From db15b6f93d828d0c4a9705e845b41d48be22b6f2 Mon Sep 17 00:00:00 2001
From: Kelvin Zhang <zhangkelvin@google.com>
Date: Wed, 3 May 2023 15:28:39 -0700
Subject: [PATCH] Improve error message of libmodprobe

Log path of module if that module is not found.

Bug: 273752147
Test: th
Change-Id: I428a116ee26f97455229df642acbdc1297098a32
---
 libmodprobe/libmodprobe.cpp     | 5 +++--
 libmodprobe/libmodprobe_ext.cpp | 4 ++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/libmodprobe/libmodprobe.cpp b/libmodprobe/libmodprobe.cpp
index 858b9555f..d20b6b10a 100644
--- a/libmodprobe/libmodprobe.cpp
+++ b/libmodprobe/libmodprobe.cpp
@@ -230,7 +230,7 @@ void Modprobe::ParseCfg(const std::string& cfg,
     }
 
     std::vector<std::string> lines = android::base::Split(cfg_contents, "\n");
-    for (const std::string line : lines) {
+    for (const auto& line : lines) {
         if (line.empty() || line[0] == '#') {
             continue;
         }
@@ -421,7 +421,8 @@ bool Modprobe::LoadWithAliases(const std::string& module_name, bool strict,
     }
 
     if (strict && !module_loaded) {
-        LOG(ERROR) << "LoadWithAliases was unable to load " << module_name;
+        LOG(ERROR) << "LoadWithAliases was unable to load " << module_name
+                   << ", tried: " << android::base::Join(modules_to_load, ", ");
         return false;
     }
     return true;
diff --git a/libmodprobe/libmodprobe_ext.cpp b/libmodprobe/libmodprobe_ext.cpp
index 94a1dc4e9..c4519e392 100644
--- a/libmodprobe/libmodprobe_ext.cpp
+++ b/libmodprobe/libmodprobe_ext.cpp
@@ -84,7 +84,7 @@ bool Modprobe::Rmmod(const std::string& module_name) {
 }
 
 bool Modprobe::ModuleExists(const std::string& module_name) {
-    struct stat fileStat;
+    struct stat fileStat {};
     if (blocklist_enabled && module_blocklist_.count(module_name)) {
         LOG(INFO) << "module " << module_name << " is blocklisted";
         return false;
@@ -95,7 +95,7 @@ bool Modprobe::ModuleExists(const std::string& module_name) {
         return false;
     }
     if (stat(deps.front().c_str(), &fileStat)) {
-        LOG(INFO) << "module " << module_name << " does not exist";
+        PLOG(INFO) << "module " << module_name << " can't be loaded; can't access " << deps.front();
         return false;
     }
     if (!S_ISREG(fileStat.st_mode)) {