mountinfo: GetMountsFromReader() remove redundant switch, fix dropped "optional" fields #81
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thaJeztah
commented
Aug 14, 2021
| case sepIdx == 7: | ||
| p.Optional = fields[6] | ||
| default: | ||
| p.Optional = strings.Join(fields[6:sepIdx-1], " ") |
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Looks like there's an off-by-one bug here; removing this switch caused it to panic;
--- FAIL: TestMountedBy (0.01s)
panic: runtime error: slice bounds out of range [6:5] [recovered]
panic: runtime error: slice bounds out of range [6:5]
- we return an error if
sepIdx == 5(earlier check) - for
sepIdx == 6we skipped (in this switch) - for
7, we take field 6 (equivalent tofields[6:7], orfields[6:sepIdx]) - for the "default" (else), we use
fields[6:sepIdx-1], which for (e.g.)sepIndex=8would do the same assepIdx=7, so we'd drop one value
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@kolyshkin PTAL |
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Looking further, I noticed that TestParseMountinfoExtraCases was not checking the |
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@AkihiroSuda ptal |
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
… fields This switch was implementing the exact same check as is done in strings.Join(); https://cs.opensource.google/go/go/+/refs/tags/go1.16.7:src/strings/strings.go;l=421-427 This only difference removing this switch makes is that it will assign an empty string to p.Optional if no optional fields are present, but given that an empty string is the default value for p.Optional, this should make no difference. This also revealed an off-by-one bug: Before this change: - we return an error if `sepIdx == 5` (earlier check) - for `sepIdx == 6` we skipped (in this switch) - for `7`, we take field 6 (equivalent to `fields[6:7]`, or `fields[6:sepIdx]`) - for the "default" (else), we use `fields[6:sepIdx-1]`, which for (e.g.) `sepIndex=8` would do the same as `sepIdx=7`, so we'd drop one value. Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
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AkihiroSuda
approved these changes
Aug 23, 2021
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This switch was implementing the exact same check as is done in
strings.Join(); https://cs.opensource.google/go/go/+/refs/tags/go1.16.7:src/strings/strings.go;l=421-427
This only difference removing this switch makes is that it will assign
an empty string to p.Optional if no optional fields are present, but
given that an empty string is the default value for p.Optional, this
should make no difference.
This also revealed an off-by-one bug:
Before this change:
sepIdx == 5(earlier check)sepIdx == 6we skipped (in this switch)7, we take field 6 (equivalent tofields[6:7], orfields[6:sepIdx])fields[6:sepIdx-1], which for (e.g.)sepIndex=8would do the same as
sepIdx=7, so we'd drop one value.