vendor/cmake/src/lib.rs

   1 //! A build dependency for running `cmake` to build a native library
   2 //!
   3 //! This crate provides some necessary boilerplate and shim support for running
   4 //! the system `cmake` command to build a native library. It will add
   5 //! appropriate cflags for building code to link into Rust, handle cross
   6 //! compilation, and use the necessary generator for the platform being
   7 //! targeted.
   8 //!
   9 //! The builder-style configuration allows for various variables and such to be
  10 //! passed down into the build as well.
  11 //!
  12 //! ## Installation
  13 //!
  14 //! Add this to your `Cargo.toml`:
  15 //!
  16 //! ```toml
  17 //! [build-dependencies]
  18 //! cmake = "0.1"
  19 //! ```
  20 //!
  21 //! ## Examples
  22 //!
  23 //! ```no_run
  24 //! use cmake;
  25 //!
  26 //! // Builds the project in the directory located in `libfoo`, installing it
  27 //! // into $OUT_DIR
  28 //! let dst = cmake::build("libfoo");
  29 //!
  30 //! println!("cargo:rustc-link-search=native={}", dst.display());
  31 //! println!("cargo:rustc-link-lib=static=foo");
  32 //! ```
  33 //!
  34 //! ```no_run
  35 //! use cmake::Config;
  36 //!
  37 //! let dst = Config::new("libfoo")
  38 //!                  .define("FOO", "BAR")
  39 //!                  .cflag("-foo")
  40 //!                  .build();
  41 //! println!("cargo:rustc-link-search=native={}", dst.display());
  42 //! println!("cargo:rustc-link-lib=static=foo");
  43 //! ```
  44
  45 #![deny(missing_docs)]
  46
  47 extern crate cc;
  48
  49 use std::env;
  50 use std::ffi::{OsStr, OsString};
  51 use std::fs::{self, File};
  52 use std::io::prelude::*;
  53 use std::io::ErrorKind;
  54 use std::path::{Path, PathBuf};
  55 use std::process::Command;
  56
  57 /// Builder style configuration for a pending CMake build.
  58 pub struct Config {
  59     path: PathBuf,
  60     generator: Option<OsString>,
  61     cflags: OsString,
  62     cxxflags: OsString,
  63     asmflags: OsString,
  64     defines: Vec<(OsString, OsString)>,
  65     deps: Vec<String>,
  66     target: Option<String>,
  67     host: Option<String>,
  68     out_dir: Option<PathBuf>,
  69     profile: Option<String>,
  70     build_args: Vec<OsString>,
  71     cmake_target: Option<String>,
  72     env: Vec<(OsString, OsString)>,
  73     static_crt: Option<bool>,
  74     uses_cxx11: bool,
  75     always_configure: bool,
  76     no_build_target: bool,
  77     verbose_cmake: bool,
  78     verbose_make: bool,
  79     pic: Option<bool>,
  80 }
  81
  82 /// Builds the native library rooted at `path` with the default cmake options.
  83 /// This will return the directory in which the library was installed.
  84 ///
  85 /// # Examples
  86 ///
  87 /// ```no_run
  88 /// use cmake;
  89 ///
  90 /// // Builds the project in the directory located in `libfoo`, installing it
  91 /// // into $OUT_DIR
  92 /// let dst = cmake::build("libfoo");
  93 ///
  94 /// println!("cargo:rustc-link-search=native={}", dst.display());
  95 /// println!("cargo:rustc-link-lib=static=foo");
  96 /// ```
  97 ///
  98 pub fn build<P: AsRef<Path>>(path: P) -> PathBuf {
  99     Config::new(path.as_ref()).build()
 100 }
 101
 102 impl Config {
 103     /// Creates a new blank set of configuration to build the project specified
 104     /// at the path `path`.
 105     pub fn new<P: AsRef<Path>>(path: P) -> Config {
 106         Config {
 107             path: env::current_dir().unwrap().join(path),
 108             generator: None,
 109             cflags: OsString::new(),
 110             cxxflags: OsString::new(),
 111             asmflags: OsString::new(),
 112             defines: Vec::new(),
 113             deps: Vec::new(),
 114             profile: None,
 115             out_dir: None,
 116             target: None,
 117             host: None,
 118             build_args: Vec::new(),
 119             cmake_target: None,
 120             env: Vec::new(),
 121             static_crt: None,
 122             uses_cxx11: false,
 123             always_configure: true,
 124             no_build_target: false,
 125             verbose_cmake: false,
 126             verbose_make: false,
 127             pic: None,
 128         }
 129     }
 130
 131     /// Sets flag for PIC. Otherwise use cc::Build platform default
 132     pub fn pic(&mut self, explicit_flag: bool) -> &mut Config {
 133         self.pic = Some(explicit_flag);
 134         self
 135     }
 136
 137     /// Sets the build-tool generator (`-G`) for this compilation.
 138     pub fn generator<T: AsRef<OsStr>>(&mut self, generator: T) -> &mut Config {
 139         self.generator = Some(generator.as_ref().to_owned());
 140         self
 141     }
 142
 143     /// Adds a custom flag to pass down to the C compiler, supplementing those
 144     /// that this library already passes.
 145     pub fn cflag<P: AsRef<OsStr>>(&mut self, flag: P) -> &mut Config {
 146         self.cflags.push(" ");
 147         self.cflags.push(flag.as_ref());
 148         self
 149     }
 150
 151     /// Adds a custom flag to pass down to the C++ compiler, supplementing those
 152     /// that this library already passes.
 153     pub fn cxxflag<P: AsRef<OsStr>>(&mut self, flag: P) -> &mut Config {
 154         self.cxxflags.push(" ");
 155         self.cxxflags.push(flag.as_ref());
 156         self
 157     }
 158
 159     /// Adds a custom flag to pass down to the ASM compiler, supplementing those
 160     /// that this library already passes.
 161     pub fn asmflag<P: AsRef<OsStr>>(&mut self, flag: P) -> &mut Config {
 162         self.asmflags.push(" ");
 163         self.asmflags.push(flag.as_ref());
 164         self
 165     }
 166
 167     /// Adds a new `-D` flag to pass to cmake during the generation step.
 168     pub fn define<K, V>(&mut self, k: K, v: V) -> &mut Config
 169     where
 170         K: AsRef<OsStr>,
 171         V: AsRef<OsStr>,
 172     {
 173         self.defines
 174             .push((k.as_ref().to_owned(), v.as_ref().to_owned()));
 175         self
 176     }
 177
 178     /// Registers a dependency for this compilation on the native library built
 179     /// by Cargo previously.
 180     ///
 181     /// This registration will modify the `CMAKE_PREFIX_PATH` environment
 182     /// variable for the build system generation step.
 183     pub fn register_dep(&mut self, dep: &str) -> &mut Config {
 184         self.deps.push(dep.to_string());
 185         self
 186     }
 187
 188     /// Sets the target triple for this compilation.
 189     ///
 190     /// This is automatically scraped from `$TARGET` which is set for Cargo
 191     /// build scripts so it's not necessary to call this from a build script.
 192     pub fn target(&mut self, target: &str) -> &mut Config {
 193         self.target = Some(target.to_string());
 194         self
 195     }
 196
 197     /// Disables the cmake target option for this compilation.
 198     ///
 199     /// Note that this isn't related to the target triple passed to the compiler!
 200     pub fn no_build_target(&mut self, no_build_target: bool) -> &mut Config {
 201         self.no_build_target = no_build_target;
 202         self
 203     }
 204
 205     /// Sets the host triple for this compilation.
 206     ///
 207     /// This is automatically scraped from `$HOST` which is set for Cargo
 208     /// build scripts so it's not necessary to call this from a build script.
 209     pub fn host(&mut self, host: &str) -> &mut Config {
 210         self.host = Some(host.to_string());
 211         self
 212     }
 213
 214     /// Sets the output directory for this compilation.
 215     ///
 216     /// This is automatically scraped from `$OUT_DIR` which is set for Cargo
 217     /// build scripts so it's not necessary to call this from a build script.
 218     pub fn out_dir<P: AsRef<Path>>(&mut self, out: P) -> &mut Config {
 219         self.out_dir = Some(out.as_ref().to_path_buf());
 220         self
 221     }
 222
 223     /// Sets the `CMAKE_BUILD_TYPE=build_type` variable.
 224     ///
 225     /// By default, this value is automatically inferred from Rust's compilation
 226     /// profile as follows:
 227     ///
 228     /// * if `opt-level=0` then `CMAKE_BUILD_TYPE=Debug`,
 229     /// * if `opt-level={1,2,3}` and:
 230     ///   * `debug=false` then `CMAKE_BUILD_TYPE=Release`
 231     ///   * otherwise `CMAKE_BUILD_TYPE=RelWithDebInfo`
 232     /// * if `opt-level={s,z}` then `CMAKE_BUILD_TYPE=MinSizeRel`
 233     pub fn profile(&mut self, profile: &str) -> &mut Config {
 234         self.profile = Some(profile.to_string());
 235         self
 236     }
 237
 238     /// Configures whether the /MT flag or the /MD flag will be passed to msvc build tools.
 239     ///
 240     /// This option defaults to `false`, and affect only msvc targets.
 241     pub fn static_crt(&mut self, static_crt: bool) -> &mut Config {
 242         self.static_crt = Some(static_crt);
 243         self
 244     }
 245
 246     /// Add an argument to the final `cmake` build step
 247     pub fn build_arg<A: AsRef<OsStr>>(&mut self, arg: A) -> &mut Config {
 248         self.build_args.push(arg.as_ref().to_owned());
 249         self
 250     }
 251
 252     /// Configure an environment variable for the `cmake` processes spawned by
 253     /// this crate in the `build` step.
 254     pub fn env<K, V>(&mut self, key: K, value: V) -> &mut Config
 255     where
 256         K: AsRef<OsStr>,
 257         V: AsRef<OsStr>,
 258     {
 259         self.env
 260             .push((key.as_ref().to_owned(), value.as_ref().to_owned()));
 261         self
 262     }
 263
 264     /// Sets the build target for the final `cmake` build step, this will
 265     /// default to "install" if not specified.
 266     pub fn build_target(&mut self, target: &str) -> &mut Config {
 267         self.cmake_target = Some(target.to_string());
 268         self
 269     }
 270
 271     /// Alters the default target triple on OSX to ensure that c++11 is
 272     /// available. Does not change the target triple if it is explicitly
 273     /// specified.
 274     ///
 275     /// This does not otherwise affect any CXX flags, i.e. it does not set
 276     /// -std=c++11 or -stdlib=libc++.
 277     pub fn uses_cxx11(&mut self) -> &mut Config {
 278         self.uses_cxx11 = true;
 279         self
 280     }
 281
 282     /// Forces CMake to always run before building the custom target.
 283     ///
 284     /// In some cases, when you have a big project, you can disable
 285     /// subsequents runs of cmake to make `cargo build` faster.
 286     pub fn always_configure(&mut self, always_configure: bool) -> &mut Config {
 287         self.always_configure = always_configure;
 288         self
 289     }
 290
 291     /// Sets very verbose output.
 292     pub fn very_verbose(&mut self, value: bool) -> &mut Config {
 293         self.verbose_cmake = value;
 294         self.verbose_make = value;
 295         self
 296     }
 297
 298     // Simple heuristic to determine if we're cross-compiling using the Android
 299     // NDK toolchain file.
 300     fn uses_android_ndk(&self) -> bool {
 301         // `ANDROID_ABI` is the only required flag:
 302         // https://developer.android.com/ndk/guides/cmake#android_abi
 303         self.defined("ANDROID_ABI")
 304             && self.defines.iter().any(|(flag, value)| {
 305                 flag == "CMAKE_TOOLCHAIN_FILE"
 306                     && Path::new(value).file_name() == Some("android.toolchain.cmake".as_ref())
 307             })
 308     }
 309
 310     /// Run this configuration, compiling the library with all the configured
 311     /// options.
 312     ///
 313     /// This will run both the build system generator command as well as the
 314     /// command to build the library.
 315     pub fn build(&mut self) -> PathBuf {
 316         let target = match self.target.clone() {
 317             Some(t) => t,
 318             None => {
 319                 let mut t = getenv_unwrap("TARGET");
 320                 if t.ends_with("-darwin") && self.uses_cxx11 {
 321                     t = t + "11"
 322                 }
 323                 t
 324             }
 325         };
 326         let host = self.host.clone().unwrap_or_else(|| getenv_unwrap("HOST"));
 327         let msvc = target.contains("msvc");
 328         let ndk = self.uses_android_ndk();
 329         let mut c_cfg = cc::Build::new();
 330         c_cfg
 331             .cargo_metadata(false)
 332             .opt_level(0)
 333             .debug(false)
 334             .warnings(false)
 335             .host(&host)
 336             .no_default_flags(ndk);
 337         if !ndk {
 338             c_cfg.target(&target);
 339         }
 340         let mut cxx_cfg = cc::Build::new();
 341         cxx_cfg
 342             .cargo_metadata(false)
 343             .cpp(true)
 344             .opt_level(0)
 345             .debug(false)
 346             .warnings(false)
 347             .host(&host)
 348             .no_default_flags(ndk);
 349         if !ndk {
 350             cxx_cfg.target(&target);
 351         }
 352         if let Some(static_crt) = self.static_crt {
 353             c_cfg.static_crt(static_crt);
 354             cxx_cfg.static_crt(static_crt);
 355         }
 356         if let Some(explicit_flag) = self.pic {
 357             c_cfg.pic(explicit_flag);
 358             cxx_cfg.pic(explicit_flag);
 359         }
 360         let c_compiler = c_cfg.get_compiler();
 361         let cxx_compiler = cxx_cfg.get_compiler();
 362         let asm_compiler = c_cfg.get_compiler();
 363
 364         let dst = self
 365             .out_dir
 366             .clone()
 367             .unwrap_or_else(|| PathBuf::from(getenv_unwrap("OUT_DIR")));
 368         let build = dst.join("build");
 369         self.maybe_clear(&build);
 370         let _ = fs::create_dir(&build);
 371
 372         // Add all our dependencies to our cmake paths
 373         let mut cmake_prefix_path = Vec::new();
 374         for dep in &self.deps {
 375             let dep = dep.to_uppercase().replace('-', "_");
 376             if let Some(root) = env::var_os(&format!("DEP_{}_ROOT", dep)) {
 377                 cmake_prefix_path.push(PathBuf::from(root));
 378             }
 379         }
 380         let system_prefix = env::var_os("CMAKE_PREFIX_PATH").unwrap_or(OsString::new());
 381         cmake_prefix_path.extend(env::split_paths(&system_prefix).map(|s| s.to_owned()));
 382         let cmake_prefix_path = env::join_paths(&cmake_prefix_path).unwrap();
 383
 384         // Build up the first cmake command to build the build system.
 385         let executable = env::var("CMAKE").unwrap_or("cmake".to_owned());
 386         let mut cmd = Command::new(&executable);
 387
 388         if self.verbose_cmake {
 389             cmd.arg("-Wdev");
 390             cmd.arg("--debug-output");
 391         }
 392
 393         cmd.arg(&self.path).current_dir(&build);
 394         let mut is_ninja = false;
 395         if let Some(ref generator) = self.generator {
 396             is_ninja = generator.to_string_lossy().contains("Ninja");
 397         }
 398         if target.contains("windows-gnu") {
 399             if host.contains("windows") {
 400                 // On MinGW we need to coerce cmake to not generate a visual
 401                 // studio build system but instead use makefiles that MinGW can
 402                 // use to build.
 403                 if self.generator.is_none() {
 404                     // If make.exe isn't found, that means we may be using a MinGW
 405                     // toolchain instead of a MSYS2 toolchain. If neither is found,
 406                     // the build cannot continue.
 407                     let has_msys2 = Command::new("make")
 408                         .arg("--version")
 409                         .output()
 410                         .err()
 411                         .map(|e| e.kind() != ErrorKind::NotFound)
 412                         .unwrap_or(true);
 413                     let has_mingw32 = Command::new("mingw32-make")
 414                         .arg("--version")
 415                         .output()
 416                         .err()
 417                         .map(|e| e.kind() != ErrorKind::NotFound)
 418                         .unwrap_or(true);
 419
 420                     let generator = match (has_msys2, has_mingw32) {
 421                         (true, _) => "MSYS Makefiles",
 422                         (false, true) => "MinGW Makefiles",
 423                         (false, false) => fail("no valid generator found for GNU toolchain; MSYS or MinGW must be installed")
 424                     };
 425
 426                     cmd.arg("-G").arg(generator);
 427                 }
 428             } else {
 429                 // If we're cross compiling onto windows, then set some
 430                 // variables which will hopefully get things to succeed. Some
 431                 // systems may need the `windres` or `dlltool` variables set, so
 432                 // set them if possible.
 433                 if !self.defined("CMAKE_SYSTEM_NAME") {
 434                     cmd.arg("-DCMAKE_SYSTEM_NAME=Windows");
 435                 }
 436                 if !self.defined("CMAKE_RC_COMPILER") {
 437                     let exe = find_exe(c_compiler.path());
 438                     if let Some(name) = exe.file_name().unwrap().to_str() {
 439                         let name = name.replace("gcc", "windres");
 440                         let windres = exe.with_file_name(name);
 441                         if windres.is_file() {
 442                             let mut arg = OsString::from("-DCMAKE_RC_COMPILER=");
 443                             arg.push(&windres);
 444                             cmd.arg(arg);
 445                         }
 446                     }
 447                 }
 448             }
 449         } else if msvc {
 450             // If we're on MSVC we need to be sure to use the right generator or
 451             // otherwise we won't get 32/64 bit correct automatically.
 452             // This also guarantees that NMake generator isn't chosen implicitly.
 453             let using_nmake_generator;
 454             if self.generator.is_none() {
 455                 cmd.arg("-G").arg(self.visual_studio_generator(&target));
 456                 using_nmake_generator = false;
 457             } else {
 458                 using_nmake_generator = self.generator.as_ref().unwrap() == "NMake Makefiles";
 459             }
 460             if !is_ninja && !using_nmake_generator {
 461                 if target.contains("x86_64") {
 462                     cmd.arg("-Thost=x64");
 463                     cmd.arg("-Ax64");
 464                 } else if target.contains("thumbv7a") {
 465                     cmd.arg("-Thost=x64");
 466                     cmd.arg("-Aarm");
 467                 } else if target.contains("aarch64") {
 468                     cmd.arg("-Thost=x64");
 469                     cmd.arg("-AARM64");
 470                 } else if target.contains("i686") {
 471                     use cc::windows_registry::{find_vs_version, VsVers};
 472                     match find_vs_version() {
 473                         Ok(VsVers::Vs16) => {
 474                             // 32-bit x86 toolset used to be the default for all hosts,
 475                             // but Visual Studio 2019 changed the default toolset to match the host,
 476                             // so we need to manually override it for x86 targets
 477                             cmd.arg("-Thost=x86");
 478                             cmd.arg("-AWin32");
 479                         }
 480                         _ => {}
 481                     };
 482                 } else {
 483                     panic!("unsupported msvc target: {}", target);
 484                 }
 485             }
 486         } else if target.contains("redox") {
 487             if !self.defined("CMAKE_SYSTEM_NAME") {
 488                 cmd.arg("-DCMAKE_SYSTEM_NAME=Generic");
 489             }
 490         } else if target.contains("solaris") {
 491             if !self.defined("CMAKE_SYSTEM_NAME") {
 492                 cmd.arg("-DCMAKE_SYSTEM_NAME=SunOS");
 493             }
 494         }
 495         if let Some(ref generator) = self.generator {
 496             cmd.arg("-G").arg(generator);
 497         }
 498         let profile = self.profile.clone().unwrap_or_else(|| {
 499             // Automatically set the `CMAKE_BUILD_TYPE` if the user did not
 500             // specify one.
 501
 502             // Determine Rust's profile, optimization level, and debug info:
 503             #[derive(PartialEq)]
 504             enum RustProfile {
 505                 Debug,
 506                 Release,
 507             }
 508             #[derive(PartialEq, Debug)]
 509             enum OptLevel {
 510                 Debug,
 511                 Release,
 512                 Size,
 513             }
 514
 515             let rust_profile = match &getenv_unwrap("PROFILE")[..] {
 516                 "debug" => RustProfile::Debug,
 517                 "release" | "bench" => RustProfile::Release,
 518                 unknown => {
 519                     eprintln!(
 520                         "Warning: unknown Rust profile={}; defaulting to a release build.",
 521                         unknown
 522                     );
 523                     RustProfile::Release
 524                 }
 525             };
 526
 527             let opt_level = match &getenv_unwrap("OPT_LEVEL")[..] {
 528                 "0" => OptLevel::Debug,
 529                 "1" | "2" | "3" => OptLevel::Release,
 530                 "s" | "z" => OptLevel::Size,
 531                 unknown => {
 532                     let default_opt_level = match rust_profile {
 533                         RustProfile::Debug => OptLevel::Debug,
 534                         RustProfile::Release => OptLevel::Release,
 535                     };
 536                     eprintln!(
 537                         "Warning: unknown opt-level={}; defaulting to a {:?} build.",
 538                         unknown, default_opt_level
 539                     );
 540                     default_opt_level
 541                 }
 542             };
 543
 544             let debug_info: bool = match &getenv_unwrap("DEBUG")[..] {
 545                 "false" => false,
 546                 "true" => true,
 547                 unknown => {
 548                     eprintln!("Warning: unknown debug={}; defaulting to `true`.", unknown);
 549                     true
 550                 }
 551             };
 552
 553             match (opt_level, debug_info) {
 554                 (OptLevel::Debug, _) => "Debug",
 555                 (OptLevel::Release, false) => "Release",
 556                 (OptLevel::Release, true) => "RelWithDebInfo",
 557                 (OptLevel::Size, _) => "MinSizeRel",
 558             }
 559             .to_string()
 560         });
 561         for &(ref k, ref v) in &self.defines {
 562             let mut os = OsString::from("-D");
 563             os.push(k);
 564             os.push("=");
 565             os.push(v);
 566             cmd.arg(os);
 567         }
 568
 569         if !self.defined("CMAKE_INSTALL_PREFIX") {
 570             let mut dstflag = OsString::from("-DCMAKE_INSTALL_PREFIX=");
 571             dstflag.push(&dst);
 572             cmd.arg(dstflag);
 573         }
 574
 575         let build_type = self
 576             .defines
 577             .iter()
 578             .find(|&&(ref a, _)| a == "CMAKE_BUILD_TYPE")
 579             .map(|x| x.1.to_str().unwrap())
 580             .unwrap_or(&profile);
 581         let build_type_upcase = build_type
 582             .chars()
 583             .flat_map(|c| c.to_uppercase())
 584             .collect::<String>();
 585
 586         {
 587             // let cmake deal with optimization/debuginfo
 588             let skip_arg = |arg: &OsStr| match arg.to_str() {
 589                 Some(s) => s.starts_with("-O") || s.starts_with("/O") || s == "-g",
 590                 None => false,
 591             };
 592             let mut set_compiler = |kind: &str, compiler: &cc::Tool, extra: &OsString| {
 593                 let flag_var = format!("CMAKE_{}_FLAGS", kind);
 594                 let tool_var = format!("CMAKE_{}_COMPILER", kind);
 595                 if !self.defined(&flag_var) {
 596                     let mut flagsflag = OsString::from("-D");
 597                     flagsflag.push(&flag_var);
 598                     flagsflag.push("=");
 599                     flagsflag.push(extra);
 600                     for arg in compiler.args() {
 601                         if skip_arg(arg) {
 602                             continue;
 603                         }
 604                         flagsflag.push(" ");
 605                         flagsflag.push(arg);
 606                     }
 607                     cmd.arg(flagsflag);
 608                 }
 609
 610                 // The visual studio generator apparently doesn't respect
 611                 // `CMAKE_C_FLAGS` but does respect `CMAKE_C_FLAGS_RELEASE` and
 612                 // such. We need to communicate /MD vs /MT, so set those vars
 613                 // here.
 614                 //
 615                 // Note that for other generators, though, this *overrides*
 616                 // things like the optimization flags, which is bad.
 617                 if self.generator.is_none() && msvc {
 618                     let flag_var_alt = format!("CMAKE_{}_FLAGS_{}", kind, build_type_upcase);
 619                     if !self.defined(&flag_var_alt) {
 620                         let mut flagsflag = OsString::from("-D");
 621                         flagsflag.push(&flag_var_alt);
 622                         flagsflag.push("=");
 623                         flagsflag.push(extra);
 624                         for arg in compiler.args() {
 625                             if skip_arg(arg) {
 626                                 continue;
 627                             }
 628                             flagsflag.push(" ");
 629                             flagsflag.push(arg);
 630                         }
 631                         cmd.arg(flagsflag);
 632                     }
 633                 }
 634
 635                 // Apparently cmake likes to have an absolute path to the
 636                 // compiler as otherwise it sometimes thinks that this variable
 637                 // changed as it thinks the found compiler, /usr/bin/cc,
 638                 // differs from the specified compiler, cc. Not entirely sure
 639                 // what's up, but at least this means cmake doesn't get
 640                 // confused?
 641                 //
 642                 // Also specify this on Windows only if we use MSVC with Ninja,
 643                 // as it's not needed for MSVC with Visual Studio generators and
 644                 // for MinGW it doesn't really vary.
 645                 if !self.defined("CMAKE_TOOLCHAIN_FILE")
 646                     && !self.defined(&tool_var)
 647                     && (env::consts::FAMILY != "windows" || (msvc && is_ninja))
 648                 {
 649                     let mut ccompiler = OsString::from("-D");
 650                     ccompiler.push(&tool_var);
 651                     ccompiler.push("=");
 652                     ccompiler.push(find_exe(compiler.path()));
 653                     #[cfg(windows)]
 654                     {
 655                         // CMake doesn't like unescaped `\`s in compiler paths
 656                         // so we either have to escape them or replace with `/`s.
 657                         use std::os::windows::ffi::{OsStrExt, OsStringExt};
 658                         let wchars = ccompiler
 659                             .encode_wide()
 660                             .map(|wchar| {
 661                                 if wchar == b'\\' as u16 {
 662                                     '/' as u16
 663                                 } else {
 664                                     wchar
 665                                 }
 666                             })
 667                             .collect::<Vec<_>>();
 668                         ccompiler = OsString::from_wide(&wchars);
 669                     }
 670                     cmd.arg(ccompiler);
 671                 }
 672             };
 673
 674             set_compiler("C", &c_compiler, &self.cflags);
 675             set_compiler("CXX", &cxx_compiler, &self.cxxflags);
 676             set_compiler("ASM", &asm_compiler, &self.asmflags);
 677         }
 678
 679         if !self.defined("CMAKE_BUILD_TYPE") {
 680             cmd.arg(&format!("-DCMAKE_BUILD_TYPE={}", profile));
 681         }
 682
 683         if self.verbose_make {
 684             cmd.arg("-DCMAKE_VERBOSE_MAKEFILE:BOOL=ON");
 685         }
 686
 687         if !self.defined("CMAKE_TOOLCHAIN_FILE") {
 688             if let Ok(s) = env::var("CMAKE_TOOLCHAIN_FILE") {
 689                 cmd.arg(&format!("-DCMAKE_TOOLCHAIN_FILE={}", s));
 690             }
 691         }
 692
 693         for &(ref k, ref v) in c_compiler.env().iter().chain(&self.env) {
 694             cmd.env(k, v);
 695         }
 696
 697         if self.always_configure || !build.join("CMakeCache.txt").exists() {
 698             run(cmd.env("CMAKE_PREFIX_PATH", cmake_prefix_path), "cmake");
 699         } else {
 700             println!("CMake project was already configured. Skipping configuration step.");
 701         }
 702
 703         let mut makeflags = None;
 704         let mut parallel_flags = None;
 705
 706         if let Ok(s) = env::var("NUM_JOBS") {
 707             match self.generator.as_ref().map(|g| g.to_string_lossy()) {
 708                 Some(ref g) if g.contains("Ninja") => {
 709                     parallel_flags = Some(format!("-j{}", s));
 710                 }
 711                 Some(ref g) if g.contains("Visual Studio") => {
 712                     parallel_flags = Some(format!("/m:{}", s));
 713                 }
 714                 Some(ref g) if g.contains("NMake") => {
 715                     // NMake creates `Makefile`s, but doesn't understand `-jN`.
 716                 }
 717                 _ if fs::metadata(&build.join("Makefile")).is_ok() => {
 718                     match env::var_os("CARGO_MAKEFLAGS") {
 719                         // Only do this on non-windows and non-bsd
 720                         // On Windows, we could be invoking make instead of
 721                         // mingw32-make which doesn't work with our jobserver
 722                         // bsdmake also does not work with our job server
 723                         Some(ref s)
 724                             if !(cfg!(windows)
 725                                 || cfg!(target_os = "openbsd")
 726                                 || cfg!(target_os = "netbsd")
 727                                 || cfg!(target_os = "freebsd")
 728                                 || cfg!(target_os = "bitrig")
 729                                 || cfg!(target_os = "dragonflybsd")) =>
 730                         {
 731                             makeflags = Some(s.clone())
 732                         }
 733
 734                         // This looks like `make`, let's hope it understands `-jN`.
 735                         _ => makeflags = Some(OsString::from(format!("-j{}", s))),
 736                     }
 737                 }
 738                 _ => {}
 739             }
 740         }
 741
 742         // And build!
 743         let target = self.cmake_target.clone().unwrap_or("install".to_string());
 744         let mut cmd = Command::new(&executable);
 745         for &(ref k, ref v) in c_compiler.env().iter().chain(&self.env) {
 746             cmd.env(k, v);
 747         }
 748
 749         if let Some(flags) = makeflags {
 750             cmd.env("MAKEFLAGS", flags);
 751         }
 752
 753         cmd.arg("--build").arg(".");
 754
 755         if !self.no_build_target {
 756             cmd.arg("--target").arg(target);
 757         }
 758
 759         cmd.arg("--config")
 760             .arg(&profile)
 761             .arg("--")
 762             .args(&self.build_args)
 763             .current_dir(&build);
 764
 765         if let Some(flags) = parallel_flags {
 766             cmd.arg(flags);
 767         }
 768
 769         run(&mut cmd, "cmake");
 770
 771         println!("cargo:root={}", dst.display());
 772         return dst;
 773     }
 774
 775     fn visual_studio_generator(&self, target: &str) -> String {
 776         use cc::windows_registry::{find_vs_version, VsVers};
 777
 778         let base = match find_vs_version() {
 779             Ok(VsVers::Vs16) => "Visual Studio 16 2019",
 780             Ok(VsVers::Vs15) => "Visual Studio 15 2017",
 781             Ok(VsVers::Vs14) => "Visual Studio 14 2015",
 782             Ok(VsVers::Vs12) => "Visual Studio 12 2013",
 783             Ok(_) => panic!(
 784                 "Visual studio version detected but this crate \
 785                  doesn't know how to generate cmake files for it, \
 786                  can the `cmake` crate be updated?"
 787             ),
 788             Err(msg) => panic!(msg),
 789         };
 790         if ["i686", "x86_64", "thumbv7a", "aarch64"]
 791             .iter()
 792             .any(|t| target.contains(t))
 793         {
 794             base.to_string()
 795         } else {
 796             panic!("unsupported msvc target: {}", target);
 797         }
 798     }
 799
 800     fn defined(&self, var: &str) -> bool {
 801         self.defines.iter().any(|&(ref a, _)| a == var)
 802     }
 803
 804     // If a cmake project has previously been built (e.g. CMakeCache.txt already
 805     // exists), then cmake will choke if the source directory for the original
 806     // project being built has changed. Detect this situation through the
 807     // `CMAKE_HOME_DIRECTORY` variable that cmake emits and if it doesn't match
 808     // we blow away the build directory and start from scratch (the recommended
 809     // solution apparently [1]).
 810     //
 811     // [1]: https://cmake.org/pipermail/cmake/2012-August/051545.html
 812     fn maybe_clear(&self, dir: &Path) {
 813         // CMake will apparently store canonicalized paths which normally
 814         // isn't relevant to us but we canonicalize it here to ensure
 815         // we're both checking the same thing.
 816         let path = fs::canonicalize(&self.path).unwrap_or(self.path.clone());
 817         let mut f = match File::open(dir.join("CMakeCache.txt")) {
 818             Ok(f) => f,
 819             Err(..) => return,
 820         };
 821         let mut u8contents = Vec::new();
 822         match f.read_to_end(&mut u8contents) {
 823             Ok(f) => f,
 824             Err(..) => return,
 825         };
 826         let contents = String::from_utf8_lossy(&u8contents);
 827         drop(f);
 828         for line in contents.lines() {
 829             if line.starts_with("CMAKE_HOME_DIRECTORY") {
 830                 let needs_cleanup = match line.split('=').next_back() {
 831                     Some(cmake_home) => fs::canonicalize(cmake_home)
 832                         .ok()
 833                         .map(|cmake_home| cmake_home != path)
 834                         .unwrap_or(true),
 835                     None => true,
 836                 };
 837                 if needs_cleanup {
 838                     println!(
 839                         "detected home dir change, cleaning out entire build \
 840                          directory"
 841                     );
 842                     fs::remove_dir_all(dir).unwrap();
 843                 }
 844                 break;
 845             }
 846         }
 847     }
 848 }
 849
 850 fn run(cmd: &mut Command, program: &str) {
 851     println!("running: {:?}", cmd);
 852     let status = match cmd.status() {
 853         Ok(status) => status,
 854         Err(ref e) if e.kind() == ErrorKind::NotFound => {
 855             fail(&format!(
 856                 "failed to execute command: {}\nis `{}` not installed?",
 857                 e, program
 858             ));
 859         }
 860         Err(e) => fail(&format!("failed to execute command: {}", e)),
 861     };
 862     if !status.success() {
 863         fail(&format!(
 864             "command did not execute successfully, got: {}",
 865             status
 866         ));
 867     }
 868 }
 869
 870 fn find_exe(path: &Path) -> PathBuf {
 871     env::split_paths(&env::var_os("PATH").unwrap_or(OsString::new()))
 872         .map(|p| p.join(path))
 873         .find(|p| fs::metadata(p).is_ok())
 874         .unwrap_or(path.to_owned())
 875 }
 876
 877 fn getenv_unwrap(v: &str) -> String {
 878     match env::var(v) {
 879         Ok(s) => s,
 880         Err(..) => fail(&format!("environment variable `{}` not defined", v)),
 881     }
 882 }
 883
 884 fn fail(s: &str) -> ! {
 885     panic!("\n{}\n\nbuild script failed, must exit now", s)
 886 }