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fix: handle hang-on-halt behavior from agoric-labs/cosmos-sdk#305
The backport referenced above has the agd process hang around after halting. Wrote a wrapper utility which scans stderr for the halt application message, interrupts the process, then propagates its error signal. Conventional shell scripting is not up to the challenge of expressing this behavior.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,60 @@ | ||
| package main | ||
|
|
||
| // Runs a subcommand until a given string is seen on a line in the stderr output, | ||
| // then sends SIGINT the subprocess and propagates its exit status. | ||
|
|
||
| import ( | ||
| "bufio" | ||
| "log" | ||
| "os" | ||
| "os/exec" | ||
| "strings" | ||
| "syscall" | ||
| ) | ||
|
|
||
| func main() { | ||
| if len(os.Args) < 3 { | ||
| log.Fatal("usage: runtillmsg msg cmd arg...") | ||
| } | ||
| msg, cmdName, args := os.Args[1], os.Args[2], os.Args[3:] | ||
|
|
||
| // launch the command and listen to its stderr | ||
| cmd := exec.Command(cmdName, args...) | ||
| stderr, err := cmd.StderrPipe() | ||
| if err != nil { | ||
| log.Fatal(err) | ||
| } | ||
| err = cmd.Start() | ||
| if err != nil { | ||
| log.Fatal(err) | ||
| } | ||
|
|
||
| // copy lines of stderr, but interrupt the command if we see msg | ||
| scanner := bufio.NewScanner(stderr) | ||
| for scanner.Scan() { | ||
| line := scanner.Text() | ||
| if strings.Contains(line, msg) { | ||
| err = cmd.Process.Signal(syscall.SIGINT) | ||
| if err != nil { | ||
| log.Fatal(err) | ||
| } | ||
| } | ||
| os.Stderr.WriteString(line + "\n") | ||
| } | ||
| err = scanner.Err() | ||
| if err != nil { | ||
| log.Fatal(err) | ||
| } | ||
| stderr.Close() | ||
|
|
||
| // wait for the command to exit, and propagate its exit code | ||
| err = cmd.Wait() | ||
| if err != nil { | ||
| if exitErr, ok := err.(*exec.ExitError); ok { | ||
| os.Exit(exitErr.ExitCode()) | ||
| } | ||
| log.Fatal(err) | ||
| os.Exit(2) | ||
| } | ||
| // if cmd.Wait returns nil, exit code was 0, so just end | ||
| } |
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