When using errno, log the actual error message

For the user it is more useful to see the actual error message,
provided by strerror(), than the pure error code.

2 files changed, 9 insertions, 8 deletions

diff --git a/src/other_tools/just_mr/launch.cpp b/src/other_tools/just_mr/launch.cpp
index d83ef8e5..ccebd966 100644
--- a/src/other_tools/just_mr/launch.cpp
+++ b/src/other_tools/just_mr/launch.cpp
@@ -14,7 +14,8 @@
 
 #include "src/other_tools/just_mr/launch.hpp"
 
-#include <cerrno>  // for errno
+#include <cerrno>   // for errno
+#include <cstring>  // for strerror()
 #include <filesystem>
 #include <utility>
 
@@ -256,6 +257,6 @@ auto CallJust(std::optional<std::filesystem::path> const& config_file,
     [[maybe_unused]] auto res =
         execvp(argv[0], static_cast<char* const*>(argv.data()));
     // execvp returns only if command errored out
-    Logger::Log(LogLevel::Error, "execvp failed with error code {}", errno);
+    Logger::Log(LogLevel::Error, "execvp failed with:\n{}", strerror(errno));
     return kExitExecError;
 }
diff --git a/src/utils/cpp/file_locking.cpp b/src/utils/cpp/file_locking.cpp
index d7f0c49a..53cba2bf 100644
--- a/src/utils/cpp/file_locking.cpp
+++ b/src/utils/cpp/file_locking.cpp
@@ -14,7 +14,8 @@
 
 #include "src/utils/cpp/file_locking.hpp"
 
-#include <cerrno>  // for errno
+#include <cerrno>   // for errno
+#include <cstring>  // for strerror()
 
 #ifdef __unix__
 #include <sys/file.h>
@@ -56,11 +57,10 @@ auto LockFile::Acquire(std::filesystem::path const& fspath,
         // attach flock
         auto err = flock(fileno(file_handle), is_shared ? LOCK_SH : LOCK_EX);
         if (err != 0) {
-            Logger::Log(
-                LogLevel::Error,
-                "LockFile: applying lock to file {} failed with errno {}",
-                lock_file->string(),
-                errno);
+            Logger::Log(LogLevel::Error,
+                        "LockFile: applying lock to file {} failed with:\n{}",
+                        lock_file->string(),
+                        strerror(errno));
             fclose(file_handle);
             return std::nullopt;
         }