Replace tagStandardXMP by define in avifjpeg.c

apps/shared/avifjpeg.c

diff --git a/apps/shared/avifjpeg.c b/apps/shared/avifjpeg.c
index 8e6356e..5f21039 100644
--- a/apps/shared/avifjpeg.c
+++ b/apps/shared/avifjpeg.c
@@ -243,7 +243,12 @@
     return NULL;
 }
 
-#define AVIF_EXTENDED_XMP_GUID_LENGTH 32
+// XMP tags
+#define AVIF_STANDARD_XMP_TAG "http://ns.adobe.com/xap/1.0/\0"
+#define AVIF_STANDARD_XMP_TAG_LENGTH 29
+#define AVIF_EXTENDED_XMP_TAG "http://ns.adobe.com/xmp/extension/\0"
+#define AVIF_EXTENDED_XMP_TAG_LENGTH 35
+
 // One way of storing the Extended XMP GUID (generated by a camera for example).
 #define AVIF_XMP_NOTE_TAG "xmpNote:HasExtendedXMP=\""
 #define AVIF_XMP_NOTE_TAG_LENGTH 24
@@ -251,8 +256,10 @@
 #define AVIF_ALTERNATIVE_XMP_NOTE_TAG "<xmpNote:HasExtendedXMP>"
 #define AVIF_ALTERNATIVE_XMP_NOTE_TAG_LENGTH 24
 
+#define AVIF_EXTENDED_XMP_GUID_LENGTH 32
+
 // Offset in APP1 segment (skip tag + guid + size + offset).
-#define AVIF_OFFSET_TILL_EXTENDED_XMP (tagExtendedXMP.size + AVIF_EXTENDED_XMP_GUID_LENGTH + 4 + 4)
+#define AVIF_OFFSET_TILL_EXTENDED_XMP (AVIF_EXTENDED_XMP_TAG_LENGTH + AVIF_EXTENDED_XMP_GUID_LENGTH + 4 + 4)
 
 // Note on setjmp() and volatile variables:
 //
@@ -388,27 +395,25 @@
         }
     }
     if (!ignoreXMP) {
-        const avifROData tagStandardXMP = { (const uint8_t *)"http://ns.adobe.com/xap/1.0/\0", 29 };
         const uint8_t * standardXMPData = NULL;
         uint32_t standardXMPSize = 0; // At most 64kB as defined by Adobe XMP Specification Part 3.
         for (jpeg_saved_marker_ptr marker = cinfo.marker_list; marker != NULL; marker = marker->next) {
-            if ((marker->marker == (JPEG_APP0 + 1)) && (marker->data_length > tagStandardXMP.size) &&
-                !memcmp(marker->data, tagStandardXMP.data, tagStandardXMP.size)) {
+            if ((marker->marker == (JPEG_APP0 + 1)) && (marker->data_length > AVIF_STANDARD_XMP_TAG_LENGTH) &&
+                !memcmp(marker->data, AVIF_STANDARD_XMP_TAG, AVIF_STANDARD_XMP_TAG_LENGTH)) {
                 if (standardXMPData) {
                     fprintf(stderr, "XMP extraction failed: invalid multiple standard XMP segments\n");
                     goto cleanup;
                 }
-                standardXMPData = marker->data + tagStandardXMP.size;
-                standardXMPSize = (uint32_t)(marker->data_length - tagStandardXMP.size);
+                standardXMPData = marker->data + AVIF_STANDARD_XMP_TAG_LENGTH;
+                standardXMPSize = (uint32_t)(marker->data_length - AVIF_STANDARD_XMP_TAG_LENGTH);
             }
         }
 
-        const avifROData tagExtendedXMP = { (const uint8_t *)"http://ns.adobe.com/xmp/extension/\0", 35 };
         avifBool foundExtendedXMP = AVIF_FALSE;
         uint8_t extendedXMPGUID[AVIF_EXTENDED_XMP_GUID_LENGTH]; // The value is common to all extended XMP segments.
         for (jpeg_saved_marker_ptr marker = cinfo.marker_list; marker != NULL; marker = marker->next) {
-            if ((marker->marker == (JPEG_APP0 + 1)) && (marker->data_length > tagExtendedXMP.size) &&
-                !memcmp(marker->data, tagExtendedXMP.data, tagExtendedXMP.size)) {
+            if ((marker->marker == (JPEG_APP0 + 1)) && (marker->data_length > AVIF_EXTENDED_XMP_TAG_LENGTH) &&
+                !memcmp(marker->data, AVIF_EXTENDED_XMP_TAG, AVIF_EXTENDED_XMP_TAG_LENGTH)) {
                 if (!standardXMPData) {
                     fprintf(stderr, "XMP extraction failed: extended XMP segment found, missing standard XMP segment\n");
                     goto cleanup;
@@ -418,7 +423,7 @@
                     fprintf(stderr, "XMP extraction failed: truncated extended XMP segment\n");
                     goto cleanup;
                 }
-                const uint8_t * guid = &marker->data[tagExtendedXMP.size];
+                const uint8_t * guid = &marker->data[AVIF_EXTENDED_XMP_TAG_LENGTH];
                 for (size_t c = 0; c < AVIF_EXTENDED_XMP_GUID_LENGTH; ++c) {
                     // According to Adobe XMP Specification Part 3 section 1.1.3.1:
                     //   "128-bit GUID stored as a 32-byte ASCII hex string, capital A-F, no null termination"
@@ -433,12 +438,12 @@
                 // According to Adobe XMP Specification Part 3 section 1.1.3.1:
                 //   "full length of the ExtendedXMP serialization as a 32-bit unsigned integer"
                 const uint32_t totalExtendedXMPSize =
-                    avifJPEGReadUint32BigEndian(&marker->data[tagExtendedXMP.size + AVIF_EXTENDED_XMP_GUID_LENGTH]);
+                    avifJPEGReadUint32BigEndian(&marker->data[AVIF_EXTENDED_XMP_TAG_LENGTH + AVIF_EXTENDED_XMP_GUID_LENGTH]);
                 // Offset in totalXMP after standardXMP.
                 // According to Adobe XMP Specification Part 3 section 1.1.3.1:
                 //   "offset of this portion as a 32-bit unsigned integer"
                 const uint32_t extendedXMPOffset =
-                    avifJPEGReadUint32BigEndian(&marker->data[tagExtendedXMP.size + AVIF_EXTENDED_XMP_GUID_LENGTH + 4]);
+                    avifJPEGReadUint32BigEndian(&marker->data[AVIF_EXTENDED_XMP_TAG_LENGTH + AVIF_EXTENDED_XMP_GUID_LENGTH + 4]);
                 if (((uint64_t)standardXMPSize + totalExtendedXMPSize) > SIZE_MAX) {
                     fprintf(stderr, "XMP extraction failed: total XMP size is too large\n");
                     goto cleanup;