qmp_add_fd() gets an fd that was received over a socket with SCM_RIGHTS and adds it to an fd set. This patch adds support that will enable adding an fd that was inherited on the command line to an fd set. Note: All of the code added to monitor_fdset_add_fd(), with the exception of the error path for non-valid fdset-id, is code motion from qmp_add_fd(). Signed-off-by: Corey Bryant <coreyb@linux.vnet.ibm.com> Reviewed-by: Eric Blake <eblake@redhat.com> --- v2: -Removed Error** parameter from monitor_fdset_add_fd() v3: -Added Error** parameter back to monitor_fdset_add_fd() -Move 'if (!mon_fdset_cur)' change to patch 1 (kwolf@redhat.com) -Move code that prevents removal of fd from fd set during init to it's own patch (eblake@redhat.com, kwolf@redhat.com) -Mention code motion in commit message (kwolf@redhat.com) v4: -Fix fd leak in qmp_add_fd() (kwolf@redhat.com) monitor.c | 157 ++++++++++++++++++++++++++++++++++---------------------------- monitor.h | 3 ++ 2 files changed, 88 insertions(+), 72 deletions(-) diff --git a/monitor.c b/monitor.c index 2e3248f..d8f66ca 100644 --- a/monitor.c +++ b/monitor.c @@ -2135,8 +2135,6 @@ AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id, bool has_opaque, { int fd; Monitor *mon = cur_mon; - MonFdset *mon_fdset = NULL; - MonFdsetFd *mon_fdset_fd; AddfdInfo *fdinfo; fd = qemu_chr_fe_get_msgfd(mon->chr); @@ -2145,78 +2143,12 @@ AddfdInfo *qmp_add_fd(bool has_fdset_id, int64_t fdset_id, bool has_opaque, goto error; } - if (has_fdset_id) { - QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { - /* Break if match found or match impossible due to ordering by ID */ - if (fdset_id <= mon_fdset->id) { - if (fdset_id < mon_fdset->id) { - mon_fdset = NULL; - } - break; - } - } + fdinfo = monitor_fdset_add_fd(fd, has_fdset_id, fdset_id, + has_opaque, opaque, errp); + if (fdinfo) { + return fdinfo; } - if (mon_fdset == NULL) { - int64_t fdset_id_prev = -1; - MonFdset *mon_fdset_cur = QLIST_FIRST(&mon_fdsets); - - if (has_fdset_id) { - if (fdset_id < 0) { - error_set(errp, QERR_INVALID_PARAMETER_VALUE, "fdset-id", - "a non-negative value"); - goto error; - } - /* Use specified fdset ID */ - QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { - mon_fdset_cur = mon_fdset; - if (fdset_id < mon_fdset_cur->id) { - break; - } - } - } else { - /* Use first available fdset ID */ - QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { - mon_fdset_cur = mon_fdset; - if (fdset_id_prev == mon_fdset_cur->id - 1) { - fdset_id_prev = mon_fdset_cur->id; - continue; - } - break; - } - } - - mon_fdset = g_malloc0(sizeof(*mon_fdset)); - if (has_fdset_id) { - mon_fdset->id = fdset_id; - } else { - mon_fdset->id = fdset_id_prev + 1; - } - - /* The fdset list is ordered by fdset ID */ - if (!mon_fdset_cur) { - QLIST_INSERT_HEAD(&mon_fdsets, mon_fdset, next); - } else if (mon_fdset->id < mon_fdset_cur->id) { - QLIST_INSERT_BEFORE(mon_fdset_cur, mon_fdset, next); - } else { - QLIST_INSERT_AFTER(mon_fdset_cur, mon_fdset, next); - } - } - - mon_fdset_fd = g_malloc0(sizeof(*mon_fdset_fd)); - mon_fdset_fd->fd = fd; - mon_fdset_fd->removed = false; - if (has_opaque) { - mon_fdset_fd->opaque = g_strdup(opaque); - } - QLIST_INSERT_HEAD(&mon_fdset->fds, mon_fdset_fd, next); - - fdinfo = g_malloc0(sizeof(*fdinfo)); - fdinfo->fdset_id = mon_fdset->id; - fdinfo->fd = mon_fdset_fd->fd; - - return fdinfo; - error: if (fd != -1) { close(fd); @@ -2301,6 +2233,87 @@ FdsetInfoList *qmp_query_fdsets(Error **errp) return fdset_list; } +AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id, + bool has_opaque, const char *opaque, + Error **errp) +{ + MonFdset *mon_fdset = NULL; + MonFdsetFd *mon_fdset_fd; + AddfdInfo *fdinfo; + + if (has_fdset_id) { + QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { + /* Break if match found or match impossible due to ordering by ID */ + if (fdset_id <= mon_fdset->id) { + if (fdset_id < mon_fdset->id) { + mon_fdset = NULL; + } + break; + } + } + } + + if (mon_fdset == NULL) { + int64_t fdset_id_prev = -1; + MonFdset *mon_fdset_cur = QLIST_FIRST(&mon_fdsets); + + if (has_fdset_id) { + if (fdset_id < 0) { + error_set(errp, QERR_INVALID_PARAMETER_VALUE, "fdset-id", + "a non-negative value"); + return NULL; + } + /* Use specified fdset ID */ + QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { + mon_fdset_cur = mon_fdset; + if (fdset_id < mon_fdset_cur->id) { + break; + } + } + } else { + /* Use first available fdset ID */ + QLIST_FOREACH(mon_fdset, &mon_fdsets, next) { + mon_fdset_cur = mon_fdset; + if (fdset_id_prev == mon_fdset_cur->id - 1) { + fdset_id_prev = mon_fdset_cur->id; + continue; + } + break; + } + } + + mon_fdset = g_malloc0(sizeof(*mon_fdset)); + if (has_fdset_id) { + mon_fdset->id = fdset_id; + } else { + mon_fdset->id = fdset_id_prev + 1; + } + + /* The fdset list is ordered by fdset ID */ + if (!mon_fdset_cur) { + QLIST_INSERT_HEAD(&mon_fdsets, mon_fdset, next); + } else if (mon_fdset->id < mon_fdset_cur->id) { + QLIST_INSERT_BEFORE(mon_fdset_cur, mon_fdset, next); + } else { + QLIST_INSERT_AFTER(mon_fdset_cur, mon_fdset, next); + } + } + + mon_fdset_fd = g_malloc0(sizeof(*mon_fdset_fd)); + mon_fdset_fd->fd = fd; + mon_fdset_fd->removed = false; + if (has_opaque) { + mon_fdset_fd->opaque = g_strdup(opaque); + } + QLIST_INSERT_HEAD(&mon_fdset->fds, mon_fdset_fd, next); + + fdinfo = g_malloc0(sizeof(*fdinfo)); + fdinfo->fdset_id = mon_fdset->id; + fdinfo->fd = mon_fdset_fd->fd; + + return fdinfo; +} + int monitor_fdset_get_fd(int64_t fdset_id, int flags) { #ifndef _WIN32 diff --git a/monitor.h b/monitor.h index b6e7d95..d4c017e 100644 --- a/monitor.h +++ b/monitor.h @@ -90,6 +90,9 @@ int qmp_qom_set(Monitor *mon, const QDict *qdict, QObject **ret); int qmp_qom_get(Monitor *mon, const QDict *qdict, QObject **ret); +AddfdInfo *monitor_fdset_add_fd(int fd, bool has_fdset_id, int64_t fdset_id, + bool has_opaque, const char *opaque, + Error **errp); 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); -- 1.7.11.4

This option can be used for passing file descriptors on the command line. It mirrors the existing add-fd QMP command which allows an fd to be passed to QEMU via SCM_RIGHTS and added to an fd set. This can be combined with commands such as -drive to link file descriptors in an fd set to a drive: qemu-kvm -add-fd fd=3,set=2,opaque="rdwr:/path/to/file" -add-fd fd=4,set=2,opaque="rdonly:/path/to/file" -drive file=/dev/fdset/2,index=0,media=disk This example adds dups of fds 3 and 4, and the accompanying opaque strings to the fd set with ID=2. qemu_open() already knows how to handle a filename of this format. qemu_open() searches the corresponding fd set for an fd and when it finds a match, QEMU goes on to use a dup of that fd just like it would have used an fd that it opened itself. Signed-off-by: Corey Bryant <coreyb@linux.vnet.ibm.com> --- v2: - The -add-fd option is new in v2 (eblake@redhat.com) v3: - Require passed fd to be > stderr (eblake@redhat.com) - Changed fds in examples to fd=3 and fd=4 - Add dup of passed fd to fd set and close passed fds after processing all -add-fd commands (eblake@redhat.com) v4 - Update fd numbers in commit message text (eblake@redhat.com) - Handle corner case of -add-fd using an fd that is already in use by QEMU (eblake@redhat.com) qemu-config.c | 22 ++++++++++++++++ qemu-options.hx | 36 ++++++++++++++++++++++++++ vl.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 136 insertions(+) diff --git a/qemu-config.c b/qemu-config.c index cd1ec21..601237d 100644 --- a/qemu-config.c +++ b/qemu-config.c @@ -653,6 +653,27 @@ QemuOptsList qemu_boot_opts = { }, }; +static QemuOptsList qemu_add_fd_opts = { + .name = "add-fd", + .head = QTAILQ_HEAD_INITIALIZER(qemu_add_fd_opts.head), + .desc = { + { + .name = "fd", + .type = QEMU_OPT_NUMBER, + .help = "file descriptor of which a duplicate is added to fd set", + },{ + .name = "set", + .type = QEMU_OPT_NUMBER, + .help = "ID of the fd set to add fd to", + },{ + .name = "opaque", + .type = QEMU_OPT_STRING, + .help = "free-form string used to describe fd", + }, + { /* end of list */ } + }, +}; + static QemuOptsList *vm_config_groups[32] = { &qemu_drive_opts, &qemu_chardev_opts, @@ -669,6 +690,7 @@ static QemuOptsList *vm_config_groups[32] = { &qemu_boot_opts, &qemu_iscsi_opts, &qemu_sandbox_opts, + &qemu_add_fd_opts, NULL, }; diff --git a/qemu-options.hx b/qemu-options.hx index 7d97f96..a70182a 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -257,6 +257,14 @@ qemu-system-i386 -drive file=file,index=2,media=disk qemu-system-i386 -drive file=file,index=3,media=disk @end example +You can open an image using pre-opened file descriptors from an fd set: +@example +qemu-system-i386 +-add-fd fd=3,set=2,opaque="rdwr:/path/to/file" +-add-fd fd=4,set=2,opaque="rdonly:/path/to/file" +-drive file=/dev/fdset/2,index=0,media=disk +@end example + You can connect a CDROM to the slave of ide0: @example qemu-system-i386 -drive file=file,if=ide,index=1,media=cdrom @@ -289,6 +297,34 @@ qemu-system-i386 -hda a -hdb b @end example ETEXI +DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd, + "-add-fd fd=fd,set=set[,opaque=opaque]\n" + " Add 'fd' to fd 'set'\n", QEMU_ARCH_ALL) +STEXI +@item -add-fd fd=@var{fd},set=@var{set}[,opaque=@var{opaque}] +@findex -add-fd + +Add a file descriptor to an fd set. Valid options are: + +@table @option +@item fd=@var{fd} +This option defines the file descriptor of which a duplicate is added to fd set. +The file descriptor cannot be stdin, stdout, or stderr. +@item set=@var{set} +This option defines the ID of the fd set to add the file descriptor to. +@item opaque=@var{opaque} +This option defines a free-form string that can be used to describe @var{fd}. +@end table + +You can open an image using pre-opened file descriptors from an fd set: +@example +qemu-system-i386 +-add-fd fd=3,set=2,opaque="rdwr:/path/to/file" +-add-fd fd=4,set=2,opaque="rdonly:/path/to/file" +-drive file=/dev/fdset/2,index=0,media=disk +@end example +ETEXI + DEF("set", HAS_ARG, QEMU_OPTION_set, "-set group.id.arg=value\n" " set <arg> parameter for item <id> of type <group>\n" diff --git a/vl.c b/vl.c index 5b357a3..47095a2 100644 --- a/vl.c +++ b/vl.c @@ -790,6 +790,71 @@ static int parse_sandbox(QemuOpts *opts, void *opaque) return 0; } +static int parse_add_fd(QemuOpts *opts, void *opaque) +{ + int fd, dupfd; + int64_t fdset_id; + const char *fd_opaque = NULL; + + fd = qemu_opt_get_number(opts, "fd", -1); + fdset_id = qemu_opt_get_number(opts, "set", -1); + fd_opaque = qemu_opt_get(opts, "opaque"); + + if (fd < 0) { + qerror_report(ERROR_CLASS_GENERIC_ERROR, + "fd option is required and must be non-negative"); + return -1; + } + + if (fd <= STDERR_FILENO) { + qerror_report(ERROR_CLASS_GENERIC_ERROR, + "fd cannot be a standard I/O stream"); + return -1; + } + + if (fcntl(fd, F_GETFD) & FD_CLOEXEC) { + qerror_report(ERROR_CLASS_GENERIC_ERROR, + "fd is not valid or already in use"); + return -1; + } + + if (fdset_id < 0) { + qerror_report(ERROR_CLASS_GENERIC_ERROR, + "set option is required and must be non-negative"); + return -1; + } + +#ifdef F_DUPFD_CLOEXEC + dupfd = fcntl(fd, F_DUPFD_CLOEXEC, 0); +#else + dupfd = dup(fd); + if (dupfd != -1) { + qemu_set_cloexec(dupfd); + } +#endif + if (dupfd == -1) { + qerror_report(ERROR_CLASS_GENERIC_ERROR, + "Error duplicating fd: %s", strerror(errno)); + return -1; + } + + /* add the duplicate fd, and optionally the opaque string, to the fd set */ + monitor_fdset_add_fd(dupfd, true, fdset_id, fd_opaque ? true : false, + fd_opaque, NULL); + + return 0; +} + +static int cleanup_add_fd(QemuOpts *opts, void *opaque) +{ + int fd; + + fd = qemu_opt_get_number(opts, "fd", -1); + close(fd); + + return 0; +} + /***********************************************************/ /* QEMU Block devices */ @@ -3309,6 +3374,11 @@ int main(int argc, char **argv, char **envp) exit(0); } break; + case QEMU_OPTION_add_fd: + opts = qemu_opts_parse(qemu_find_opts("add-fd"), optarg, 0); + if (!opts) { + exit(0); + } default: os_parse_cmd_args(popt->index, optarg); } @@ -3320,6 +3390,14 @@ int main(int argc, char **argv, char **envp) exit(1); } + if (qemu_opts_foreach(qemu_find_opts("add-fd"), parse_add_fd, NULL, 1)) { + exit(1); + } + + if (qemu_opts_foreach(qemu_find_opts("add-fd"), cleanup_add_fd, NULL, 1)) { + exit(1); + } + if (machine == NULL) { fprintf(stderr, "No machine found.\n"); exit(1); -- 1.7.11.4