Rearrange library code into separate files.

We split the library code into these separate files:

 - guestfs.c: creating handles, closing handles, handle-related variables
 - actions.c: generated library-side stubs for each action
 - bindtests.c: generated code to test bindings
 - launch.c: launching the appliance
 - proto.c: the library side of the daemon communications protocol

This is just code movement.

1 files changed, 1250 insertions, 0 deletions

diff --git a/src/launch.c b/src/launch.c
new file mode 100644
index 00000000..7cd5a561
--- /dev/null
+++ b/src/launch.c
@@ -0,0 +1,1250 @@
+/* libguestfs
+ * Copyright (C) 2009-2010 Red Hat Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <config.h>
+
+#define _BSD_SOURCE /* for mkdtemp, usleep */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <inttypes.h>
+#include <unistd.h>
+#include <string.h>
+#include <fcntl.h>
+#include <time.h>
+#include <sys/stat.h>
+#include <sys/select.h>
+#include <dirent.h>
+#include <signal.h>
+
+#include <rpc/types.h>
+#include <rpc/xdr.h>
+
+#ifdef HAVE_ERRNO_H
+#include <errno.h>
+#endif
+
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+
+#ifdef HAVE_SYS_WAIT_H
+#include <sys/wait.h>
+#endif
+
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+
+#ifdef HAVE_SYS_UN_H
+#include <sys/un.h>
+#endif
+
+#include <arpa/inet.h>
+#include <netinet/in.h>
+
+#include "c-ctype.h"
+#include "glthread/lock.h"
+#include "ignore-value.h"
+
+#include "guestfs.h"
+#include "guestfs-internal.h"
+#include "guestfs-internal-actions.h"
+#include "guestfs_protocol.h"
+
+static int check_peer_euid (guestfs_h *g, int sock, uid_t *rtn);
+static int qemu_supports (guestfs_h *g, const char *option);
+
+/* Add a string to the current command line. */
+static void
+incr_cmdline_size (guestfs_h *g)
+{
+  if (g->cmdline == NULL) {
+    /* g->cmdline[0] is reserved for argv[0], set in guestfs_launch. */
+    g->cmdline_size = 1;
+    g->cmdline = safe_malloc (g, sizeof (char *));
+    g->cmdline[0] = NULL;
+  }
+
+  g->cmdline_size++;
+  g->cmdline = safe_realloc (g, g->cmdline, sizeof (char *) * g->cmdline_size);
+}
+
+static int
+add_cmdline (guestfs_h *g, const char *str)
+{
+  if (g->state != CONFIG) {
+    error (g,
+        _("command line cannot be altered after qemu subprocess launched"));
+    return -1;
+  }
+
+  incr_cmdline_size (g);
+  g->cmdline[g->cmdline_size-1] = safe_strdup (g, str);
+  return 0;
+}
+
+int
+guestfs__config (guestfs_h *g,
+                 const char *qemu_param, const char *qemu_value)
+{
+  if (qemu_param[0] != '-') {
+    error (g, _("guestfs_config: parameter must begin with '-' character"));
+    return -1;
+  }
+
+  /* A bit fascist, but the user will probably break the extra
+   * parameters that we add if they try to set any of these.
+   */
+  if (STREQ (qemu_param, "-kernel") ||
+      STREQ (qemu_param, "-initrd") ||
+      STREQ (qemu_param, "-nographic") ||
+      STREQ (qemu_param, "-serial") ||
+      STREQ (qemu_param, "-full-screen") ||
+      STREQ (qemu_param, "-std-vga") ||
+      STREQ (qemu_param, "-vnc")) {
+    error (g, _("guestfs_config: parameter '%s' isn't allowed"), qemu_param);
+    return -1;
+  }
+
+  if (add_cmdline (g, qemu_param) != 0) return -1;
+
+  if (qemu_value != NULL) {
+    if (add_cmdline (g, qemu_value) != 0) return -1;
+  }
+
+  return 0;
+}
+
+int
+guestfs__add_drive_with_if (guestfs_h *g, const char *filename,
+                            const char *drive_if)
+{
+  size_t len = strlen (filename) + 64;
+  char buf[len];
+
+  if (strchr (filename, ',') != NULL) {
+    error (g, _("filename cannot contain ',' (comma) character"));
+    return -1;
+  }
+
+  /* cache=off improves reliability in the event of a host crash.
+   *
+   * However this option causes qemu to try to open the file with
+   * O_DIRECT.  This fails on some filesystem types (notably tmpfs).
+   * So we check if we can open the file with or without O_DIRECT,
+   * and use cache=off (or not) accordingly.
+   *
+   * This test also checks for the presence of the file, which
+   * is a documented semantic of this interface.
+   */
+  int fd = open (filename, O_RDONLY|O_DIRECT);
+  if (fd >= 0) {
+    close (fd);
+    snprintf (buf, len, "file=%s,cache=off,if=%s", filename, drive_if);
+  } else {
+    fd = open (filename, O_RDONLY);
+    if (fd >= 0) {
+      close (fd);
+      snprintf (buf, len, "file=%s,if=%s", filename, drive_if);
+    } else {
+      perrorf (g, "%s", filename);
+      return -1;
+    }
+  }
+
+  return guestfs__config (g, "-drive", buf);
+}
+
+int
+guestfs__add_drive_ro_with_if (guestfs_h *g, const char *filename,
+                               const char *drive_if)
+{
+  if (strchr (filename, ',') != NULL) {
+    error (g, _("filename cannot contain ',' (comma) character"));
+    return -1;
+  }
+
+  if (access (filename, F_OK) == -1) {
+    perrorf (g, "%s", filename);
+    return -1;
+  }
+
+  size_t len = strlen (filename) + 64;
+  char buf[len];
+
+  snprintf (buf, len, "file=%s,snapshot=on,if=%s", filename, drive_if);
+
+  return guestfs__config (g, "-drive", buf);
+}
+
+int
+guestfs__add_drive (guestfs_h *g, const char *filename)
+{
+  return guestfs__add_drive_with_if (g, filename, DRIVE_IF);
+}
+
+int
+guestfs__add_drive_ro (guestfs_h *g, const char *filename)
+{
+  return guestfs__add_drive_ro_with_if (g, filename, DRIVE_IF);
+}
+
+int
+guestfs__add_cdrom (guestfs_h *g, const char *filename)
+{
+  if (strchr (filename, ',') != NULL) {
+    error (g, _("filename cannot contain ',' (comma) character"));
+    return -1;
+  }
+
+  if (access (filename, F_OK) == -1) {
+    perrorf (g, "%s", filename);
+    return -1;
+  }
+
+  return guestfs__config (g, "-cdrom", filename);
+}
+
+/* Returns true iff file is contained in dir. */
+static int
+dir_contains_file (const char *dir, const char *file)
+{
+  int dirlen = strlen (dir);
+  int filelen = strlen (file);
+  int len = dirlen+filelen+2;
+  char path[len];
+
+  snprintf (path, len, "%s/%s", dir, file);
+  return access (path, F_OK) == 0;
+}
+
+/* Returns true iff every listed file is contained in 'dir'. */
+static int
+dir_contains_files (const char *dir, ...)
+{
+  va_list args;
+  const char *file;
+
+  va_start (args, dir);
+  while ((file = va_arg (args, const char *)) != NULL) {
+    if (!dir_contains_file (dir, file)) {
+      va_end (args);
+      return 0;
+    }
+  }
+  va_end (args);
+  return 1;
+}
+
+static void print_timestamped_message (guestfs_h *g, const char *fs, ...);
+static int build_supermin_appliance (guestfs_h *g, const char *path, char **kernel, char **initrd);
+static int is_openable (guestfs_h *g, const char *path, int flags);
+static void print_cmdline (guestfs_h *g);
+
+static const char *kernel_name = "vmlinuz." REPO "." host_cpu;
+static const char *initrd_name = "initramfs." REPO "." host_cpu ".img";
+
+int
+guestfs__launch (guestfs_h *g)
+{
+  const char *tmpdir;
+  char dir_template[PATH_MAX];
+  int r, pmore;
+  size_t len;
+  int wfd[2], rfd[2];
+  int tries;
+  char *path, *pelem, *pend;
+  char *kernel = NULL, *initrd = NULL;
+  int null_vmchannel_sock;
+  char unixsock[256];
+  struct sockaddr_un addr;
+
+  /* Configured? */
+  if (!g->cmdline) {
+    error (g, _("you must call guestfs_add_drive before guestfs_launch"));
+    return -1;
+  }
+
+  if (g->state != CONFIG) {
+    error (g, _("the libguestfs handle has already been launched"));
+    return -1;
+  }
+
+  /* Start the clock ... */
+  gettimeofday (&g->launch_t, NULL);
+
+  /* Make the temporary directory. */
+#ifdef P_tmpdir
+  tmpdir = P_tmpdir;
+#else
+  tmpdir = "/tmp";
+#endif
+
+  tmpdir = getenv ("TMPDIR") ? : tmpdir;
+  snprintf (dir_template, sizeof dir_template, "%s/libguestfsXXXXXX", tmpdir);
+
+  if (!g->tmpdir) {
+    g->tmpdir = safe_strdup (g, dir_template);
+    if (mkdtemp (g->tmpdir) == NULL) {
+      perrorf (g, _("%s: cannot create temporary directory"), dir_template);
+      goto cleanup0;
+    }
+  }
+
+  /* Allow anyone to read the temporary directory.  There are no
+   * secrets in the kernel or initrd files.  The socket in this
+   * directory won't be readable but anyone can see it exists if they
+   * want. (RHBZ#610880).
+   */
+  if (chmod (g->tmpdir, 0755) == -1)
+    fprintf (stderr, "chmod: %s: %m (ignored)\n", g->tmpdir);
+
+  /* First search g->path for the supermin appliance, and try to
+   * synthesize a kernel and initrd from that.  If it fails, we
+   * try the path search again looking for a backup ordinary
+   * appliance.
+   */
+  pelem = path = safe_strdup (g, g->path);
+  do {
+    pend = strchrnul (pelem, ':');
+    pmore = *pend == ':';
+    *pend = '\0';
+    len = pend - pelem;
+
+    /* Empty element of "." means cwd. */
+    if (len == 0 || (len == 1 && *pelem == '.')) {
+      if (g->verbose)
+        fprintf (stderr,
+                 "looking for supermin appliance in current directory\n");
+      if (dir_contains_files (".",
+                              "supermin.d", "kmod.whitelist", NULL)) {
+        if (build_supermin_appliance (g, ".", &kernel, &initrd) == -1)
+          return -1;
+        break;
+      }
+    }
+    /* Look at <path>/supermin* etc. */
+    else {
+      if (g->verbose)
+        fprintf (stderr, "looking for supermin appliance in %s\n", pelem);
+
+      if (dir_contains_files (pelem,
+                              "supermin.d", "kmod.whitelist", NULL)) {
+        if (build_supermin_appliance (g, pelem, &kernel, &initrd) == -1)
+          return -1;
+        break;
+      }
+    }
+
+    pelem = pend + 1;
+  } while (pmore);
+
+  free (path);
+
+  if (kernel == NULL || initrd == NULL) {
+    /* Search g->path for the kernel and initrd. */
+    pelem = path = safe_strdup (g, g->path);
+    do {
+      pend = strchrnul (pelem, ':');
+      pmore = *pend == ':';
+      *pend = '\0';
+      len = pend - pelem;
+
+      /* Empty element or "." means cwd. */
+      if (len == 0 || (len == 1 && *pelem == '.')) {
+        if (g->verbose)
+          fprintf (stderr,
+                   "looking for appliance in current directory\n");
+        if (dir_contains_files (".", kernel_name, initrd_name, NULL)) {
+          kernel = safe_strdup (g, kernel_name);
+          initrd = safe_strdup (g, initrd_name);
+          break;
+        }
+      }
+      /* Look at <path>/kernel etc. */
+      else {
+        if (g->verbose)
+          fprintf (stderr, "looking for appliance in %s\n", pelem);
+
+        if (dir_contains_files (pelem, kernel_name, initrd_name, NULL)) {
+          kernel = safe_malloc (g, len + strlen (kernel_name) + 2);
+          initrd = safe_malloc (g, len + strlen (initrd_name) + 2);
+          sprintf (kernel, "%s/%s", pelem, kernel_name);
+          sprintf (initrd, "%s/%s", pelem, initrd_name);
+          break;
+        }
+      }
+
+      pelem = pend + 1;
+    } while (pmore);
+
+    free (path);
+  }
+
+  if (kernel == NULL || initrd == NULL) {
+    error (g, _("cannot find %s or %s on LIBGUESTFS_PATH (current path = %s)"),
+           kernel_name, initrd_name, g->path);
+    goto cleanup0;
+  }
+
+  if (g->verbose)
+    print_timestamped_message (g, "begin testing qemu features");
+
+  /* Get qemu help text and version. */
+  if (qemu_supports (g, NULL) == -1)
+    goto cleanup0;
+
+  /* Choose which vmchannel implementation to use. */
+  if (CAN_CHECK_PEER_EUID && qemu_supports (g, "-net user")) {
+    /* The "null vmchannel" implementation.  Requires SLIRP (user mode
+     * networking in qemu) but no other vmchannel support.  The daemon
+     * will connect back to a random port number on localhost.
+     */
+    struct sockaddr_in addr;
+    socklen_t addrlen = sizeof addr;
+
+    g->sock = socket (AF_INET, SOCK_STREAM, IPPROTO_TCP);
+    if (g->sock == -1) {
+      perrorf (g, "socket");
+      goto cleanup0;
+    }
+    addr.sin_family = AF_INET;
+    addr.sin_port = htons (0);
+    addr.sin_addr.s_addr = htonl (INADDR_LOOPBACK);
+    if (bind (g->sock, (struct sockaddr *) &addr, addrlen) == -1) {
+      perrorf (g, "bind");
+      goto cleanup0;
+    }
+
+    if (listen (g->sock, 256) == -1) {
+      perrorf (g, "listen");
+      goto cleanup0;
+    }
+
+    if (getsockname (g->sock, (struct sockaddr *) &addr, &addrlen) == -1) {
+      perrorf (g, "getsockname");
+      goto cleanup0;
+    }
+
+    if (fcntl (g->sock, F_SETFL, O_NONBLOCK) == -1) {
+      perrorf (g, "fcntl");
+      goto cleanup0;
+    }
+
+    null_vmchannel_sock = ntohs (addr.sin_port);
+    if (g->verbose)
+      fprintf (stderr, "null_vmchannel_sock = %d\n", null_vmchannel_sock);
+  } else {
+    /* Using some vmchannel impl.  We need to create a local Unix
+     * domain socket for qemu to use.
+     */
+    snprintf (unixsock, sizeof unixsock, "%s/sock", g->tmpdir);
+    unlink (unixsock);
+    null_vmchannel_sock = 0;
+  }
+
+  if (!g->direct) {
+    if (pipe (wfd) == -1 || pipe (rfd) == -1) {
+      perrorf (g, "pipe");
+      goto cleanup0;
+    }
+  }
+
+  if (g->verbose)
+    print_timestamped_message (g, "finished testing qemu features");
+
+  r = fork ();
+  if (r == -1) {
+    perrorf (g, "fork");
+    if (!g->direct) {
+      close (wfd[0]);
+      close (wfd[1]);
+      close (rfd[0]);
+      close (rfd[1]);
+    }
+    goto cleanup0;
+  }
+
+  if (r == 0) {			/* Child (qemu). */
+    char buf[256];
+    const char *vmchannel = NULL;
+
+    /* Set up the full command line.  Do this in the subprocess so we
+     * don't need to worry about cleaning up.
+     */
+    g->cmdline[0] = g->qemu;
+
+    /* qemu sometimes needs this option to enable hardware
+     * virtualization, but some versions of 'qemu-kvm' will use KVM
+     * regardless (even where this option appears in the help text).
+     * It is rumoured that there are versions of qemu where supplying
+     * this option when hardware virtualization is not available will
+     * cause qemu to fail, so we we have to check at least that
+     * /dev/kvm is openable.  That's not reliable, since /dev/kvm
+     * might be openable by qemu but not by us (think: SELinux) in
+     * which case the user would not get hardware virtualization,
+     * although at least shouldn't fail.  A giant clusterfuck with the
+     * qemu command line, again.
+     */
+    if (qemu_supports (g, "-enable-kvm") &&
+        is_openable (g, "/dev/kvm", O_RDWR))
+      add_cmdline (g, "-enable-kvm");
+
+    /* Newer versions of qemu (from around 2009/12) changed the
+     * behaviour of monitors so that an implicit '-monitor stdio' is
+     * assumed if we are in -nographic mode and there is no other
+     * -monitor option.  Only a single stdio device is allowed, so
+     * this broke the '-serial stdio' option.  There is a new flag
+     * called -nodefaults which gets rid of all this default crud, so
+     * let's use that to avoid this and any future surprises.
+     */
+    if (qemu_supports (g, "-nodefaults"))
+      add_cmdline (g, "-nodefaults");
+
+    add_cmdline (g, "-nographic");
+    add_cmdline (g, "-serial");
+    add_cmdline (g, "stdio");
+
+    snprintf (buf, sizeof buf, "%d", g->memsize);
+    add_cmdline (g, "-m");
+    add_cmdline (g, buf);
+
+    /* Force exit instead of reboot on panic */
+    add_cmdline (g, "-no-reboot");
+
+    /* These options recommended by KVM developers to improve reliability. */
+    if (qemu_supports (g, "-no-hpet"))
+      add_cmdline (g, "-no-hpet");
+
+    if (qemu_supports (g, "-rtc-td-hack"))
+      add_cmdline (g, "-rtc-td-hack");
+
+    /* If qemu has SLIRP (user mode network) enabled then we can get
+     * away with "no vmchannel", where we just connect back to a random
+     * host port.
+     */
+    if (null_vmchannel_sock) {
+      add_cmdline (g, "-net");
+      add_cmdline (g, "user,vlan=0,net=" NETWORK);
+
+      snprintf (buf, sizeof buf,
+                "guestfs_vmchannel=tcp:" ROUTER ":%d",
+                null_vmchannel_sock);
+      vmchannel = strdup (buf);
+    }
+
+    /* New-style -net user,guestfwd=... syntax for guestfwd.  See:
+     *
+     * http://git.savannah.gnu.org/cgit/qemu.git/commit/?id=c92ef6a22d3c71538fcc48fb61ad353f7ba03b62
+     *
+     * The original suggested format doesn't work, see:
+     *
+     * http://lists.gnu.org/archive/html/qemu-devel/2009-07/msg01654.html
+     *
+     * However Gerd Hoffman privately suggested to me using -chardev
+     * instead, which does work.
+     */
+    else if (qemu_supports (g, "-chardev") && qemu_supports (g, "guestfwd")) {
+      snprintf (buf, sizeof buf,
+                "socket,id=guestfsvmc,path=%s,server,nowait", unixsock);
+
+      add_cmdline (g, "-chardev");
+      add_cmdline (g, buf);
+
+      snprintf (buf, sizeof buf,
+                "user,vlan=0,net=" NETWORK ","
+                "guestfwd=tcp:" GUESTFWD_ADDR ":" GUESTFWD_PORT
+                "-chardev:guestfsvmc");
+
+      add_cmdline (g, "-net");
+      add_cmdline (g, buf);
+
+      vmchannel = "guestfs_vmchannel=tcp:" GUESTFWD_ADDR ":" GUESTFWD_PORT;
+    }
+
+    /* Not guestfwd.  HOPEFULLY this qemu uses the older -net channel
+     * syntax, or if not then we'll get a quick failure.
+     */
+    else {
+      snprintf (buf, sizeof buf,
+                "channel," GUESTFWD_PORT ":unix:%s,server,nowait", unixsock);
+
+      add_cmdline (g, "-net");
+      add_cmdline (g, buf);
+      add_cmdline (g, "-net");
+      add_cmdline (g, "user,vlan=0,net=" NETWORK);
+
+      vmchannel = "guestfs_vmchannel=tcp:" GUESTFWD_ADDR ":" GUESTFWD_PORT;
+    }
+    add_cmdline (g, "-net");
+    add_cmdline (g, "nic,model=" NET_IF ",vlan=0");
+
+#define LINUX_CMDLINE							\
+    "panic=1 "         /* force kernel to panic if daemon exits */	\
+    "console=ttyS0 "   /* serial console */				\
+    "udevtimeout=300 " /* good for very slow systems (RHBZ#480319) */	\
+    "noapic "          /* workaround for RHBZ#502058 - ok if not SMP */ \
+    "acpi=off "        /* we don't need ACPI, turn it off */		\
+    "printk.time=1 "   /* display timestamp before kernel messages */   \
+    "cgroup_disable=memory " /* saves us about 5 MB of RAM */
+
+    /* Linux kernel command line. */
+    snprintf (buf, sizeof buf,
+              LINUX_CMDLINE
+              "%s "             /* (selinux) */
+              "%s "             /* (vmchannel) */
+              "%s "             /* (verbose) */
+              "TERM=%s "        /* (TERM environment variable) */
+              "%s",             /* (append) */
+              g->selinux ? "selinux=1 enforcing=0" : "selinux=0",
+              vmchannel ? vmchannel : "",
+              g->verbose ? "guestfs_verbose=1" : "",
+              getenv ("TERM") ? : "linux",
+              g->append ? g->append : "");
+
+    add_cmdline (g, "-kernel");
+    add_cmdline (g, (char *) kernel);
+    add_cmdline (g, "-initrd");
+    add_cmdline (g, (char *) initrd);
+    add_cmdline (g, "-append");
+    add_cmdline (g, buf);
+
+    /* Finish off the command line. */
+    incr_cmdline_size (g);
+    g->cmdline[g->cmdline_size-1] = NULL;
+
+    if (g->verbose)
+      print_cmdline (g);
+
+    if (!g->direct) {
+      /* Set up stdin, stdout. */
+      close (0);
+      close (1);
+      close (wfd[1]);
+      close (rfd[0]);
+
+      if (dup (wfd[0]) == -1) {
+      dup_failed:
+        perror ("dup failed");
+        _exit (EXIT_FAILURE);
+      }
+      if (dup (rfd[1]) == -1)
+        goto dup_failed;
+
+      close (wfd[0]);
+      close (rfd[1]);
+    }
+
+#if 0
+    /* Set up a new process group, so we can signal this process
+     * and all subprocesses (eg. if qemu is really a shell script).
+     */
+    setpgid (0, 0);
+#endif
+
+    setenv ("LC_ALL", "C", 1);
+
+    execv (g->qemu, g->cmdline); /* Run qemu. */
+    perror (g->qemu);
+    _exit (EXIT_FAILURE);
+  }
+
+  /* Parent (library). */
+  g->pid = r;
+
+  free (kernel);
+  kernel = NULL;
+  free (initrd);
+  initrd = NULL;
+
+  /* Fork the recovery process off which will kill qemu if the parent
+   * process fails to do so (eg. if the parent segfaults).
+   */
+  g->recoverypid = -1;
+  if (g->recovery_proc) {
+    r = fork ();
+    if (r == 0) {
+      pid_t qemu_pid = g->pid;
+      pid_t parent_pid = getppid ();
+
+      /* Writing to argv is hideously complicated and error prone.  See:
+       * http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/utils/misc/ps_status.c?rev=1.33.2.1;content-type=text%2Fplain
+       */
+
+      /* Loop around waiting for one or both of the other processes to
+       * disappear.  It's fair to say this is very hairy.  The PIDs that
+       * we are looking at might be reused by another process.  We are
+       * effectively polling.  Is the cure worse than the disease?
+       */
+      for (;;) {
+        if (kill (qemu_pid, 0) == -1) /* qemu's gone away, we aren't needed */
+          _exit (EXIT_SUCCESS);
+        if (kill (parent_pid, 0) == -1) {
+          /* Parent's gone away, qemu still around, so kill qemu. */
+          kill (qemu_pid, 9);
+          _exit (EXIT_SUCCESS);
+        }
+        sleep (2);
+      }
+    }
+
+    /* Don't worry, if the fork failed, this will be -1.  The recovery
+     * process isn't essential.
+     */
+    g->recoverypid = r;
+  }
+
+  if (!g->direct) {
+    /* Close the other ends of the pipe. */
+    close (wfd[0]);
+    close (rfd[1]);
+
+    if (fcntl (wfd[1], F_SETFL, O_NONBLOCK) == -1 ||
+        fcntl (rfd[0], F_SETFL, O_NONBLOCK) == -1) {
+      perrorf (g, "fcntl");
+      goto cleanup1;
+    }
+
+    g->fd[0] = wfd[1];		/* stdin of child */
+    g->fd[1] = rfd[0];		/* stdout of child */
+  } else {
+    g->fd[0] = open ("/dev/null", O_RDWR);
+    if (g->fd[0] == -1) {
+      perrorf (g, "open /dev/null");
+      goto cleanup1;
+    }
+    g->fd[1] = dup (g->fd[0]);
+    if (g->fd[1] == -1) {
+      perrorf (g, "dup");
+      close (g->fd[0]);
+      goto cleanup1;
+    }
+  }
+
+  if (null_vmchannel_sock) {
+    int sock = -1;
+    uid_t uid;
+
+    /* Null vmchannel implementation: We listen on g->sock for a
+     * connection.  The connection could come from any local process
+     * so we must check it comes from the appliance (or at least
+     * from our UID) for security reasons.
+     */
+    while (sock == -1) {
+      sock = guestfs__accept_from_daemon (g);
+      if (sock == -1)
+        goto cleanup1;
+
+      if (check_peer_euid (g, sock, &uid) == -1)
+        goto cleanup1;
+      if (uid != geteuid ()) {
+        fprintf (stderr,
+                 "libguestfs: warning: unexpected connection from UID %d to port %d\n",
+                 uid, null_vmchannel_sock);
+        close (sock);
+        sock = -1;
+        continue;
+      }
+    }
+
+    if (fcntl (sock, F_SETFL, O_NONBLOCK) == -1) {
+      perrorf (g, "fcntl");
+      goto cleanup1;
+    }
+
+    close (g->sock);
+    g->sock = sock;
+  } else {
+    /* Other vmchannel.  Open the Unix socket.
+     *
+     * The vmchannel implementation that got merged with qemu sucks in
+     * a number of ways.  Both ends do connect(2), which means that no
+     * one knows what, if anything, is connected to the other end, or
+     * if it becomes disconnected.  Even worse, we have to wait some
+     * indeterminate time for qemu to create the socket and connect to
+     * it (which happens very early in qemu's start-up), so any code
+     * that uses vmchannel is inherently racy.  Hence this silly loop.
+     */
+    g->sock = socket (AF_UNIX, SOCK_STREAM, 0);
+    if (g->sock == -1) {
+      perrorf (g, "socket");
+      goto cleanup1;
+    }
+
+    if (fcntl (g->sock, F_SETFL, O_NONBLOCK) == -1) {
+      perrorf (g, "fcntl");
+      goto cleanup1;
+    }
+
+    addr.sun_family = AF_UNIX;
+    strncpy (addr.sun_path, unixsock, UNIX_PATH_MAX);
+    addr.sun_path[UNIX_PATH_MAX-1] = '\0';
+
+    tries = 100;
+    /* Always sleep at least once to give qemu a small chance to start up. */
+    usleep (10000);
+    while (tries > 0) {
+      r = connect (g->sock, (struct sockaddr *) &addr, sizeof addr);
+      if ((r == -1 && errno == EINPROGRESS) || r == 0)
+        goto connected;
+
+      if (errno != ENOENT)
+        perrorf (g, "connect");
+      tries--;
+      usleep (100000);
+    }
+
+    error (g, _("failed to connect to vmchannel socket"));
+    goto cleanup1;
+
+  connected: ;
+  }
+
+  g->state = LAUNCHING;
+
+  /* Wait for qemu to start and to connect back to us via vmchannel and
+   * send the GUESTFS_LAUNCH_FLAG message.
+   */
+  uint32_t size;
+  void *buf = NULL;
+  r = guestfs__recv_from_daemon (g, &size, &buf);
+  free (buf);
+
+  if (r == -1) return -1;
+
+  if (size != GUESTFS_LAUNCH_FLAG) {
+    error (g, _("guestfs_launch failed, see earlier error messages"));
+    goto cleanup1;
+  }
+
+  if (g->verbose)
+    print_timestamped_message (g, "appliance is up");
+
+  /* This is possible in some really strange situations, such as
+   * guestfsd starts up OK but then qemu immediately exits.  Check for
+   * it because the caller is probably expecting to be able to send
+   * commands after this function returns.
+   */
+  if (g->state != READY) {
+    error (g, _("qemu launched and contacted daemon, but state != READY"));
+    goto cleanup1;
+  }
+
+  return 0;
+
+ cleanup1:
+  if (!g->direct) {
+    close (wfd[1]);
+    close (rfd[0]);
+  }
+  if (g->pid > 0) kill (g->pid, 9);
+  if (g->recoverypid > 0) kill (g->recoverypid, 9);
+  waitpid (g->pid, NULL, 0);
+  if (g->recoverypid > 0) waitpid (g->recoverypid, NULL, 0);
+  g->fd[0] = -1;
+  g->fd[1] = -1;
+  g->pid = 0;
+  g->recoverypid = 0;
+  memset (&g->launch_t, 0, sizeof g->launch_t);
+
+ cleanup0:
+  if (g->sock >= 0) {
+    close (g->sock);
+    g->sock = -1;
+  }
+  g->state = CONFIG;
+  free (kernel);
+  free (initrd);
+  return -1;
+}
+
+/* This function is used to print the qemu command line before it gets
+ * executed, when in verbose mode.
+ */
+static void
+print_cmdline (guestfs_h *g)
+{
+  int i = 0;
+  int needs_quote;
+
+  while (g->cmdline[i]) {
+    if (g->cmdline[i][0] == '-') /* -option starts a new line */
+      fprintf (stderr, " \\\n   ");
+
+    if (i > 0) fputc (' ', stderr);
+
+    /* Does it need shell quoting?  This only deals with simple cases. */
+    needs_quote = strcspn (g->cmdline[i], " ") != strlen (g->cmdline[i]);
+
+    if (needs_quote) fputc ('\'', stderr);
+    fprintf (stderr, "%s", g->cmdline[i]);
+    if (needs_quote) fputc ('\'', stderr);
+    i++;
+  }
+
+  fputc ('\n', stderr);
+}
+
+/* This function does the hard work of building the supermin appliance
+ * on the fly.  'path' is the directory containing the control files.
+ * 'kernel' and 'initrd' are where we will return the names of the
+ * kernel and initrd (only initrd is built).  The work is done by
+ * an external script.  We just tell it where to put the result.
+ */
+static int
+build_supermin_appliance (guestfs_h *g, const char *path,
+                          char **kernel, char **initrd)
+{
+  char cmd[4096];
+  int r, len;
+
+  if (g->verbose)
+    print_timestamped_message (g, "begin building supermin appliance");
+
+  len = strlen (g->tmpdir);
+  *kernel = safe_malloc (g, len + 8);
+  snprintf (*kernel, len+8, "%s/kernel", g->tmpdir);
+  *initrd = safe_malloc (g, len + 8);
+  snprintf (*initrd, len+8, "%s/initrd", g->tmpdir);
+
+  /* Set a sensible umask in the subprocess, so kernel and initrd
+   * output files are world-readable (RHBZ#610880).
+   */
+  snprintf (cmd, sizeof cmd,
+            "umask 0002; "
+            "febootstrap-supermin-helper%s "
+            "-k '%s/kmod.whitelist' "
+            "'%s/supermin.d' "
+            host_cpu " "
+            "%s %s",
+            g->verbose ? " --verbose" : "",
+            path,
+            path,
+            *kernel, *initrd);
+  if (g->verbose)
+    print_timestamped_message (g, "%s", cmd);
+
+  r = system (cmd);
+  if (r == -1 || WEXITSTATUS(r) != 0) {
+    error (g, _("external command failed: %s"), cmd);
+    free (*kernel);
+    free (*initrd);
+    *kernel = *initrd = NULL;
+    return -1;
+  }
+
+  if (g->verbose)
+    print_timestamped_message (g, "finished building supermin appliance");
+
+  return 0;
+}
+
+/* Compute Y - X and return the result in milliseconds.
+ * Approximately the same as this code:
+ * http://www.mpp.mpg.de/~huber/util/timevaldiff.c
+ */
+static int64_t
+timeval_diff (const struct timeval *x, const struct timeval *y)
+{
+  int64_t msec;
+
+  msec = (y->tv_sec - x->tv_sec) * 1000;
+  msec += (y->tv_usec - x->tv_usec) / 1000;
+  return msec;
+}
+
+static void
+print_timestamped_message (guestfs_h *g, const char *fs, ...)
+{
+  va_list args;
+  char *msg;
+  int err;
+  struct timeval tv;
+
+  va_start (args, fs);
+  err = vasprintf (&msg, fs, args);
+  va_end (args);
+
+  if (err < 0) return;
+
+  gettimeofday (&tv, NULL);
+
+  fprintf (stderr, "[%05" PRIi64 "ms] %s\n",
+           timeval_diff (&g->launch_t, &tv), msg);
+
+  free (msg);
+}
+
+static int read_all (guestfs_h *g, FILE *fp, char **ret);
+
+/* Test qemu binary (or wrapper) runs, and do 'qemu -help' and
+ * 'qemu -version' so we know what options this qemu supports and
+ * the version.
+ */
+static int
+test_qemu (guestfs_h *g)
+{
+  char cmd[1024];
+  FILE *fp;
+
+  snprintf (cmd, sizeof cmd, "LC_ALL=C '%s' -nographic -help", g->qemu);
+
+  fp = popen (cmd, "r");
+  /* qemu -help should always work (qemu -version OTOH wasn't
+   * supported by qemu 0.9).  If this command doesn't work then it
+   * probably indicates that the qemu binary is missing.
+   */
+  if (!fp) {
+    /* XXX This error is never printed, even if the qemu binary
+     * doesn't exist.  Why?
+     */
+  error:
+    perrorf (g, _("%s: command failed: If qemu is located on a non-standard path, try setting the LIBGUESTFS_QEMU environment variable."), cmd);
+    return -1;
+  }
+
+  if (read_all (g, fp, &g->qemu_help) == -1)
+    goto error;
+
+  if (pclose (fp) == -1)
+    goto error;
+
+  snprintf (cmd, sizeof cmd, "LC_ALL=C '%s' -nographic -version 2>/dev/null",
+	    g->qemu);
+
+  fp = popen (cmd, "r");
+  if (fp) {
+    /* Intentionally ignore errors. */
+    read_all (g, fp, &g->qemu_version);
+    pclose (fp);
+  }
+
+  return 0;
+}
+
+static int
+read_all (guestfs_h *g, FILE *fp, char **ret)
+{
+  int r, n = 0;
+  char *p;
+
+ again:
+  if (feof (fp)) {
+    *ret = safe_realloc (g, *ret, n + 1);
+    (*ret)[n] = '\0';
+    return n;
+  }
+
+  *ret = safe_realloc (g, *ret, n + BUFSIZ);
+  p = &(*ret)[n];
+  r = fread (p, 1, BUFSIZ, fp);
+  if (ferror (fp)) {
+    perrorf (g, "read");
+    return -1;
+  }
+  n += r;
+  goto again;
+}
+
+/* Test if option is supported by qemu command line (just by grepping
+ * the help text).
+ *
+ * The first time this is used, it has to run the external qemu
+ * binary.  If that fails, it returns -1.
+ *
+ * To just do the first-time run of the qemu binary, call this with
+ * option == NULL, in which case it will return -1 if there was an
+ * error doing that.
+ */
+static int
+qemu_supports (guestfs_h *g, const char *option)
+{
+  if (!g->qemu_help) {
+    if (test_qemu (g) == -1)
+      return -1;
+  }
+
+  if (option == NULL)
+    return 1;
+
+  return strstr (g->qemu_help, option) != NULL;
+}
+
+/* Check if a file can be opened. */
+static int
+is_openable (guestfs_h *g, const char *path, int flags)
+{
+  int fd = open (path, flags);
+  if (fd == -1) {
+    if (g->verbose)
+      perror (path);
+    return 0;
+  }
+  close (fd);
+  return 1;
+}
+
+/* Check the peer effective UID for a TCP socket.  Ideally we'd like
+ * SO_PEERCRED for a loopback TCP socket.  This isn't possible on
+ * Linux (but it is on Solaris!) so we read /proc/net/tcp instead.
+ */
+static int
+check_peer_euid (guestfs_h *g, int sock, uid_t *rtn)
+{
+#if CAN_CHECK_PEER_EUID
+  struct sockaddr_in peer;
+  socklen_t addrlen = sizeof peer;
+
+  if (getpeername (sock, (struct sockaddr *) &peer, &addrlen) == -1) {
+    perrorf (g, "getpeername");
+    return -1;
+  }
+
+  if (peer.sin_family != AF_INET ||
+      ntohl (peer.sin_addr.s_addr) != INADDR_LOOPBACK) {
+    error (g, "check_peer_euid: unexpected connection from non-IPv4, non-loopback peer (family = %d, addr = %s)",
+           peer.sin_family, inet_ntoa (peer.sin_addr));
+    return -1;
+  }
+
+  struct sockaddr_in our;
+  addrlen = sizeof our;
+  if (getsockname (sock, (struct sockaddr *) &our, &addrlen) == -1) {
+    perrorf (g, "getsockname");
+    return -1;
+  }
+
+  FILE *fp = fopen ("/proc/net/tcp", "r");
+  if (fp == NULL) {
+    perrorf (g, "/proc/net/tcp");
+    return -1;
+  }
+
+  char line[256];
+  if (fgets (line, sizeof line, fp) == NULL) { /* Drop first line. */
+    error (g, "unexpected end of file in /proc/net/tcp");
+    fclose (fp);
+    return -1;
+  }
+
+  while (fgets (line, sizeof line, fp) != NULL) {
+    unsigned line_our_addr, line_our_port, line_peer_addr, line_peer_port;
+    int dummy0, dummy1, dummy2, dummy3, dummy4, dummy5, dummy6;
+    int line_uid;
+
+    if (sscanf (line, "%d:%08X:%04X %08X:%04X %02X %08X:%08X %02X:%08X %08X %d",
+                &dummy0,
+                &line_our_addr, &line_our_port,
+                &line_peer_addr, &line_peer_port,
+                &dummy1, &dummy2, &dummy3, &dummy4, &dummy5, &dummy6,
+                &line_uid) == 12) {
+      /* Note about /proc/net/tcp: local_address and rem_address are
+       * always in network byte order.  However the port part is
+       * always in host byte order.
+       *
+       * The sockname and peername that we got above are in network
+       * byte order.  So we have to byte swap the port but not the
+       * address part.
+       */
+      if (line_our_addr == our.sin_addr.s_addr &&
+          line_our_port == ntohs (our.sin_port) &&
+          line_peer_addr == peer.sin_addr.s_addr &&
+          line_peer_port == ntohs (peer.sin_port)) {
+        *rtn = line_uid;
+        fclose (fp);
+        return 0;
+      }
+    }
+  }
+
+  error (g, "check_peer_euid: no matching TCP connection found in /proc/net/tcp");
+  fclose (fp);
+  return -1;
+#else /* !CAN_CHECK_PEER_EUID */
+  /* This function exists but should never be called in this
+   * configuration.
+   */
+  abort ();
+#endif /* !CAN_CHECK_PEER_EUID */
+}
+
+/* You had to call this function after launch in versions <= 1.0.70,
+ * but it is now a no-op.
+ */
+int
+guestfs__wait_ready (guestfs_h *g)
+{
+  if (g->state != READY)  {
+    error (g, _("qemu has not been launched yet"));
+    return -1;
+  }
+
+  return 0;
+}
+
+int
+guestfs__kill_subprocess (guestfs_h *g)
+{
+  if (g->state == CONFIG) {
+    error (g, _("no subprocess to kill"));
+    return -1;
+  }
+
+  if (g->verbose)
+    fprintf (stderr, "sending SIGTERM to process %d\n", g->pid);
+
+  if (g->pid > 0) kill (g->pid, SIGTERM);
+  if (g->recoverypid > 0) kill (g->recoverypid, 9);
+
+  return 0;
+}
+
+/* Access current state. */
+int
+guestfs__is_config (guestfs_h *g)
+{
+  return g->state == CONFIG;
+}
+
+int
+guestfs__is_launching (guestfs_h *g)
+{
+  return g->state == LAUNCHING;
+}
+
+int
+guestfs__is_ready (guestfs_h *g)
+{
+  return g->state == READY;
+}
+
+int
+guestfs__is_busy (guestfs_h *g)
+{
+  return g->state == BUSY;
+}
+
+int
+guestfs__get_state (guestfs_h *g)
+{
+  return g->state;
+}