Commit adb696f3 authored by Corey Bryant's avatar Corey Bryant Committed by Kevin Wolf
Browse files

block: Enable qemu_open/close to work with fd sets 



When qemu_open is passed a filename of the "/dev/fdset/nnn"
format (where nnn is the fdset ID), an fd with matching access
mode flags will be searched for within the specified monitor
fd set.  If the fd is found, a dup of the fd will be returned
from qemu_open.

Signed-off-by: default avatarCorey Bryant <coreyb@linux.vnet.ibm.com>
Signed-off-by: default avatarKevin Wolf <kwolf@redhat.com>
parent 2e1e79da

Makefile

+3 −3
Original line number Diff line number Diff line
@@ -148,9 +148,6 @@ install-libcacard: libcacard.la 
	$(call quiet-command,$(MAKE) $(SUBDIR_MAKEFLAGS) -C libcacard V="$(V)" TARGET_DIR="$*/" install-libcacard,)

endif



vscclient$(EXESUF): $(libcacard-y) $(oslib-obj-y) $(trace-obj-y) qemu-timer-common.o libcacard/vscclient.o

	$(call quiet-command,$(CC) $(LDFLAGS) -o $@ $^ $(libcacard_libs) $(LIBS),"  LINK  $@")



######################################################################



qemu-img.o: qemu-img-cmds.h
@@ -166,6 +163,9 @@ qemu-io$(EXESUF): qemu-io.o cmd.o $(tools-obj-y) $(block-obj-y) 


qemu-bridge-helper$(EXESUF): qemu-bridge-helper.o



vscclient$(EXESUF): $(libcacard-y) $(oslib-obj-y) $(trace-obj-y) $(tools-obj-y) qemu-timer-common.o libcacard/vscclient.o

	$(call quiet-command,$(CC) $(LDFLAGS) -o $@ $^ $(libcacard_libs) $(LIBS),"  LINK  $@")



fsdev/virtfs-proxy-helper$(EXESUF): fsdev/virtfs-proxy-helper.o fsdev/virtio-9p-marshal.o oslib-posix.o $(trace-obj-y)

fsdev/virtfs-proxy-helper$(EXESUF): LIBS += -lcap

cutils.c

+5 −0
Original line number Diff line number Diff line
@@ -383,6 +383,11 @@ int qemu_parse_fd(const char *param) 
    return fd;

}



int qemu_parse_fdset(const char *param)

{

    return qemu_parse_fd(param);

}



/* round down to the nearest power of 2*/

int64_t pow2floor(int64_t value)

{

monitor.c

+85 −1
Original line number Diff line number Diff line
@@ -154,6 +154,7 @@ typedef struct MonFdset MonFdset; 
struct MonFdset {

    int64_t id;

    QLIST_HEAD(, MonFdsetFd) fds;

    QLIST_HEAD(, MonFdsetFd) dup_fds;

    QLIST_ENTRY(MonFdset) next;

};
@@ -2398,7 +2399,7 @@ static void monitor_fdset_cleanup(MonFdset *mon_fdset) 
        }

    }



    if (QLIST_EMPTY(&mon_fdset->fds)) {

    if (QLIST_EMPTY(&mon_fdset->fds) && QLIST_EMPTY(&mon_fdset->dup_fds)) {

        QLIST_REMOVE(mon_fdset, next);

        g_free(mon_fdset);

    }
@@ -2555,6 +2556,89 @@ FdsetInfoList *qmp_query_fdsets(Error **errp) 
    return fdset_list;

}



int monitor_fdset_get_fd(int64_t fdset_id, int flags)

{

    MonFdset *mon_fdset;

    MonFdsetFd *mon_fdset_fd;

    int mon_fd_flags;



#ifndef _WIN32

    QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {

        if (mon_fdset->id != fdset_id) {

            continue;

        }

        QLIST_FOREACH(mon_fdset_fd, &mon_fdset->fds, next) {

            mon_fd_flags = fcntl(mon_fdset_fd->fd, F_GETFL);

            if (mon_fd_flags == -1) {

                return -1;

            }



            if ((flags & O_ACCMODE) == (mon_fd_flags & O_ACCMODE)) {

                return mon_fdset_fd->fd;

            }

        }

        errno = EACCES;

        return -1;

    }

#endif



    errno = ENOENT;

    return -1;

}



int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd)

{

    MonFdset *mon_fdset;

    MonFdsetFd *mon_fdset_fd_dup;



    QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {

        if (mon_fdset->id != fdset_id) {

            continue;

        }

        QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) {

            if (mon_fdset_fd_dup->fd == dup_fd) {

                return -1;

            }

        }

        mon_fdset_fd_dup = g_malloc0(sizeof(*mon_fdset_fd_dup));

        mon_fdset_fd_dup->fd = dup_fd;

        QLIST_INSERT_HEAD(&mon_fdset->dup_fds, mon_fdset_fd_dup, next);

        return 0;

    }

    return -1;

}



static int monitor_fdset_dup_fd_find_remove(int dup_fd, bool remove)

{

    MonFdset *mon_fdset;

    MonFdsetFd *mon_fdset_fd_dup;



    QLIST_FOREACH(mon_fdset, &mon_fdsets, next) {

        QLIST_FOREACH(mon_fdset_fd_dup, &mon_fdset->dup_fds, next) {

            if (mon_fdset_fd_dup->fd == dup_fd) {

                if (remove) {

                    QLIST_REMOVE(mon_fdset_fd_dup, next);

                    if (QLIST_EMPTY(&mon_fdset->dup_fds)) {

                        monitor_fdset_cleanup(mon_fdset);

                    }

                }

                return mon_fdset->id;

            }

        }

    }

    return -1;

}



int monitor_fdset_dup_fd_find(int dup_fd)

{

    return monitor_fdset_dup_fd_find_remove(dup_fd, false);

}



int monitor_fdset_dup_fd_remove(int dup_fd)

{

    return monitor_fdset_dup_fd_find_remove(dup_fd, true);

}



/* mon_cmds and info_cmds would be sorted at runtime */

static mon_cmd_t mon_cmds[] = {

#include "hmp-commands.h"

monitor.h

+5 −0
Original line number Diff line number Diff line
@@ -87,4 +87,9 @@ int qmp_qom_set(Monitor *mon, const QDict *qdict, QObject **ret); 


int qmp_qom_get(Monitor *mon, const QDict *qdict, QObject **ret);



int monitor_fdset_get_fd(int64_t fdset_id, int flags);

int monitor_fdset_dup_fd_add(int64_t fdset_id, int dup_fd);

int monitor_fdset_dup_fd_remove(int dup_fd);

int monitor_fdset_dup_fd_find(int dup_fd);



#endif /* !MONITOR_H */

osdep.c

+111 −0
Original line number Diff line number Diff line
@@ -48,6 +48,7 @@ extern int madvise(caddr_t, size_t, int); 
#include "qemu-common.h"

#include "trace.h"

#include "qemu_socket.h"

#include "monitor.h"



static bool fips_enabled = false;
@@ -78,6 +79,66 @@ int qemu_madvise(void *addr, size_t len, int advice) 
#endif

}



#ifndef _WIN32

/*

 * Dups an fd and sets the flags

 */

static int qemu_dup_flags(int fd, int flags)

{

    int ret;

    int serrno;

    int dup_flags;

    int setfl_flags;



#ifdef F_DUPFD_CLOEXEC

    ret = fcntl(fd, F_DUPFD_CLOEXEC, 0);

#else

    ret = dup(fd);

    if (ret != -1) {

        qemu_set_cloexec(ret);

    }

#endif

    if (ret == -1) {

        goto fail;

    }



    dup_flags = fcntl(ret, F_GETFL);

    if (dup_flags == -1) {

        goto fail;

    }



    if ((flags & O_SYNC) != (dup_flags & O_SYNC)) {

        errno = EINVAL;

        goto fail;

    }



    /* Set/unset flags that we can with fcntl */

    setfl_flags = O_APPEND | O_ASYNC | O_DIRECT | O_NOATIME | O_NONBLOCK;

    dup_flags &= ~setfl_flags;

    dup_flags |= (flags & setfl_flags);

    if (fcntl(ret, F_SETFL, dup_flags) == -1) {

        goto fail;

    }



    /* Truncate the file in the cases that open() would truncate it */

    if (flags & O_TRUNC ||

            ((flags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))) {

        if (ftruncate(ret, 0) == -1) {

            goto fail;

        }

    }



    return ret;



fail:

    serrno = errno;

    if (ret != -1) {

        close(ret);

    }

    errno = serrno;

    return -1;

}

#endif



/*

 * Opens a file with FD_CLOEXEC set
@@ -87,6 +148,41 @@ int qemu_open(const char *name, int flags, ...) 
    int ret;

    int mode = 0;



#ifndef _WIN32

    const char *fdset_id_str;



    /* Attempt dup of fd from fd set */

    if (strstart(name, "/dev/fdset/", &fdset_id_str)) {

        int64_t fdset_id;

        int fd, dupfd;



        fdset_id = qemu_parse_fdset(fdset_id_str);

        if (fdset_id == -1) {

            errno = EINVAL;

            return -1;

        }



        fd = monitor_fdset_get_fd(fdset_id, flags);

        if (fd == -1) {

            return -1;

        }



        dupfd = qemu_dup_flags(fd, flags);

        if (dupfd == -1) {

            return -1;

        }



        ret = monitor_fdset_dup_fd_add(fdset_id, dupfd);

        if (ret == -1) {

            close(dupfd);

            errno = EINVAL;

            return -1;

        }



        return dupfd;

    }

#endif



    if (flags & O_CREAT) {

        va_list ap;
@@ -109,6 +205,21 @@ int qemu_open(const char *name, int flags, ...) 


int qemu_close(int fd)

{

    int64_t fdset_id;



    /* Close fd that was dup'd from an fdset */

    fdset_id = monitor_fdset_dup_fd_find(fd);

    if (fdset_id != -1) {

        int ret;



        ret = close(fd);

        if (ret == 0) {

            monitor_fdset_dup_fd_remove(fd);

        }



        return ret;

    }



    return close(fd);

}