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String.pathExtension should allow "..name" file names but not ".." #1410

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Merged
merged 1 commit into from
Jul 8, 2025
Merged

String.pathExtension should allow "..name" file names but not ".." #1410

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17 changes: 11 additions & 6 deletions Sources/FoundationEssentials/String/String+Path.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -224,14 +224,19 @@ extension String {
}

internal var pathExtension: String {
let lastComponent = lastPathComponent.utf8
guard lastComponent.last != ._dot,
!lastComponent.starts(with: [._dot, ._dot]),
let lastDot = lastComponent.lastIndex(of: ._dot),
lastDot != lastComponent.startIndex else {
let utf8Component = lastPathComponent.utf8
guard utf8Component.last != ._dot,
let lastDot = utf8Component.lastIndex(of: ._dot),
// Don't treat a hidden file name as an extension
lastDot != utf8Component.startIndex else {
return ""
}
let result = String(lastPathComponent[lastComponent.index(after: lastDot)...])
let utf8FileName = utf8Component[..<lastDot]
// Guard against "." and ".." file names
if (utf8FileName.count == 1 || utf8FileName.count == 2) && utf8FileName.allSatisfy({ $0 == ._dot }) {
return ""
}
let result = String(lastPathComponent[utf8Component.index(after: lastDot)...])
guard validatePathExtension(result) else {
return ""
}
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13 changes: 13 additions & 0 deletions Tests/FoundationEssentialsTests/StringTests.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -854,16 +854,29 @@ private struct StringTests {
#expect("/foo/bar/.zip".deletingPathExtension() == "/foo/bar/.zip")
#expect("..".deletingPathExtension() == "..")
#expect("..zip".deletingPathExtension() == "..zip")
#expect("/..".deletingPathExtension() == "/..")
#expect("/..zip".deletingPathExtension() == "/..zip")
#expect("/foo/bar/..zip".deletingPathExtension() == "/foo/bar/..zip")
#expect("/foo/bar/baz..zip".deletingPathExtension() == "/foo/bar/baz.")
#expect("...".deletingPathExtension() == "...")
#expect("...zip".deletingPathExtension() == "...zip")
#expect("/...".deletingPathExtension() == "/...")
#expect("/...zip".deletingPathExtension() == "/...zip")
#expect("/foo/bar/...zip".deletingPathExtension() == "/foo/bar/...zip")
#expect("/foo/bar/baz...zip".deletingPathExtension() == "/foo/bar/baz..")
#expect("/foo.bar/bar.baz/baz.zip".deletingPathExtension() == "/foo.bar/bar.baz/baz")
#expect("/.././.././a.zip".deletingPathExtension() == "/.././.././a")
#expect("/.././.././.".deletingPathExtension() == "/.././.././.")

// File names starting with "." or ".." are OK
// as long as they aren't exactly "." or ".."
#expect("..name.txt".deletingPathExtension() == "..name")
#expect("/..name.txt".deletingPathExtension() == "/..name")
#expect("....txt".deletingPathExtension() == "...")
#expect("/....txt".deletingPathExtension() == "/...")
#expect(".name.txt".deletingPathExtension() == ".name")
#expect("/.name.txt".deletingPathExtension() == "/.name")

#expect("path.foo".deletingPathExtension() == "path")
#expect("path.foo.zip".deletingPathExtension() == "path.foo")
#expect("/path.foo".deletingPathExtension() == "/path")
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