Feature : Enable LLDB Debugging for R Dev Container

.devcontainer/devcontainer.json

@@ -4,6 +4,9 @@
     "hostRequirements": {
         "cpus": 4
     },
+    "runArgs": [
+    "--cap-add=SYS_PTRACE"
+    ],
     "customizations": {
         "vscode": {
             "settings": {
@@ -12,8 +15,8 @@
                 "editor.detectIndentation": false,
                 "r.lsp.diagnostics": false,
                 "r.plot.useHttpgd": true,
+                "r.rterm.linux": "/workspaces/r-dev-env/scripts/launch_r.sh",
                 "r.rpath.linux": "/usr/bin/R",
-                "r.rterm.linux": "/usr/bin/R",
                 "terminal.integrated.sendKeybindingsToShell": true,
                 "svn.multipleFolders.enabled": true,
                 "workbench.editorAssociations": {
@@ -28,9 +31,10 @@
                 "johnstoncode.svn-scm",
                 "ms-vscode.cpptools",
                 "MS-vsliveshare.vsliveshare",
-                "natqe.reload"
+                "natqe.reload",
+                "vadimcn.vscode-lldb"
             ]
         }
     },
-    "postCreateCommand": "find . -wholename '*.git*'  -type d -prune -o -type f -exec chown vscode:vscode {} \\; && sh /workspaces/r-dev-env/scripts/localscript.sh"
+"postCreateCommand": "find . -wholename '.git*' -type d -prune -o -type f -exec chown vscode:vscode {} \\; && sh ./scripts/localscript.sh"
 }

.devcontainer/launch.json

@@ -0,0 +1,12 @@
+{
+"version": "0.2.0",
+"configurations": [
+    {
+      "name": "(lldb) Attach to R",
+      "type": "lldb",
+      "request": "attach",
+      "pid": "${command:pickMyProcess}",
+      "stopOnEntry": false
+    }
+  ]
+}

docs/tutorials/building_r.md

@@ -55,7 +55,22 @@ mkdir -p $BUILDDIR
 cd $BUILDDIR
 ```
 
-**5) Configure the build**
+**5) Set CFLAGS (Optional—For Debugging C Code)**
+
+- **This step is optional and recommended for those who want to debug C code.**
+- Set the `CFLAGS` environment variable before running configure:
+
+```bash
+CFLAGS="-g -O0"
+```
+
+- These flags modify the configuration defined in the next step,
+so that when R is built, C code will be compiled with debugging
+symbols (`-g`) and compiler optimizations will be disabled
+(`-O0`) so that the structure of the code closely matches the
+original source.
+
+**6) Configure the build**
 
 - After we change directory, we must run the configure script from the source
 directory.  This step takes ~1 minute on the codespace.
@@ -80,7 +95,7 @@ $TOP_SRCDIR/configure --with-valgrind-instrumentation=1
 
     ![alt text](../assets/rdev7.png)
 
-**6) Build R**
+**7) Build R**
 
 Having configured R, we run `make` to build R. This take 5-10 minutes on the
 codespace.
@@ -89,7 +104,7 @@ codespace.
 make
 ```
 
-**7) Check R**
+**8) Check R**
 
 Check that the build of R passes R's standard checks:
 
@@ -101,7 +116,7 @@ This takes a couple of minutes in the codespace. The check will stop with a
 error message if any of the tests fail. If this happens, see [SVN
 Help](./svn_help.md) for how to revert to a version that passes check.
 
-**8) Make R terminals use the built R**
+**9) Make R terminals use the built R**
 
 Run the `which_r` script to set which R to use for R terminals in VSCode. When
 prompted, enter the number corresponding to `r-devel`
@@ -125,7 +140,7 @@ built![^1]
 selected version is saved in the VSCode settings, so will be saved when you stop
 and restart the codespace.
 
-**9) Make contributions**
+**10) Make contributions**
 
 - After having built the current development version of R, we can now make
   changes to the source code and contribute to the project.

scripts/allow_ptrace.c

@@ -0,0 +1,6 @@
+#include <sys/prctl.h>
+
+__attribute__((constructor))
+static void allow_ptrace(void) {
+    prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY);
+}

scripts/launch_r.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+export LD_PRELOAD=/workspaces/r-dev-env/scripts/allow_ptrace.so
+exec /usr/bin/R "$@"

scripts/localscript.sh

@@ -9,21 +9,21 @@ local_script(){
 WORK_DIR=$PWD
 VSCODE_DIR="$WORK_DIR/.vscode"
 DEVCONTAINER_JSON="$WORK_DIR/.devcontainer/devcontainer.json"
+SCRIPTS_DIR="$WORK_DIR/scripts"
 
 # Create patch directory in workspace root ($PWD at start)
 PATCHDIR="$WORK_DIR/patches"
 mkdir -p $PATCHDIR
 mkdir -p $VSCODE_DIR
 
 # Copy the which_r and set_build_r function definitions to .bashrc
-cat $WORK_DIR/scripts/which_r.sh >> ~/.bashrc
-cat $WORK_DIR/scripts/set_build_r.sh >> ~/.bashrc
+cat $SCRIPTS_DIR/which_r.sh >> ~/.bashrc
+cat $SCRIPTS_DIR/set_build_r.sh >> ~/.bashrc
 
 # Copy over the welcome message script to be run when bash terminal starts
-cat $WORK_DIR/scripts/welcome_msg.sh >> ~/.bashrc
+cat $SCRIPTS_DIR/welcome_msg.sh >> ~/.bashrc
 
 #bash ~/.bashrc
-
 # Remove git directory if it exists
 rm -rf .git
 
@@ -38,3 +38,9 @@ fi
 
 # Run the main function
 local_script
+
+# 1. Build the ptrace helper library
+gcc -shared -fPIC -o "$SCRIPTS_DIR/allow_ptrace.so" "$SCRIPTS_DIR/allow_ptrace.c"
+
+# 2. Mark the wrapper executable
+chmod +x "$SCRIPTS_DIR/launch_r.sh"

scripts/which_r.sh

@@ -1,68 +1,53 @@
-
+#!/usr/bin/env bash
 
 which_r() {
-  # Specify the parent directory
-  parent_dir="$WORK_DIR/build"
-
-  # Path to the settings.json file
-  settings_file_path=$WORK_DIR/.vscode/settings.json
+  parent_dir="$PWD/build"
+  settings_file_path="$PWD/.vscode/settings.json"
+  launch_script="$PWD/scripts/launch_r.sh"
 
-  built_in_r_version=$(R --version | grep "^R version" | awk '{print $3}')
+  built_in_r_version=$(R --version | awk '/^R version/ {print $3}')
 
-  # Ask user which R version to use
   echo "Which version of R should be used in new R terminals?"
-  echo "  1. R $built_in_r_version (release version built into this container)"
+  echo "  1. R $built_in_r_version (built-in)"
 
-  # Check for additional R versions in subdirectories
+  # Detect additional R builds
+  subdirs=()
+  counter=2
   if [ -d "$parent_dir" ]; then
-    # Create an array to store subdirectory names
-    subdirs=()
-
-    # Loop through subdirectories and print numbered list
-    counter=2  # Start counter at 2 to avoid conflict with built-in R
     for dir in "$parent_dir"/*; do
-      if [ -d "$dir/bin" ] && [ -x "$dir/bin/R" ]; then
-        subdir=$(basename "$dir")
-        subdirs+=("$subdir")  # Populate subdirs array
-        echo "  $counter. $subdir"
+      if [ -x "$dir/bin/R" ]; then
+        subdirs+=("$(basename "$dir")")
+        echo "  $counter. ${subdirs[-1]}"
         ((counter++))
       fi
     done
   fi
 
-  # If no additional R builds were found
-  if [ ${#subdirs[@]} -eq 0 ]; then
-    range=1
-    echo "No additional R builds available."
-  else
-    range=$((counter - 1))
-  fi
+  range=$((counter - 1))
+  [ "${#subdirs[@]}" -eq 0 ] && echo "No additional R builds found."
 
-  # Get user choice
-  read -p "Enter the number corresponding to the selected version: " choice
+  read -p "Enter number (1–$range): " choice
 
-  # Define selected version based on choice
-  if [[ "$choice" -eq 1 ]]; then
-    # Use built-in R
-    selected_version="/usr/bin/R"
-  elif [[ "$choice" -ge 2 ]] && [[ "$choice" -lt "$counter" ]]; then
-    # Use R from chosen subdirectory
-    chosen_subdir="${subdirs[((choice - 2))]}"
-    selected_version="$parent_dir/$chosen_subdir/bin/R"
+  if [ "$choice" -eq 1 ] 2>/dev/null; then
+    selected="/usr/bin/R"
+  elif [ "$choice" -ge 2 ] && [ "$choice" -le "$range" ] 2>/dev/null; then
+    idx=$((choice - 2))
+    selected="$parent_dir/${subdirs[$idx]}/bin/R"
   else
-    # Invalid choice, default to built-in R
-    if [[ $range -eq 1 ]]; then
-      echo "Invalid choice, please enter 1. Defaulting to built-in R version."
-    else
-      echo "Invalid choice, please select options between 1 to $range. Defaulting to built-in R version."
-    fi
-    selected_version="/usr/bin/R"
+    echo "Invalid choice; defaulting to built-in"
+    selected="/usr/bin/R"
   fi
 
-  # Update settings.json with the chosen R path
-  updated_settings_data=$(cat "$settings_file_path" | jq --arg subdir "$selected_version" '."r.rterm.linux"=$subdir | ."r.rpath.linux"=$subdir')
-  echo "$updated_settings_data" > "$settings_file_path"
+  # Update launch_r.sh to call the selected R
+  sed -i "s|^exec .*/R|exec $selected|" "$launch_script"
+
+  # Update VS Code setting if it exists
+  if [ -f "$settings_file_path" ]; then
+    jq --arg r "$selected" '."r.rpath.linux"=$r' \
+      "$settings_file_path" > "${settings_file_path}.tmp" \
+      && mv "${settings_file_path}.tmp" "$settings_file_path"
+  fi
 
-  echo "R terminal will now use version: $selected_version"
-  echo "To update the HTML help, click \"Reload\" in the VS Code status bar (bottom right) to reload your VS Code window."
+  echo "Now using R at: $selected"
+  echo "Reload VS Code to apply updates."
 }