,7 @@
#include "libc/intrin/atomic.h"
#include "libc/intrin/bsf.h"
#include "libc/intrin/describebacktrace.internal.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/popcnt.h"
#include "libc/intrin/strace.internal.h"
#include "libc/intrin/weaken.h"
@ -169,53 +170,59 @@ static textwindows bool __sig_start(struct PosixThread *pt, int sig,
}
static textwindows sigaction_f __sig_handler(unsigned rva) {
atomic_fetch_add_explicit(&__sig.count, 1, memory_order_relaxed);
return (sigaction_f)(__executable_start + rva);
}
textwindows int __sig_raise(int sig, int sic) {
textwindows int __sig_raise(volatile int sig, int sic) {
// create machine context object
struct PosixThread *pt = _pthread_self();
ucontext_t ctx = {.uc_sigmask = pt->tib->tib_sigmask};
struct NtContext nc;
nc.ContextFlags = kNtContextFull;
GetThreadContext(GetCurrentThread(), &nc);
_ntcontext2linux(&ctx, &nc);
// bitset of kinds of handlers called
volatile int handler_was_called = 0;
// loop over pending signals
ucontext_t ctx;
getcontext(&ctx);
if (!sig) {
if ((sig = __sig_get(ctx.uc_sigmask))) {
sic = SI_KERNEL;
} else {
return handler_was_called;
}
}
// process signal(s)
int handler_was_called = 0;
do {
// start the signal
unsigned rva, flags;
if (__sig_start(pt, sig, &rva, &flags)) {
if (flags & SA_RESETHAND) {
STRACE("resetting %G handler", sig);
__sighandrvas[sig] = (int32_t)(intptr_t)SIG_DFL;
}
// update the signal mask in preparation for signal handller
sigset_t blocksigs = __sighandmask[sig];
if (!(flags & SA_NODEFER)) blocksigs |= 1ull << (sig - 1);
ctx.uc_sigmask = atomic_fetch_or_explicit(
&pt->tib->tib_sigmask, blocksigs, memory_order_acquire);
// call the user's signal handler
char ssbuf[2][128];
siginfo_t si = {.si_signo = sig, .si_code = sic};
STRACE("__sig_raise(%G, %t) mask %s → %s", sig, __sig_handler(rva),
(DescribeSigset)(ssbuf[0], 0, &ctx.uc_sigmask),
(DescribeSigset)(ssbuf[1], 0, (sigset_t *)&pt->tib->tib_sigmask));
__sig_handler(rva)(sig, &si, &ctx);
(void)ssbuf;
// restore the original signal mask
atomic_store_explicit(&pt->tib->tib_sigmask, ctx.uc_sigmask,
memory_order_release);
handler_was_called |= (flags & SA_RESTART) ? 2 : 1;
unsigned rva, flags;
struct PosixThread *pt = _pthread_self();
if (__sig_start(pt, sig, &rva, &flags)) {
if (flags & SA_RESETHAND) {
STRACE("resetting %G handler", sig);
__sighandrvas[sig] = (int32_t)(intptr_t)SIG_DFL;
}
sic = SI_KERNEL;
} while ((sig = __sig_get(ctx.uc_sigmask)));
return handler_was_called;
// update the signal mask in preparation for signal handller
sigset_t blocksigs = __sighandmask[sig];
if (!(flags & SA_NODEFER)) blocksigs |= 1ull << (sig - 1);
ctx.uc_sigmask = atomic_fetch_or_explicit(&pt->tib->tib_sigmask, blocksigs,
memory_order_acquire);
// call the user's signal handler
char ssbuf[2][128];
siginfo_t si = {.si_signo = sig, .si_code = sic};
STRACE("__sig_raise(%G, %t) mask %s → %s", sig, __sig_handler(rva),
(DescribeSigset)(ssbuf[0], 0, &ctx.uc_sigmask),
(DescribeSigset)(ssbuf[1], 0, (sigset_t *)&pt->tib->tib_sigmask));
__sig_handler(rva)(sig, &si, &ctx);
(void)ssbuf;
// record this handler
handler_was_called |= (flags & SA_RESTART) ? 2 : 1;
}
// restore sigmask
// loop back to top
// jump where handler says
sig = 0;
return setcontext(&ctx);
}
textwindows int __sig_relay(int sig, int sic, sigset_t waitmask) {
@ -258,7 +265,6 @@ static textwindows wontreturn void __sig_tramp(struct SignalFrame *sf) {
struct CosmoTib *tib = __get_tls();
struct PosixThread *pt = (struct PosixThread *)tib->tib_pthread;
for (;;) {
atomic_fetch_add_explicit(&__sig.count, 1, memory_order_relaxed);
// update the signal mask in preparation for signal handller
sigset_t blocksigs = __sighandmask[sig];
@ -513,9 +519,6 @@ static int __sig_crash_sig(struct NtExceptionPointers *ep, int *code) {
static void __sig_unmaskable(struct NtExceptionPointers *ep, int code, int sig,
struct CosmoTib *tib) {
// increment the signal count for getrusage()
atomic_fetch_add_explicit(&__sig.count, 1, memory_order_relaxed);
// log vital crash information reliably for --strace before doing much
// we don't print this without the flag since raw numbers scare people
// this needs at least one page of stack memory in order to get logged