Skip to content

Commit

Permalink
#139: feature for making symlinks relative (#140)
Browse files Browse the repository at this point in the history
  • Loading branch information
@MattesMrzik
MattesMrzik authored Jan 4, 2024
1 parent 6f1be94 commit bae97bc
Show file tree
Hide file tree
Showing 4 changed files with 640 additions and 18 deletions.
22 changes: 20 additions & 2 deletions cli/src/main/java/com/devonfw/tools/ide/io/FileAccess.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -59,10 +59,28 @@ public interface FileAccess {
void move(Path source, Path targetDir);

/**
* @param source the source {@link Path} to link to.
* Creates a symbolic link. If the given {@code targetLink} already exists and is a symbolic link or a Windows
* junction, it will be replaced. In case of missing privileges, Windows Junctions may be used as fallback, which must
* point to absolute paths. Therefore, the created link will be absolute instead of relative.
*
* @param source the source {@link Path} to link to, may be relative or absolute.
* @param targetLink the {@link Path} where the symbolic link shall be created pointing to {@code source}.
* @param relative - {@code true} if the symbolic link shall be relative, {@code false} if it shall be absolute.
*/
void symlink(Path source, Path targetLink);
void symlink(Path source, Path targetLink, boolean relative);

/**
* Creates a relative symbolic link. If the given {@code targetLink} already exists and is a symbolic link or a
* Windows junction, it will be replaced. In case of missing privileges, Windows Junctions may be used as fallback,
* which must point to absolute paths. Therefore, the created link will be absolute instead of relative.
*
* @param source the source {@link Path} to link to, may be relative or absolute.
* @param targetLink the {@link Path} where the symbolic link shall be created pointing to {@code source}.
*/
default void symlink(Path source, Path targetLink) {

symlink(source, targetLink, true);
}

/**
* @param source the source {@link Path file or folder} to copy.
Expand Down
162 changes: 147 additions & 15 deletions cli/src/main/java/com/devonfw/tools/ide/io/FileAccessImpl.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,8 +13,11 @@
import java.net.http.HttpResponse;
import java.nio.file.FileSystemException;
import java.nio.file.Files;
import java.nio.file.LinkOption;
import java.nio.file.NoSuchFileException;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.BasicFileAttributes;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
Expand Down Expand Up @@ -290,28 +293,158 @@ private void copyRecursive(Path source, Path target, FileCopyMode mode) throws I
}
}

/**
* Deletes the given {@link Path} if it is a symbolic link or a Windows junction. And throws an
* {@link IllegalStateException} if there is a file at the given {@link Path} that is neither a symbolic link nor a
* Windows junction.
*
* @param path the {@link Path} to delete.
* @throws IOException if the actual {@link Files#delete(Path) deletion} fails.
*/
private void deleteLinkIfExists(Path path) throws IOException {

boolean exists = false;
boolean isJunction = false;
if (this.context.getSystemInfo().isWindows()) {
try { // since broken junctions are not detected by Files.exists(brokenJunction)
BasicFileAttributes attr = Files.readAttributes(path, BasicFileAttributes.class, LinkOption.NOFOLLOW_LINKS);
exists = true;
isJunction = attr.isOther() && attr.isDirectory();
} catch (NoSuchFileException e) {
// ignore, since there is no previous file at the location, so nothing to delete
return;
}
}
exists = exists || Files.exists(path); // "||" since broken junctions are not detected by
// Files.exists(brokenJunction)
boolean isSymlink = exists && Files.isSymbolicLink(path);

assert !(isSymlink && isJunction);

if (exists) {
if (isJunction || isSymlink) {
this.context.info("Deleting previous " + (isJunction ? "junction" : "symlink") + " at " + path);
Files.delete(path);
} else {
throw new IllegalStateException(
"The file at " + path + " was not deleted since it is not a symlink or a Windows junction");
}
}
}

/**
* Adapts the given {@link Path} to be relative or absolute depending on the given {@code relative} flag.
* Additionally, {@link Path#toRealPath(LinkOption...)} is applied to {@code source}.
*
* @param source the {@link Path} to adapt.
* @param targetLink the {@link Path} used to calculate the relative path to the {@code source} if {@code relative} is
* set to {@code true}.
* @param relative the {@code relative} flag.
* @return the adapted {@link Path}.
* @see FileAccessImpl#symlink(Path, Path, boolean)
*/
private Path adaptPath(Path source, Path targetLink, boolean relative) throws IOException {

if (source.isAbsolute()) {
try {
source = source.toRealPath(LinkOption.NOFOLLOW_LINKS); // to transform ../d1/../d2 to ../d2
} catch (IOException e) {
throw new IOException(
"Calling toRealPath() on the source (" + source + ") in method FileAccessImpl.adaptPath() failed.", e);
}
if (relative) {
source = targetLink.getParent().relativize(source);
// to make relative links like this work: dir/link -> dir
source = (source.toString().isEmpty()) ? Paths.get(".") : source;
}
} else { // source is relative
if (relative) {
// even though the source is already relative, toRealPath should be called to transform paths like
// this ../d1/../d2 to ../d2
source = targetLink.getParent()
.relativize(targetLink.resolveSibling(source).toRealPath(LinkOption.NOFOLLOW_LINKS));
source = (source.toString().isEmpty()) ? Paths.get(".") : source;
} else { // !relative
try {
source = targetLink.resolveSibling(source).toRealPath(LinkOption.NOFOLLOW_LINKS);
} catch (IOException e) {
throw new IOException("Calling toRealPath() on " + targetLink + ".resolveSibling(" + source
+ ") in method FileAccessImpl.adaptPath() failed.", e);
}
}
}
return source;
}

/**
* Creates a Windows junction at {@code targetLink} pointing to {@code source}.
*
* @param source must be another Windows junction or a directory.
* @param targetLink the location of the Windows junction.
*/
private void createWindowsJunction(Path source, Path targetLink) {

this.context.trace("Creating a Windows junction at " + targetLink + " with " + source + " as source.");
Path fallbackPath;
if (!source.isAbsolute()) {
this.context.warning(
"You are on Windows and you do not have permissions to create symbolic links. Junctions are used as an "
+ "alternative, however, these can not point to relative paths. So the source (" + source
+ ") is interpreted as an absolute path.");
try {
fallbackPath = targetLink.resolveSibling(source).toRealPath(LinkOption.NOFOLLOW_LINKS);
} catch (IOException e) {
throw new IllegalStateException(
"Since Windows junctions are used, the source must be an absolute path. The transformation of the passed "
+ "source (" + source + ") to an absolute path failed.",
e);
}

} else {
fallbackPath = source;
}
if (!Files.isDirectory(fallbackPath)) { // if source is a junction. This returns true as well.
throw new IllegalStateException(
"These junctions can only point to directories or other junctions. Please make sure that the source ("
+ fallbackPath + ") is one of these.");
}
this.context.newProcess().executable("cmd")
.addArgs("/c", "mklink", "/d", "/j", targetLink.toString(), fallbackPath.toString()).run();
}

@Override
public void symlink(Path source, Path targetLink) {
public void symlink(Path source, Path targetLink, boolean relative) {

this.context.trace("Creating symbolic link {} pointing to {}", targetLink, source);
Path adaptedSource = null;
try {
if (Files.exists(targetLink) && Files.isSymbolicLink(targetLink)) {
this.context.debug("Deleting symbolic link to be re-created at {}", targetLink);
Files.delete(targetLink);
}
Files.createSymbolicLink(targetLink, source);
adaptedSource = adaptPath(source, targetLink, relative);
} catch (IOException e) {
throw new IllegalStateException("Failed to adapt source for source (" + source + ") target (" + targetLink
+ ") and relative (" + relative + ")", e);
}
this.context.trace("Creating {} symbolic link {} pointing to {}", adaptedSource.isAbsolute() ? "" : "relative",
targetLink, adaptedSource);

try {
deleteLinkIfExists(targetLink);
} catch (IOException e) {
throw new IllegalStateException("Failed to delete previous symlink or Windows junction at " + targetLink, e);
}

try {
Files.createSymbolicLink(targetLink, adaptedSource);
} catch (FileSystemException e) {
if (this.context.getSystemInfo().isWindows()) {
this.context.info(
"Due to lack of permissions, Microsofts mklink with junction has to be used to create a Symlink. See https://github.com/devonfw/IDEasy/blob/main/documentation/symlinks.asciidoc for further details. Error was: "
+ e.getMessage());
this.context.newProcess().executable("cmd")
.addArgs("/c", "mklink", "/d", "/j", targetLink.toString(), source.toString()).run();
this.context.info("Due to lack of permissions, Microsoft's mklink with junction had to be used to create "
+ "a Symlink. See https://github.com/devonfw/IDEasy/blob/main/documentation/symlinks.asciidoc for "
+ "further details. Error was: " + e.getMessage());
createWindowsJunction(adaptedSource, targetLink);
} else {
throw new RuntimeException(e);
}
} catch (IOException e) {
throw new IllegalStateException("Failed to create a symbolic link " + targetLink + " pointing to " + source, e);
throw new IllegalStateException("Failed to create a " + (adaptedSource.isAbsolute() ? "" : "relative")
+ "symbolic link " + targetLink + " pointing to " + source, e);
}
}

Expand Down Expand Up @@ -398,8 +531,7 @@ public void delete(Path path) {
try {
if (Files.isSymbolicLink(path)) {
Files.delete(path);
}
else {
} else {
deleteRecursive(path);
}
} catch (IOException e) {
Expand Down
Loading

0 comments on commit bae97bc

Please sign in to comment.