Command line argument handling.

diff --git a/TODO b/TODO
index ad9e6e9..1d7cb36 100644 (file)
--- a/TODO
+++ b/TODO
@@ -54,21 +54,6 @@ ie. CentOS 5.3, Fedora 11, Debian.
 
 ----------------------------------------------------------------------
 
 
 ----------------------------------------------------------------------
 

-Qemu options -- After discussion with the KVM developers, they have
-recommended some flags which will improve the safety and reliability
-of KVM.  Need to test that these also work under qemu (or at least, do
-no harm):
-
--no-hpet      HPET support is broken and should be disabled.
-
--rtc-td-hack  Keeps the rtc clock source track time correctly.
-
--drive file=...,if=[ide|virtio],cache=off
-              cache=off is necessary to improve reliability in the
-             event of a system crash when writing.
-
-----------------------------------------------------------------------
-

 "Standalone/local mode"
 
 Instead of running guestfsd (the daemon) inside qemu, there should be
 "Standalone/local mode"
 
 Instead of running guestfsd (the daemon) inside qemu, there should be

diff --git a/guestfs.pod b/guestfs.pod
index f26880c..10c6ad8 100644 (file)
--- a/guestfs.pod
+++ b/guestfs.pod
@@ -759,6 +759,9 @@ For example:
 
  LIBGUESTFS_QEMU=/tmp/qemu.wrapper guestfish
 
 
  LIBGUESTFS_QEMU=/tmp/qemu.wrapper guestfish
 

+Note that libguestfs also calls qemu with the -help and -version
+options in order to determine features.
+

 =head1 ENVIRONMENT VARIABLES
 
 =over 4
 =head1 ENVIRONMENT VARIABLES
 
 =over 4

diff --git a/src/generator.ml b/src/generator.ml
index 341924f..f8e3934 100755 (executable)
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -373,7 +373,7 @@ for whatever operations you want to perform (ie. read access if you
 just want to read the image or write access if you want to modify the
 image).
 
 just want to read the image or write access if you want to modify the
 image).
 

-This is equivalent to the qemu parameter C<-drive file=filename>.
+This is equivalent to the qemu parameter C<-drive file=filename,cache=off>.

 
 Note that this call checks for the existence of C<filename>.  This
 stops you from specifying other types of drive which are supported
 
 Note that this call checks for the existence of C<filename>.  This
 stops you from specifying other types of drive which are supported

diff --git a/src/guestfs.c b/src/guestfs.c
index f7f64de..02b3ceb 100644 (file)
--- a/src/guestfs.c
+++ b/src/guestfs.c
@@ -162,6 +162,8 @@ struct guestfs_h
 
   char *tmpdir;                        /* Temporary directory containing socket. */
 
 
   char *tmpdir;                        /* Temporary directory containing socket. */
 

+  char *qemu_help, *qemu_version; /* Output of qemu -help, qemu -version. */
+

   char **cmdline;              /* Qemu command line. */
   int cmdline_size;
 
   char **cmdline;              /* Qemu command line. */
   int cmdline_size;
 


@@ -346,6 +348,8 @@ guestfs_close (guestfs_h *g)
   free (g->path);
   free (g->qemu);
   free (g->append);
   free (g->path);
   free (g->qemu);
   free (g->append);

+  free (g->qemu_help);
+  free (g->qemu_version);

   free (g);
 }
 
   free (g);
 }
 


@@ -638,7 +642,6 @@ guestfs_config (guestfs_h *g,
       strcmp (qemu_param, "-initrd") == 0 ||
       strcmp (qemu_param, "-nographic") == 0 ||
       strcmp (qemu_param, "-serial") == 0 ||
       strcmp (qemu_param, "-initrd") == 0 ||
       strcmp (qemu_param, "-nographic") == 0 ||
       strcmp (qemu_param, "-serial") == 0 ||

-      strcmp (qemu_param, "-vnc") == 0 ||

       strcmp (qemu_param, "-full-screen") == 0 ||
       strcmp (qemu_param, "-std-vga") == 0 ||
       strcmp (qemu_param, "-vnc") == 0) {
       strcmp (qemu_param, "-full-screen") == 0 ||
       strcmp (qemu_param, "-std-vga") == 0 ||
       strcmp (qemu_param, "-vnc") == 0) {


@@ -671,7 +674,8 @@ guestfs_add_drive (guestfs_h *g, const char *filename)
     return -1;
   }
 
     return -1;
   }
 

-  snprintf (buf, len, "file=%s", filename);
+  /* cache=off improves reliability in the event of a host crash. */
+  snprintf (buf, len, "file=%s,cache=off", filename);

 
   return guestfs_config (g, "-drive", buf);
 }
 
   return guestfs_config (g, "-drive", buf);
 }


@@ -745,6 +749,8 @@ dir_contains_files (const char *dir, ...)
 }
 
 static int build_supermin_appliance (guestfs_h *g, const char *path, char **kernel, char **initrd);
 }
 
 static int build_supermin_appliance (guestfs_h *g, const char *path, char **kernel, char **initrd);

+static int test_qemu (guestfs_h *g);
+static int qemu_supports (guestfs_h *g, const char *option);

 
 static const char *kernel_name = "vmlinuz." REPO "." host_cpu;
 static const char *initrd_name = "initramfs." REPO "." host_cpu ".img";
 
 static const char *kernel_name = "vmlinuz." REPO "." host_cpu;
 static const char *initrd_name = "initramfs." REPO "." host_cpu ".img";


@@ -879,12 +885,16 @@ guestfs_launch (guestfs_h *g)
   /* Choose a suitable memory size.  Previously we tried to choose
    * a minimal memory size, but this isn't really necessary since
    * recent QEMU and KVM don't do anything nasty like locking
   /* Choose a suitable memory size.  Previously we tried to choose
    * a minimal memory size, but this isn't really necessary since
    * recent QEMU and KVM don't do anything nasty like locking

-   * memory into core any more.  This we can safely choose a
+   * memory into core any more.  Thus we can safely choose a

    * large, generous amount of memory, and it'll just get swapped
    * on smaller systems.
    */
   memsize = 384;
 
    * large, generous amount of memory, and it'll just get swapped
    * on smaller systems.
    */
   memsize = 384;
 

+  /* Get qemu help text and version. */
+  if (test_qemu (g) == -1)
+    goto cleanup0;
+

   /* Make the vmchannel socket. */
   snprintf (unixsock, sizeof unixsock, "%s/sock", g->tmpdir);
   unlink (unixsock);
   /* Make the vmchannel socket. */
   snprintf (unixsock, sizeof unixsock, "%s/sock", g->tmpdir);
   unlink (unixsock);


@@ -946,6 +956,15 @@ guestfs_launch (guestfs_h *g)
     add_cmdline (g, "user,vlan=0");
     add_cmdline (g, "-net");
     add_cmdline (g, "nic,model=virtio,vlan=0");
     add_cmdline (g, "user,vlan=0");
     add_cmdline (g, "-net");
     add_cmdline (g, "nic,model=virtio,vlan=0");

+
+    /* 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");
+
+    /* Finish off the command line. */

     incr_cmdline_size (g);
     g->cmdline[g->cmdline_size-1] = NULL;
 
     incr_cmdline_size (g);
     g->cmdline[g->cmdline_size-1] = NULL;
 


@@ -1171,6 +1190,90 @@ build_supermin_appliance (guestfs_h *g, const char *path,
   return 0;
 }
 
   return 0;
 }
 

+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;
+
+  free (g->qemu_help);
+  free (g->qemu_version);
+  g->qemu_help = NULL;
+  g->qemu_version = NULL;
+
+  snprintf (cmd, sizeof cmd, "'%s' -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, "'%s' -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).
+ */
+static int
+qemu_supports (guestfs_h *g, const char *option)
+{
+  return g->qemu_help && strstr (g->qemu_help, option) != NULL;
+}
+

 static void
 finish_wait_ready (guestfs_h *g, void *vp)
 {
 static void
 finish_wait_ready (guestfs_h *g, void *vp)
 {