util/oslib-posix.c

   1 /*
   2  * os-posix-lib.c
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  * Copyright (c) 2010 Red Hat, Inc.
   6  *
   7  * QEMU library functions on POSIX which are shared between QEMU and
   8  * the QEMU tools.
   9  *
  10  * Permission is hereby granted, free of charge, to any person obtaining a copy
  11  * of this software and associated documentation files (the "Software"), to deal
  12  * in the Software without restriction, including without limitation the rights
  13  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  14  * copies of the Software, and to permit persons to whom the Software is
  15  * furnished to do so, subject to the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be included in
  18  * all copies or substantial portions of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  23  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  25  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  26  * THE SOFTWARE.
  27  */
  28
  29 #include "qemu/osdep.h"
  30 #include <termios.h>
  31
  32 #include <glib/gprintf.h>
  33
  34 #include "sysemu/sysemu.h"
  35 #include "trace.h"
  36 #include "qapi/error.h"
  37 #include "qemu/sockets.h"
  38 #include <libgen.h>
  39 #include <sys/signal.h>
  40 #include "qemu/cutils.h"
  41
  42 #ifdef CONFIG_LINUX
  43 #include <sys/syscall.h>
  44 #endif
  45
  46 #ifdef __FreeBSD__
  47 #include <sys/sysctl.h>
  48 #include <sys/user.h>
  49 #include <libutil.h>
  50 #endif
  51
  52 #include "qemu/mmap-alloc.h"
  53
  54 #ifdef CONFIG_DEBUG_STACK_USAGE
  55 #include "qemu/error-report.h"
  56 #endif
  57
  58 #define MAX_MEM_PREALLOC_THREAD_COUNT (MIN(sysconf(_SC_NPROCESSORS_ONLN), 16))
  59
  60 struct MemsetThread {
  61     char *addr;
  62     uint64_t numpages;
  63     uint64_t hpagesize;
  64     QemuThread pgthread;
  65     sigjmp_buf env;
  66 };
  67 typedef struct MemsetThread MemsetThread;
  68
  69 static MemsetThread *memset_thread;
  70 static int memset_num_threads;
  71 static bool memset_thread_failed;
  72
  73 int qemu_get_thread_id(void)
  74 {
  75 #if defined(__linux__)
  76     return syscall(SYS_gettid);
  77 #else
  78     return getpid();
  79 #endif
  80 }
  81
  82 int qemu_daemon(int nochdir, int noclose)
  83 {
  84     return daemon(nochdir, noclose);
  85 }
  86
  87 void *qemu_oom_check(void *ptr)
  88 {
  89     if (ptr == NULL) {
  90         fprintf(stderr, "Failed to allocate memory: %s\n", strerror(errno));
  91         abort();
  92     }
  93     return ptr;
  94 }
  95
  96 void *qemu_try_memalign(size_t alignment, size_t size)
  97 {
  98     void *ptr;
  99
 100     if (alignment < sizeof(void*)) {
 101         alignment = sizeof(void*);
 102     }
 103
 104 #if defined(_POSIX_C_SOURCE) && !defined(__sun__)
 105     int ret;
 106     ret = posix_memalign(&ptr, alignment, size);
 107     if (ret != 0) {
 108         errno = ret;
 109         ptr = NULL;
 110     }
 111 #elif defined(CONFIG_BSD)
 112     ptr = valloc(size);
 113 #else
 114     ptr = memalign(alignment, size);
 115 #endif
 116     trace_qemu_memalign(alignment, size, ptr);
 117     return ptr;
 118 }
 119
 120 void *qemu_memalign(size_t alignment, size_t size)
 121 {
 122     return qemu_oom_check(qemu_try_memalign(alignment, size));
 123 }
 124
 125 /* alloc shared memory pages */
 126 void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment)
 127 {
 128     size_t align = QEMU_VMALLOC_ALIGN;
 129     void *ptr = qemu_ram_mmap(-1, size, align, false);
 130
 131     if (ptr == MAP_FAILED) {
 132         return NULL;
 133     }
 134
 135     if (alignment) {
 136         *alignment = align;
 137     }
 138
 139     trace_qemu_anon_ram_alloc(size, ptr);
 140     return ptr;
 141 }
 142
 143 void qemu_vfree(void *ptr)
 144 {
 145     trace_qemu_vfree(ptr);
 146     free(ptr);
 147 }
 148
 149 void qemu_anon_ram_free(void *ptr, size_t size)
 150 {
 151     trace_qemu_anon_ram_free(ptr, size);
 152     qemu_ram_munmap(ptr, size);
 153 }
 154
 155 void qemu_set_block(int fd)
 156 {
 157     int f;
 158     f = fcntl(fd, F_GETFL);
 159     fcntl(fd, F_SETFL, f & ~O_NONBLOCK);
 160 }
 161
 162 void qemu_set_nonblock(int fd)
 163 {
 164     int f;
 165     f = fcntl(fd, F_GETFL);
 166     fcntl(fd, F_SETFL, f | O_NONBLOCK);
 167 }
 168
 169 int socket_set_fast_reuse(int fd)
 170 {
 171     int val = 1, ret;
 172
 173     ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
 174                      (const char *)&val, sizeof(val));
 175
 176     assert(ret == 0);
 177
 178     return ret;
 179 }
 180
 181 void qemu_set_cloexec(int fd)
 182 {
 183     int f;
 184     f = fcntl(fd, F_GETFD);
 185     fcntl(fd, F_SETFD, f | FD_CLOEXEC);
 186 }
 187
 188 /*
 189  * Creates a pipe with FD_CLOEXEC set on both file descriptors
 190  */
 191 int qemu_pipe(int pipefd[2])
 192 {
 193     int ret;
 194
 195 #ifdef CONFIG_PIPE2
 196     ret = pipe2(pipefd, O_CLOEXEC);
 197     if (ret != -1 || errno != ENOSYS) {
 198         return ret;
 199     }
 200 #endif
 201     ret = pipe(pipefd);
 202     if (ret == 0) {
 203         qemu_set_cloexec(pipefd[0]);
 204         qemu_set_cloexec(pipefd[1]);
 205     }
 206
 207     return ret;
 208 }
 209
 210 int qemu_utimens(const char *path, const struct timespec *times)
 211 {
 212     struct timeval tv[2], tv_now;
 213     struct stat st;
 214     int i;
 215 #ifdef CONFIG_UTIMENSAT
 216     int ret;
 217
 218     ret = utimensat(AT_FDCWD, path, times, AT_SYMLINK_NOFOLLOW);
 219     if (ret != -1 || errno != ENOSYS) {
 220         return ret;
 221     }
 222 #endif
 223     /* Fallback: use utimes() instead of utimensat() */
 224
 225     /* happy if special cases */
 226     if (times[0].tv_nsec == UTIME_OMIT && times[1].tv_nsec == UTIME_OMIT) {
 227         return 0;
 228     }
 229     if (times[0].tv_nsec == UTIME_NOW && times[1].tv_nsec == UTIME_NOW) {
 230         return utimes(path, NULL);
 231     }
 232
 233     /* prepare for hard cases */
 234     if (times[0].tv_nsec == UTIME_NOW || times[1].tv_nsec == UTIME_NOW) {
 235         gettimeofday(&tv_now, NULL);
 236     }
 237     if (times[0].tv_nsec == UTIME_OMIT || times[1].tv_nsec == UTIME_OMIT) {
 238         stat(path, &st);
 239     }
 240
 241     for (i = 0; i < 2; i++) {
 242         if (times[i].tv_nsec == UTIME_NOW) {
 243             tv[i].tv_sec = tv_now.tv_sec;
 244             tv[i].tv_usec = tv_now.tv_usec;
 245         } else if (times[i].tv_nsec == UTIME_OMIT) {
 246             tv[i].tv_sec = (i == 0) ? st.st_atime : st.st_mtime;
 247             tv[i].tv_usec = 0;
 248         } else {
 249             tv[i].tv_sec = times[i].tv_sec;
 250             tv[i].tv_usec = times[i].tv_nsec / 1000;
 251         }
 252     }
 253
 254     return utimes(path, &tv[0]);
 255 }
 256
 257 char *
 258 qemu_get_local_state_pathname(const char *relative_pathname)
 259 {
 260     return g_strdup_printf("%s/%s", CONFIG_QEMU_LOCALSTATEDIR,
 261                            relative_pathname);
 262 }
 263
 264 void qemu_set_tty_echo(int fd, bool echo)
 265 {
 266     struct termios tty;
 267
 268     tcgetattr(fd, &tty);
 269
 270     if (echo) {
 271         tty.c_lflag |= ECHO | ECHONL | ICANON | IEXTEN;
 272     } else {
 273         tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
 274     }
 275
 276     tcsetattr(fd, TCSANOW, &tty);
 277 }
 278
 279 static char exec_dir[PATH_MAX];
 280
 281 void qemu_init_exec_dir(const char *argv0)
 282 {
 283     char *dir;
 284     char *p = NULL;
 285     char buf[PATH_MAX];
 286
 287     assert(!exec_dir[0]);
 288
 289 #if defined(__linux__)
 290     {
 291         int len;
 292         len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
 293         if (len > 0) {
 294             buf[len] = 0;
 295             p = buf;
 296         }
 297     }
 298 #elif defined(__FreeBSD__)
 299     {
 300         static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
 301         size_t len = sizeof(buf) - 1;
 302
 303         *buf = '\0';
 304         if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
 305             *buf) {
 306             buf[sizeof(buf) - 1] = '\0';
 307             p = buf;
 308         }
 309     }
 310 #endif
 311     /* If we don't have any way of figuring out the actual executable
 312        location then try argv[0].  */
 313     if (!p) {
 314         if (!argv0) {
 315             return;
 316         }
 317         p = realpath(argv0, buf);
 318         if (!p) {
 319             return;
 320         }
 321     }
 322     dir = g_path_get_dirname(p);
 323
 324     pstrcpy(exec_dir, sizeof(exec_dir), dir);
 325
 326     g_free(dir);
 327 }
 328
 329 char *qemu_get_exec_dir(void)
 330 {
 331     return g_strdup(exec_dir);
 332 }
 333
 334 static void sigbus_handler(int signal)
 335 {
 336     int i;
 337     if (memset_thread) {
 338         for (i = 0; i < memset_num_threads; i++) {
 339             if (qemu_thread_is_self(&memset_thread[i].pgthread)) {
 340                 siglongjmp(memset_thread[i].env, 1);
 341             }
 342         }
 343     }
 344 }
 345
 346 static void *do_touch_pages(void *arg)
 347 {
 348     MemsetThread *memset_args = (MemsetThread *)arg;
 349     char *addr = memset_args->addr;
 350     uint64_t numpages = memset_args->numpages;
 351     uint64_t hpagesize = memset_args->hpagesize;
 352     sigset_t set, oldset;
 353     int i = 0;
 354
 355     /* unblock SIGBUS */
 356     sigemptyset(&set);
 357     sigaddset(&set, SIGBUS);
 358     pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
 359
 360     if (sigsetjmp(memset_args->env, 1)) {
 361         memset_thread_failed = true;
 362     } else {
 363         for (i = 0; i < numpages; i++) {
 364             memset(addr, 0, 1);
 365             addr += hpagesize;
 366         }
 367     }
 368     pthread_sigmask(SIG_SETMASK, &oldset, NULL);
 369     return NULL;
 370 }
 371
 372 static bool touch_all_pages(char *area, size_t hpagesize, size_t numpages,
 373                             int smp_cpus)
 374 {
 375     uint64_t numpages_per_thread, size_per_thread;
 376     char *addr = area;
 377     int i = 0;
 378
 379     memset_thread_failed = false;
 380     memset_num_threads = MIN(smp_cpus, MAX_MEM_PREALLOC_THREAD_COUNT);
 381     memset_thread = g_new0(MemsetThread, memset_num_threads);
 382     numpages_per_thread = (numpages / memset_num_threads);
 383     size_per_thread = (hpagesize * numpages_per_thread);
 384     for (i = 0; i < memset_num_threads; i++) {
 385         memset_thread[i].addr = addr;
 386         memset_thread[i].numpages = (i == (memset_num_threads - 1)) ?
 387                                     numpages : numpages_per_thread;
 388         memset_thread[i].hpagesize = hpagesize;
 389         qemu_thread_create(&memset_thread[i].pgthread, "touch_pages",
 390                            do_touch_pages, &memset_thread[i],
 391                            QEMU_THREAD_JOINABLE);
 392         addr += size_per_thread;
 393         numpages -= numpages_per_thread;
 394     }
 395     for (i = 0; i < memset_num_threads; i++) {
 396         qemu_thread_join(&memset_thread[i].pgthread);
 397     }
 398     g_free(memset_thread);
 399     memset_thread = NULL;
 400
 401     return memset_thread_failed;
 402 }
 403
 404 void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus,
 405                      Error **errp)
 406 {
 407     int ret;
 408     struct sigaction act, oldact;
 409     size_t hpagesize = qemu_fd_getpagesize(fd);
 410     size_t numpages = DIV_ROUND_UP(memory, hpagesize);
 411
 412     memset(&act, 0, sizeof(act));
 413     act.sa_handler = &sigbus_handler;
 414     act.sa_flags = 0;
 415
 416     ret = sigaction(SIGBUS, &act, &oldact);
 417     if (ret) {
 418         error_setg_errno(errp, errno,
 419             "os_mem_prealloc: failed to install signal handler");
 420         return;
 421     }
 422
 423     /* touch pages simultaneously */
 424     if (touch_all_pages(area, hpagesize, numpages, smp_cpus)) {
 425         error_setg(errp, "os_mem_prealloc: Insufficient free host memory "
 426             "pages available to allocate guest RAM\n");
 427     }
 428
 429     ret = sigaction(SIGBUS, &oldact, NULL);
 430     if (ret) {
 431         /* Terminate QEMU since it can't recover from error */
 432         perror("os_mem_prealloc: failed to reinstall signal handler");
 433         exit(1);
 434     }
 435 }
 436
 437
 438 static struct termios oldtty;
 439
 440 static void term_exit(void)
 441 {
 442     tcsetattr(0, TCSANOW, &oldtty);
 443 }
 444
 445 static void term_init(void)
 446 {
 447     struct termios tty;
 448
 449     tcgetattr(0, &tty);
 450     oldtty = tty;
 451
 452     tty.c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP
 453                           |INLCR|IGNCR|ICRNL|IXON);
 454     tty.c_oflag |= OPOST;
 455     tty.c_lflag &= ~(ECHO|ECHONL|ICANON|IEXTEN);
 456     tty.c_cflag &= ~(CSIZE|PARENB);
 457     tty.c_cflag |= CS8;
 458     tty.c_cc[VMIN] = 1;
 459     tty.c_cc[VTIME] = 0;
 460
 461     tcsetattr(0, TCSANOW, &tty);
 462
 463     atexit(term_exit);
 464 }
 465
 466 int qemu_read_password(char *buf, int buf_size)
 467 {
 468     uint8_t ch;
 469     int i, ret;
 470
 471     printf("password: ");
 472     fflush(stdout);
 473     term_init();
 474     i = 0;
 475     for (;;) {
 476         ret = read(0, &ch, 1);
 477         if (ret == -1) {
 478             if (errno == EAGAIN || errno == EINTR) {
 479                 continue;
 480             } else {
 481                 break;
 482             }
 483         } else if (ret == 0) {
 484             ret = -1;
 485             break;
 486         } else {
 487             if (ch == '\r' ||
 488                 ch == '\n') {
 489                 ret = 0;
 490                 break;
 491             }
 492             if (i < (buf_size - 1)) {
 493                 buf[i++] = ch;
 494             }
 495         }
 496     }
 497     term_exit();
 498     buf[i] = '\0';
 499     printf("\n");
 500     return ret;
 501 }
 502
 503
 504 char *qemu_get_pid_name(pid_t pid)
 505 {
 506     char *name = NULL;
 507
 508 #if defined(__FreeBSD__)
 509     /* BSDs don't have /proc, but they provide a nice substitute */
 510     struct kinfo_proc *proc = kinfo_getproc(pid);
 511
 512     if (proc) {
 513         name = g_strdup(proc->ki_comm);
 514         free(proc);
 515     }
 516 #else
 517     /* Assume a system with reasonable procfs */
 518     char *pid_path;
 519     size_t len;
 520
 521     pid_path = g_strdup_printf("/proc/%d/cmdline", pid);
 522     g_file_get_contents(pid_path, &name, &len, NULL);
 523     g_free(pid_path);
 524 #endif
 525
 526     return name;
 527 }
 528
 529
 530 pid_t qemu_fork(Error **errp)
 531 {
 532     sigset_t oldmask, newmask;
 533     struct sigaction sig_action;
 534     int saved_errno;
 535     pid_t pid;
 536
 537     /*
 538      * Need to block signals now, so that child process can safely
 539      * kill off caller's signal handlers without a race.
 540      */
 541     sigfillset(&newmask);
 542     if (pthread_sigmask(SIG_SETMASK, &newmask, &oldmask) != 0) {
 543         error_setg_errno(errp, errno,
 544                          "cannot block signals");
 545         return -1;
 546     }
 547
 548     pid = fork();
 549     saved_errno = errno;
 550
 551     if (pid < 0) {
 552         /* attempt to restore signal mask, but ignore failure, to
 553          * avoid obscuring the fork failure */
 554         (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
 555         error_setg_errno(errp, saved_errno,
 556                          "cannot fork child process");
 557         errno = saved_errno;
 558         return -1;
 559     } else if (pid) {
 560         /* parent process */
 561
 562         /* Restore our original signal mask now that the child is
 563          * safely running. Only documented failures are EFAULT (not
 564          * possible, since we are using just-grabbed mask) or EINVAL
 565          * (not possible, since we are using correct arguments).  */
 566         (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
 567     } else {
 568         /* child process */
 569         size_t i;
 570
 571         /* Clear out all signal handlers from parent so nothing
 572          * unexpected can happen in our child once we unblock
 573          * signals */
 574         sig_action.sa_handler = SIG_DFL;
 575         sig_action.sa_flags = 0;
 576         sigemptyset(&sig_action.sa_mask);
 577
 578         for (i = 1; i < NSIG; i++) {
 579             /* Only possible errors are EFAULT or EINVAL The former
 580              * won't happen, the latter we expect, so no need to check
 581              * return value */
 582             (void)sigaction(i, &sig_action, NULL);
 583         }
 584
 585         /* Unmask all signals in child, since we've no idea what the
 586          * caller's done with their signal mask and don't want to
 587          * propagate that to children */
 588         sigemptyset(&newmask);
 589         if (pthread_sigmask(SIG_SETMASK, &newmask, NULL) != 0) {
 590             Error *local_err = NULL;
 591             error_setg_errno(&local_err, errno,
 592                              "cannot unblock signals");
 593             error_report_err(local_err);
 594             _exit(1);
 595         }
 596     }
 597     return pid;
 598 }
 599
 600 void *qemu_alloc_stack(size_t *sz)
 601 {
 602     void *ptr, *guardpage;
 603 #ifdef CONFIG_DEBUG_STACK_USAGE
 604     void *ptr2;
 605 #endif
 606     size_t pagesz = getpagesize();
 607 #ifdef _SC_THREAD_STACK_MIN
 608     /* avoid stacks smaller than _SC_THREAD_STACK_MIN */
 609     long min_stack_sz = sysconf(_SC_THREAD_STACK_MIN);
 610     *sz = MAX(MAX(min_stack_sz, 0), *sz);
 611 #endif
 612     /* adjust stack size to a multiple of the page size */
 613     *sz = ROUND_UP(*sz, pagesz);
 614     /* allocate one extra page for the guard page */
 615     *sz += pagesz;
 616
 617     ptr = mmap(NULL, *sz, PROT_READ | PROT_WRITE,
 618                MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 619     if (ptr == MAP_FAILED) {
 620         abort();
 621     }
 622
 623 #if defined(HOST_IA64)
 624     /* separate register stack */
 625     guardpage = ptr + (((*sz - pagesz) / 2) & ~pagesz);
 626 #elif defined(HOST_HPPA)
 627     /* stack grows up */
 628     guardpage = ptr + *sz - pagesz;
 629 #else
 630     /* stack grows down */
 631     guardpage = ptr;
 632 #endif
 633     if (mprotect(guardpage, pagesz, PROT_NONE) != 0) {
 634         abort();
 635     }
 636
 637 #ifdef CONFIG_DEBUG_STACK_USAGE
 638     for (ptr2 = ptr + pagesz; ptr2 < ptr + *sz; ptr2 += sizeof(uint32_t)) {
 639         *(uint32_t *)ptr2 = 0xdeadbeaf;
 640     }
 641 #endif
 642
 643     return ptr;
 644 }
 645
 646 #ifdef CONFIG_DEBUG_STACK_USAGE
 647 static __thread unsigned int max_stack_usage;
 648 #endif
 649
 650 void qemu_free_stack(void *stack, size_t sz)
 651 {
 652 #ifdef CONFIG_DEBUG_STACK_USAGE
 653     unsigned int usage;
 654     void *ptr;
 655
 656     for (ptr = stack + getpagesize(); ptr < stack + sz;
 657          ptr += sizeof(uint32_t)) {
 658         if (*(uint32_t *)ptr != 0xdeadbeaf) {
 659             break;
 660         }
 661     }
 662     usage = sz - (uintptr_t) (ptr - stack);
 663     if (usage > max_stack_usage) {
 664         error_report("thread %d max stack usage increased from %u to %u",
 665                      qemu_get_thread_id(), max_stack_usage, usage);
 666         max_stack_usage = usage;
 667     }
 668 #endif
 669
 670     munmap(stack, sz);
 671 }
 672
 673 void sigaction_invoke(struct sigaction *action,
 674                       struct qemu_signalfd_siginfo *info)
 675 {
 676     siginfo_t si = { 0 };
 677     si.si_signo = info->ssi_signo;
 678     si.si_errno = info->ssi_errno;
 679     si.si_code = info->ssi_code;
 680
 681     /* Convert the minimal set of fields defined by POSIX.
 682      * Positive si_code values are reserved for kernel-generated
 683      * signals, where the valid siginfo fields are determined by
 684      * the signal number.  But according to POSIX, it is unspecified
 685      * whether SI_USER and SI_QUEUE have values less than or equal to
 686      * zero.
 687      */
 688     if (info->ssi_code == SI_USER || info->ssi_code == SI_QUEUE ||
 689         info->ssi_code <= 0) {
 690         /* SIGTERM, etc.  */
 691         si.si_pid = info->ssi_pid;
 692         si.si_uid = info->ssi_uid;
 693     } else if (info->ssi_signo == SIGILL || info->ssi_signo == SIGFPE ||
 694                info->ssi_signo == SIGSEGV || info->ssi_signo == SIGBUS) {
 695         si.si_addr = (void *)(uintptr_t)info->ssi_addr;
 696     } else if (info->ssi_signo == SIGCHLD) {
 697         si.si_pid = info->ssi_pid;
 698         si.si_status = info->ssi_status;
 699         si.si_uid = info->ssi_uid;
 700     } else if (info->ssi_signo == SIGIO) {
 701         si.si_band = info->ssi_band;
 702     }
 703     action->sa_sigaction(info->ssi_signo, &si, NULL);
 704 }