cosmos: add experimental c wrapper around cosmos sdk

Author: analogrelay

Cargo.toml

@@ -21,7 +21,7 @@ members = [
   "sdk/template/azure_template_core",
   "sdk/template/azure_template",
   "sdk/storage/azure_storage_common",
-  "sdk/storage/azure_storage_blob",
+  "sdk/storage/azure_storage_blob", "sdk/cosmos/cosmosclient",
 ]
 exclude = [
   "eng/scripts",

sdk/cosmos/azure_data_cosmos/Cargo.toml

@@ -37,6 +37,7 @@ workspace = true
 
 [features]
 default = ["hmac_rust"]
+_internal_c = [] # Internal feature used to expose additional types/functions as needed to build libcosmosclient.
 key_auth = [] # Enables support for key-based authentication (Primary Keys and Resource Tokens)
 preview_query_engine = ["serde_json/raw_value"] # Enables support for the PREVIEW external query engine
 hmac_rust = ["azure_core/hmac_rust"]

sdk/cosmos/cosmosclient/.gitignore

@@ -0,0 +1 @@
+build/

sdk/cosmos/cosmosclient/CMakeLists.txt

@@ -0,0 +1,31 @@
+project(cosmosctest C)
+cmake_minimum_required(VERSION 4.1)
+
+# CMake automatically uses this option, but we should define it.
+option(BUILD_SHARED_LIBS "Build using shared libraries" ON)
+
+include(FetchContent)
+include(CTest)
+
+FetchContent_Declare(
+    Corrosion
+    GIT_REPOSITORY https://github.com/corrosion-rs/corrosion.git
+    GIT_TAG v0.5.2
+)
+FetchContent_MakeAvailable(Corrosion)
+
+corrosion_import_crate(
+    MANIFEST_PATH ./Cargo.toml
+    CRATETYPES staticlib cdylib
+)
+
+set(TEST_FILES
+    ./c_tests/version.c)
+
+foreach(test_file ${TEST_FILES})
+    get_filename_component(test_name ${test_file} NAME_WE)
+    add_executable(${test_name} ${test_file})
+    target_link_libraries(${test_name} PRIVATE cosmosclient)
+    add_test(${test_name} ${test_name})
+endforeach()
+

sdk/cosmos/cosmosclient/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "cosmosclient"
+description = "C library wrapping the Azure CosmosDB SDK for Rust"
+version = "0.27.0"
+authors.workspace = true
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+rust-version.workspace = true
+
+[lib]
+crate-type = ["cdylib", "staticlib"]
+
+[dependencies]
+azure_data_cosmos = { path = "../azure_data_cosmos", features = ["_internal_c"] }
+
+[build-dependencies]
+cbindgen = "0.29.0"
+
+[lints]
+workspace = true

sdk/cosmos/cosmosclient/build.rs

@@ -0,0 +1,38 @@
+fn main() {
+    let build_id = format!(
+        "$Id: {}, Version: {}, Commit: {}, Branch: {}, Build ID: {}, Build Number: {}, Timestamp: {}$",
+        env!("CARGO_PKG_NAME"),
+        env!("CARGO_PKG_VERSION"),
+        option_env!("BUILD_SOURCEVERSION").unwrap_or("unknown"),
+        option_env!("BUILD_SOURCEBRANCH").unwrap_or("unknown"),
+        option_env!("BUILD_BUILDID").unwrap_or("unknown"),
+        option_env!("BUILD_BUILDNUMBER").unwrap_or("unknown"),
+        std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap_or_default()
+            .as_secs(),
+    );
+    println!("cargo:rustc-env=BUILD_IDENTIFIER={}", build_id);
+
+    let mut header: String = r"// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+// This file is auto-generated by cbindgen. Do not edit manually.
+"
+    .to_string();
+    header.push_str(&format!("// Build identifier: {}\n", build_id));
+
+    let crate_dir = std::env::var("CARGO_MANIFEST_DIR").unwrap();
+    cbindgen::Builder::new()
+        .with_crate(crate_dir)
+        .with_language(cbindgen::Language::C)
+        .with_after_include(format!(
+            "\n// Specifies the version of cosmosclient this header file was generated from.\n// This should match the version of libcosmosclient you are referencing.\n#define COSMOSCLIENT_H_VERSION \"{}\"",
+            env!("CARGO_PKG_VERSION")
+        ))
+        .with_cpp_compat(true)
+        .with_header(header)
+        .generate()
+        .expect("unable to generate bindings")
+        .write_to_file("include/cosmosclient.h");
+}

sdk/cosmos/cosmosclient/c_tests/README.md

@@ -0,0 +1,5 @@
+# Cosmos Client C Tests
+
+This directory contains tests written in C that utilize the Cosmos Client library. The tests are designed to validate the functionality of the Cosmos Client C API, ensuring that it correctly interacts with the Azure CosmosDB service.
+
+Building this directory requires CMake, Rust, and a C compiler.

sdk/cosmos/cosmosclient/c_tests/version.c

@@ -0,0 +1,17 @@
+#include <stdio.h>
+#include <string.h>
+#include "../include/cosmosclient.h"
+
+int main() {
+    const char *version = cosmosclient_version();
+    const char *header_version = COSMOSCLIENT_H_VERSION;
+    printf("Cosmos Client Version: %s\n", version);
+    printf("Header Version: %s\n", header_version);
+    if (!strcmp(version, header_version)) {
+        printf("Version match successful.\n");
+        return 0;
+    } else {
+        printf("Version mismatch: %s != %s\n", version, header_version);
+        return 1;
+    }
+}

sdk/cosmos/cosmosclient/include/.gitignore

@@ -0,0 +1,3 @@
+# Ignore everything except this ignore file, this directory contains build artifacts
+*
+!.gitignore

sdk/cosmos/cosmosclient/src/lib.rs

@@ -0,0 +1,33 @@
+use std::ffi::{c_char, CStr, CString};
+
+#[no_mangle] // Necessary to prevent the compiler from stripping it when optimizing
+/// cbindgen:ignore
+pub static BUILD_IDENTIFIER: &CStr = const {
+    // This does a few funky things to make sure we can stay in a const context
+    // Which ensures the string is generated as a c-str at compile time
+    // and thus appears properly if you run `strings [lib] | grep "\$Id:"`
+    const BUILD_IDENTIFIER_STR: &str = env!("BUILD_IDENTIFIER");
+    const BUILD_IDENTIFIER_BYTES: [u8; BUILD_IDENTIFIER_STR.len() + 1] = const {
+        let mut cstrbuf: [u8; BUILD_IDENTIFIER_STR.len() + 1] = [0; BUILD_IDENTIFIER_STR.len() + 1];
+        let mut i = 0;
+        // For loops over ranges don't really work in const contexts.
+        while i < BUILD_IDENTIFIER_STR.len() {
+            cstrbuf[i] = BUILD_IDENTIFIER_STR.as_bytes()[i];
+            i += 1;
+        }
+        cstrbuf
+    };
+    match CStr::from_bytes_with_nul(&BUILD_IDENTIFIER_BYTES) {
+        Ok(cstr) => cstr,
+        Err(_) => panic!("BUILD_IDENTIFIER is not a valid C string"),
+    }
+};
+
+#[no_mangle]
+/// Returns a constant C string containing the version of the Cosmos Client library.
+pub extern "C" fn cosmosclient_version() -> *const c_char {
+    let version = env!("CARGO_PKG_VERSION");
+    CString::new(version)
+        .expect("failed to create CString from version")
+        .into_raw()
+}