From 00b96ad08dcbf339f87a732782b7fd232351de4c Mon Sep 17 00:00:00 2001
From: Even Rouault <even.rouault@spatialys.com>
Date: Tue, 9 Jan 2024 22:19:27 +0100
Subject: [PATCH] emess(): avoid potential unsafe uses

---
 src/apps/cs2cs.cpp | 4 ++--
 src/apps/emess.h   | 9 ++++++++-
 src/apps/proj.cpp  | 2 +-
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/apps/cs2cs.cpp b/src/apps/cs2cs.cpp
index e9baa726e1..b6a1ed123b 100644
--- a/src/apps/cs2cs.cpp
+++ b/src/apps/cs2cs.cpp
@@ -899,7 +899,7 @@ int main(int argc, char **argv) {
             sourceEpochDbl = c_locale_stod(sourceEpoch);
         } catch (const std::exception &e) {
             sourceEpochDbl = 0;
-            emess(3, e.what());
+            emess(3, "%s", e.what());
         }
         srcMetadata =
             proj_coordinate_metadata_create(nullptr, src, sourceEpochDbl);
@@ -917,7 +917,7 @@ int main(int argc, char **argv) {
             targetEpochDbl = c_locale_stod(targetEpoch);
         } catch (const std::exception &e) {
             targetEpochDbl = 0;
-            emess(3, e.what());
+            emess(3, "%s", e.what());
         }
         dstMetadata =
             proj_coordinate_metadata_create(nullptr, dst, targetEpochDbl);
diff --git a/src/apps/emess.h b/src/apps/emess.h
index b09262e5f3..68a50fd472 100644
--- a/src/apps/emess.h
+++ b/src/apps/emess.h
@@ -19,6 +19,13 @@ extern struct EMESS emess_dat;
 
 #endif /* use type */
 
-void emess(int, const char *, ...);
+#if defined(__GNUC__)
+#define EMESS_PRINT_FUNC_FORMAT(format_idx, arg_idx)                           \
+    __attribute__((__format__(__printf__, format_idx, arg_idx)))
+#else
+#define EMESS_PRINT_FUNC_FORMAT(format_idx, arg_idx)
+#endif
+
+void emess(int, const char *, ...) EMESS_PRINT_FUNC_FORMAT(2, 3);
 
 #endif /* end EMESS_H */
diff --git a/src/apps/proj.cpp b/src/apps/proj.cpp
index c3e5b1c57d..3fa94e75b9 100644
--- a/src/apps/proj.cpp
+++ b/src/apps/proj.cpp
@@ -279,7 +279,7 @@ static void vprocess(FILE *fid) {
         }
 
         if (proj_context_errno(nullptr)) {
-            emess(-1, proj_errno_string(proj_context_errno(nullptr)));
+            emess(-1, "%s", proj_errno_string(proj_context_errno(nullptr)));
             continue;
         }