From 3a54e4f8372e050c5d373d62319a07f9816aaf0f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marco=20Trevisan=20=28Trevi=C3=B1o=29?= <mail@3v1n0.net>
Date: Mon, 22 Jun 2026 13:39:00 +0200
Subject: [PATCH] fpi-log: Add atomic and unique check for FP_DEBUG_TRANSFER

Rather than check it all the times the variable, just rely on an atomic
check that is just done once for all
---
 doc/libfprint-2-sections.txt |  1 +
 libfprint/fpi-log.c          | 21 +++++++++++++++++++++
 libfprint/fpi-log.h          |  2 ++
 libfprint/fpi-spi-transfer.c |  2 +-
 libfprint/fpi-usb-transfer.c |  3 ++-
 5 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/doc/libfprint-2-sections.txt b/doc/libfprint-2-sections.txt
index e6bb0ef3..d37d8404 100644
--- a/doc/libfprint-2-sections.txt
+++ b/doc/libfprint-2-sections.txt
@@ -353,6 +353,7 @@ fp_dbg_hex_dump_data
 fp_info
 fp_warn
 fp_err
+fpi_log_is_debug_transfer_enabled
 BUG_ON
 BUG
 </SECTION>
diff --git a/libfprint/fpi-log.c b/libfprint/fpi-log.c
index 40e223ca..daeb5281 100644
--- a/libfprint/fpi-log.c
+++ b/libfprint/fpi-log.c
@@ -21,6 +21,27 @@
 
 #include "fpi-log.h"
 
+/**
+ * fpi_log_is_debug_transfer_enabled:
+ *
+ * Checks if the %FP_DEBUG_TRANSFER environment variable is set.
+ *
+ * Returns: %TRUE if %FP_DEBUG_TRANSFER is set, %FALSE otherwise
+ */
+gboolean
+fpi_log_is_debug_transfer_enabled (void)
+{
+  static gsize debug_transfer_enabled = 0;
+
+  if (g_once_init_enter (&debug_transfer_enabled))
+    {
+      gsize enabled = g_getenv ("FP_DEBUG_TRANSFER") != NULL ? TRUE : G_MAXSIZE;
+      g_once_init_leave (&debug_transfer_enabled, enabled);
+    }
+
+  return debug_transfer_enabled == TRUE;
+}
+
 /**
  * fpi_dbg_hex_dump_data:
  * @buf: Bytes buffer to dump
diff --git a/libfprint/fpi-log.h b/libfprint/fpi-log.h
index cbc7026b..46380289 100644
--- a/libfprint/fpi-log.h
+++ b/libfprint/fpi-log.h
@@ -124,3 +124,5 @@ void (fpi_dbg_hex_dump_bytes) (const gchar *log_domain,
 #define fp_dbg_hex_dump_bytes(bytes) \
   (fpi_dbg_hex_dump_bytes) \
   (G_LOG_DOMAIN, (bytes))
+
+gboolean fpi_log_is_debug_transfer_enabled (void);
diff --git a/libfprint/fpi-spi-transfer.c b/libfprint/fpi-spi-transfer.c
index 79931ae4..fdba4aae 100644
--- a/libfprint/fpi-spi-transfer.c
+++ b/libfprint/fpi-spi-transfer.c
@@ -52,7 +52,7 @@ G_DEFINE_BOXED_TYPE (FpiSpiTransfer, fpi_spi_transfer, fpi_spi_transfer_ref, fpi
 static void
 log_transfer (FpiSpiTransfer *transfer, gboolean submit, GError *error)
 {
-  if (g_getenv ("FP_DEBUG_TRANSFER"))
+  if (fpi_log_is_debug_transfer_enabled ())
     {
       if (submit)
         {
diff --git a/libfprint/fpi-usb-transfer.c b/libfprint/fpi-usb-transfer.c
index 721a2510..9defff08 100644
--- a/libfprint/fpi-usb-transfer.c
+++ b/libfprint/fpi-usb-transfer.c
@@ -18,6 +18,7 @@
  */
 
 #include "fpi-usb-transfer.h"
+#include "fpi-log.h"
 
 /**
  * SECTION:fpi-usb-transfer
@@ -38,7 +39,7 @@ G_DEFINE_BOXED_TYPE (FpiUsbTransfer, fpi_usb_transfer, fpi_usb_transfer_ref, fpi
 static void
 log_transfer (FpiUsbTransfer *transfer, gboolean submit, GError *error)
 {
-  if (g_getenv ("FP_DEBUG_TRANSFER"))
+  if (fpi_log_is_debug_transfer_enabled ())
     {
       if (!submit)
         {