[Bug 1003583] Re: make the "--close-all-fds" option in lxc-start on by default

[Serge Hallyn]

** Description changed:

- Since the lxc-start command quits with an error if any inherited FDs are
- not disconnected, why is it necessary to specify --close-all-fds at all?
+ ============================
+ SRU Justification
+ Impact: callers of lxc-start can have confusing failures to start
+ Development fix: always close all fds
+ Stable fix: same as development fix
+ Test case:
+   1. lxc-create -t ubuntu -n p1
+   2. cat > execme.c << EOF
+ #include <stdio.h>
+ #include <unistd.h>
+ 
+ int main()
+ {
+         FILE *f = fopen("/tmp/ab", "w");
+         //int ret = execl("/usr/bin/lxc-start", "/usr/bin/lxc-start", "-d", "-n", "p1", NULL);
+         int ret = execl("/usr/bin/lxc-start", "/usr/bin/lxc-start", "-n", "p1", NULL);
+         printf("should not be here (ret %d)\n", ret);
+ }
+ EOF
+    3. make execme
+    4. sudo ./execme
+    Without this patch, the container will fail to start with an error message
+    saying an fd was inherited.  With the patch, the container will start (and
+    the fd will have been closed)
+ Regression potential: if anyone was counting on lxc-start to fail when started
+ with open fds, that will no longer happen.
+ ============================
+ Since the lxc-start command quits with an error if any inherited FDs are not disconnected, why is it necessary to specify --close-all-fds at all?
  
  (I just spent an hour debugging a situation where some FDs were falling
  through from parent processes only in the remote deployment
  configuration...)

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https://bugs.launchpad.net/bugs/1003583

Title:
  make the "--close-all-fds" option in lxc-start on by default

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