[libpng16] Fixed race conditions in parallel make builds. With higher degrees

of parallelism during 'make' the use of the same temporary file names such
as 'dfn*' can result in a race where a temporary file from one arm of the
build is deleted or overwritten in another arm.  This changes the
temporary files for suffix rules to always use $* and ensures that the
non-suffix rules use unique file names.

ANNOUNCE

@@ -1,5 +1,5 @@
 
-Libpng 1.6.0alpha01 - December 5, 2011
+Libpng 1.6.0alpha01 - December 8, 2011
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -107,7 +107,7 @@ Version 1.5.7beta05 [(PENDING RELEASE)]
   Added MINGW support to CMakeLists.txt
   Reject invalid compression flag or method when reading the iTXt chunk.
 
-Version 1.6.0alpha01 [December 5, 2011]
+Version 1.6.0alpha01 [December 8, 2011]
   Removed machine-generated configure files from the GIT repository (they will
     continue to appear in the tarball distributions).
   Restored the new 'simplified' API, which was deleted from libpng-1.5.7.
@@ -135,6 +135,12 @@ Version 1.6.0alpha01 [December 5, 2011]
     as in libpng-1.5.4.
   Put CRLF line endings in the owatcom project files.
   Fixed minor memset/sizeof errors in pngvalid.c.
+  Fixed race conditions in parallel make builds. With higher degress of
+    parallelism during 'make' the use of the same temporary file names such
+    as 'dfn*' can result in a race where a temporary file from one arm of the
+    build is deleted or overwritten in another arm.  This changes the
+    temporary files for suffix rules to always use $* and ensures that the
+    non-suffix rules use unique file names.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net:
 (subscription required; visit

CHANGES

@@ -3752,7 +3752,7 @@ Version 1.5.7beta05 [(PENDING RELEASE)]
   Added MINGW support to CMakeLists.txt
   Reject invalid compression flag or method when reading the iTXt chunk.
 
-Version 1.6.0alpha01 [December 5, 2011]
+Version 1.6.0alpha01 [December 8, 2011]
   Removed machine-generated configure files from the GIT repository (they will
     continue to appear in the tarball distributions).
   Restored the new 'simplified' API, which was deleted from libpng-1.5.7.
@@ -3780,6 +3780,12 @@ Version 1.6.0alpha01 [December 5, 2011]
     as in libpng-1.5.4.
   Put CRLF line endings in the owatcom project files.
   Fixed minor memset/sizeof errors in pngvalid.c.
+  Fixed race conditions in parallel make builds. With higher degress of
+    parallelism during 'make' the use of the same temporary file names such
+    as 'dfn*' can result in a race where a temporary file from one arm of the
+    build is deleted or overwritten in another arm.  This changes the
+    temporary files for suffix rules to always use $* and ensures that the
+    non-suffix rules use unique file names.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit

Makefile.am

@@ -88,7 +88,7 @@ EXTRA_DIST= \
 
 SCRIPT_CLEANFILES=scripts/*.out scripts/*.chk scripts/pnglibconf.dfn
 
-CLEANFILES= dfn.c dfn?.out pngout.png libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.pc \
+CLEANFILES= *.tf? pngout.png libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@.pc \
 	libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@-config libpng.vers libpng.sym \
 	check.new pnglibconf.* symbols.new pngtest-log.txt \
 	$(SCRIPT_CLEANFILES)
@@ -143,47 +143,49 @@ SYMBOL_CFLAGS = -DPNGLIB_LIBNAME='PNG@PNGLIB_MAJOR@@PNGLIB_MINOR@_0'\
 		-DPNG_NO_USE_READ_MACROS -DPNG_BUILDING_SYMBOL_TABLE
 
 .dfn.out:
-	rm -f $@ dfn.c dfn?.out
+	rm -f $@ $*.c $*.tf[123]
 	test -d scripts || mkdir scripts
-	echo '#include "$<"' >dfn.c
+	echo '#include "$<"' >$*.c
 	$(DFNCPP) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) @LIBPNG_DEFINES@\
-	    $(CPPFLAGS) $(SYMBOL_CFLAGS) dfn.c > dfn1.out
+	    $(CPPFLAGS) $(SYMBOL_CFLAGS) $*.c > $*.tf1
 	$(SED) -n -e 's|^.*PNG_DEFN_MAGIC *-\(.*\)- *PNG_DEFN_END.*$$|\1|p'\
-	    dfn1.out >dfn2.out
-	$(SED) -e 's| *PNG_JOIN *||g' -e 's| *$$||' dfn2.out >dfn3.out
-	rm -f dfn.c dfn[12].out
-	mv dfn3.out $@
+	    $*.tf1 >$*.tf2
+	$(SED) -e 's| *PNG_JOIN *||g' -e 's| *$$||' $*.tf2 >$*.tf3
+	rm -f $*.c $*.tf[12]
+	mv $*.tf3 $@
 
 # The .dfn file for pnglibconf.h is machine generated
 pnglibconf.dfn: scripts/pnglibconf.dfa scripts/options.awk pngconf.h
-	rm -f $@ dfn?.out
-	$(AWK) -f ${srcdir}/scripts/options.awk out=dfn1.out version=search\
+	rm -f $@ $*.tf[45]
+	$(AWK) -f ${srcdir}/scripts/options.awk out=$*.tf4 version=search\
 	    ${srcdir}/pngconf.h ${srcdir}/scripts/pnglibconf.dfa\
 	    $(DFA_XTRA) 1>&2
-	$(AWK) -f ${srcdir}/scripts/options.awk out=dfn2.out dfn1.out 1>&2
-	rm dfn1.out
-	mv dfn2.out $@
+	$(AWK) -f ${srcdir}/scripts/options.awk out=$*.tf5 $*.tf4 1>&2
+	rm $*.tf4
+	mv $*.tf5 $@
 
 # Symbol checks (.def and .out files should match)
 scripts/symbols.chk: scripts/checksym.awk scripts/symbols.def scripts/symbols.out
+
 .out.chk:
-	rm -f $@ symbols.new
+	rm -f $@ $*.new
 	$(AWK) -f ${srcdir}/scripts/checksym.awk ${srcdir}/scripts/${*F}.def\
-	    $< >&2
-	mv symbols.new $@
+	    of="$*.new" $< >&2
+	mv $*.new $@
 
 # used on demand to regenerate the standard header, CPPFLAGS should
 # be empty - no non-standard defines
 scripts/pnglibconf.dfn: scripts/pnglibconf.dfa scripts/options.awk pngconf.h
-	rm -f $@ dfn?.out
+	rm -f $@ pnglibconf.tf[67]
 	test -z "$(CPPFLAGS)"
 	echo "com @PNGLIB_VERSION@ STANDARD API DEFINITION" |\
-	$(AWK) -f ${srcdir}/scripts/options.awk out=dfn1.out logunsupported=1
-		version=search ${srcdir}/pngconf.h -\
-		${srcdir}/scripts/pnglibconf.dfa 1>&2
-	$(AWK) -f ${srcdir}/scripts/options.awk out=dfn2.out dfn1.out 1>&2
-	rm dfn1.out
-	mv dfn2.out $@
+	$(AWK) -f ${srcdir}/scripts/options.awk out=pnglibconf.tf6\
+	    logunsupported=1 version=search ${srcdir}/pngconf.h -\
+	    ${srcdir}/scripts/pnglibconf.dfa 1>&2
+	$(AWK) -f ${srcdir}/scripts/options.awk out=pnglibconf.tf7\
+	    pnglibconf.tf6 1>&2
+	rm pnglibconf.tf6
+	mv pnglibconf.tf7 $@
 
 $(libpng@PNGLIB_MAJOR@@PNGLIB_MINOR@_la_OBJECTS): png.h pngconf.h \
 	pnglibconf.h pngpriv.h pngdebug.h pnginfo.h pngstruct.h

scripts/checksym.awk

@@ -5,8 +5,9 @@
 # awk -f checksym.awk official-def list-to-check
 #
 # Output is a file in the current directory called 'symbols.new',
-# stdout holds error messages.  Error code indicates success or
-# failure.
+# the value of the awk variable "of" (which can be changed on the
+# command line if required.)  stdout holds error messages.  Error
+# code indicates success or failure.
 #
 # NOTE: this is a pure, old fashioned, awk script.  It will
 # work with any awk
@@ -21,6 +22,7 @@ BEGIN{
    mastero = 0      # highest ordinal in master file
    symbolo = 0      # highest ordinal in png.h
    missing = "error"# log an error on missing symbols
+   of="symbols.new" # default to a fixed name
 }
 
 # Read existing definitions from the master file (the first
@@ -151,11 +153,11 @@ END{
 
       # Finally generate symbols.new
       if (symbol[o] != "")
-         print " " symbol[o], "@" o > "symbols.new"
+         print " " symbol[o], "@" o > of
    }
 
    if (err != 0) {
-      print "*** A new list is in symbols.new ***"
+      print "*** A new list is in", of, "***"
       exit 1
    }
 }