From 5b7bcc462f37e9ba37504c7d2b3d3e91d643c635 Mon Sep 17 00:00:00 2001
From: Qiu Chaofan <qcf@ecnelises.com>
Date: Mon, 29 Aug 2022 16:07:14 +0800
Subject: [PATCH] Support AIX operating system

---
 src/lib.rs      |  1 +
 src/platform.rs |  2 +-
 src/tz_aix.rs   | 26 ++++++++++++++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 src/tz_aix.rs

diff --git a/src/lib.rs b/src/lib.rs
index 81c321f..b98c155 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -52,6 +52,7 @@ mod ffi_utils;
     any(target_os = "illumos", target_os = "solaris"),
     path = "tz_illumos.rs"
 )]
+#[cfg_attr(target_os = "aix", path = "tz_aix.rs")]
 #[cfg_attr(target_os = "android", path = "tz_android.rs")]
 #[cfg_attr(target_os = "haiku", path = "tz_haiku.rs")]
 mod platform;
diff --git a/src/platform.rs b/src/platform.rs
index 5992bf3..e83e874 100644
--- a/src/platform.rs
+++ b/src/platform.rs
@@ -5,5 +5,5 @@ pub fn get_timezone_inner() -> std::result::Result<String, crate::GetTimezoneErr
 #[cfg(not(feature = "fallback"))]
 compile_error!(
     "iana-time-zone is currently implemented for Linux, Window, MacOS, FreeBSD, NetBSD, \
-    OpenBSD, Dragonfly, WebAssembly (browser), iOS, Illumos, Android, Solaris and Haiku.",
+    OpenBSD, Dragonfly, WebAssembly (browser), iOS, Illumos, Android, AIX, Solaris and Haiku.",
 );
diff --git a/src/tz_aix.rs b/src/tz_aix.rs
new file mode 100644
index 0000000..5fdf9b8
--- /dev/null
+++ b/src/tz_aix.rs
@@ -0,0 +1,26 @@
+use std::fs::OpenOptions;
+use std::io::{BufRead, BufReader};
+use std::env;
+
+pub(crate) fn get_timezone_inner() -> Result<String, crate::GetTimezoneError> {
+    env::var("TZ").map_err(|_| crate::GetTimezoneError::OsError)
+}
+
+fn read_environment() -> Result<String, crate::GetTimezoneError> {
+    // https://www.ibm.com/docs/en/aix/7.2?topic=files-environment-file
+
+    let file = OpenOptions::new().read(true).open("/etc/environment")?;
+    let mut reader = BufReader::new(file);
+    let mut line = String::with_capacity(80);
+    loop {
+        line.clear();
+        let count = reader.read_line(&mut line)?;
+        if count == 0 {
+            return Err(crate::GetTimezoneError::FailedParsingString);
+        } else if line.starts_with("TZ=") {
+            line.truncate(line.trim_end().len());
+            line.replace_range(..3, "");
+            return Ok(line);
+        }
+    }
+}