spngsave: name ICC profiles (#3068)

lovell · web-flow · commit d3a1d4df1b5b · 2022-09-28T16:28:44.000+01:00
The PNG spec requires that the iCCP chunk has a profile name with
a minumum length of 1 (we use the same "icc" name as pngsave).
diff --git a/ChangeLog b/ChangeLog
@@ -6,6 +6,7 @@
 - reduce latency on dzsave kill [kleisauke]
 - improve text too large check [kleisauke]
 - fix subifd writing for small images [ruven]
+- name ICC profiles in spngsave [lovell]
 
 24/7/22 started 8.13.1
 - fix im7 feature detection in meson
diff --git a/libvips/foreign/spngsave.c b/libvips/foreign/spngsave.c
@@ -217,7 +217,7 @@ vips_foreign_save_spng_metadata( VipsForeignSaveSpng *spng, VipsImage *in )
 			"of ICC profile\n", length );
 #endif /*DEBUG*/
 
-		vips_strncpy( iccp.profile_name, "", 
+		vips_strncpy( iccp.profile_name, "icc",
 			sizeof( iccp.profile_name ) );
 		iccp.profile_len = length;
 		iccp.profile = (void *) data;
