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 4 and 5, 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(a)linux.vnet.ibm.com&gt; --- v2: - The -add-fd option is new in v2 (eblake(a)redhat.com) v3: - Require passed fd to be > stderr (eblake(a)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(a)redhat.com) qemu-config.c | 22 ++++++++++++++++++ qemu-options.hx | 36 +++++++++++++++++++++++++++++ vl.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 130 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..83205c0 100644 --- a/vl.c +++ b/vl.c @@ -790,6 +790,65 @@ 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 (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 +3368,11 @@ 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 +3384,14 @@ 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