Feature : Enable LLDB Debugging for R Dev Container

.devcontainer/devcontainer.json

@@ -1,6 +1,7 @@
 {
     "name": "R-Dev-Env",
     "image": "ghcr.io/r-devel/r-dev-env:devel",
+    "runArgs": ["--cap-add=SYS_PTRACE"],
     "hostRequirements": {
         "cpus": 4
     },
@@ -9,8 +10,6 @@
             "settings": {
                 "git.ignoredRepositories": ["."],
                   "files.exclude": {
-                       "**/.vscode": true,
-                       "**/.devcontainer": true,
                        "**/.git": true,
                        "**/.github": true,
                        "**/.gitignore": true,
@@ -19,16 +18,15 @@
                        "**/.markdownlint-cli2.yaml": true,
                        "**/.pre-commit-config.yaml": true,
                        "**/Dockerfile": true,
-                       "**/mkdocs.yml": true,
-                       "**/scripts": true
+                       "**/mkdocs.yml": true
   },
                 "editor.tabSize": 8,
                 "editor.indentSize": 4,
                 "editor.detectIndentation": false,
                 "r.lsp.diagnostics": false,
                 "r.plot.useHttpgd": true,
                 "r.rpath.linux": "/usr/bin/R",
-                "r.rterm.linux": "/usr/bin/R",
+                "r.rterm.linux": "/workspaces/r-dev-env/scripts/launch_r.sh",
                 "terminal.integrated.sendKeybindingsToShell": true,
                 "svn.multipleFolders.enabled": true,
                 "workbench.editorAssociations": {
@@ -43,7 +41,8 @@
                 "johnstoncode.svn-scm",
                 "ms-vscode.cpptools",
                 "MS-vsliveshare.vsliveshare",
-                "natqe.reload"
+                "natqe.reload",
+                "vadimcn.vscode-lldb"
             ]
         }
     },

.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 +1,7 @@
+#include <sys/prctl.h>
+#include <stdio.h>
+
+__attribute__((constructor)) void allow_ptrace() {
+    prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY);
+    fprintf(stderr, "allow_ptrace: called\n");
+}

scripts/launch_r.sh

@@ -0,0 +1,4 @@
+#!/bin/bash
+export LD_PRELOAD=/workspaces/r-dev-env/scripts/allow_ptrace.so
+# exec /workspaces/r-dev-env/build/r-devel/bin/R "$@"
+exec /usr/bin/R "$@"

scripts/localscript.sh

@@ -27,11 +27,21 @@ cat $WORK_DIR/scripts/welcome_msg.sh >> ~/.bashrc
 # Remove git directory if it exists
 #rm -rf .git
 
+# copy launch.json for debugging config if present
+if [ -f "$WORK_DIR/.devcontainer/launch.json" ]; then
+    cp "$WORK_DIR/.devcontainer/launch.json" "$VSCODE_DIR/launch.json"
+fi
+
 # copying vscode extension settings from devcontainer json to vscode settings json using jq
 if [ -f "$DEVCONTAINER_JSON" ]; then
         jq '.customizations.vscode.settings' "$DEVCONTAINER_JSON" > "$VSCODE_DIR/settings.json"
 fi
 
+# Build the ptrace helper library
+gcc -shared -fPIC -o "$WORK_DIR/scripts/allow_ptrace.so" "$WORK_DIR/scripts/allow_ptrace.c"
+
+# Mark the wrapper executable
+chmod +x "$WORK_DIR/scripts/launch_r.sh"
 
 }
 

scripts/which_r.sh

@@ -3,6 +3,7 @@
 which_r() {
   # Specify the parent directory
   parent_dir="$WORK_DIR/build"
+  launch_script="$WORK_DIR/scripts/launch_r.sh"
 
   # Path to the settings.json file
   settings_file_path=$WORK_DIR/.vscode/settings.json
@@ -59,9 +60,21 @@ which_r() {
     selected_version="/usr/bin/R"
   fi
 
+  # Update launch_r.sh to call the selected R binary
+  if [ -f "$launch_script" ]; then
+    sed -i "s|^exec .*/R|exec $selected_version|" "$launch_script"
+  else
+    echo "Warning: launch_r.sh script not found, skipping update."
+  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" > "$settings_file_path"
+  if [ -f "$settings_file_path" ]; then
+    tmpfile="${settings_file_path}.tmp.$$"
+    jq --arg r "$selected_version" '."r.rpath.linux"=$r' "$settings_file_path" > "$tmpfile" && mv "$tmpfile" "$settings_file_path"
+  else
+    echo "Warning: VS Code settings.json not found, skipping update."
+  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."