From 6b13969dae31b45dd6dd45515f0c326f2bab2de0 Mon Sep 17 00:00:00 2001
From: "K.J. Valencik" <kjvalencik@gmail.com>
Date: Mon, 26 Apr 2021 11:11:22 -0400
Subject: [PATCH] Add Android support to gimli (#415)

---
 Cargo.toml             |  8 +++++++-
 build.rs               | 35 +++++++++++++++++++++++++++++++++++
 src/android-api.c      |  4 ++++
 src/symbolize/gimli.rs |  1 +
 4 files changed, 47 insertions(+), 1 deletion(-)
 create mode 100644 build.rs
 create mode 100644 src/android-api.c

diff --git a/Cargo.toml b/Cargo.toml
index 71db617f..a72d5336 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -2,6 +2,7 @@
 name = "backtrace"
 version = "0.3.57"
 authors = ["The Rust Project Developers"]
+build = "build.rs"
 license = "MIT/Apache-2.0"
 readme = "README.md"
 repository = "https://github.com/rust-lang/backtrace-rs"
@@ -22,7 +23,7 @@ exclude = ['crates/without_debuginfo', 'crates/macos_frames_test', 'crates/line-
 cfg-if = "1.0"
 rustc-demangle = "0.1.4"
 backtrace-sys = { path = "crates/backtrace-sys", version = "0.1.35", optional = true, default_features = false }
-libc = { version = "0.2.87", default-features = false }
+libc = { version = "0.2.94", default-features = false }
 
 # Optionally enable the ability to serialize a `Backtrace`, controlled through
 # the `serialize-*` features below.
@@ -46,6 +47,11 @@ features = ['read_core', 'elf', 'macho', 'pe', 'unaligned', 'archive']
 [target.'cfg(windows)'.dependencies]
 winapi = { version = "0.3.3", optional = true }
 
+[build-dependencies]
+# Only needed for Android, but cannot be target dependent
+# https://github.com/rust-lang/cargo/issues/4932
+cc = "1.0.67"
+
 [dev-dependencies]
 dylib-dep = { path = "crates/dylib-dep" }
 libloading = "0.6"
diff --git a/build.rs b/build.rs
new file mode 100644
index 00000000..abe896df
--- /dev/null
+++ b/build.rs
@@ -0,0 +1,35 @@
+extern crate cc;
+
+use std::env;
+
+fn main() {
+    match env::var("CARGO_CFG_TARGET_OS").unwrap_or_default().as_str() {
+        "android" => build_android(),
+        _ => {}
+    }
+}
+
+fn build_android() {
+    let expansion = cc::Build::new().file("src/android-api.c").expand();
+    let expansion = match std::str::from_utf8(&expansion) {
+        Ok(s) => s,
+        Err(_) => return,
+    };
+    println!("expanded android version detection:\n{}", expansion);
+    let marker = "APIVERSION";
+    let i = match expansion.find(marker) {
+        Some(i) => i,
+        None => return,
+    };
+    let version = match expansion[i + marker.len() + 1..].split_whitespace().next() {
+        Some(s) => s,
+        None => return,
+    };
+    let version = match version.parse::<u32>() {
+        Ok(n) => n,
+        Err(_) => return,
+    };
+    if version >= 21 {
+        println!("cargo:rustc-cfg=feature=\"dl_iterate_phdr\"");
+    }
+}
diff --git a/src/android-api.c b/src/android-api.c
new file mode 100644
index 00000000..1bfeadf5
--- /dev/null
+++ b/src/android-api.c
@@ -0,0 +1,4 @@
+// Used from the build script to detect the value of the `__ANDROID_API__`
+// builtin #define
+
+APIVERSION __ANDROID_API__
diff --git a/src/symbolize/gimli.rs b/src/symbolize/gimli.rs
index bcd362ce..6002426a 100644
--- a/src/symbolize/gimli.rs
+++ b/src/symbolize/gimli.rs
@@ -154,6 +154,7 @@ cfg_if::cfg_if! {
             target_os = "linux",
             target_os = "fuchsia",
             target_os = "freebsd",
+            all(target_os = "android", feature = "dl_iterate_phdr"),
         ),
         not(target_env = "uclibc"),
     ))] {