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authorNicolas Lacasse <nlacasse@google.com>2018-07-25 09:10:32 -0700
committerShentubot <shentubot@google.com>2018-07-25 09:11:45 -0700
commit1129b35c92034d04ed22cf69e270ed9c034069d7 (patch)
treec632bcb8969ee49fc31ab7148883cbe17712fd62 /runsc/cmd
parent32aa0f5465832c437a9de83c1c1a04b615d68122 (diff)
runsc: Fix "exec" command when called without --pid-file.
When "exec" command is called without the "--detach" flag, we spawn a second "exec" command and wait for that one to start. We use the pid file passed in --pid-file to detect when this second command has started running. However if "exec" is called with no --pid-file flag, this system breaks down, as we don't have a pid file to wait for. This CL ensures that the second instance of the "exec" command always writes a pid-file, so the wait is successful. PiperOrigin-RevId: 206002403 Change-Id: If9f2be31eb6e831734b1b833f25054ec71ab94a6
Diffstat (limited to 'runsc/cmd')
-rw-r--r--runsc/cmd/exec.go20
1 files changed, 19 insertions, 1 deletions
diff --git a/runsc/cmd/exec.go b/runsc/cmd/exec.go
index cbce07c8e..4ee370656 100644
--- a/runsc/cmd/exec.go
+++ b/runsc/cmd/exec.go
@@ -20,6 +20,7 @@ import (
"io/ioutil"
"os"
"os/exec"
+ "path/filepath"
"strconv"
"strings"
"syscall"
@@ -156,11 +157,28 @@ func (ex *Exec) execAndWait(waitStatus *syscall.WaitStatus) subcommands.ExitStat
Fatalf("error getting bin path: %v", err)
}
var args []string
+
+ // The command needs to write a pid file so that execAndWait can tell
+ // when it has started. If no pid-file was provided, we should use a
+ // filename in a temp directory.
+ pidFile := ex.pidFile
+ if pidFile == "" {
+ tmpDir, err := ioutil.TempDir("", "exec-pid-")
+ if err != nil {
+ Fatalf("error creating TempDir: %v", err)
+ }
+ defer os.RemoveAll(tmpDir)
+ pidFile = filepath.Join(tmpDir, "pid")
+ args = append(args, "--pid-file="+pidFile)
+ }
+
+ // Add the rest of the args, excluding the "detach" flag.
for _, a := range os.Args[1:] {
if !strings.Contains(a, "detach") {
args = append(args, a)
}
}
+
cmd := exec.Command(binPath, args...)
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
@@ -175,7 +193,7 @@ func (ex *Exec) execAndWait(waitStatus *syscall.WaitStatus) subcommands.ExitStat
// '--process' file is deleted as soon as this process returns and the child
// may fail to read it.
ready := func() (bool, error) {
- _, err := os.Stat(ex.pidFile)
+ _, err := os.Stat(pidFile)
if err == nil {
// File appeared, we're done!
return true, nil