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https://github.com/PerpetualSoftware/pad.git
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xarmian
71fa167614
* fix(documents): the rename cascade matches a legacy title's links in their escaped form, so a title containing | \ or ] no longer leaves its links stale or rewrites a link to another target (BUG-2806) * test(documents): a linker holding only the escaped link must be found by the scan (BUG-2806) * docs(links,models): the ReplaceTitle limitation notes reflect the escaped cascade (BUG-2806) * fix(documents): a link is decided by the wiki grammar, so every encoding of a legacy title's link is rewritten, and the scan allocates nothing under the cascade's memory bound (BUG-2806) * refactor(links): drop the replaceAll helper ReplaceTitle no longer uses, keeping its termination reasoning on ReplaceTitle (BUG-2806) * fix(documents): the refusal of | and \ in a new title gives its true reason, since the rename cascade now finds their escaped links (BUG-2806)
71 lines
2.9 KiB
Go
71 lines
2.9 KiB
Go
package links
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import (
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"strings"
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"testing"
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"time"
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)
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// ReplaceTitle used to re-scan its own output: it looped "find old in result,
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// splice new in" until no match remained, so the text it had just inserted was
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// searched again. When the NEW title contains the OLD link token that never
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// terminates and the string grows without bound.
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//
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// The caller runs inside the rename transaction, so a hang here does not merely
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// wedge one request — it holds that transaction open while exhausting memory.
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// On Postgres it also holds the workspace rename advisory lock (BUG-2778) and
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// blocks every other rename in the workspace; on SQLite that lock is a no-op
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// and the transaction's own BEGIN IMMEDIATE write lock does the equivalent
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// damage.
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//
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// Found by Codex round 2 on BUG-2785, while enumerating the ways the cascade's
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// retry loop could fail to terminate.
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func TestReplaceTitle_TerminatesWhenNewTitleEmbedsOldToken(t *testing.T) {
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// `[[A]]` -> `[[A]] [[A]]`, whose output still contains `[[A]]`. Against the
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// old implementation this grew until it was killed; a probe ran 3s without
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// finishing.
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cases := []struct{ name, old, new string }{
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{"new title re-embeds the whole old token", "A", "A]] [[A"},
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{"new title re-embeds it twice", "A", "A]] [[A]] [[A"},
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{"old token embedded mid-title", "X", "pre A]] [[X]] [[post"},
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}
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for _, tc := range cases {
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t.Run(tc.name, func(t *testing.T) {
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done := make(chan string, 1)
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go func() { done <- ReplaceTitle("x [["+tc.old+"]] y", tc.old, tc.new) }()
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select {
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case got := <-done:
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// The property under test is TERMINATION, and specifically that
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// the substitution happens once per occurrence in the INPUT.
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//
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// The substitution is counted in the form ReplaceTitle emits:
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// the ESCAPED title (BUG-2806), so `A]] [[A` is written as
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// `[[A\]\] [[A]]`, ONE link to the new title. It used to emit
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// the raw title, which made two links to nothing (BUG-2796);
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// that is fixed, and the count is taken on the escaped literal
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// because the raw one no longer appears at all.
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if n := strings.Count(got, "[["+EscapeWikiTitle(tc.new)+"]]"); n != 1 {
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t.Errorf("substituted %d times, want exactly 1 (one occurrence in the input)\n got: %q", n, got)
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}
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case <-time.After(5 * time.Second):
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t.Fatal("ReplaceTitle did not terminate: the replacement re-scanned its own output, " +
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"which grows without bound when the new title contains the old link token")
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}
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})
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}
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}
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// The ordinary path has to keep working, and this is the control that would
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// catch a "fix" that terminated by doing nothing.
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func TestReplaceTitle_StillRewritesEveryOccurrence(t *testing.T) {
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got := ReplaceTitle("[[Old]] middle [[Old]] end", "Old", "New")
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if want := "[[New]] middle [[New]] end"; got != want {
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t.Errorf("got %q, want %q", got, want)
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}
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if strings.Contains(got, "[[Old]]") {
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t.Errorf("an occurrence survived: %q", got)
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}
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}
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