[devel] Improved missing symbol handling in checksym.awk; symbols missing in

both the old and new files can now be optionally ignored, treated as errors
or warnings.

ANNOUNCE

@@ -462,6 +462,9 @@ Version 1.5.0beta56 [December 7, 2010]
 Version 1.5.0beta57 [December 7, 2010]
   Documented the pngvalid gamma error summary with additional comments and
     print statements.
+  Improved missing symbol handling in checksym.awk; symbols missing in both
+    the old and new files can now be optionally ignored, treated as errors
+    or warnings.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net:
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CHANGES

@@ -3100,6 +3100,9 @@ Version 1.5.0beta56 [December 7, 2010]
 Version 1.5.0beta57 [December 7, 2010]
   Documented the pngvalid gamma error summary with additional comments and
     print statements.
+  Improved missing symbol handling in checksym.awk; symbols missing in both
+    the old and new files can now be optionally ignored, treated as errors
+    or warnings.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

scripts/checksym.awk

@@ -20,6 +20,7 @@ BEGIN{
    lasto = 0        # last ordinal value from png.h
    mastero = 0      # highest ordinal in master file
    symbolo = 0      # highest ordinal in png.h
+   missing = "error"# log an error on missing symbols
 }
 
 # Read existing definitions from the master file (the first
@@ -44,6 +45,13 @@ FILENAME==master && NF==2 && $2~/^@/ && $1!~/^;/ {
       print master ": bad export line format:", $0
    err = 1
 }
+FILENAME==master && $1==";missing" && NF==2{
+   # This allows the master file to control how missing symbols
+   # are handled; symbols that aren't in either the master or
+   # the new file.  Valid values are 'ignore', 'warning' and
+   # 'error'
+   missing = $2
+}
 FILENAME==master {
    next
 }
@@ -112,11 +120,19 @@ END{
          }
       }
       if (unexported != 0) {
-         # Symbols in the .def but not in the new file are errors
+         # Symbols in the .def but not in the new file are errors, but
+         # the 'unexported' symbols aren't in either.  By default this
+         # is an error too (see the setting of 'missing' at the start),
+         # but this can be reset on the command line or by stuff in the
+         # file - see the comments above.
+         if (missing != "ignore") {
             if (o-1 > unexported)
-            print "png.h: warning: unexported symbol definitions:", unexported "-" o-1
+               print "png.h:", missing ": missing symbols:", unexported "-" o-1
             else
-            print "png.h: warning: unexported symbol definition:", unexported
+               print "png.h:", missing ": missing symbol:", unexported
+            if (missing != "warning")
+               err = 1
+         }
          unexported = 0
       }
       if (symbol[o] != "" && removed[o] != "") {

scripts/pngwin.def

@@ -3,6 +3,12 @@
 ; On OS/2 uncomment lines preceded by ;0S2
 ;--------------------------------------------------------------
 
+; make scripts/pngwin.chk will validate this file against the
+; build of libpng, the following line tells the check code to
+; ignore symbols (ordinal values) that are missing in both
+; files.
+;missing ignore
+
 ; If you give the library an explicit name one or other files
 ; may need modifying to support the new name on one or more
 ; systems.