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Fix race condition surrounding global orgWriter

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Since writers are normally only used synchronously (i.e. to write one document
at a time), we don't guard modifications to their internal
state (e.g. temporarily replacing the string.Builder in WriteNodesAsString)
against race conditions.

The package global `orgWriter` and corresponding use cases of it (`org.String`,
`$node.String`) break that pattern - the writer is potentially used from
multiple go routines at the same time. This results in race conditions that
manifest as error messages like e.g.

    could not write output: runtime error: invalid memory address or nil pointer dereference. Using unrendered content.

Additionally, since we catch panics in `Document.Write`, the corresponding
stack trace is lost and dependents of go-org never know what hit them.

As using a writer across simultaneously across go routines is not a standard
pattern, we'll sync the use of the global `orgWriter` instead of trying to make
the actual writer threadsafe; less code noise for the common use case.
This commit is contained in:
Niklas Fasching 2023-03-12 11:08:19 +01:00
parent 18314a9f41
commit 5464ab37d2
12 changed files with 41 additions and 35 deletions
Download patch file Download diff file Expand all files Collapse all files

24
org/inline.go
View file

@ -400,7 +400,7 @@ func isValidPostChar(r rune) bool {
func isValidBorderChar(r rune) bool { return !unicode.IsSpace(r) }
func (l RegularLink) Kind() string {
description := String(l.Description)
description := String(l.Description...)
descProtocol, descExt := strings.SplitN(description, ":", 2)[0], path.Ext(description)
if ok := descProtocol == "file" || descProtocol == "http" || descProtocol == "https"; ok && imageExtensionRegexp.MatchString(descExt) {
return "image"
@ -420,14 +420,14 @@ func (l RegularLink) Kind() string {
return "regular"
}
func (n Text) String() string { return orgWriter.WriteNodesAsString(n) }
func (n LineBreak) String() string { return orgWriter.WriteNodesAsString(n) }
func (n ExplicitLineBreak) String() string { return orgWriter.WriteNodesAsString(n) }
func (n StatisticToken) String() string { return orgWriter.WriteNodesAsString(n) }
func (n Emphasis) String() string { return orgWriter.WriteNodesAsString(n) }
func (n InlineBlock) String() string { return orgWriter.WriteNodesAsString(n) }
func (n LatexFragment) String() string { return orgWriter.WriteNodesAsString(n) }
func (n FootnoteLink) String() string { return orgWriter.WriteNodesAsString(n) }
func (n RegularLink) String() string { return orgWriter.WriteNodesAsString(n) }
func (n Macro) String() string { return orgWriter.WriteNodesAsString(n) }
func (n Timestamp) String() string { return orgWriter.WriteNodesAsString(n) }
func (n Text) String() string { return String(n) }
func (n LineBreak) String() string { return String(n) }
func (n ExplicitLineBreak) String() string { return String(n) }
func (n StatisticToken) String() string { return String(n) }
func (n Emphasis) String() string { return String(n) }
func (n InlineBlock) String() string { return String(n) }
func (n LatexFragment) String() string { return String(n) }
func (n FootnoteLink) String() string { return String(n) }
func (n RegularLink) String() string { return String(n) }
func (n Macro) String() string { return String(n) }
func (n Timestamp) String() string { return String(n) }