+/*
+ * shared.c: Shared memory handling, and daemon launching
+ *
+ * Author:
+ * Dick Porter (dick@ximian.com)
+ *
+ * (C) 2002 Ximian, Inc.
+ */
+
/*
* Code to support inter-process sharing of handles.
*
* that I may as well take advantage of sysV shared memory too.
* Actually, semaphores seem to be buggy, or I was using them
* incorrectly :-). I've replaced the sysV semaphore with a shared
- * integer controlled with Interlocked functions.
-
+ * integer controlled with Interlocked functions. And I've since
+ * replaced that with a separate process to serialise access to the
+ * shared memory, to avoid the possibility of DOS by leaving the
+ * shared memory locked, and also to allow the shared memory to be
+ * cleaned up.
+ *
* mmap() files have the advantage of avoiding namespace collisions,
* but have the disadvantage of needing cleaning up, and also msync().
* sysV shared memory has a really stupid way of getting random key
* IDs, which can lead to collisions.
*
- * I deliberately don't ever delete the shared memory: I'd like to
- * have been able to set the shared memory segment to destroy itself
- * on last close, but it doesn't support that. (Setting IPC_RMID on a
- * segment causes subsequent shmat() with the same key to get a new
- * segment :-( ). The function to delete the shared memory segment is
- * only called from a debugging tool (mono/handles/shmdel).
+ * Having tried sysv shm, I tested mmap() and found that MAP_SHARED
+ * makes msync() irrelevent, and both types need cleaning up. Seeing
+ * as mmap() doesn't suffer from the bonkers method of allocating
+ * segments, it seems to be the best method.
*
- * w32 processes do not have the POSIX parent-child relationship, so a
- * process handle is available to any other process to find out exit
- * status. Handles are destroyed when the last reference to them is
- * closed. New handles can be created for long lasting items such as
- * processes or threads, and also for named synchronisation objects so
- * long as these haven't been deleted by having the last referencing
- * handle closed.
+ * This shared memory is needed because w32 processes do not have the
+ * POSIX parent-child relationship, so a process handle is available
+ * to any other process to find out exit status. Handles are
+ * destroyed when the last reference to them is closed. New handles
+ * can be created for long lasting items such as processes or threads,
+ * and also for named synchronisation objects so long as these haven't
+ * been deleted by having the last referencing handle closed.
*/
+
#include <config.h>
#include <glib.h>
#include <stdio.h>
+#include <fcntl.h>
#include <unistd.h>
+#include <sys/mman.h>
#include <sys/types.h>
-#include <sys/ipc.h>
-#include <sys/shm.h>
+#include <sys/stat.h>
#include <errno.h>
#include <string.h>
#include <mono/io-layer/wapi.h>
#include <mono/io-layer/wapi-private.h>
#include <mono/io-layer/shared.h>
+#include <mono/io-layer/daemon-private.h>
#undef DEBUG
-gpointer _wapi_shm_attach (gboolean daemon)
+/* Define this to make it easier to run valgrind on the daemon. Then
+ * the first process to start will turn into a daemon without forking
+ * (the debug utility mono/handles/hps is ideal for this.)
+ */
+#undef VALGRINDING
+
+guchar *_wapi_shm_file (_wapi_shm_t type, guint32 segment)
{
- gpointer shm_seg;
- int shm_id;
- key_t key;
- gboolean fork_daemon=FALSE;
- struct _WapiHandleShared_list *data;
-
- /*
- * This is an attempt to get a unique key id. The first arg
- * to ftok is a path, so when the config file support is done
- * we should use that.
+ static guchar file[_POSIX_PATH_MAX];
+ guchar *name = NULL, *filename, *dir, *wapi_dir;
+ gchar machine_name[256];
+
+ if (gethostname(machine_name, sizeof(machine_name)) != 0)
+ machine_name[0] = '\0';
+
+ /* Change the filename whenever the format of the contents
+ * changes
+ */
+ if(type==WAPI_SHM_DATA) {
+ name=g_strdup_printf ("shared_data-%s-%d-%d",
+ machine_name, _WAPI_HANDLE_VERSION, segment);
+ } else if (type==WAPI_SHM_SCRATCH) {
+ name=g_strdup_printf ("shared_scratch-%s-%d-%d",
+ machine_name, _WAPI_HANDLE_VERSION, segment);
+ } else {
+ g_assert_not_reached ();
+ }
+
+ /* I don't know how nfs affects mmap. If mmap() of files on
+ * nfs mounts breaks, then there should be an option to set
+ * the directory.
+ */
+ wapi_dir=getenv ("MONO_SHARED_DIR");
+ if(wapi_dir==NULL) {
+ filename=g_build_filename (g_get_home_dir (), ".wapi", name,
+ NULL);
+ } else {
+ filename=g_build_filename (wapi_dir, ".wapi", name, NULL);
+ }
+ g_free (name);
+
+ g_snprintf (file, _POSIX_PATH_MAX, "%s", filename);
+ g_free (filename);
+
+ /* No need to check if the dir already exists or check
+ * mkdir() errors, because on any error the open() call will
+ * report the problem.
*/
- key=ftok (g_get_home_dir (), _WAPI_HANDLE_VERSION);
+ dir=g_path_get_dirname (file);
+ mkdir (dir, 0755);
+ g_free (dir);
+
+ return(file);
+}
+
+gpointer _wapi_shm_file_expand (gpointer mem, _wapi_shm_t type,
+ guint32 segment, guint32 old_len,
+ guint32 new_len)
+{
+ int fd;
+ gpointer new_mem;
+ guchar *filename=_wapi_shm_file (type, segment);
+ int ret;
+
+ if(old_len>=new_len) {
+ return(mem);
+ }
+
+ munmap (mem, old_len);
+
+ fd=open (filename, O_RDWR, 0600);
+ if(fd==-1) {
+ g_critical (G_GNUC_PRETTY_FUNCTION
+ ": shared file [%s] open error: %s", filename,
+ g_strerror (errno));
+ return(NULL);
+ }
+
+ if(lseek (fd, new_len-1, SEEK_SET)==-1) {
+ g_critical (G_GNUC_PRETTY_FUNCTION
+ ": shared file [%s] lseek error: %s", filename,
+ g_strerror (errno));
+ return(NULL);
+ }
+
+ do {
+ ret=write (fd, "", 1);
+ }
+ while (ret==-1 && errno==EINTR);
+
+ if(ret==-1) {
+ g_critical (G_GNUC_PRETTY_FUNCTION
+ ": shared file [%s] write error: %s", filename,
+ g_strerror (errno));
+ return(NULL);
+ }
+
+ close (fd);
+
+ new_mem=_wapi_shm_file_map (type, segment, NULL, NULL);
+
+ return(new_mem);
+}
+
+static int _wapi_shm_file_open (const guchar *filename, _wapi_shm_t type,
+ gboolean *created)
+{
+ int fd;
+ struct stat statbuf;
+ guint32 wanted_size = 0;
+ int ret;
+
+ if(created) {
+ *created=FALSE;
+ }
+
+ if(type==WAPI_SHM_DATA) {
+ wanted_size=sizeof(struct _WapiHandleShared_list);
+ } else if (type==WAPI_SHM_SCRATCH) {
+ wanted_size=sizeof(struct _WapiHandleScratch) +
+ (_WAPI_SHM_SCRATCH_SIZE - MONO_ZERO_ARRAY_LENGTH);
+ } else {
+ g_assert_not_reached ();
+ }
try_again:
- shm_id=shmget (key, sizeof(struct _WapiHandleShared_list)+
- _WAPI_SHM_SCRATCH_SIZE, IPC_CREAT | IPC_EXCL | 0600);
- if(shm_id==-1 && errno==EEXIST) {
- /* Cool, we dont have to fork the handle daemon, but
- * we still need to try and get the shm_id.
- */
- shm_id=shmget (key, 0, 0600);
-
- /* it's possible that the shared memory segment was
- * deleted in between seeing if it exists, and
- * attaching it. If we got an error here, just try
- * attaching it again.
+ /* No O_CREAT yet, because we need to initialise the file if
+ * we have to create it.
+ */
+ fd=open (filename, O_RDWR, 0600);
+ if(fd==-1 && errno==ENOENT) {
+ /* OK, its up to us to create it. O_EXCL to avoid a
+ * race condition where two processes can
+ * simultaneously try and create the file
*/
- if(shm_id==-1) {
+ fd=open (filename, O_CREAT|O_EXCL|O_RDWR, 0600);
+ if(fd==-1 && errno==EEXIST) {
+ /* It's possible that the file was created in
+ * between finding it didn't exist, and trying
+ * to create it. Just try opening it again
+ */
goto try_again;
- }
- } else if (shm_id!=-1) {
- /* We created the shared memory segment, so we need to
- * fork the handle daemon too
- */
- fork_daemon=TRUE;
+ } else if (fd==-1) {
+ g_critical (G_GNUC_PRETTY_FUNCTION
+ ": shared file [%s] open error: %s",
+ filename, g_strerror (errno));
+ return(-1);
+ } else {
+ /* We created the file, so we need to expand
+ * the file and inform the caller so it can
+ * fork the handle daemon too.
+ *
+ * (wanted_size-1, because we're about to
+ * write the other byte to actually expand the
+ * file.)
+ */
+ if(lseek (fd, wanted_size-1, SEEK_SET)==-1) {
+ g_critical (G_GNUC_PRETTY_FUNCTION ": shared file [%s] lseek error: %s", filename, g_strerror (errno));
+ close (fd);
+ unlink (filename);
+ return(-1);
+ }
+
+ do {
+ ret=write (fd, "", 1);
+ }
+ while (ret==-1 && errno==EINTR);
+
+ if(ret==-1) {
+ g_critical (G_GNUC_PRETTY_FUNCTION ": shared file [%s] write error: %s", filename, g_strerror (errno));
+ close (fd);
+ unlink (filename);
+ return(-1);
+ }
+
+ if(created) {
+ *created=TRUE;
+ }
- /* sysv shared mem is set to all zero when allocated,
- * so we don't need to do any more initialisation here
- */
- } else {
- /* Some error other than EEXIST */
- g_message (G_GNUC_PRETTY_FUNCTION ": shmget error: %s",
- strerror (errno));
- exit (-1);
+ /* The contents of the file is set to all
+ * zero, because it is opened up with lseek,
+ * so we don't need to do any more
+ * initialisation here
+ */
+ }
+ } else if(fd==-1) {
+ g_critical (G_GNUC_PRETTY_FUNCTION
+ ": shared file [%s] open error: %s", filename,
+ g_strerror (errno));
+ return(-1);
}
- /* From now on, we need to delete the shm segment before
- * exiting on error if we created it (ie, if
- * fork_daemon==TRUE)
+ /* From now on, we need to delete the file before exiting on
+ * error if we created it (ie, if *created==TRUE)
*/
- shm_seg=shmat (shm_id, NULL, 0);
- if(shm_seg==(gpointer)-1) {
- g_message (G_GNUC_PRETTY_FUNCTION ": shmat error: %s",
- strerror (errno));
- if(fork_daemon==TRUE) {
- _wapi_shm_destroy ();
+
+ /* Use stat to find the file size (instead of hard coding it)
+ * because we can expand the file later if needed (for more
+ * handles or scratch space.)
+ */
+ if(fstat (fd, &statbuf)==-1) {
+ g_critical (G_GNUC_PRETTY_FUNCTION ": fstat error: %s",
+ g_strerror (errno));
+ if(created && *created==TRUE) {
+ unlink (filename);
}
- exit (-1);
+ close (fd);
+ return(-1);
}
- if(daemon==TRUE) {
- /* No more to do in the daemon */
- return(shm_seg);
+ if(statbuf.st_size < wanted_size) {
+ close (fd);
+ if(created && *created==TRUE) {
+#ifdef HAVE_LARGE_FILE_SUPPORT
+ /* Keep gcc quiet... */
+ g_critical (G_GNUC_PRETTY_FUNCTION ": shared file [%s] is not big enough! (found %lld, need %d bytes)", filename, statbuf.st_size, wanted_size);
+#else
+ g_critical (G_GNUC_PRETTY_FUNCTION ": shared file [%s] is not big enough! (found %ld, need %d bytes)", filename, statbuf.st_size, wanted_size);
+#endif
+ unlink (filename);
+ return(-1);
+ } else {
+ /* We didn't create it, so just try opening it again */
+ goto try_again;
+ }
+ }
+
+ return(fd);
+}
+
+gpointer _wapi_shm_file_map (_wapi_shm_t type, guint32 segment,
+ gboolean *created, off_t *size)
+{
+ gpointer shm_seg;
+ int fd;
+ struct stat statbuf;
+ guchar *filename=_wapi_shm_file (type, segment);
+
+ fd=_wapi_shm_file_open (filename, type, created);
+ if(fd==-1) {
+ g_critical (G_GNUC_PRETTY_FUNCTION
+ ": shared file [%s] open error", filename);
+ return(NULL);
+ }
+
+ if(fstat (fd, &statbuf)==-1) {
+ g_critical (G_GNUC_PRETTY_FUNCTION ": fstat error: %s",
+ g_strerror (errno));
+ close (fd);
+ return(NULL);
+ }
+ if(size) {
+ *size=statbuf.st_size;
+ }
+
+ shm_seg=mmap (NULL, statbuf.st_size, PROT_READ|PROT_WRITE, MAP_SHARED,
+ fd, 0);
+ if(shm_seg==MAP_FAILED) {
+ g_critical (G_GNUC_PRETTY_FUNCTION ": mmap error: %s",
+ g_strerror (errno));
+ close (fd);
+ return(NULL);
}
- data=shm_seg;
+ close (fd);
+ return(shm_seg);
+}
+
+/*
+ * _wapi_shm_attach:
+ * @success: Was it a success
+ *
+ * Attach to the shared memory file or create it if it did not
+ * exist. If it was created and daemon was FALSE a new daemon is
+ * forked into existence. Returns the memory area the file was mmapped
+ * to.
+ */
+gboolean _wapi_shm_attach (struct _WapiHandleShared_list **data,
+ struct _WapiHandleScratch **scratch)
+{
+ gboolean data_created=FALSE, scratch_created=FALSE;
+ off_t data_size, scratch_size;
+ int tries, closing_tries=0;
+
+map_again:
+ *data=_wapi_shm_file_map (WAPI_SHM_DATA, 0, &data_created, &data_size);
+ if(*data==NULL) {
+ return(FALSE);
+ }
+
+ *scratch=_wapi_shm_file_map (WAPI_SHM_SCRATCH, 0, &scratch_created,
+ &scratch_size);
+ if(*scratch==NULL) {
+ if(data_created) {
+ _wapi_shm_destroy ();
+ }
+ return(FALSE);
+ }
+
+ if(scratch_created)
+ (*scratch)->data_len = scratch_size -
+ (sizeof(struct _WapiHandleScratch) - MONO_ZERO_ARRAY_LENGTH);
- if(fork_daemon==TRUE) {
+ if(data_created==FALSE && (*data)->daemon_running==DAEMON_CLOSING) {
+ /* Daemon is closing down, give it a few ms and try
+ * again.
+ */
+
+ struct timespec sleepytime;
+
+ /* Something must have gone wrong, so delete the
+ * shared segments and try again.
+ */
+ _wapi_shm_destroy ();
+
+ munmap (*data, data_size);
+ munmap (*scratch, scratch_size);
+
+ if(closing_tries++ == 5) {
+ /* Still can't get going, so bail out */
+ g_warning ("The handle daemon is stuck closing");
+ return(FALSE);
+ }
+
+ sleepytime.tv_sec=0;
+ sleepytime.tv_nsec=10000000; /* 10ms */
+
+ nanosleep (&sleepytime, NULL);
+ goto map_again;
+ }
+
+ if(data_created==TRUE) {
+#ifdef VALGRINDING
+ /* _wapi_daemon_main() does not return */
+ _wapi_daemon_main (*data, *scratch);
+
+ /* But just in case... */
+ (*data)->daemon_running=DAEMON_DIED_AT_STARTUP;
+ exit (-1);
+#else
pid_t pid;
pid=fork ();
if(pid==-1) {
- g_message (G_GNUC_PRETTY_FUNCTION ": fork error: %s",
- strerror (errno));
+ g_critical (G_GNUC_PRETTY_FUNCTION ": fork error: %s",
+ strerror (errno));
_wapi_shm_destroy ();
- exit (-1);
+ return(FALSE);
} else if (pid==0) {
+ int i;
+
/* child */
setsid ();
- execl (MONO_BINDIR "/mono-handle-d", "mono-handle-d",
- NULL);
- g_message (G_GNUC_PRETTY_FUNCTION ": exec error: %s",
- strerror (errno));
- data->daemon_running=2;
+
+ /* FIXME: Set process title to something
+ * informative
+ */
+
+ /* Start the daemon with a clean sheet of file
+ * descriptors
+ */
+ for(i=3; i<getdtablesize (); i++) {
+ close (i);
+ }
+
+ /* _wapi_daemon_main() does not return */
+ _wapi_daemon_main (*data, *scratch);
+
+ /* But just in case... */
+ (*data)->daemon_running=DAEMON_DIED_AT_STARTUP;
exit (-1);
}
/* parent carries on */
+#ifdef DEBUG
+ g_message (G_GNUC_PRETTY_FUNCTION ": Daemon pid %d", pid);
+#endif
+#endif /* !VALGRINDING */
}
- /* Set up the handle daemon connection */
-
- while(data->daemon_running==0) {
+ for(tries=0; (*data)->daemon_running==DAEMON_STARTING && tries < 100;
+ tries++) {
/* wait for the daemon to sort itself out. To be
* completely safe, we should have a timeout before
* giving up.
nanosleep (&sleepytime, NULL);
}
- if(data->daemon_running==2) {
+ if(tries==100 && (*data)->daemon_running==DAEMON_STARTING) {
+ /* Daemon didnt get going */
+ struct timespec sleepytime;
+
+ /* Something must have gone wrong, so delete the
+ * shared segments and try again.
+ */
+ _wapi_shm_destroy ();
+
+ /* Daemon didn't get going, give it a few ms and try
+ * again.
+ */
+
+ munmap (*data, data_size);
+ munmap (*scratch, scratch_size);
+
+ if(closing_tries++ == 5) {
+ /* Still can't get going, so bail out */
+ g_warning ("The handle daemon didnt start up properly");
+ return(FALSE);
+ }
+
+ sleepytime.tv_sec=0;
+ sleepytime.tv_nsec=10000000; /* 10ms */
+
+ nanosleep (&sleepytime, NULL);
+ goto map_again;
+ }
+
+ if((*data)->daemon_running==DAEMON_DIED_AT_STARTUP) {
/* Oh dear, the daemon had an error starting up */
- if(fork_daemon==TRUE) {
+ if(data_created==TRUE) {
_wapi_shm_destroy ();
}
- g_error ("Handle daemon failed to start");
+ g_warning ("Handle daemon failed to start");
+ return(FALSE);
+ }
+
+ /* Do some sanity checking on the shared memory we
+ * attached
+ */
+ if(((*data)->daemon_running!=DAEMON_RUNNING) ||
+#ifdef NEED_LINK_UNLINK
+ (strncmp ((*data)->daemon, "/tmp/mono-handle-daemon-",
+ 24)!=0)) {
+#else
+ (strncmp ((*data)->daemon+1, "mono-handle-daemon-", 19)!=0)) {
+#endif
+ g_warning ("Shared memory sanity check failed.");
+ g_warning("status: %d", (*data)->daemon_running);
+#ifdef NEED_LINK_UNLINK
+ g_warning("daemon: [%s]", (*data)->daemon);
+#else
+ g_warning("daemon: [%s]", (*data)->daemon+1);
+#endif
+ return(FALSE);
}
/* From now on, it's up to the daemon to delete the shared
* memory segment
*/
-
- return(shm_seg);
+
+ return(TRUE);
}
void _wapi_shm_destroy (void)
{
#ifndef DISABLE_SHARED_HANDLES
- int shm_id;
- key_t key;
-
- /*
- * This is an attempt to get a unique key id. The
- * first arg to ftok is a path, so when the config
- * file support is done we should use that.
+#ifdef DEBUG
+ g_message (G_GNUC_PRETTY_FUNCTION ": unlinking shared data");
+#endif
+ /* Only delete the first segments. The daemon will destroy
+ * any others when it exits
*/
- key=ftok (g_get_home_dir (), _WAPI_HANDLE_VERSION);
-
- shm_id=shmget (key, 0, 0600);
- if(shm_id==-1 && errno==ENOENT) {
- return;
- } else if (shm_id==-1) {
- g_message (G_GNUC_PRETTY_FUNCTION ": shmget error: %s",
- strerror (errno));
- exit (-1);
- }
- if(shmctl (shm_id, IPC_RMID, NULL)==-1) {
- g_message (G_GNUC_PRETTY_FUNCTION ": shmctl error: %s",
- strerror (errno));
- exit (-1);
- }
+ unlink (_wapi_shm_file (WAPI_SHM_DATA, 0));
+ unlink (_wapi_shm_file (WAPI_SHM_SCRATCH, 0));
#endif /* DISABLE_SHARED_HANDLES */
}
+
projects / mono.git / blobdiff