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chore: centralize temp files and prefer streaming IO (#4668)

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* chore: centralize temp files and prefer streaming IO

Catalogers that create temp files ad-hoc can easily forget cleanup,
leaking files on disk. Similarly, io.ReadAll is convenient but risks
OOM on large or malicious inputs.

Introduce internal/tmpdir to manage all cataloger temp storage under
a single root directory with automatic cleanup. Prefer streaming
parsers (bufio.Scanner, json/yaml.NewDecoder, io.LimitReader) over
buffering entire inputs into memory. Add ruleguard rules to enforce
both practices going forward.

Signed-off-by: Will Murphy <willmurphyscode@users.noreply.github.com>

* chore: go back to old release parsing

Signed-off-by: Will Murphy <willmurphyscode@users.noreply.github.com>

* simplify to limit reader in version check

Signed-off-by: Will Murphy <willmurphyscode@users.noreply.github.com>

* chore: regex change postponed

Signed-off-by: Will Murphy <willmurphyscode@users.noreply.github.com>

* simplify supplement release to limitreader

Signed-off-by: Will Murphy <willmurphyscode@users.noreply.github.com>

---------

Signed-off-by: Will Murphy <willmurphyscode@users.noreply.github.com>
This commit is contained in:
Will Murphy
2026-03-18 10:53:51 -04:00
committed by GitHub
parent a3dacf5ecd
commit e38851143e
56 changed files with 704 additions and 214 deletions
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test/rules/rules.go
+44
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@@ -24,6 +24,50 @@ func isPtr(ctx *dsl.VarFilterContext) bool {
return strings.HasPrefix(ctx.Type.String(), "*") || strings.HasPrefix(ctx.Type.Underlying().String(), "*")
}
// nolint:unused
func noUnboundedReads(m dsl.Matcher) {
// flag io.ReadAll where the argument is not already wrapped in io.LimitReader
m.Match(`io.ReadAll($reader)`).
Where(!m["reader"].Text.Matches(`(?i)LimitReader|LimitedReader`)).
Report("do not use unbounded io.ReadAll; wrap the reader with io.LimitReader or use a streaming parser")
// flag io.Copy only when the destination is an in-memory buffer
// io.Copy to files, hash writers, encoders, etc. is streaming and safe
m.Match(`io.Copy($dst, $src)`).
Where((m["dst"].Type.Is(`*bytes.Buffer`) || m["dst"].Type.Is(`*strings.Builder`)) && !m["src"].Text.Matches(`(?i)LimitReader|LimitedReader`)).
Report("do not use unbounded io.Copy to in-memory buffer; wrap the source reader with io.LimitReader")
}
// nolint:unused
func noDirectTempFiles(m dsl.Matcher) {
// catalogers must use tmpdir.FromContext(ctx) instead of creating temp files/dirs directly,
// so that all temp storage is centrally managed and cleaned up
m.Match(
`os.CreateTemp($*_)`,
`os.MkdirTemp($*_)`,
).
Where(m.File().PkgPath.Matches(`/cataloger/`)).
Report("do not use os.CreateTemp/os.MkdirTemp in catalogers; use tmpdir.FromContext(ctx) instead")
}
// nolint:unused
func tmpCleanupDeferred(m dsl.Matcher) {
// ensure the cleanup function returned by NewFile/NewChild is deferred, not discarded
m.Match(
`$_, $cleanup, $err := $x.NewFile($*_); if $*_ { $*_ }; $next`,
`$_, $cleanup, $err = $x.NewFile($*_); if $*_ { $*_ }; $next`,
).
Where(!m["next"].Text.Matches(`^defer `)).
Report("defer the cleanup function returned by NewFile immediately after the error check")
m.Match(
`$_, $cleanup, $err := $x.NewChild($*_); if $*_ { $*_ }; $next`,
`$_, $cleanup, $err = $x.NewChild($*_); if $*_ { $*_ }; $next`,
).
Where(!m["next"].Text.Matches(`^defer `)).
Report("defer the cleanup function returned by NewChild immediately after the error check")
}
// nolint:unused
func packagesInRelationshipsAsValues(m dsl.Matcher) {
m.Import("github.com/anchore/syft/syft/artifact")