Rework error handling to check context.State

Currently the debos error handling sets an exitcode during the run, then
exits with that code once execution has finished. This paradigm is quite
fragile, so let's switch around the error handling to use context.State
to track errors and check the state of this variable after the run has
completed.

While we are here, rename the checkError function to handleError to better
describe the function's intent and make it return a boolean to show that
an error has been handled. Rework the do_run function to also return a
boolean to show that an error occurred during the run.

Signed-off-by: Christopher Obbard <chris.obbard@collabora.com>

cmd/debos/debos.go

@@ -15,18 +15,18 @@ import (
  "github.com/jessevdk/go-flags"
 )
 
-func checkError(context *debos.DebosContext, err error, a debos.Action, stage string) int {
+func handleError(context *debos.DebosContext, err error, a debos.Action, stage string) bool {
  if err == nil {
- return 0
+ return false
  }
 
  context.State = debos.Failed
  log.Printf("Action `%s` failed at stage %s, error: %s", a, stage, err)
  debos.DebugShell(*context)
- return 1
+ return true
 }
 
-func do_run(r actions.Recipe, context *debos.DebosContext) int {
+func do_run(r actions.Recipe, context *debos.DebosContext) bool {
  for _, a := range r.Actions {
  err := a.Run(context)
 
@@ -35,12 +35,12 @@ func do_run(r actions.Recipe, context *debos.DebosContext) int {
  defer a.Cleanup(context)
 
  // Check the state of Run method
- if exitcode := checkError(context, err, a, "Run"); exitcode != 0 {
- return exitcode
+ if handleError(context, err, a, "Run") {
+ return false
  }
  }
 
- return 0
+ return true
 }
 
 func warnLocalhost(variable string, value string) {
@@ -88,11 +88,12 @@ func main() {
  "no_proxy",
  }
 
- var exitcode int = 0
  // Allow to run all deferred calls prior to os.Exit()
- defer func() {
- os.Exit(exitcode)
- }()
+ defer func(context debos.DebosContext) {
+ if context.State == debos.Failed {
+ os.Exit(1)
+ }
+ }(context)
 
  parser := flags.NewParser(&options, flags.Default)
  fakemachineBackends := parser.FindOptionByLongName("fakemachine-backend")
@@ -104,20 +105,20 @@ func main() {
  if ok && flagsErr.Type == flags.ErrHelp {
  return
  } else {
- exitcode = 1
+ context.State = debos.Failed
  return
  }
  }
 
  if len(args) != 1 {
  log.Println("No recipe given!")
- exitcode = 1
+ context.State = debos.Failed
  return
  }
 
  if options.DisableFakeMachine && options.Backend != "auto" {
  log.Println("--disable-fakemachine and --fakemachine-backend are mutually exclusive")
- exitcode = 1
+ context.State = debos.Failed
  return
  }
 
@@ -140,12 +141,12 @@ func main() {
  r := actions.Recipe{}
  if _, err := os.Stat(file); os.IsNotExist(err) {
  log.Println(err)
- exitcode = 1
+ context.State = debos.Failed
  return
  }
  if err := r.Parse(file, options.PrintRecipe, options.Verbose, options.TemplateVars); err != nil {
  log.Println(err)
- exitcode = 1
+ context.State = debos.Failed
  return
  }
 
@@ -169,7 +170,7 @@ func main() {
  if options.Backend == "auto" {
  runInFakeMachine = false
  } else {
- exitcode = 1
+ context.State = debos.Failed
  return
  }
  }
@@ -233,7 +234,7 @@ func main() {
 
  for _, a := range r.Actions {
  err = a.Verify(&context)
- if exitcode = checkError(&context, err, a, "Verify"); exitcode != 0 {
+ if handleError(&context, err, a, "Verify") {
  return
  }
  }
@@ -253,7 +254,7 @@ func main() {
  memsize, err := units.RAMInBytes(options.Memory)
  if err != nil {
  fmt.Printf("Couldn't parse memory size: %v\n", err)
- exitcode = 1
+ context.State = debos.Failed
  return
  }
  m.SetMemory(int(memsize / 1024 / 1024))
@@ -268,7 +269,7 @@ func main() {
  size, err := units.FromHumanSize(options.ScratchSize)
  if err != nil {
  fmt.Printf("Couldn't parse scratch size: %v\n", err)
- exitcode = 1
+ context.State = debos.Failed
  return
  }
  m.SetScratch(size, "")
@@ -310,14 +311,15 @@ func main() {
  defer a.PostMachineCleanup(&context)
 
  err = a.PreMachine(&context, m, &args)
- if exitcode = checkError(&context, err, a, "PreMachine"); exitcode != 0 {
+ if handleError(&context, err, a, "PreMachine") {
  return
  }
  }
 
- exitcode, err = m.RunInMachineWithArgs(args)
+ exitcode, err := m.RunInMachineWithArgs(args)
  if err != nil {
  fmt.Println(err)
+ context.State = debos.Failed
  return
  }
 
@@ -328,7 +330,7 @@ func main() {
 
  for _, a := range r.Actions {
  err = a.PostMachine(&context)
- if exitcode = checkError(&context, err, a, "Postmachine"); exitcode != 0 {
+ if handleError(&context, err, a, "PostMachine") {
  return
  }
  }
@@ -343,7 +345,7 @@ func main() {
  defer a.PostMachineCleanup(&context)
 
  err = a.PreNoMachine(&context)
- if exitcode = checkError(&context, err, a, "PreNoMachine"); exitcode != 0 {
+ if handleError(&context, err, a, "PreNoMachine") {
  return
  }
  }
@@ -353,20 +355,19 @@ func main() {
  if _, err = os.Stat(context.Rootdir); os.IsNotExist(err) {
  err = os.Mkdir(context.Rootdir, 0755)
  if err != nil && os.IsNotExist(err) {
- exitcode = 1
+ context.State = debos.Failed
  return
  }
  }
 
- exitcode = do_run(r, &context)
- if exitcode != 0 {
+ if !do_run(r, &context) {
  return
  }
 
  if !fakemachine.InMachine() {
  for _, a := range r.Actions {
  err = a.PostMachine(&context)
- if exitcode = checkError(&context, err, a, "PostMachine"); exitcode != 0 {
+ if handleError(&context, err, a, "PostMachine") {
  return
  }
  }