Stefan Feenstra created IO-860:
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Summary: Missing reserved filenames for Windows in FileSystem.java
(superscript digits for COM and LPT)
Key: IO-860
URL: https://issues.apache.org/jira/browse/IO-860
Project: Commons IO
Issue Type: Bug
Components: Utilities
Affects Versions: 2.17.0
Reporter: Stefan Feenstra
Per Microsoft documentation, the following filenames are also reserved
filenames: LPT¹, LPT², LPT³, COM¹, COM² and COM³.
As far as I can tell, only the non-superscript filenames are marked as illegal
in the FileSystem.WINDOWS enum. These six filenames should also be added as
reserved filenames, as they can not be used for regular files. (e.g. trying to
create a file called COM³ will fail).
Quote from the [microsoft
documentation|[https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file#win32-file-namespaces|https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file#file-and-directory-names]]:
{code:java}
Windows recognizes the 8-bit ISO/IEC 8859-1
superscript digits ¹, ², and ³ as digits and treats them as valid parts
of COM# and LPT# device names, making them reserved in every directory. {code}
Testing code to reproduce: (there should be no output)
{code:java}
import org.apache.commons.io.FileSystem;
public class FilenameTest {
public static void main(String[] args) {
char[] digitsWithSuperScript = {'1', '2', '3', '4', '5', '6', '7', '8',
'9', '¹', '²', '³'};
for (String filenamesPrefix : new String[]{"LPT", "COM"}) {
for (char digit : digitsWithSuperScript) {
final String filename = filenamesPrefix + digit;
checkFilename(filename, true);
// Base filename should be reserved
checkFilename(filename + ".tar.gz", true);
// Extensions should be ignored
checkFilename(filename + ".txt", true);
// Non-extension suffixes are ok.
checkFilename(filename + "additional_text", false);
}
}
for (String reservedFileName : new String[]{"CON", "PRN", "AUX", "NUL",
"CONIN$", "CONOUT$"}) {
// Base filename should be reserved
checkFilename(reservedFileName, true);
// Extensions should be ignored
checkFilename(reservedFileName + ".tar.gz", true);
// Non-extension suffixes are ok.
checkFilename(reservedFileName + "additional_text", false);
}
}
static void checkFilename(String filename, boolean isReserved) {
boolean isReservedAccordingToAPI =
FileSystem.WINDOWS.isReservedFileName(filename);
if (isReserved != isReservedAccordingToAPI) {
if (isReserved) {
System.out.printf("'%s' is reserved according to the spec but
not according to FileSystem.isReservedFileName%n", filename);
} else {
System.out.printf("'%s' is not reserved according to the spec
but is according to FileSystem.isReservedFileName%n", filename);
}
} else {
// Spec and API match
}
}
}{code}
Link to relevant code:
[https://github.com/apache/commons-io/blob/ec0fd2c98f0bf94d6d87c6adf237430e606e2e23/src/main/java/org/apache/commons/io/FileSystem.java#L91C16-L92C116]
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