From cf595b81d53a4fdeb30694a271bf1cfe1bd55c34 Mon Sep 17 00:00:00 2001
From: Tristan Ross <tristan.ross@determinate.systems>
Date: Tue, 23 Sep 2025 12:04:06 -0700
Subject: [PATCH] libmain-c: add nix_set_log_format function

---
 src/libmain-c/nix_api_main.cc | 13 +++++++++++++
 src/libmain-c/nix_api_main.h  |  8 ++++++++
 2 files changed, 21 insertions(+)

diff --git a/src/libmain-c/nix_api_main.cc b/src/libmain-c/nix_api_main.cc
index 2d4f588a8..0ee965dc8 100644
--- a/src/libmain-c/nix_api_main.cc
+++ b/src/libmain-c/nix_api_main.cc
@@ -4,6 +4,7 @@
 #include "nix_api_util_internal.h"
 
 #include "nix/main/plugin.hh"
+#include "nix/main/loggers.hh"
 
 extern "C" {
 
@@ -17,4 +18,16 @@ nix_err nix_init_plugins(nix_c_context * context)
     NIXC_CATCH_ERRS
 }
 
+nix_err nix_set_log_format(nix_c_context * context, const char * format)
+{
+    if (context)
+        context->last_err_code = NIX_OK;
+    if (format == nullptr)
+        return nix_set_err_msg(context, NIX_ERR_UNKNOWN, "Log format is null");
+    try {
+        nix::setLogFormat(format);
+    }
+    NIXC_CATCH_ERRS
+}
+
 } // extern "C"
diff --git a/src/libmain-c/nix_api_main.h b/src/libmain-c/nix_api_main.h
index 3957b992f..3d5d12c15 100644
--- a/src/libmain-c/nix_api_main.h
+++ b/src/libmain-c/nix_api_main.h
@@ -30,6 +30,14 @@ extern "C" {
  */
 nix_err nix_init_plugins(nix_c_context * context);
 
+/**
+ * @brief Sets the log format
+ *
+ * @param[out] context Optional, stores error information
+ * @param[in] format The string name of the format.
+ */
+nix_err nix_set_log_format(nix_c_context * context, const char * format);
+
 // cffi end
 #ifdef __cplusplus
 }