make-dissectors-reg: optimize by factoring out the loops

Instead of calling the grep/sed pipelines for each file, build the
list of files in the beginning and call each pipeline only once,
passing the list to the first grep.

This results in a massive speedup in Cygwin; in my test, the time
it takes to run make-dissector-reg . dissectors packet-*.c in dissectors/epan
is reduced from ~116 to ~3 seconds. I also tried it on NetBSD, where
the time do to the same goes from ~6 to ~0.5 seconds.

Amend makefile comments to elide mentions of invoking multiple processes
per file.

Change-Id: Iad441e7d2b6cc3669dada57646e2f8f6b987fd34
Reviewed-on: https://code.wireshark.org/review/2826
Reviewed-by: Anders Broman <a.broman58@gmail.com>

29 files changed, 176 insertions, 220 deletions

diff --git a/epan/dissectors/Makefile.am b/epan/dissectors/Makefile.am
index 80a066c078..b48d3edd52 100644
--- a/epan/dissectors/Makefile.am
+++ b/epan/dissectors/Makefile.am
@@ -86,11 +86,11 @@ x11-dissector: $(top_srcdir)/tools/process-x11-fields.pl x11-fields $(top_srcdir
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the register.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows. Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "dissectors", to indicate that we should build
diff --git a/epan/dissectors/Makefile.nmake b/epan/dissectors/Makefile.nmake
index 0af94105ca..35edf09baf 100644
--- a/epan/dissectors/Makefile.nmake
+++ b/epan/dissectors/Makefile.nmake
@@ -65,11 +65,11 @@ packet-rrc.obj : packet-rrc.c
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the register.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "dissectors", to indicate that we should build
diff --git a/plugins/asn1/Makefile.am b/plugins/asn1/Makefile.am
index 405d9e47e7..f7d4401fc1 100644
--- a/plugins/asn1/Makefile.am
+++ b/plugins/asn1/Makefile.am
@@ -70,11 +70,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/asn1/Makefile.nmake b/plugins/asn1/Makefile.nmake
index 678ddb88bf..6b8cf60419 100644
--- a/plugins/asn1/Makefile.nmake
+++ b/plugins/asn1/Makefile.nmake
@@ -64,11 +64,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/docsis/Makefile.am b/plugins/docsis/Makefile.am
index bc53f5d911..bc2d65cc97 100644
--- a/plugins/docsis/Makefile.am
+++ b/plugins/docsis/Makefile.am
@@ -70,11 +70,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/docsis/Makefile.nmake b/plugins/docsis/Makefile.nmake
index 93331e7e1d..29088bdc55 100644
--- a/plugins/docsis/Makefile.nmake
+++ b/plugins/docsis/Makefile.nmake
@@ -64,11 +64,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/ethercat/Makefile.am b/plugins/ethercat/Makefile.am
index 7a602a88cf..2cfe58d70b 100644
--- a/plugins/ethercat/Makefile.am
+++ b/plugins/ethercat/Makefile.am
@@ -70,11 +70,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/ethercat/Makefile.nmake b/plugins/ethercat/Makefile.nmake
index fa4542afb9..efcb7da2d1 100644
--- a/plugins/ethercat/Makefile.nmake
+++ b/plugins/ethercat/Makefile.nmake
@@ -64,11 +64,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/gryphon/Makefile.am b/plugins/gryphon/Makefile.am
index 1593e28392..67cd086582 100644
--- a/plugins/gryphon/Makefile.am
+++ b/plugins/gryphon/Makefile.am
@@ -72,11 +72,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/gryphon/Makefile.nmake b/plugins/gryphon/Makefile.nmake
index a652e83f55..b5bc9ec6df 100644
--- a/plugins/gryphon/Makefile.nmake
+++ b/plugins/gryphon/Makefile.nmake
@@ -64,11 +64,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/irda/Makefile.am b/plugins/irda/Makefile.am
index f83062f2d8..5af7e9cf2a 100644
--- a/plugins/irda/Makefile.am
+++ b/plugins/irda/Makefile.am
@@ -70,11 +70,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/irda/Makefile.nmake b/plugins/irda/Makefile.nmake
index 79c2b8f62e..d13b42a3c3 100644
--- a/plugins/irda/Makefile.nmake
+++ b/plugins/irda/Makefile.nmake
@@ -64,11 +64,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/m2m/Makefile.am b/plugins/m2m/Makefile.am
index 6ba2b773cb..15b665e1ff 100644
--- a/plugins/m2m/Makefile.am
+++ b/plugins/m2m/Makefile.am
@@ -70,11 +70,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/m2m/Makefile.nmake b/plugins/m2m/Makefile.nmake
index 9e06f165a1..b566f98062 100644
--- a/plugins/m2m/Makefile.nmake
+++ b/plugins/m2m/Makefile.nmake
@@ -64,11 +64,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/mate/Makefile.am b/plugins/mate/Makefile.am
index 64679ff9e9..f3a2b7b05c 100644
--- a/plugins/mate/Makefile.am
+++ b/plugins/mate/Makefile.am
@@ -77,11 +77,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/mate/Makefile.nmake b/plugins/mate/Makefile.nmake
index 48fcaf39f7..7d301d9694 100644
--- a/plugins/mate/Makefile.nmake
+++ b/plugins/mate/Makefile.nmake
@@ -70,11 +70,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/opcua/Makefile.am b/plugins/opcua/Makefile.am
index 43f33fd4ea..4c32a3eccd 100644
--- a/plugins/opcua/Makefile.am
+++ b/plugins/opcua/Makefile.am
@@ -71,11 +71,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/opcua/Makefile.nmake b/plugins/opcua/Makefile.nmake
index 3e0d49825a..ce27752704 100644
--- a/plugins/opcua/Makefile.nmake
+++ b/plugins/opcua/Makefile.nmake
@@ -64,11 +64,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/profinet/Makefile.am b/plugins/profinet/Makefile.am
index bbe106f61b..719ed9cf8c 100644
--- a/plugins/profinet/Makefile.am
+++ b/plugins/profinet/Makefile.am
@@ -70,11 +70,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/profinet/Makefile.nmake b/plugins/profinet/Makefile.nmake
index b4ad8cb15a..d431fcc680 100644
--- a/plugins/profinet/Makefile.nmake
+++ b/plugins/profinet/Makefile.nmake
@@ -64,11 +64,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/unistim/Makefile.am b/plugins/unistim/Makefile.am
index df6d1d1f47..929ca44251 100644
--- a/plugins/unistim/Makefile.am
+++ b/plugins/unistim/Makefile.am
@@ -71,11 +71,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/unistim/Makefile.nmake b/plugins/unistim/Makefile.nmake
index 412850997c..5451ec04ce 100644
--- a/plugins/unistim/Makefile.nmake
+++ b/plugins/unistim/Makefile.nmake
@@ -64,11 +64,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/wimax/Makefile.am b/plugins/wimax/Makefile.am
index c6ee98c72b..f9b617d5c6 100644
--- a/plugins/wimax/Makefile.am
+++ b/plugins/wimax/Makefile.am
@@ -70,11 +70,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/wimax/Makefile.nmake b/plugins/wimax/Makefile.nmake
index 52c4ea0604..981cf8f1d1 100644
--- a/plugins/wimax/Makefile.nmake
+++ b/plugins/wimax/Makefile.nmake
@@ -64,11 +64,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/wimaxasncp/Makefile.am b/plugins/wimaxasncp/Makefile.am
index 1da4282bdc..49fad9d261 100644
--- a/plugins/wimaxasncp/Makefile.am
+++ b/plugins/wimaxasncp/Makefile.am
@@ -73,11 +73,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/wimaxasncp/Makefile.nmake b/plugins/wimaxasncp/Makefile.nmake
index 163773ac23..8fe22f3b00 100644
--- a/plugins/wimaxasncp/Makefile.nmake
+++ b/plugins/wimaxasncp/Makefile.nmake
@@ -68,11 +68,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/wimaxmacphy/Makefile.am b/plugins/wimaxmacphy/Makefile.am
index 17957b1d16..a78814bb0c 100644
--- a/plugins/wimaxmacphy/Makefile.am
+++ b/plugins/wimaxmacphy/Makefile.am
@@ -70,11 +70,11 @@ LIBS =
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/plugins/wimaxmacphy/Makefile.nmake b/plugins/wimaxmacphy/Makefile.nmake
index 860a21a7b3..0b4139a4ce 100644
--- a/plugins/wimaxmacphy/Makefile.nmake
+++ b/plugins/wimaxmacphy/Makefile.nmake
@@ -64,11 +64,11 @@ $(PLUGIN_NAME).dll $(PLUGIN_NAME).exp $(PLUGIN_NAME).lib : $(OBJECTS) $(LINK_PLU
 # pass only the first few names in the list to the shell, for some
 # reason.
 #
-# Therefore, we have a script to generate the plugin.c file.
-# The shell script runs slowly, as multiple greps and seds are run
-# for each input file; this is especially slow on Windows.  Therefore,
-# if Python is present (as indicated by PYTHON being defined), we run
-# a faster Python script to do that work instead.
+# Therefore, we use a script to generate the register.c file.
+# There are two versions of the script, a shell and a Python version.
+# The Python script runs faster, since it uses caching to speed up
+# repeated runs and doesn't invoke external processes, so we prefer
+# that if Python is available.
 #
 # The first argument is the directory in which the source files live.
 # The second argument is "plugin", to indicate that we should build
diff --git a/tools/make-dissector-reg b/tools/make-dissector-reg
index d28793e1d5..72e896d0b2 100755
--- a/tools/make-dissector-reg
+++ b/tools/make-dissector-reg
@@ -27,6 +27,22 @@ fi
 #
 # All subsequent arguments are the files to scan.
 #
+files=''
+
+for f in "$@"
+do
+	# This won't work if any filenames contain spaces.
+	# However, this script is called by make, which doesn't support
+	# spaces either.
+	if [ -f "$f" ]
+	then
+		files="$files $f"
+	else
+		files="$files $srcdir/$f"
+	fi
+done
+
+
 rm -f ${outfile}-tmp
 echo '/* Do not modify this file.  */' >${outfile}-tmp
 echo '/* It is created automatically by the Makefile. */'>>${outfile}-tmp
@@ -54,26 +70,11 @@ EOF
 	#
 	# Build code to call all the protocol registration routines.
 	#
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^proto_register_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^void proto_register_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
+	grep '^proto_register_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
+
+	grep '^void proto_register_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
 else
 	cat <<"EOF" >>${outfile}-tmp
 #include "register.h"
@@ -84,26 +85,11 @@ EOF
 	#
 	# Build code to call all the protocol registration routines.
 	#
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^proto_register_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_REGISTER, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^void proto_register_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_REGISTER, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
+	grep '^proto_register_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_REGISTER, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
+
+	grep '^void proto_register_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_REGISTER, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
 
 fi
 echo '}' >>${outfile}-tmp
@@ -119,52 +105,22 @@ WS_DLL_PUBLIC_DEF void
 plugin_reg_handoff(void)
 {
 EOF
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^proto_reg_handoff_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^void proto_reg_handoff_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
+	grep '^proto_reg_handoff_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
+
+	grep '^void proto_reg_handoff_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); \1 ();}/' >>${outfile}-tmp
 else
 	cat <<"EOF" >>${outfile}-tmp
 void
 register_all_protocol_handoffs(register_cb cb, gpointer client_data)
 {
 EOF
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^proto_reg_handoff_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_HANDOFF, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
-	for f in "$@"
-	do
-		if [ -f $f ]
-		then
-			srcfile=$f
-		else
-			srcfile=$srcdir/$f
-		fi
-		grep '^void proto_reg_handoff_[a-z_0-9A-Z]* *(' $srcfile 2>/dev/null | grep -v ';'
-	done | sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_HANDOFF, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
+	grep '^proto_reg_handoff_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^\([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_HANDOFF, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
+
+	grep '^void proto_reg_handoff_[a-z_0-9A-Z]* *(' $files 2>/dev/null | grep -v ';' \
+		| sed -e 's/^.*://' -e 's/^void \([a-z_0-9A-Z]*\).*/  {extern void \1 (void); if(cb) (*cb)(RA_HANDOFF, \"\1\", client_data); \1 ();}/' >>${outfile}-tmp
 fi
 echo '}' >>${outfile}-tmp
 if [ "$registertype" = plugin ]