fix(profiling-ffi): Windows extern statics need __declspec(dllimport)

builder/Cargo.toml

@@ -44,6 +44,7 @@ tar = "0.4.41"
 tools = { path = "../tools" }
 toml = "0.8.19"
 serde = "1.0.209"
+regex = "1.10"
 
 [[bin]]
 name = "release"

builder/src/common.rs

@@ -3,9 +3,8 @@
 
 use crate::arch;
 use crate::module::Module;
-use crate::utils::project_root;
+use crate::utils::{adjust_extern_symbols, project_root};
 use anyhow::Result;
-use std::fs;
 use std::path::PathBuf;
 use std::process::Command;
 use std::rc::Rc;
@@ -41,7 +40,8 @@ impl Module for Common {
         let target_path: PathBuf = [self.target_include.as_ref(), "common.h"].iter().collect();
 
         let origin_path: PathBuf = [self.source_include.as_ref(), "common.h"].iter().collect();
-        fs::copy(origin_path, target_path).expect("Failed to copy common.h");
+        adjust_extern_symbols(&origin_path, &target_path).expect("Failed to adjust extern symbols");
+
         Ok(())
     }
 }

builder/src/crashtracker.rs

@@ -3,7 +3,7 @@
 
 use crate::arch;
 use crate::module::Module;
-use crate::utils::project_root;
+use crate::utils::{adjust_extern_symbols, project_root};
 use anyhow::Result;
 use std::fs;
 use std::path::PathBuf;
@@ -106,7 +106,8 @@ impl CrashTracker {
             .collect();
 
         let headers = vec![target_path.to_str().unwrap()];
-        fs::copy(origin_path, &target_path).expect("Failed to copy crashtracker.h");
+        adjust_extern_symbols(&origin_path, &target_path)
+            .expect("Failed to adjust extern symbols for crashtracker.h");
 
         dedup_headers(self.base_header.as_ref(), &headers);
 

builder/src/profiling.rs

@@ -3,7 +3,7 @@
 
 use crate::arch;
 use crate::module::Module;
-use crate::utils::{file_replace, project_root};
+use crate::utils::{adjust_extern_symbols, file_replace, project_root};
 use anyhow::Result;
 use serde::Deserialize;
 use std::ffi::OsStr;
@@ -67,7 +67,8 @@ impl Profiling {
         for header in &headers {
             origin_path.set_file_name(header);
             target_path.set_file_name(header);
-            fs::copy(&origin_path, &target_path).expect("Failed to copy the header");
+            adjust_extern_symbols(&origin_path, &target_path)
+                .expect("Failed to adjust extern symbols");
 
             // Exclude blazesym header from deduplication
             if !target_path.to_str().unwrap().contains("blazesym.h") {

builder/src/utils.rs

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 use anyhow::{anyhow, Result};
+use regex::Regex;
 use std::fs::{self, OpenOptions};
 use std::io::Write;
 use std::path::{Path, PathBuf};
@@ -26,3 +27,37 @@ pub fn project_root() -> PathBuf {
         .unwrap()
         .to_path_buf()
 }
+
+pub(crate) fn adjust_extern_symbols(
+    file_in: impl AsRef<Path>,
+    file_out: impl AsRef<Path>,
+) -> Result<()> {
+    let content = fs::read_to_string(file_in)?;
+    let re = Regex::new(r#"(?m)^(\s*)extern\s+(.+;)$"#).unwrap();
+
+    // Replace function using captures
+    let new_content = re.replace_all(&content, |caps: &regex::Captures| {
+        let full_match = caps.get(0).unwrap().as_str();
+        let indent = &caps[1];
+        let declaration = &caps[2];
+
+        // Skip if it's extern "C", already has LIBDD_DLLIMPORT, or contains '(' (function)
+        if full_match.contains("extern \"C\"")
+            || full_match.contains("LIBDD_DLLIMPORT")
+            || full_match.contains('(')
+        {
+            return full_match.to_string();
+        }
+
+        // Keep indent + "extern " + "LIBDD_DLL_IMPORT " + declaration
+        format!("{}extern LIBDD_DLLIMPORT {}", indent, declaration)
+    });
+
+    let mut file = OpenOptions::new()
+        .write(true)
+        .truncate(true)
+        .create(true)
+        .open(file_out)?;
+    file.write_all(new_content.as_bytes())
+        .map_err(|err| anyhow!("failed to write file: {}", err))
+}

libdd-common-ffi/cbindgen.toml

@@ -42,6 +42,12 @@ after_includes = """
 #  define DDOG_CHECK_RETURN __attribute__((__warn_unused_result__))
 #else
 #  define DDOG_CHECK_RETURN
+#endif
+
+#ifdef _WIN32
+#define LIBDD_DLLIMPORT __declspec(dllimport)
+#else
+#define LIBDD_DLLIMPORT
 #endif"""
 
 [export]

windows/build-artifacts.ps1

@@ -8,6 +8,23 @@ function Invoke-Call {
     }
 }
 
+function Add-DllImportToGlobals {
+    param (
+        [string]$HeaderPath
+    )
+    $content = [System.IO.File]::ReadAllText($HeaderPath)
+    $pattern = '(?m)^(\s*)extern\s+(?!\"C\")(?!.*LIBDD_DLLIMPORT)(?!.*\()(.+;)$'
+    $updated = [System.Text.RegularExpressions.Regex]::Replace(
+        $content,
+        $pattern,
+        '$1extern LIBDD_DLLIMPORT $2'
+    )
+    if ($updated -ne $content) {
+        $utf8NoBom = New-Object System.Text.UTF8Encoding($false)
+        [System.IO.File]::WriteAllText($HeaderPath, $updated, $utf8NoBom)
+    }
+}
+
 $output_dir = $args[0]
 
 if ([string]::IsNullOrEmpty($output_dir)) {
@@ -61,6 +78,12 @@ Invoke-Call -ScriptBlock { cbindgen --crate libdd-telemetry-ffi --config libdd-t
 Invoke-Call -ScriptBlock { cbindgen --crate libdd-data-pipeline-ffi --config libdd-data-pipeline-ffi/cbindgen.toml --output $output_dir"\data-pipeline.h" }
 Invoke-Call -ScriptBlock { cbindgen --crate libdd-crashtracker-ffi --config libdd-crashtracker-ffi/cbindgen.toml --output $output_dir"\crashtracker.h" }
 Invoke-Call -ScriptBlock { cbindgen --crate libdd-library-config-ffi --config libdd-library-config-ffi/cbindgen.toml --output $output_dir"\library-config.h" }
+Add-DllImportToGlobals $output_dir"\common.h"
+Add-DllImportToGlobals $output_dir"\profiling.h"
+Add-DllImportToGlobals $output_dir"\telemetry.h"
+Add-DllImportToGlobals $output_dir"\data-pipeline.h"
+Add-DllImportToGlobals $output_dir"\crashtracker.h"
+Add-DllImportToGlobals $output_dir"\library-config.h"
 Invoke-Call -ScriptBlock { .\target\release\dedup_headers $output_dir"\common.h"  $output_dir"\profiling.h" $output_dir"\telemetry.h" $output_dir"\data-pipeline.h" $output_dir"\crashtracker.h" $output_dir"\library-config.h"}
 
 Write-Host "Build finished"  -ForegroundColor Magenta