fix: IOS sysroot options

There are a few ongoing issues with the current compilation which are
fixed:

1. Ensured to provide a correct sysroot required for some of the clang
   compilers according to rust-lang/rust-bindgen#1229
2. Automated the sysroot search both for ffmpeg build and bingen and
   ensured that the path is valid (new xcode version appends \n which
   breaks everythin)
3. Fixed some of the wronly passed parameters and enabled featuers for
hardeward decoding on ioss

Author: dmtrKovalenko

Cargo.toml

@@ -96,6 +96,10 @@ build-lib-x265             = ["build"]
 build-lib-avs              = ["build"]
 build-lib-xvid             = ["build"]
 
+# hardware accelleration
+build-videotoolbox =  ["build"]
+build-audiotoolbox =  ["build"]
+
 # protocols
 build-lib-smbclient = ["build"]
 build-lib-ssh       = ["build"]

build.rs

@@ -7,7 +7,7 @@ use std::env;
 use std::fmt::Write as FmtWrite;
 use std::fs::{self, File};
 use std::io::{self, BufRead, BufReader, Write};
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::str;
 
@@ -195,7 +195,43 @@ fn get_ffmpet_target_os() -> String {
     }
 }
 
-fn build() -> io::Result<()> {
+/// Find the sysroot required for a cross compilation by ffmpeg **and** bindgen
+/// @see https://github.com/rust-lang/rust-bindgen/issues/1229
+fn find_sysroot() -> Option<String> {
+    if env::var("CARGO_FEATURE_BUILD").is_err() || env::var("HOST") == env::var("TARGET") {
+        return None;
+    }
+
+    if let Ok(sysroot) = env::var("SYSROOT") {
+        return Some(sysroot.to_string());
+    }
+
+    if env::var("CARGO_CFG_TARGET_OS").as_deref() == Ok("ios") {
+        let xcode_output = Command::new("xcrun")
+            .args(["--sdk", "iphoneos", "--show-sdk-path"])
+            .output()
+            .expect("failed to run xcrun");
+
+        if !xcode_output.status.success() {
+            panic!("Failed to run xcrun to get the ios sysroot, please install xcode tools or provide sysroot using $SYSROOT env. Error: {}", String::from_utf8_lossy(&xcode_output.stderr));
+        }
+
+        let string = String::from_utf8(xcode_output.stdout)
+            .expect("Failed to parse xcrun output")
+            .replace("\n", "");
+
+        if !Path::new(&string).exists() {
+            panic!("xcrun returned invalid sysroot path: {}", string);
+        }
+
+        return Some(string);
+    }
+
+    println!("cargo:warnning=Detected cross compilation but sysroot not provided");
+    None
+}
+
+fn build(sysroot: Option<&str>) -> io::Result<()> {
     let source_dir = source();
 
     // Command's path is not relative to command's current_dir
@@ -233,7 +269,27 @@ fn build() -> io::Result<()> {
             "--arch={}",
             env::var("CARGO_CFG_TARGET_ARCH").unwrap()
         ));
-        configure.arg(format!("--target_os={}", get_ffmpet_target_os()));
+        configure.arg(format!("--target-os={}", get_ffmpet_target_os()));
+    }
+
+    // for ios it is required to provide sysroot for both configure and bindgen
+    // for macos the easiest way is to run xcrun, for other platform we support $SYSROOT var
+    if env::var("CARGO_CFG_TARGET_OS").as_deref() == Ok("ios") {
+        let sysroot = sysroot.expect("The sysroot is required for ios cross compilation, make sure to have available xcode or provide the $SYSROOT env var");
+        configure.arg(format!("--sysroot={}", sysroot));
+
+        let cc = Command::new("xcrun")
+            .args(["--sdk", "iphoneos", "-f", "clang"])
+            .output()
+            .expect("failed to run xcrun")
+            .stdout;
+
+        configure.arg(format!(
+            "--cc={}",
+            str::from_utf8(&cc)
+                .expect("Failed to parse xcrun output")
+                .trim()
+        ));
     }
 
     // control debug build
@@ -348,6 +404,23 @@ fn build() -> io::Result<()> {
     enable!(configure, "BUILD_LIB_AVS", "libavs");
     enable!(configure, "BUILD_LIB_XVID", "libxvid");
 
+    if env::var("CARGO_FEATURE_BUILD_VIDEOTOOLBOX").is_ok() {
+        configure.arg("--enable-videotoolbox");
+
+        if target != host && env::var("CARGO_CFG_TARGET_OS").as_deref() == Ok("ios") {
+            configure.arg("--extra-cflags=-mios-version-min=11.0");
+        }
+
+        if target != host && env::var("CARGO_CFG_TARGET_OS").as_deref() == Ok("macos") {
+            configure.arg("--extra-cflags=-mmacosx-version-min=10.11");
+        }
+    }
+
+    if env::var("CARGO_FEATURE_BUILD_AUDIOTOOLBOX").is_ok() {
+        configure.arg("--enable-audiotoolbox");
+        configure.arg("--extra-cflags=-mios-version-min=11.0");
+    }
+
     // other external libraries
     enable!(configure, "BUILD_LIB_DRM", "libdrm");
     enable!(configure, "BUILD_NVENC", "nvenc");
@@ -671,6 +744,7 @@ fn main() {
     let statik = env::var("CARGO_FEATURE_STATIC").is_ok();
     let ffmpeg_major_version: u32 = env!("CARGO_PKG_VERSION_MAJOR").parse().unwrap();
 
+    let sysroot = find_sysroot();
     let include_paths: Vec<PathBuf> = if env::var("CARGO_FEATURE_BUILD").is_ok() {
         println!(
             "cargo:rustc-link-search=native={}",
@@ -680,7 +754,7 @@ fn main() {
         if fs::metadata(search().join("lib").join("libavutil.a")).is_err() {
             fs::create_dir_all(output()).expect("failed to create build directory");
             fetch().unwrap();
-            build().unwrap();
+            build(sysroot.as_deref()).unwrap();
         }
 
         // Check additional required libraries.
@@ -1253,6 +1327,10 @@ fn main() {
         .size_t_is_usize(true)
         .parse_callbacks(Box::new(Callbacks));
 
+    if let Some(sysroot) = sysroot.as_deref() {
+        builder = builder.clang_arg(format!("--sysroot={}", sysroot));
+    }
+
     // The input headers we would like to generate
     // bindings for.
     if env::var("CARGO_FEATURE_AVCODEC").is_ok() {