Add pretty printers for the NPTL lock types

This patch adds pretty printers for the following NPTL types:

- pthread_mutex_t
- pthread_mutexattr_t
- pthread_cond_t
- pthread_condattr_t
- pthread_rwlock_t
- pthread_rwlockattr_t

To load the pretty printers into your gdb session, do the following:

python
import sys
sys.path.insert(0, '/path/to/glibc/build/nptl/pretty-printers')
end

source /path/to/glibc/source/pretty-printers/nptl-printers.py

You can check which printers are registered and enabled by issuing the
'info pretty-printer' gdb command. Printers should trigger automatically when
trying to print a variable of one of the types mentioned above.

The printers are architecture-independent, and were tested on an AMD64 running
Ubuntu 14.04 and an x86 VM running Fedora 24.

In order to work, the printers need to know the values of various flags that
are scattered throughout pthread.h and pthreadP.h as enums and #defines. Since
replicating these constants in the printers file itself would create a
maintenance burden, I wrote a script called gen-py-const.awk that Makerules uses
to extract the constants. This script is pretty much the same as gen-as-const.awk,
except it doesn't cast the constant values to 'long' and is thorougly documented.
The constants need only to be enumerated in a .pysym file, which is then referenced
by a Make variable called gen-py-const-headers.

As for the install directory, I discussed this with Mike Frysinger and Siddhesh
Poyarekar, and we agreed that it can be handled in a separate patch, and shouldn't
block merging of this one.

In addition, I've written a series of test cases for the pretty printers.
Each lock type (mutex, condvar and rwlock) has two test programs, one for itself
and other for its related 'attributes' object. Each test program in turn has a
PExpect-based Python script that drives gdb and compares its output to the
expected printer's. The tests run on the glibc host, which is assumed to have
both gdb and PExpect; if either is absent the tests will fail with code 77
(UNSUPPORTED). For cross-testing you should use cross-test-ssh.sh as test-wrapper.
I've tested the printers on both native builds and a cross build using a Beaglebone
Black running Debian, with the build system's filesystem shared with the board
through NFS.

Finally, I've written a README that explains all this and more.

	* INSTALL: Regenerated.
	* Makeconfig: Add comments and whitespace to make the control flow
	clearer.
	(+link-printers-tests, +link-pie-printers-tests, CFLAGS-printers-tests,
	installed-rtld-LDFLAGS, built-rtld-LDFLAGS, link-libc-rpath,
	link-libc-tests-after-rpath-link, link-libc-printers-tests): New.
	(rtld-LDFLAGS, rtld-tests-LDFLAGS, link-libc-tests-rpath-link,
	link-libc-tests): Use the new variables as required.
	* Makerules ($(py-const)): New rule.
	generated: Add $(py-const).
	* README.pretty-printers: New file.
	* Rules (tests-printers-programs, tests-printers-out, py-env): New.
	(others): Depend on $(py-const).
	(tests): Depend on $(tests-printers-programs) or $(tests-printers-out),
	as required.  Pass $(tests-printers) to merge-test-results.sh.
	* manual/install.texi: Add requirements for testing the pretty printers.
	* nptl/Makefile (gen-py-const-headers, pretty-printers, tests-printers,
	CFLAGS-test-mutexattr-printers.c CFLAGS-test-mutex-printers.c,
	CFLAGS-test-condattr-printers.c, CFLAGS-test-cond-printers.c,
	CFLAGS-test-rwlockattr-printers.c CFLAGS-test-rwlock-printers.c,
	tests-printers-libs): Define.
	* nptl/nptl-printers.py: New file.
	* nptl/nptl_lock_constants.pysym: Likewise.
	* nptl/test-cond-printers.c: Likewise.
	* nptl/test-cond-printers.py: Likewise.
	* nptl/test-condattr-printers.c: Likewise.
	* nptl/test-condattr-printers.py: Likewise.
	* nptl/test-mutex-printers.c: Likewise.
	* nptl/test-mutex-printers.py: Likewise.
	* nptl/test-mutexattr-printers.c: Likewise.
	* nptl/test-mutexattr-printers.py: Likewise.
	* nptl/test-rwlock-printers.c: Likewise.
	* nptl/test-rwlock-printers.py: Likewise.
	* nptl/test-rwlockattr-printers.c: Likewise.
	* nptl/test-rwlockattr-printers.py: Likewise.
	* scripts/gen-py-const.awk: Likewise.
	* scripts/test_printers_common.py: Likewise.
	* scripts/test_printers_exceptions.py: Likewise.

1 files changed, 41 insertions, 3 deletions

diff --git a/Rules b/Rules
index 466db07..714e917 100644
--- a/Rules
+++ b/Rules
@@ -108,17 +108,28 @@ endif
 
 .PHONY: others tests bench bench-build
 
+# Test programs for the pretty printers.
+tests-printers-programs := $(addprefix $(objpfx),$(tests-printers))
+
+# .out files with the output of running the pretty printer tests.
+tests-printers-out := $(patsubst %,$(objpfx)%.out,$(tests-printers))
+
 ifeq ($(build-programs),yes)
 others: $(addprefix $(objpfx),$(others) $(sysdep-others) $(extra-objs))
 else
 others: $(addprefix $(objpfx),$(extra-objs))
 endif
+
+# Generate constant files for Python pretty printers if required.
+others: $(py-const)
+
 ifeq ($(run-built-tests),no)
 tests: $(addprefix $(objpfx),$(filter-out $(tests-unsupported),$(tests)) \
-			     $(test-srcs)) $(tests-special)
+			     $(test-srcs)) $(tests-special) \
+       $(tests-printers-programs)
 xtests: tests $(xtests-special)
 else
-tests: $(tests:%=$(objpfx)%.out) $(tests-special)
+tests: $(tests:%=$(objpfx)%.out) $(tests-special) $(tests-printers-out)
 xtests: tests $(xtests:%=$(objpfx)%.out) $(xtests-special)
 endif
 
@@ -131,7 +142,8 @@ tests-expected = $(tests)
 endif
 tests:
 	$(..)scripts/merge-test-results.sh -s $(objpfx) $(subdir) \
-	  $(sort $(tests-expected) $(tests-special-notdir:.out=)) \
+	  $(sort $(tests-expected) $(tests-special-notdir:.out=) \
+	  $(tests-printers)) \
 	  > $(objpfx)subdir-tests.sum
 xtests:
 	$(..)scripts/merge-test-results.sh -s $(objpfx) $(subdir) \
@@ -241,6 +253,32 @@ endif
 
 endif	# tests
 
+ifneq "$(strip $(tests-printers))" ""
+# We're defining this here for now; later it'll be defined at configure time
+# inside Makeconfig.
+PYTHON := python
+
+# Static pattern rule for building the test programs for the pretty printers.
+$(tests-printers-programs): %: %.o $(tests-printers-libs) \
+  $(sort $(filter $(common-objpfx)lib%,$(link-libc-static-tests))) \
+  $(addprefix $(csu-objpfx),start.o) $(+preinit) $(+postinit)
+	$(+link-printers-tests)
+
+# Add the paths to the generated constants file and test_common_printers.py
+# to PYTHONPATH so the test scripts can find them.
+py-env := PYTHONPATH=$(py-const-dir):$(..)scripts:$${PYTHONPATH}
+
+# Static pattern rule that matches the test-* targets to their .c and .py
+# prerequisites.  It'll run the corresponding test script for each test program
+# we compiled and place its output in the corresponding .out file.
+# The pretty printer files and test_common_printers.py must be present for all.
+$(tests-printers-out): $(objpfx)%.out: $(objpfx)% %.py %.c $(pretty-printers) \
+		       $(..)scripts/test_printers_common.py
+	$(test-wrapper-env) $(py-env) \
+	    $(PYTHON) $*.py $*.c $(objpfx)$* $(pretty-printers) > $@; \
+	$(evaluate-test)
+endif
+
 
 .PHONY: distclean realclean subdir_distclean subdir_realclean \
 	subdir_clean subdir_mostlyclean subdir_testclean