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rpm/rpmio/rpmsq.c

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/** \ingroup rpmio
* \file rpmio/rpmsq.c
*/
#include "system.h"
#include <signal.h>
#include <sys/signal.h>
#include <sys/wait.h>
#include <search.h>
#if defined(HAVE_PTHREAD_H)
#include <pthread.h>
/* XXX suggested in bugzilla #159024 */
#if PTHREAD_MUTEX_DEFAULT != PTHREAD_MUTEX_NORMAL
#error RPM expects PTHREAD_MUTEX_DEFAULT == PTHREAD_MUTEX_NORMAL
#endif
#ifndef PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
static pthread_mutex_t rpmsigTbl_lock = PTHREAD_MUTEX_INITIALIZER;
#else
static pthread_mutex_t rpmsigTbl_lock = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
#endif
#define DO_LOCK() pthread_mutex_lock(&rpmsigTbl_lock);
#define DO_UNLOCK() pthread_mutex_unlock(&rpmsigTbl_lock);
#define INIT_LOCK() \
{ pthread_mutexattr_t attr; \
(void) pthread_mutexattr_init(&attr); \
(void) pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE); \
(void) pthread_mutex_init (&rpmsigTbl_lock, &attr); \
(void) pthread_mutexattr_destroy(&attr); \
rpmsigTbl_sigchld->active = 0; \
}
#define ADD_REF(__tbl) (__tbl)->active++
#define SUB_REF(__tbl) --(__tbl)->active
#define CLEANUP_HANDLER(__handler, __arg, __oldtypeptr) \
(void) pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, (__oldtypeptr));\
pthread_cleanup_push((__handler), (__arg));
#define CLEANUP_RESET(__execute, __oldtype) \
pthread_cleanup_pop(__execute); \
(void) pthread_setcanceltype ((__oldtype), &(__oldtype));
#define SAME_THREAD(_a, _b) pthread_equal(((pthread_t)_a), ((pthread_t)_b))
#define ME() ((void *)pthread_self())
#else
#define DO_LOCK()
#define DO_UNLOCK()
#define INIT_LOCK()
#define ADD_REF(__tbl) (0)
#define SUB_REF(__tbl) (0)
#define CLEANUP_HANDLER(__handler, __arg, __oldtypeptr)
#define CLEANUP_RESET(__execute, __oldtype)
#define SAME_THREAD(_a, _b) (42)
#define ME() (((void *)getpid()))
#endif /* HAVE_PTHREAD_H */
#define _RPMSQ_INTERNAL
#include <rpm/rpmsq.h>
#include "debug.h"
#define _RPMSQ_DEBUG 0
int _rpmsq_debug = _RPMSQ_DEBUG;
static struct rpmsqElem rpmsqRock;
static rpmsq rpmsqQueue = &rpmsqRock;
/** \ingroup rpmsq
* Insert node into from queue.
* @param elem node to link
* @param prev previous node from queue
* @return 0 on success
*/
static int rpmsqInsert(void * elem, void * prev)
{
rpmsq sq = (rpmsq) elem;
int ret = -1;
if (sq != NULL) {
#ifdef _RPMSQ_DEBUG
if (_rpmsq_debug)
fprintf(stderr, " Insert(%p): %p\n", ME(), sq);
#endif
ret = sighold(SIGCHLD);
if (ret == 0) {
sq->child = 0;
sq->reaped = 0;
sq->status = 0;
sq->reaper = 1;
sq->pipes[0] = sq->pipes[1] = -1;
sq->id = ME();
ret = pthread_mutex_init(&sq->mutex, NULL);
insque(elem, (prev != NULL ? prev : rpmsqQueue));
ret = sigrelse(SIGCHLD);
}
}
return ret;
}
/** \ingroup rpmsq
* Remove node from queue.
* @param elem node to link
* @return 0 on success
*/
static int rpmsqRemove(void * elem)
{
rpmsq sq = (rpmsq) elem;
int ret = -1;
if (elem != NULL) {
#ifdef _RPMSQ_DEBUG
if (_rpmsq_debug)
fprintf(stderr, " Remove(%p): %p\n", ME(), sq);
#endif
ret = sighold (SIGCHLD);
if (ret == 0) {
remque(elem);
/* Unlock the mutex and then destroy it */
if((ret = pthread_mutex_unlock(&sq->mutex)) == 0)
ret = pthread_mutex_destroy(&sq->mutex);
sq->id = NULL;
if (sq->pipes[1]) ret = close(sq->pipes[1]);
if (sq->pipes[0]) ret = close(sq->pipes[0]);
sq->pipes[0] = sq->pipes[1] = -1;
#ifdef NOTYET /* rpmpsmWait debugging message needs */
sq->reaper = 1;
sq->status = 0;
sq->reaped = 0;
sq->child = 0;
#endif
ret = sigrelse(SIGCHLD);
}
}
return ret;
}
static sigset_t rpmsqCaught;
static struct rpmsig_s {
int signum;
rpmsqAction_t handler;
int active;
struct sigaction oact;
} rpmsigTbl[] = {
{ SIGINT, rpmsqAction },
#define rpmsigTbl_sigint (&rpmsigTbl[0])
{ SIGQUIT, rpmsqAction },
#define rpmsigTbl_sigquit (&rpmsigTbl[1])
{ SIGCHLD, rpmsqAction },
#define rpmsigTbl_sigchld (&rpmsigTbl[2])
{ SIGHUP, rpmsqAction },
#define rpmsigTbl_sighup (&rpmsigTbl[3])
{ SIGTERM, rpmsqAction },
#define rpmsigTbl_sigterm (&rpmsigTbl[4])
{ SIGPIPE, rpmsqAction },
#define rpmsigTbl_sigpipe (&rpmsigTbl[5])
{ -1, NULL },
};
int rpmsqIsCaught(int signum)
{
return sigismember(&rpmsqCaught, signum);
}
#ifdef SA_SIGINFO
void rpmsqAction(int signum,
void * info, void * context)
#else
void rpmsqAction(int signum)
#endif
{
int save = errno;
rpmsig tbl;
for (tbl = rpmsigTbl; tbl->signum >= 0; tbl++) {
if (tbl->signum != signum)
continue;
(void) sigaddset(&rpmsqCaught, signum);
switch (signum) {
case SIGCHLD:
while (1) {
rpmsq sq;
int status = 0;
pid_t reaped = waitpid(0, &status, WNOHANG);
/* XXX errno set to ECHILD/EINVAL/EINTR. */
if (reaped <= 0)
break;
/* XXX insque(3)/remque(3) are dequeue, not ring. */
for (sq = rpmsqQueue->q_forw;
sq != NULL && sq != rpmsqQueue;
sq = sq->q_forw)
{
int ret;
if (sq->child != reaped)
continue;
sq->reaped = reaped;
sq->status = status;
/* Unlock the mutex. The waiter will then be able to
* aquire the lock.
*
* XXX: jbj, wtd, if this fails?
*/
ret = pthread_mutex_unlock(&sq->mutex);
break;
}
}
break;
default:
break;
}
break;
}
errno = save;
}
int rpmsqEnable(int signum, rpmsqAction_t handler)
{
int tblsignum = (signum >= 0 ? signum : -signum);
struct sigaction sa;
rpmsig tbl;
int ret = -1;
(void) DO_LOCK ();
if (rpmsqQueue->id == NULL)
rpmsqQueue->id = ME();
for (tbl = rpmsigTbl; tbl->signum >= 0; tbl++) {
if (tblsignum != tbl->signum)
continue;
if (signum >= 0) { /* Enable. */
if (ADD_REF(tbl) <= 0) {
(void) sigdelset(&rpmsqCaught, tbl->signum);
/* XXX Don't set a signal handler if already SIG_IGN */
(void) sigaction(tbl->signum, NULL, &tbl->oact);
if (tbl->oact.sa_handler == SIG_IGN)
continue;
(void) sigemptyset (&sa.sa_mask);
#ifdef SA_SIGINFO
sa.sa_flags = SA_SIGINFO;
#else
sa.sa_flags = 0;
#endif
sa.sa_sigaction = (void*)(handler != NULL ? handler : tbl->handler);
if (sigaction(tbl->signum, &sa, &tbl->oact) < 0) {
SUB_REF(tbl);
break;
}
tbl->active = 1; /* XXX just in case */
if (handler != NULL)
tbl->handler = handler;
}
} else { /* Disable. */
if (SUB_REF(tbl) <= 0) {
if (sigaction(tbl->signum, &tbl->oact, NULL) < 0)
break;
tbl->active = 0; /* XXX just in case */
tbl->handler = (handler != NULL ? handler : rpmsqAction);
}
}
ret = tbl->active;
break;
}
(void) DO_UNLOCK ();
return ret;
}
pid_t rpmsqFork(rpmsq sq)
{
pid_t pid;
int xx;
int nothreads = 0; /* XXX: Shouldn't this be a global? */
if (sq->reaper) {
xx = rpmsqInsert(sq, NULL);
#ifdef _RPMSQ_DEBUG
if (_rpmsq_debug)
fprintf(stderr, " Enable(%p): %p\n", ME(), sq);
#endif
xx = rpmsqEnable(SIGCHLD, NULL);
}
xx = pipe(sq->pipes);
xx = sighold(SIGCHLD);
/*
* Initialize the cond var mutex. We have to aquire the lock we
* use for the condition before we fork. Otherwise it is possible for
* the child to exit, we get sigchild and the sig handler to send
* the condition signal before we are waiting on the condition.
*/
if (!nothreads) {
if(pthread_mutex_lock(&sq->mutex)) {
/* Yack we did not get the lock, lets just give up */
xx = close(sq->pipes[0]);
xx = close(sq->pipes[1]);
sq->pipes[0] = sq->pipes[1] = -1;
goto out;
}
}
pid = fork();
if (pid < (pid_t) 0) { /* fork failed. */
sq->child = (pid_t)-1;
xx = close(sq->pipes[0]);
xx = close(sq->pipes[1]);
sq->pipes[0] = sq->pipes[1] = -1;
goto out;
} else if (pid == (pid_t) 0) { /* Child. */
int yy;
/* Block to permit parent time to wait. */
xx = close(sq->pipes[1]);
xx = read(sq->pipes[0], &yy, sizeof(yy));
xx = close(sq->pipes[0]);
sq->pipes[0] = sq->pipes[1] = -1;
#ifdef _RPMSQ_DEBUG
if (_rpmsq_debug)
fprintf(stderr, " Child(%p): %p child %d\n", ME(), sq, getpid());
#endif
} else { /* Parent. */
sq->child = pid;
#ifdef _RPMSQ_DEBUG
if (_rpmsq_debug)
fprintf(stderr, " Parent(%p): %p child %d\n", ME(), sq, sq->child);
#endif
}
out:
xx = sigrelse(SIGCHLD);
return sq->child;
}
/**
* Wait for child process to be reaped, and unregister SIGCHLD handler.
* @todo Rewrite to use waitpid on helper thread.
* @param sq scriptlet queue element
* @return 0 on success
*/
static int rpmsqWaitUnregister(rpmsq sq)
{
int nothreads = 0;
int ret = 0;
int xx;
/* Protect sq->reaped from handler changes. */
ret = sighold(SIGCHLD);
/* Start the child, linux often runs child before parent. */
if (sq->pipes[0] >= 0)
xx = close(sq->pipes[0]);
if (sq->pipes[1] >= 0)
xx = close(sq->pipes[1]);
sq->pipes[0] = sq->pipes[1] = -1;
/* Put a stopwatch on the time spent waiting to measure performance gain. */
(void) rpmswEnter(&sq->op, -1);
/* Wait for handler to receive SIGCHLD. */
while (ret == 0 && sq->reaped != sq->child) {
if (nothreads)
/* Note that sigpause re-enables SIGCHLD. */
ret = sigpause(SIGCHLD);
else {
xx = sigrelse(SIGCHLD);
/*
* We start before the fork with this mutex locked;
* The only one that unlocks this the signal handler.
* So if we get the lock the child has been reaped.
*/
ret = pthread_mutex_lock(&sq->mutex);
xx = sighold(SIGCHLD);
}
}
/* Accumulate stopwatch time spent waiting, potential performance gain. */
sq->ms_scriptlets += rpmswExit(&sq->op, -1)/1000;
xx = sigrelse(SIGCHLD);
#ifdef _RPMSQ_DEBUG
if (_rpmsq_debug)
fprintf(stderr, " Wake(%p): %p child %d reaper %d ret %d\n", ME(), sq, sq->child, sq->reaper, ret);
#endif
/* Remove processed SIGCHLD item from queue. */
xx = rpmsqRemove(sq);
/* Disable SIGCHLD handler on refcount == 0. */
xx = rpmsqEnable(-SIGCHLD, NULL);
#ifdef _RPMSQ_DEBUG
if (_rpmsq_debug)
fprintf(stderr, " Disable(%p): %p\n", ME(), sq);
#endif
return ret;
}
pid_t rpmsqWait(rpmsq sq)
{
#ifdef _RPMSQ_DEBUG
if (_rpmsq_debug)
fprintf(stderr, " Wait(%p): %p child %d reaper %d\n", ME(), sq, sq->child, sq->reaper);
#endif
if (sq->reaper) {
(void) rpmsqWaitUnregister(sq);
} else {
pid_t reaped;
int status;
do {
reaped = waitpid(sq->child, &status, 0);
} while (reaped >= 0 && reaped != sq->child);
sq->reaped = reaped;
sq->status = status;
#ifdef _RPMSQ_DEBUG
if (_rpmsq_debug)
fprintf(stderr, " Waitpid(%p): %p child %d reaped %d\n", ME(), sq, sq->child, sq->reaped);
#endif
}
#ifdef _RPMSQ_DEBUG
if (_rpmsq_debug)
fprintf(stderr, " Fini(%p): %p child %d status 0x%x\n", ME(), sq, sq->child, sq->status);
#endif
return sq->reaped;
}
void * rpmsqThread(void * (*start) (void * arg), void * arg)
{
pthread_t pth;
int ret;
ret = pthread_create(&pth, NULL, start, arg);
return (ret == 0 ? (void *)pth : NULL);
}
int rpmsqJoin(void * thread)
{
pthread_t pth = (pthread_t) thread;
if (thread == NULL)
return EINVAL;
return pthread_join(pth, NULL);
}
int rpmsqThreadEqual(void * thread)
{
pthread_t t1 = (pthread_t) thread;
pthread_t t2 = pthread_self();
return pthread_equal(t1, t2);
}
/**
* SIGCHLD cancellation handler.
*/
static void
sigchld_cancel (void *arg)
{
pid_t child = *(pid_t *) arg;
pid_t result;
(void) kill(child, SIGKILL);
do {
result = waitpid(child, NULL, 0);
} while (result == (pid_t)-1 && errno == EINTR);
(void) DO_LOCK ();
if (SUB_REF (rpmsigTbl_sigchld) == 0) {
(void) rpmsqEnable(-SIGQUIT, NULL);
(void) rpmsqEnable(-SIGINT, NULL);
}
(void) DO_UNLOCK ();
}
/**
* Execute a command, returning its status.
*/
int
rpmsqExecve (const char ** argv)
{
int oldtype;
int status = -1;
pid_t pid = 0;
pid_t result;
sigset_t newMask, oldMask;
#ifndef PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
INIT_LOCK ();
#endif
(void) DO_LOCK ();
if (ADD_REF (rpmsigTbl_sigchld) == 0) {
if (rpmsqEnable(SIGINT, NULL) < 0) {
SUB_REF (rpmsigTbl_sigchld);
goto out;
}
if (rpmsqEnable(SIGQUIT, NULL) < 0) {
SUB_REF (rpmsigTbl_sigchld);
goto out_restore_sigint;
}
}
(void) DO_UNLOCK ();
(void) sigemptyset (&newMask);
(void) sigaddset (&newMask, SIGCHLD);
if (sigprocmask (SIG_BLOCK, &newMask, &oldMask) < 0) {
(void) DO_LOCK ();
if (SUB_REF (rpmsigTbl_sigchld) == 0)
goto out_restore_sigquit_and_sigint;
goto out;
}
CLEANUP_HANDLER(sigchld_cancel, &pid, &oldtype);
pid = fork ();
if (pid < (pid_t) 0) { /* fork failed. */
goto out;
} else if (pid == (pid_t) 0) { /* Child. */
/* Restore the signals. */
(void) sigaction (SIGINT, &rpmsigTbl_sigint->oact, NULL);
(void) sigaction (SIGQUIT, &rpmsigTbl_sigquit->oact, NULL);
(void) sigprocmask (SIG_SETMASK, &oldMask, NULL);
/* Reset rpmsigTbl lock and refcnt. */
INIT_LOCK ();
(void) execve (argv[0], (char *const *) argv, environ);
_exit (127);
} else { /* Parent. */
do {
result = waitpid(pid, &status, 0);
} while (result == (pid_t)-1 && errno == EINTR);
if (result != pid)
status = -1;
}
CLEANUP_RESET(0, oldtype);
(void) DO_LOCK ();
if ((SUB_REF (rpmsigTbl_sigchld) == 0 &&
(rpmsqEnable(-SIGINT, NULL) < 0 || rpmsqEnable (-SIGQUIT, NULL) < 0))
|| sigprocmask (SIG_SETMASK, &oldMask, NULL) != 0)
{
status = -1;
}
goto out;
out_restore_sigquit_and_sigint:
(void) rpmsqEnable(-SIGQUIT, NULL);
out_restore_sigint:
(void) rpmsqEnable(-SIGINT, NULL);
out:
(void) DO_UNLOCK ();
return status;
}
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