printed warnings+errors in color

if stderr is terminal

code adapted from MartinPulec/gjtiff

Author: MartinPulec

src/gpujpeg_common.c

@@ -41,10 +41,14 @@
 #include <stdbool.h>
 #include <string.h>                         // for strcmp, strerror, strlen, strrchr
 #if defined(_MSC_VER)
+  #include <io.h>                           // for _isatty
   #include <windows.h>
+  #define isatty _isatty
+  #define fileno _fileno
   #define strcasecmp _stricmp
 #else
   #include <strings.h>
+  #include <unistd.h>                       // for isatty
 #endif
 #ifdef GPUJPEG_USE_OPENGL
     #define GL_GLEXT_PROTOTYPES
@@ -2245,4 +2249,23 @@ gpujpeg_cuda_memcpy_async_partially_pinned(void* dst, const void* src, size_t co
     return err;
 }
 
+const char* gj_fg_red = "";
+const char* gj_fg_yellow = "";
+const char* gj_term_reset = "";
+void
+gpujpeg_init_term_colors()
+{
+    static bool init;
+    if ( init ) {
+        return;
+    }
+    if ( isatty(fileno(stderr)) ) {
+        // gj_fg_bold = "\033[1m";
+        gj_fg_red = "\033[31m";
+        gj_fg_yellow = "\033[33m";
+        gj_term_reset = "\033[0m";
+    }
+    init = true;
+}
+
 /* vi: set expandtab sw=4 : */

src/gpujpeg_common_internal.h

@@ -116,8 +116,21 @@ enum {
 
 #define PRINTF(...) (void)fprintf(stderr, __VA_ARGS__)
 
+extern const char *gj_fg_red;
+extern const char *gj_fg_yellow;
+extern const char *gj_term_reset;
+// check __VA_OPT__ presence
+#if __STDC_VERSION__ >= 202311L || __cplusplus >= 202002L || __GNUC__ >= 12 || \
+    __clang_major__ >= 9
+        #define ERROR_MSG(fmt, ...)                                                                                    \
+            (void)fprintf(stderr, "%s[GPUJPEG] [Error] " fmt "%s", gj_fg_red __VA_OPT__(, ) __VA_ARGS__, gj_term_reset)
+        #define WARN_MSG(fmt, ...)                                                                                     \
+            (void)fprintf(stderr, "%s[GPUJPEG] [Warning] " fmt "%s", gj_fg_yellow __VA_OPT__(, ) __VA_ARGS__,          \
+                          gj_term_reset)
+#else
 #define ERROR_MSG(...) (void)fprintf(stderr, "[GPUJPEG] [Error] " __VA_ARGS__)
 #define WARN_MSG(...) (void)fprintf(stderr, "[GPUJPEG] [Warning] " __VA_ARGS__)
+#endif
 #define VERBOSE_MSG(log_level, ...)                                                                                    \
     if ( log_level >= GPUJPEG_LL_VERBOSE )                                                                             \
         (void)fprintf(stderr, "[GPUJPEG] [Verbose] " __VA_ARGS__)
@@ -522,6 +535,8 @@ gpujpeg_cuda_memcpy_async_partially_pinned(void* dst, const void* src, size_t co
 
 void*
 gpujpeg_cuda_malloc_host(size_t size);
+void
+gpujpeg_init_term_colors();
 
 #ifdef __cplusplus
 } // extern "C"

src/gpujpeg_decoder.c

@@ -95,6 +95,7 @@ gpujpeg_decoder_output_set_custom_cuda(struct gpujpeg_decoder_output* output, ui
 struct gpujpeg_decoder*
 gpujpeg_decoder_create(cudaStream_t stream)
 {
+    gpujpeg_init_term_colors();
     struct gpujpeg_decoder* decoder = (struct gpujpeg_decoder*) calloc(1, sizeof(struct gpujpeg_decoder));
     if ( decoder == NULL )
         return NULL;

src/gpujpeg_encoder.c

@@ -1,6 +1,6 @@
 /**
  * @file
- * Copyright (c) 2011-2024, CESNET z.s.p.o
+ * Copyright (c) 2011-2025, CESNET
  * Copyright (c) 2011, Silicon Genome, LLC.
  *
  * All rights reserved.
@@ -97,6 +97,7 @@ gpujpeg_encoder_input_texture(struct gpujpeg_opengl_texture* texture)
 struct gpujpeg_encoder*
 gpujpeg_encoder_create(cudaStream_t stream)
 {
+    gpujpeg_init_term_colors();
     struct gpujpeg_encoder* encoder = (struct gpujpeg_encoder*) calloc(1, sizeof(struct gpujpeg_encoder));
     if ( encoder == NULL ) {
         return NULL;