[Libguestfs] [PATCH 2/3] Add direct appliance mode flag and implementation.
Richard W.M. Jones
rjones at redhat.com
Tue Sep 22 19:01:09 UTC 2009
--
Richard Jones, Emerging Technologies, Red Hat http://et.redhat.com/~rjones
virt-top is 'top' for virtual machines. Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top
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>From be3817af8e577815770b466796698261d0491e21 Mon Sep 17 00:00:00 2001
From: Richard Jones <rjones at trick.home.annexia.org>
Date: Tue, 22 Sep 2009 19:52:56 +0100
Subject: [PATCH 2/3] Add direct appliance mode flag and implementation.
When the g->direct flag is set, the appliance stdin/stdout
are not connected to the library. Instead they inherit the
stdin/stdout of the caller.
This is used to implement virt-rescue.
---
src/generator.ml | 25 +++++++++++++
src/guestfs.c | 102 ++++++++++++++++++++++++++++++++++++-----------------
2 files changed, 94 insertions(+), 33 deletions(-)
diff --git a/src/generator.ml b/src/generator.ml
index e5e2681..1dd8b20 100755
--- a/src/generator.ml
+++ b/src/generator.ml
@@ -808,6 +808,31 @@ C<LIBGUESTFS_TRACE> is defined and set to C<1>.");
"\
Return the command trace flag.");
+ ("set_direct", (RErr, [Bool "direct"]), -1, [FishAlias "direct"],
+ [InitNone, Always, TestOutputFalse (
+ [["set_direct"; "false"];
+ ["get_direct"]])],
+ "enable or disable direct appliance mode",
+ "\
+If the direct appliance mode flag is enabled, then stdin and
+stdout are passed directly through to the appliance once it
+is launched.
+
+One consequence of this is that log messages aren't caught
+by the library and handled by C<guestfs_set_log_message_callback>,
+but go straight to stdout.
+
+You probably don't want to use this unless you know what you
+are doing.
+
+The default is disabled.");
+
+ ("get_direct", (RBool "direct", []), -1, [],
+ [],
+ "get direct appliance mode flag",
+ "\
+Return the direct appliance mode flag.");
+
]
(* daemon_functions are any functions which cause some action
diff --git a/src/guestfs.c b/src/guestfs.c
index 6eafcf5..03089ea 100644
--- a/src/guestfs.c
+++ b/src/guestfs.c
@@ -119,6 +119,7 @@ struct guestfs_h
int verbose;
int trace;
int autosync;
+ int direct;
char *path; /* Path to kernel, initrd. */
char *qemu; /* Qemu binary. */
@@ -651,6 +652,19 @@ guestfs__get_trace (guestfs_h *g)
return g->trace;
}
+int
+guestfs__set_direct (guestfs_h *g, int d)
+{
+ g->direct = !!d;
+ return 0;
+}
+
+int
+guestfs__get_direct (guestfs_h *g)
+{
+ return g->direct;
+}
+
/* Add a string to the current command line. */
static void
incr_cmdline_size (guestfs_h *g)
@@ -1018,18 +1032,22 @@ guestfs__launch (guestfs_h *g)
null_vmchannel_sock = 0;
}
- if (pipe (wfd) == -1 || pipe (rfd) == -1) {
- perrorf (g, "pipe");
- goto cleanup0;
+ if (!g->direct) {
+ if (pipe (wfd) == -1 || pipe (rfd) == -1) {
+ perrorf (g, "pipe");
+ goto cleanup0;
+ }
}
r = fork ();
if (r == -1) {
perrorf (g, "fork");
- close (wfd[0]);
- close (wfd[1]);
- close (rfd[0]);
- close (rfd[1]);
+ if (!g->direct) {
+ close (wfd[0]);
+ close (wfd[1]);
+ close (rfd[0]);
+ close (rfd[1]);
+ }
goto cleanup0;
}
@@ -1151,22 +1169,24 @@ guestfs__launch (guestfs_h *g)
if (g->verbose)
print_cmdline (g);
- /* Set up stdin, stdout. */
- close (0);
- close (1);
- close (wfd[1]);
- close (rfd[0]);
+ 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 (1);
+ }
+ if (dup (rfd[1]) == -1)
+ goto dup_failed;
- if (dup (wfd[0]) == -1) {
- dup_failed:
- perror ("dup failed");
- _exit (1);
+ close (wfd[0]);
+ close (rfd[1]);
}
- 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
@@ -1225,18 +1245,32 @@ guestfs__launch (guestfs_h *g)
/* Start the clock ... */
time (&g->start_t);
- /* Close the other ends of the pipe. */
- close (wfd[0]);
- close (rfd[1]);
+ 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;
- }
+ 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 */
+ 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;
@@ -1346,8 +1380,10 @@ guestfs__launch (guestfs_h *g)
return 0;
cleanup1:
- close (wfd[1]);
- close (rfd[0]);
+ if (!g->direct) {
+ close (wfd[1]);
+ close (rfd[0]);
+ }
kill (g->pid, 9);
if (g->recoverypid > 0) kill (g->recoverypid, 9);
waitpid (g->pid, NULL, 0);
--
1.6.2.5
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