From c1121fad3fda4af4fac95f704fd46e9fe3f44ea6 Mon Sep 17 00:00:00 2001
From: patr0nus <dk4rest@gmail.com>
Date: Tue, 29 Dec 2020 01:51:59 +0800
Subject: [PATCH 1/3] Check if the universal library is updated

---
 src/lipo.rs | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/lipo.rs b/src/lipo.rs
index caf41b5..449af19 100644
--- a/src/lipo.rs
+++ b/src/lipo.rs
@@ -5,6 +5,18 @@ use failure::ResultExt;
 use log::info;
 use std::fs;
 use std::process::Command;
+use std::path::Path;
+
+fn is_output_updated(output: impl AsRef<Path>, inputs: impl IntoIterator<Item=impl AsRef<Path>>) -> std::io::Result<bool> {
+    let output_mtime = fs::metadata(output)?.modified()?;
+    for input in inputs {
+        let input_mtime = fs::metadata(input)?.modified()?;
+        if input_mtime > output_mtime {
+            return Ok(false)
+        }
+    }
+    Ok(true)
+}
 
 pub(crate) fn build(cargo: &Cargo, meta: &Meta, targets: &[impl AsRef<str>]) -> Result<()> {
     for package in meta.packages() {
@@ -37,13 +49,18 @@ pub(crate) fn build(cargo: &Cargo, meta: &Meta, targets: &[impl AsRef<str>]) ->
 
         output.push(&lib_name);
 
-        let mut cmd = Command::new("lipo");
-        cmd.arg("-create").arg("-output").arg(output);
-        cmd.args(inputs);
+        if let Ok(true) = is_output_updated(&output, &inputs) {
+            info!("Universal library for {} is updated", package.name());
+        }
+        else {
+            let mut cmd = Command::new("lipo");
+            cmd.arg("-create").arg("-output").arg(output);
+            cmd.args(inputs);
 
-        info!("Creating universal library for {}", package.name());
+            info!("Creating universal library for {}", package.name());
 
-        crate::exec::run(cmd)?;
+            crate::exec::run(cmd)?;
+        }
     }
 
     Ok(())

From 1df1ea15f1fa260448284c0342c92855bc2eb2d1 Mon Sep 17 00:00:00 2001
From: patr0nus <dk4rest@gmail.com>
Date: Wed, 20 Jan 2021 23:06:34 +0800
Subject: [PATCH 2/3] Refactor `is_output_updated` to `should_update_output` &&
 rustfmt

---
 src/lipo.rs | 45 ++++++++++++++++++++++++++++++++-------------
 1 file changed, 32 insertions(+), 13 deletions(-)

diff --git a/src/lipo.rs b/src/lipo.rs
index 449af19..d3a13dc 100644
--- a/src/lipo.rs
+++ b/src/lipo.rs
@@ -7,15 +7,22 @@ use std::fs;
 use std::process::Command;
 use std::path::Path;
 
-fn is_output_updated(output: impl AsRef<Path>, inputs: impl IntoIterator<Item=impl AsRef<Path>>) -> std::io::Result<bool> {
-    let output_mtime = fs::metadata(output)?.modified()?;
+fn should_update_output(
+    output: impl AsRef<Path>,
+    inputs: impl IntoIterator<Item = impl AsRef<Path>>,
+) -> std::io::Result<bool> {
+    let output_metadata = match fs::metadata(output) {
+        Ok(metadata) => metadata,
+        Err(_) => return Ok(true),
+    };
+    let output_mtime = output_metadata.modified()?;
     for input in inputs {
         let input_mtime = fs::metadata(input)?.modified()?;
         if input_mtime > output_mtime {
-            return Ok(false)
+            return Ok(true);
         }
     }
-    Ok(true)
+    Ok(false)
 }
 
 pub(crate) fn build(cargo: &Cargo, meta: &Meta, targets: &[impl AsRef<str>]) -> Result<()> {
@@ -49,18 +56,30 @@ pub(crate) fn build(cargo: &Cargo, meta: &Meta, targets: &[impl AsRef<str>]) ->
 
         output.push(&lib_name);
 
-        if let Ok(true) = is_output_updated(&output, &inputs) {
-            info!("Universal library for {} is updated", package.name());
+        match should_update_output(&output, &inputs) {
+            Ok(true) => {}
+            Ok(false) => {
+                info!(
+                    "Universal library is up-to-date, skipping lipo invocation for {}",
+                    package.name()
+                );
+                continue;
+            }
+            Err(e) => {
+                warn!(
+                    "Failed to check if universal library for {:?} is up-to-date: {}",
+                    package.name(),
+                    e
+                )
+            }
         }
-        else {
-            let mut cmd = Command::new("lipo");
-            cmd.arg("-create").arg("-output").arg(output);
-            cmd.args(inputs);
+        let mut cmd = Command::new("lipo");
+        cmd.arg("-create").arg("-output").arg(output);
+        cmd.args(inputs);
 
-            info!("Creating universal library for {}", package.name());
+        info!("Creating universal library for {}", package.name());
 
-            crate::exec::run(cmd)?;
-        }
+        crate::exec::run(cmd)?;
     }
 
     Ok(())

From f076aca9b8c2430f483caa54487142d5b63579e9 Mon Sep 17 00:00:00 2001
From: "Wang, Chi" <patr0nus@users.noreply.github.com>
Date: Wed, 20 Jan 2021 23:39:22 +0800
Subject: [PATCH 3/3] Add missing `use`

---
 src/lipo.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lipo.rs b/src/lipo.rs
index d3a13dc..54a4277 100644
--- a/src/lipo.rs
+++ b/src/lipo.rs
@@ -2,7 +2,7 @@ use crate::Result;
 use crate::cargo::Cargo;
 use crate::meta::Meta;
 use failure::ResultExt;
-use log::info;
+use log::{info, warn};
 use std::fs;
 use std::process::Command;
 use std::path::Path;