This patch makes the UUIDs in the XMP header optional, depending on the
setting of the environment variable GS_GENERATE_UUIDS.

If the environment variable GS_GENERATE_UUIDS is set to "0" or "no", it will
not write out the Document UUID field and also will write the Instance ID
field value as "".

Upstream does not want to do this.

See: https://bugs.ghostscript.com/show_bug.cgi?id=698208
diff --git a/devices/vector/gdevpdfe.c b/devices/vector/gdevpdfe.c
index f083f1e93..a19c64ac0 100644
--- a/devices/vector/gdevpdfe.c
+++ b/devices/vector/gdevpdfe.c
@@ -624,7 +624,7 @@ pdf_write_document_metadata(gx_device_pdf *pdev, const byte digest[6])
         return code;
 
     /* PDF/A XMP reference recommends setting UUID to empty. If not empty must be a URI */
-    if (pdev->PDFA != 0)
+    if (pdev->PDFA != 0 || (getenv("GS_GENERATE_UUIDS") && (strcasecmp(getenv("GS_GENERATE_UUIDS"), "0") == 0 || strcasecmp(getenv("GS_GENERATE_UUIDS"), "no") == 0)))
         instance_uuid[0] = 0x00;
 
     cre_date_time_len = pdf_get_docinfo_item(pdev, "/CreationDate", cre_date_time, sizeof(cre_date_time));
@@ -730,14 +730,17 @@ pdf_write_document_metadata(gx_device_pdf *pdev, const byte digest[6])
             pdf_xml_tag_close(s, "rdf:Description");
             pdf_xml_newline(s);
 
-            pdf_xml_tag_open_beg(s, "rdf:Description");
-            pdf_xml_copy(s, " rdf:about=\"\"");
-            pdf_xml_attribute_name(s, "xmlns:xapMM");
-            pdf_xml_attribute_value(s, "http://ns.adobe.com/xap/1.0/mm/");
-            pdf_xml_attribute_name(s, "xapMM:DocumentID");
-            pdf_xml_attribute_value(s, document_uuid);
-            pdf_xml_tag_end_empty(s);
-            pdf_xml_newline(s);
+            if (!getenv("GS_GENERATE_UUIDS") || (strcasecmp(getenv("GS_GENERATE_UUIDS"), "0") != 0 && strcasecmp(getenv("GS_GENERATE_UUIDS"), "no") != 0))
+            {
+                pdf_xml_tag_open_beg(s, "rdf:Description");
+                pdf_xml_copy(s, " rdf:about=\"\"");
+                pdf_xml_attribute_name(s, "xmlns:xapMM");
+                pdf_xml_attribute_value(s, "http://ns.adobe.com/xap/1.0/mm/");
+                pdf_xml_attribute_name(s, "xapMM:DocumentID");
+                pdf_xml_attribute_value(s, document_uuid);
+                pdf_xml_tag_end_empty(s);
+                pdf_xml_newline(s);
+            }
 
             pdf_xml_tag_open_beg(s, "rdf:Description");
             pdf_xml_copy(s, " rdf:about=\"\"");
bbb03530aee6e42d9ff582c&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-09-24 13:49:53 +0200'>2023-09-24</span></td><td><a href='/guix/commit/etc/committer.scm.in?id=670fc6ee50a2882fba8004de7d9d24e80459add2'>etc/committer: Speed up surrounding-sexp.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2023-09-24 13:49:53 +0200'>2023-09-24</span></td><td><a href='/guix/commit/etc/committer.scm.in?id=5027bc19d8a3c7bac1d89d80fc3c717ae3ec399a'>etc/committer: Avoid reading original files more than once.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2023-09-24 13:49:53 +0200'>2023-09-24</span></td><td><a href='/guix/commit/etc/committer.scm.in?id=10c6387f5bafc3d9a3ea5477eb72566ede7af4d0'>etc/committer: Do not record positions when reading from git files.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2023-09-24 13:49:53 +0200'>2023-09-24</span></td><td><a href='/guix/commit/etc/committer.scm.in?id=0836af9a3b33813e69ece7075fbc222fdb85bfb3'>etc/committer: Do not recompute changes when there are no definitions.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>