Move msys path support into DependencySet, removing it from the general Path system.

This is the only place that should actually need it.

PiperOrigin-RevId: 179054861

3 files changed, 71 insertions, 60 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/util/DependencySet.java b/src/main/java/com/google/devtools/build/lib/util/DependencySet.java
index 358610d14d..e2ce5fb6ce 100644
--- a/src/main/java/com/google/devtools/build/lib/util/DependencySet.java
+++ b/src/main/java/com/google/devtools/build/lib/util/DependencySet.java
@@ -24,6 +24,7 @@ import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.concurrent.atomic.AtomicReference;
 
 /**
  * Representation of a set of file dependencies for a given output file. There
@@ -99,10 +100,18 @@ public final class DependencySet {
    * Adds a given dependency to this DependencySet instance.
    */
   private void addDependency(String dep) {
+    dep = translatePath(dep);
     Path depPath = root.getRelative(dep);
     dependencies.add(depPath);
   }
 
+  private String translatePath(String path) {
+    if (OS.getCurrent() != OS.WINDOWS) {
+      return path;
+    }
+    return WindowsPath.translateWindowsPath(path);
+  }
+
   /**
    * Reads a dotd file into this DependencySet instance.
    */
@@ -241,4 +250,64 @@ public final class DependencySet {
   public int hashCode() {
     return dependencies.hashCode();
   }
+
+  private static final class WindowsPath {
+    private static final AtomicReference<String> UNIX_ROOT = new AtomicReference<>(null);
+
+    private static String translateWindowsPath(String path) {
+      int n = path.length();
+      if (n == 0 || path.charAt(0) != '/') {
+        return path;
+      }
+      if (n >= 2 && isAsciiLetter(path.charAt(1)) && (n == 2 || path.charAt(2) == '/')) {
+        StringBuilder sb = new StringBuilder(path.length());
+        sb.append(Character.toUpperCase(path.charAt(1)));
+        sb.append(":/");
+        sb.append(path, 2, path.length());
+        return sb.toString();
+      } else {
+        String unixRoot = getUnixRoot();
+        return unixRoot + path;
+      }
+    }
+
+    private static boolean isAsciiLetter(char c) {
+      return (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z');
+    }
+
+    private static String getUnixRoot() {
+      String value = UNIX_ROOT.get();
+      if (value == null) {
+        String jvmFlag = "bazel.windows_unix_root";
+        value = determineUnixRoot(jvmFlag);
+        if (value == null) {
+          throw new IllegalStateException(
+              String.format(
+                  "\"%1$s\" JVM flag is not set. Use the --host_jvm_args flag. "
+                      + "For example: "
+                      + "\"--host_jvm_args=-D%1$s=c:/tools/msys64\".",
+                  jvmFlag));
+        }
+        value = value.replace('\\', '/');
+        if (value.length() > 3 && value.endsWith("/")) {
+          value = value.substring(0, value.length() - 1);
+        }
+        UNIX_ROOT.set(value);
+      }
+      return value;
+    }
+
+    private static String determineUnixRoot(String jvmArgName) {
+      // Get the path from a JVM flag, if specified.
+      String path = System.getProperty(jvmArgName);
+      if (path == null) {
+        return null;
+      }
+      path = path.trim();
+      if (path.isEmpty()) {
+        return null;
+      }
+      return path;
+    }
+  }
 }
diff --git a/src/main/java/com/google/devtools/build/lib/vfs/Path.java b/src/main/java/com/google/devtools/build/lib/vfs/Path.java
index 6fe6118b9a..1d3947dcdc 100644
--- a/src/main/java/com/google/devtools/build/lib/vfs/Path.java
+++ b/src/main/java/com/google/devtools/build/lib/vfs/Path.java
@@ -78,11 +78,6 @@ public class Path implements Comparable<Path>, Serializable, SkylarkPrintable {
     /**
      * Makes the proper invocation of {@link FileSystem#getCachedChildPathInternal}, doing
      * filesystem-specific logic if necessary.
-     *
-     * <p>On Unix filesystems this method merely calls through to {@code
-     * FileSystem.getCachedChildPathInternal(parent, child)}, but on Windows this can be used to
-     * handle the translatation of absolute Unix paths to absolute Windows paths, e.g. "/c" to "C:/"
-     * or "/usr" to "C:/tools/msys64/usr".
      */
     Path getCachedChildPathInternal(Path path, String childName);
   }
diff --git a/src/main/java/com/google/devtools/build/lib/windows/WindowsFileSystem.java b/src/main/java/com/google/devtools/build/lib/windows/WindowsFileSystem.java
index 21de058e07..af97e27d3d 100644
--- a/src/main/java/com/google/devtools/build/lib/windows/WindowsFileSystem.java
+++ b/src/main/java/com/google/devtools/build/lib/windows/WindowsFileSystem.java
@@ -32,7 +32,6 @@ import java.nio.file.Files;
 import java.nio.file.LinkOption;
 import java.nio.file.attribute.DosFileAttributes;
 import java.util.Arrays;
-import java.util.concurrent.atomic.AtomicReference;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import javax.annotation.Nullable;
@@ -106,42 +105,11 @@ public class WindowsFileSystem extends JavaIoFileSystem {
     private static Path getCachedChildPathInternalImpl(
         Path parent, String child, Function<String, String> resolver) {
       if (parent != null && parent.isRootDirectory()) {
-        // This is a top-level directory. It's either a drive name ("C:" or "c") or some other
-        // Unix path (e.g. "/usr").
-        //
-        // We need to translate it to an absolute Windows path. The correct way would be looking
-        // up /etc/mtab to see if any mount point matches the prefix of the path, and change the
-        // prefix to the mounted path. Looking up /etc/mtab each time we create a path however
-        // would be too expensive so we use a heuristic instead.
-        //
-        // If the name looks like a volume name ("C:" or "c") then we treat it as such, otherwise
-        // we make it relative to UNIX_ROOT, thus "/usr" becomes "C:/tools/msys64/usr".
-        //
-        // This heuristic ignores other mount points as well as procfs.
-
-        // TODO(laszlocsomor): use GetLogicalDrives to retrieve the list of drives and only apply
-        // this heuristic for the valid drives. It's possible that the user has a directory "/a"
-        // but no "A:\" drive, so in that case we should prepend the MSYS root.
-
+        // This is a top-level directory. It must be a drive name ("C:" or "c").
         if (WindowsPath.isWindowsVolumeName(child)) {
           child = WindowsPath.getDriveLetter((WindowsPath) parent, child) + ":";
         } else {
-          if (UNIX_ROOT.get() == null) {
-            String jvmFlag = "bazel.windows_unix_root";
-            PathFragment value = determineUnixRoot(jvmFlag);
-            if (value == null) {
-              throw new IllegalStateException(
-                  String.format(
-                      "\"%1$s\" JVM flag is not set. Use the --host_jvm_args flag or export the "
-                          + "BAZEL_SH environment variable. For example "
-                          + "\"--host_jvm_args=-D%1$s=c:/tools/msys64\" or "
-                          + "\"set BAZEL_SH=c:/tools/msys64/usr/bin/bash.exe\". "
-                          + "parent=(%2$s) name=(%3$s)",
-                      jvmFlag, parent, child));
-            }
-            UNIX_ROOT.set(value);
-          }
-          parent = parent.getRelative(UNIX_ROOT.get());
+          throw new IllegalArgumentException("Cannot create Unix-style paths on Windows.");
         }
       }
 
@@ -303,8 +271,6 @@ public class WindowsFileSystem extends JavaIoFileSystem {
     return WindowsPathFactory.createForTesting(mockResolver);
   }
 
-  private static final AtomicReference<PathFragment> UNIX_ROOT = new AtomicReference<>(null);
-
   public static final LinkOption[] NO_OPTIONS = new LinkOption[0];
   public static final LinkOption[] NO_FOLLOW = new LinkOption[] {LinkOption.NOFOLLOW_LINKS};
 
@@ -478,23 +444,4 @@ public class WindowsFileSystem extends JavaIoFileSystem {
     return Files.readAttributes(
         file.toPath(), DosFileAttributes.class, symlinkOpts(followSymlinks));
   }
-
-  private static PathFragment determineUnixRoot(String jvmArgName) {
-    // Get the path from a JVM flag, if specified.
-    String path = System.getProperty(jvmArgName);
-    if (path == null) {
-      return null;
-    }
-
-    path = path.trim();
-    if (path.isEmpty()) {
-      return null;
-    }
-
-    PathFragment result = PathFragment.create(path);
-    if (result.getDriveLetter() == '\0' || !result.isAbsolute()) {
-      return null;
-    }
-    return result;
-  }
 }