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-rw-r--r--rpmio/rpmsq.c366
1 files changed, 366 insertions, 0 deletions
diff --git a/rpmio/rpmsq.c b/rpmio/rpmsq.c
new file mode 100644
index 0000000..4e69ad0
--- /dev/null
+++ b/rpmio/rpmsq.c
@@ -0,0 +1,366 @@
+/** \ingroup rpmio
+ * \file rpmio/rpmsq.c
+ */
+
+#include "system.h"
+
+#include <signal.h>
+#include <sys/signal.h>
+#include <sys/wait.h>
+#include <search.h>
+#include <errno.h>
+#include <stdio.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 ADD_REF(__tbl) (__tbl)->active++
+#define SUB_REF(__tbl) --(__tbl)->active
+
+#define ME() ((void *)pthread_self())
+
+#define _RPMSQ_INTERNAL
+#include <rpm/rpmsq.h>
+
+#include "debug.h"
+
+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) {
+ 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) {
+ 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;
+ 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, siginfo_t * 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 = (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);
+ 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;
+ } else { /* Parent. */
+ sq->child = pid;
+ }
+
+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);
+
+ /* Remove processed SIGCHLD item from queue. */
+ xx = rpmsqRemove(sq);
+
+ /* Disable SIGCHLD handler on refcount == 0. */
+ xx = rpmsqEnable(-SIGCHLD, NULL);
+
+ return ret;
+}
+
+pid_t rpmsqWait(rpmsq sq)
+{
+ 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;
+ }
+
+ return sq->reaped;
+}
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