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authorPřemysl Janouch <p@janouch.name>2019-04-16 00:07:00 +0200
committerPřemysl Janouch <p@janouch.name>2019-04-16 00:07:00 +0200
commita4a399b8127b8930b7e725af55ed6d129b4c654e (patch)
treed5cbdeb1755c2b9a3fcdeae22f089e997dd0ea45 /cmd
parent2bd4f5921cb91bef2f39b231ac57a5fba5b782d2 (diff)
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sklad: prevent creating container cycles
Diffstat (limited to 'cmd')
-rw-r--r--cmd/sklad/container.tmpl2
-rw-r--r--cmd/sklad/db.go15
-rw-r--r--cmd/sklad/main.go2
3 files changed, 16 insertions, 3 deletions
diff --git a/cmd/sklad/container.tmpl b/cmd/sklad/container.tmpl
index b3ce98f..200bb19 100644
--- a/cmd/sklad/container.tmpl
+++ b/cmd/sklad/container.tmpl
@@ -12,6 +12,8 @@
<p>Chyba: Řadu u neprázdných obalů nelze měnit.
{{ else if .ErrorCannotChangeNumber }}
<p>Chyba: Číslo obalu v řadě nelze měnit.
+{{ else if .ErrorWouldContainItself }}
+<p>Chyba: Obal by obsahoval sám sebe.
{{ else if .ErrorContainerInUse }}
<p>Chyba: Obal se používá.
{{ else if .Error }}
diff --git a/cmd/sklad/db.go b/cmd/sklad/db.go
index a6cdda8..262a164 100644
--- a/cmd/sklad/db.go
+++ b/cmd/sklad/db.go
@@ -163,6 +163,7 @@ var errNoSuchContainer = errors.New("no such container")
var errCannotChangeSeriesNotEmpty = errors.New(
"cannot change the series of a non-empty container")
var errCannotChangeNumber = errors.New("cannot change the number")
+var errWouldContainItself = errors.New("container would contain itself")
var errContainerInUse = errors.New("container is in use")
// Find and filter out the container in O(n).
@@ -204,19 +205,27 @@ func dbContainerCreate(c *Container) error {
}
func dbContainerUpdate(c *Container, updated Container) error {
- newId := updated.Id()
+ newID := updated.Id()
if updated.Series != c.Series && len(c.Children()) > 0 {
return errCannotChangeSeriesNotEmpty
}
if updated.Number != c.Number {
return errCannotChangeNumber
}
- if _, ok := indexContainer[newId]; ok && newId != c.Id() {
+ if _, ok := indexContainer[newID]; ok && newID != c.Id() {
return errContainerAlreadyExists
}
if updated.Parent != c.Parent {
+ // Relying on the invariant that we can't change the ID
+ // of a non-empty container.
+ for pv := &updated; pv.Parent != ""; pv = indexContainer[pv.Parent] {
+ if pv.Parent == updated.Id() {
+ return errWouldContainItself
+ }
+ }
+
indexChildren[c.Parent] = filterContainer(indexChildren[c.Parent], c)
- indexChildren[newId] = append(indexChildren[newId], c)
+ indexChildren[newID] = append(indexChildren[newID], c)
}
*c = updated
return dbCommit()
diff --git a/cmd/sklad/main.go b/cmd/sklad/main.go
index 22d25b7..decd894 100644
--- a/cmd/sklad/main.go
+++ b/cmd/sklad/main.go
@@ -130,6 +130,7 @@ func handleContainer(w http.ResponseWriter, r *http.Request) {
ErrorNoSuchContainer bool
ErrorCannotChangeSeriesNotEmpty bool
ErrorCannotChangeNumber bool
+ ErrorWouldContainItself bool
ErrorContainerInUse bool
Container *Container
Children []*Container
@@ -141,6 +142,7 @@ func handleContainer(w http.ResponseWriter, r *http.Request) {
ErrorNoSuchContainer: err == errNoSuchContainer,
ErrorCannotChangeSeriesNotEmpty: err == errCannotChangeSeriesNotEmpty,
ErrorCannotChangeNumber: err == errCannotChangeNumber,
+ ErrorWouldContainItself: err == errWouldContainItself,
ErrorContainerInUse: err == errContainerInUse,
Container: container,
Children: children,