gpujpeg_exif: small improvements

make this prettier (IYWU+enum) + use localtime_s (since we are an library
we should not call thread-unsafe functions)

Author: MartinPulec

src/compat/time.h

@@ -0,0 +1,55 @@
+/**
+ * @file   compat/time.h
+ * @author Martin Pulec     <[email protected]>
+ *
+ * time-related compatibility header
+ */
+/*
+ * Copyright (c) 2024-2025 CESNET, zájmové sdružení právnických osob
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, is permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of CESNET nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING,
+ * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+ * EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef COMPAT_TIME_H_7C0E2D4B_7D55_4107_918B_7BF2BEB92428
+#define COMPAT_TIME_H_7C0E2D4B_7D55_4107_918B_7BF2BEB92428
+
+#include <time.h>
+
+#ifndef __STDC_LIB_EXT1__
+#ifdef _WIN32
+#define gmtime_s(timer, buf) gmtime_s(buf, timer)
+#define localtime_s(timer, buf) localtime_s(buf, timer)
+#else
+#define gmtime_s gmtime_r
+#define localtime_s localtime_r
+#endif
+#endif // ! defined __STDC_LIB_EXT1__
+
+#endif // !defined COMPAT_TIME_H_7C0E2D4B_7D55_4107_918B_7BF2BEB92428

src/gpujpeg_exif.c

@@ -29,22 +29,32 @@
 
 #include "gpujpeg_exif.h"
 
-#include <assert.h>
-#include <ctype.h>
-#include <stdint.h>
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>    // for strftime
-
+#include <assert.h>                    // for assert
+#include <ctype.h>                     // for isdigit
+#include <stdint.h>                    // for uint8_t, uint32_t, uint16_t
+#include <stdio.h>                     // for printf
+#include <stdlib.h>                    // for size_t, NULL, free, abort, calloc
+#include <string.h>                    // for memcpy, strlen, memmove, strcmp
+#include <time.h>                      // for strftime, time, time_t
+// IWYU pragma: no_include <endian.h> # via compat/endian.h.
+
+// for strncasecmp
 #ifdef _WIN32
 #define strncasecmp _strnicmp
+#else
+#include <strings.h>
 #endif
 
-#include "compat/endian.h"
-#include "gpujpeg_common_internal.h"
-#include "gpujpeg_encoder_internal.h"
-#include "gpujpeg_marker.h"
-#include "gpujpeg_writer.h"
+#include "../libgpujpeg/gpujpeg_common.h"  // for gpujpeg_image_parameters, gpuj...
+#include "../libgpujpeg/gpujpeg_encoder.h" // for GPUJPEG_ENC_OPT_EXIF_TAG
+#include "../libgpujpeg/gpujpeg_type.h"    // for gpujpeg_color_space
+#include "compat/endian.h"                 // IWYU pragma: keep for htobe32
+#include "compat/time.h"                   // IWYU pragma: keep for localtime_s
+#include "gpujpeg_common_internal.h"       // for gpujpeg_coder, ERROR_MSG, WARN...
+#include "gpujpeg_encoder_internal.h"      // for gpujpeg_encoder
+#include "gpujpeg_marker.h"                // for gpujpeg_marker_code
+#include "gpujpeg_util.h"                  // for ARR_SIZE
+#include "gpujpeg_writer.h"                // for gpujpeg_writer, gpujpeg_writer...
 
 enum exif_tag_type {
     ET_NONE = 0,
@@ -129,6 +139,7 @@ enum {
     ETIFF_INCHES = 2,
     NEXT_IFD_PTR_SZ = 4,
     IFD_ITEM_SZ = 12,
+    DPI_DEFAULT = 72,
     EEXIF_FIRST = 0x827A, // (Exposure time) first tag id of Exif Private Tags
 };
 
@@ -321,11 +332,12 @@ gpujpeg_write_0th(struct gpujpeg_encoder* encoder, const uint8_t* start)
 {
     char date_time[] = "    :  :     :  :  "; // unknown val by Exif 2.3
     time_t now = time(NULL);
-    (void) strftime(date_time, sizeof date_time, "%Y:%m:%d %H:%M:%S", localtime(&now));
+    struct tm buf;
+    (void) strftime(date_time, sizeof date_time, "%Y:%m:%d %H:%M:%S", localtime_s(&now, &buf));
     struct tag_value tags[] = {
         {ETIFF_ORIENTATION,       {.uvalue = ETIFF_ORIENT_HORIZONTAL}},
-        {ETIFF_XRESOLUTION,       {.urational = {72, 1}}             },
-        {ETIFF_YRESOLUTION,       {.urational = {72, 1}}             },
+        {ETIFF_XRESOLUTION,       {.urational = {DPI_DEFAULT, 1}}    },
+        {ETIFF_YRESOLUTION,       {.urational = {DPI_DEFAULT, 1}}    },
         {ETIFF_RESOLUTION_UNIT,   {.uvalue = ETIFF_INCHES}           },
         {ETIFF_SOFTWARE,          {.csvalue = "GPUJPEG"}             },
         {ETIFF_DATE_TIME ,        {.csvalue = date_time}             },