Add comments to functions

1 files changed, 35 insertions, 3 deletions

diff --git a/src/main/java/io/github/jshipit/SysUtils.java b/src/main/java/io/github/jshipit/SysUtils.java
index 59450ad..ed14612 100644
--- a/src/main/java/io/github/jshipit/SysUtils.java
+++ b/src/main/java/io/github/jshipit/SysUtils.java
@@ -4,10 +4,19 @@ import com.sun.jna.Platform;
 
 import java.io.File;
 
+/*
+* A class for running system commands
+ */
 public class SysUtils {
 
-
+    /*
+     * Untar a tarball to a directory
+     *
+     * @param in The tarball to untar
+     * @param out The directory to untar to
+     */
     public void untar(String in, String out) {
+        // We do not use the Java tar library because it does not care about unix permissions. Common Java L
         new File(out).mkdirs();
         ProcessBuilder pb = new ProcessBuilder("tar", "-xf", in, "-C", out);
         pb.inheritIO();
@@ -19,10 +28,20 @@ public class SysUtils {
         }
     }
 
+    /*
+     * Execute a command in a bwrap sandbox
+     *
+     * @param args The arguments to pass to bwrap
+     * @param execute Whether to execute the command or just return the command
+     *
+     * @return The command that was executed. Empty string if execute is true
+     */
     public String execInBwrap(String[] args, boolean execute) {
         if (!execute) {
             return "bwrap "+String.join(" ", args);
         }
+        // ProcessBuilder wraps the args in quotes, since all args are passed at once, they are all quoted together
+        // This breaks bwrap (and many other commands), so we use bash -c to execute the command with the entire command as the arg
         ProcessBuilder pb = new ProcessBuilder("bash", "-c", "bwrap "+String.join(" ", args));
         pb.inheritIO();
         try {
@@ -34,12 +53,24 @@ public class SysUtils {
         return "";
     }
 
+    /*
+     * Creates an overlay mount
+     *
+     * @param lower The lower directories to use
+     * @param upper The upper directory to use
+     * @param target The target directory to mount to
+     * @param work The work directory to use
+     * @param execute Whether to execute the command or just return the command
+     *
+     * @return The command that was executed. Empty string if execute is true
+     */
     public String overlayMount(String[] lower, String upper, String target, String work, boolean execute) {
         if (!execute) {
             return "mount -t overlay overlay -o lowerdir="+String.join(":", lower)+",upperdir="+upper+",workdir="+work+" "+target;
         }
         if (Platform.isLinux()) {
-
+            // unshare creates a new user namespace, so we can mount without root
+            // This only works on Linux version 5.11 and above, which everyone should have by now
             ProcessBuilder pb = new ProcessBuilder("unshare", "--user", "--map-root-user", "--mount", "mount", "-t", "overlay", "overlay", "-o", "lowerdir="+String.join(":", lower)+",upperdir="+upper+",workdir="+work, target);
             pb.inheritIO();
             try {
@@ -50,8 +81,9 @@ public class SysUtils {
             }
 
         } else {
+            // Since other *nix systems do not have overlayfs or unshare, we just print an error
+            // I would be surprised if you even got this far on Windows
             System.out.println("Platform not supported.");
-            System.out.println("mount -t overlay overlay -o lowerdir="+String.join(":", lower)+",upperdir="+upper+",workdir="+work+" "+target);
         }
         return "";
     }