Avoid a possible recursive copy when destination (build_dir) is underneath source directory. Update docs to match.

book-example/src/cli/build.md

@@ -35,5 +35,6 @@ not specified it will default to the value of the `build.build-dir` key in
 
 -------------------
 
-***Note:*** *Make sure to run the build command in the root directory and not in
-the source directory*
+***Note:*** *The build command copies all files (excluding files with `.md` extension) from the source directory
+into the build directory. If the build directory is under the source directory it is not copied as this would
+result in a recursive copy until your disk is full.*

src/renderer/html_handlebars/hbs_renderer.rs

@@ -291,6 +291,7 @@ impl Renderer for HtmlHandlebars {
         let src_dir = ctx.root.join(&ctx.config.book.src);
         let destination = &ctx.destination;
         let book = &ctx.book;
+        let build_dir = ctx.root.join(&ctx.config.build.build_dir);
 
         if destination.exists() {
             utils::fs::remove_dir_content(destination)
@@ -377,8 +378,8 @@ impl Renderer for HtmlHandlebars {
             }
         }
 
-        // Copy all remaining files
-        utils::fs::copy_files_except_ext(&src_dir, &destination, true, &["md"])?;
+        // Copy all remaining files, avoid a recursive copy from/to the book build dir
+        utils::fs::copy_files_except_ext(&src_dir, &destination, true, Some(&build_dir), &["md"])?;
 
         Ok(())
     }

src/utils/fs.rs

@@ -95,13 +95,15 @@ pub fn copy_files_except_ext(
     from: &Path,
     to: &Path,
     recursive: bool,
+    avoid_dir: Option<&PathBuf>,
     ext_blacklist: &[&str],
 ) -> Result<()> {
     debug!(
-        "Copying all files from {} to {} (blacklist: {:?})",
+        "Copying all files from {} to {} (blacklist: {:?}), avoiding {:?}",
         from.display(),
         to.display(),
-        ext_blacklist
+        ext_blacklist,
+        avoid_dir
     );
 
     // Check that from and to are different
@@ -119,6 +121,12 @@ pub fn copy_files_except_ext(
                 continue;
             }
 
+            if let Some(avoid) = avoid_dir {
+                if entry.path() == *avoid {
+                    continue;
+                }
+            }
+
             // check if output dir already exists
             if !to.join(entry.file_name()).exists() {
                 fs::create_dir(&to.join(entry.file_name()))?;
@@ -128,6 +136,7 @@ pub fn copy_files_except_ext(
                 &from.join(entry.file_name()),
                 &to.join(entry.file_name()),
                 true,
+                avoid_dir,
                 ext_blacklist,
             )?;
         } else if metadata.is_file() {
@@ -215,7 +224,7 @@ mod tests {
         }
 
         if let Err(e) =
-            copy_files_except_ext(&tmp.path(), &tmp.path().join("output"), true, &["md"])
+            copy_files_except_ext(&tmp.path(), &tmp.path().join("output"), true, None, &["md"])
         {
             panic!("Error while executing the function:\n{:?}", e);
         }