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runtime: handle underscore in Linux kernel release strings #170

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runtime: handle underscore in Linux kernel release strings #170

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1 change: 1 addition & 0 deletions src/runtime/export_linux_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ const SigeventMaxSize = _sigev_max_size

var NewOSProc0 = newosproc0
var Mincore = mincore
var ParseRelease = parseRelease

type Siginfo siginfo
type Sigevent sigevent
6 changes: 4 additions & 2 deletions src/runtime/os_linux.go
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Expand Up @@ -962,9 +962,11 @@ func getKernelVersion() kernelVersion {
// semver syntax, but allows the minor and patch versions to be
// elided.
func parseRelease(rel string) (major, minor, patch int, ok bool) {
// Strip anything after a dash or plus.
// Strip anything after a dash, plus, or underscore. Some
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@creachadair creachadair May 22, 2026

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The change seems fine, but we no longer actually follow semver grammar, strictly speaking (to be fair, Synology et al. started it). Maybe note this in the doc comment above? E.g.,

// parseRelease parses a dot-separated version number.
// It follows semver syntax, but allows the minor and patch
// versions to be elided, and accepts "_" as a separator for
// pre-release labels in addition to "-".

or words to that effect.

(Likewise we don't handle build labels either, though if we got one of those on a kernel release we probably have bigger issues 😅)

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@bradfitz bradfitz May 22, 2026

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Strictly speaking, this code from Go (which is like 10 years old) never did semver... it also parse "4.5" without a patch.

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@creachadair creachadair May 22, 2026

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Yeah, I don't think we need to match the spec, my comment was mostly just about updating the comment. But it's unexported, so certainly not essential.

// embedded Linux vendors (e.g., Synology) append a platform
// identifier with an underscore, like "3.4.35_hi3535".
for i := 0; i < len(rel); i++ {
if rel[i] == '-' || rel[i] == '+' {
if rel[i] == '-' || rel[i] == '+' || rel[i] == '_' {
rel = rel[:i]
break
}
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25 changes: 25 additions & 0 deletions src/runtime/runtime_linux_test.go
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Expand Up @@ -53,6 +53,31 @@ func TestMincoreErrorSign(t *testing.T) {
}
}

func TestParseRelease(t *testing.T) {
tests := []struct {
in string
major, minor, patch int
ok bool
}{
{"6.1.0", 6, 1, 0, true},
{"5.15.0-91-generic", 5, 15, 0, true},
{"4.19.0+", 4, 19, 0, true},
// Synology embedded Linux appends a platform identifier
// after an underscore.
{"3.4.35_hi3535", 3, 4, 35, true},
{"2.6.32_synology", 2, 6, 32, true},
{"3.10", 3, 10, 0, true},
{"bogus", 0, 0, 0, false},
}
for _, tt := range tests {
major, minor, patch, ok := ParseRelease(tt.in)
if major != tt.major || minor != tt.minor || patch != tt.patch || ok != tt.ok {
t.Errorf("ParseRelease(%q) = (%d, %d, %d, %v); want (%d, %d, %d, %v)",
tt.in, major, minor, patch, ok, tt.major, tt.minor, tt.patch, tt.ok)
}
}
}

func TestKernelStructSize(t *testing.T) {
// Check that the Go definitions of structures exchanged with the kernel are
// the same size as what the kernel defines.
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