[Qemu-devel] [PATCH v2] do not chdir(/) in qemu-nbd before opening all files

[Qemu-devel] [PATCH v2] do not chdir(/) in qemu-nbd before opening all files

[Michael Tokarev]

When qemu-nbd becomes a daemon it calls daemon(3) with
nochdir=0, so daemon(3) changes current directory to /.
But at this time, qemu-nbd did not open any user-specified
files yet, so by changing current directory, all non-absolute
paths becomes wrong.  The solution is to pass nochdir=1 to
daemon(3) function, and to chdir("/") after all init has
been performed, before entering the main loop, -- just like
a good daemon should do.

This patch is applicable for -stable.

Signed-Off-By: Michael Tokarev <mjt@tls.msk.ru>
---
 qemu-nbd.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/qemu-nbd.c b/qemu-nbd.c
index e76c782..b1b5ae6 100644
--- a/qemu-nbd.c
+++ b/qemu-nbd.c
@@ -431,3 +431,3 @@ int main(int argc, char **argv)
             close(stderr_fd[0]);
-            ret = qemu_daemon(0, 0);
+            ret = qemu_daemon(1, 0);
 
@@ -529,2 +529,8 @@ int main(int argc, char **argv)
 
+    /* now when the initialization is (almost) complete, chdir("/")
+     * to free any busy filesystems */
+    if (chdir("/") < 0) {
+        err(EXIT_FAILURE, "Could not chdir to root directory");
+    }
+
     do {
-- 
1.7.2.5