Overhaul testing library constructors

We want to make it easier to test a bunch of different functions that
might be invoked in constructors of other libraries.

It seems conceivable that with these snippets, we could design other
tests that also work across a wide range of intercepted functions.

.gitignore

@@ -2,10 +2,8 @@
 *.so.1
 timetest
 test/getrandom_test
-test/lib*.o
 test/lib*.so
-test/use_lib_random
-test/use_lib_getpid
+test/use_lib_*
 test/repeat_random
 test/getentropy_test
 test/syscall_test

test/Makefile

@@ -6,6 +6,8 @@ LDFLAGS = -lrt -lpthread
 SRC = timetest.c
 OBJ = ${SRC:.c=.o}
 
+TESTFUNCS = $(notdir $(basename $(wildcard snippets/*.c)))
+
 all: timetest test
 
 .c.o:
@@ -25,7 +27,7 @@ functest:
 %_test: %_test.c
 	${CC} -o $@ ${CFLAGS} $<
 
-randomtest: getrandom_test use_lib_random librandom.so repeat_random getentropy_test
+randomtest: getrandom_test use_lib_getrandom libgetrandom.so repeat_random getentropy_test
 	./randomtest.sh
 
 getpidtest: use_lib_getpid libgetpid.so
@@ -34,17 +36,23 @@ getpidtest: use_lib_getpid libgetpid.so
 syscalltest: syscall_test
 	./syscalltest.sh
 
-lib%.o: lib%.c
-	${CC} -c -o $@ -fpic ${CFLAGS} $<
 
-lib%.so: lib%.o
-	${CC} -o $@ -shared ${CFLAGS} $<
+## testing when interception points get called in library constructors:
 
-use_lib_%: use_lib_%.c lib%.so
-	${CC} -L. -o $@ ${CFLAGS}  $< -l$*
+test_library_constructors: test_constructors.sh $(foreach f,${TESTFUNCS},use_lib_${f} lib${f}.so)
+	true $(foreach f,${TESTFUNCS},&& ./test_constructors.sh ${f})
+
+lib%.so: _libtest.c snippets/%.c
+	sed s/FUNC_NAME/$*/g < _libtest.c | ${CC} -shared -o $@ -fpic ${CFLAGS} -x c -
+
+use_lib_%: _use_lib_test.c snippets/%.c lib%.so
+	sed s/FUNC_NAME/$*/g < _use_lib_test.c | ${CC} -L. -o $@ ${CFLAGS} -x c - -l$*
+
+
+## cleanup and metainformation
 
 clean:
-	@rm -f ${OBJ} timetest getrandom_test lib*.o lib*.so use_lib_random use_lib_getpid syscall_test
+	@rm -f ${OBJ} timetest getrandom_test syscall_test $(foreach f,${TESTFUNCS},use_lib_${f} lib${f}.so)
 
 distclean: clean
 	@echo

test/_libtest.c

@@ -0,0 +1,8 @@
+#include "snippets/include_headers.h"
+#define where "library"
+void FUNC_NAME_as_needed() {
+  printf("  called FUNC_NAME_as_needed() \n");
+}
+static __attribute__((constructor)) void init_FUNC_NAME() {
+#include "snippets/FUNC_NAME.c"
+}

test/_use_lib_test.c

@@ -0,0 +1,7 @@
+#include "snippets/include_headers.h"
+extern void FUNC_NAME_as_needed();
+#define where "program"
+int main() {
+  FUNC_NAME_as_needed();
+#include "snippets/FUNC_NAME.c"
+}

test/libgetpid.c

@@ -1,13 +0,0 @@
-#include <stdio.h>
-#include <sys/types.h>
-#include <unistd.h>
-
-void getpid_func() {
-  printf("  called getpid_func()\n");
-}
-
-
-static __attribute__((constructor)) void getpid_init() {
-  pid_t pid = getpid();
-  printf("  getpid() yielded %d\n", pid);
-}

test/libgetpid.h

@@ -1,6 +0,0 @@
-#ifndef __LIBGETPID_H__
-#define __LIBGETPID_H__
-
-extern void getpid_func();
-
-#endif

test/librandom.c

@@ -1,17 +0,0 @@
-#include <stdio.h>
-#include <sys/random.h>
-
-void func() {
-  printf("  called func()\n");
-}
-
-
-static __attribute__((constructor)) void rnd_init() {
-  unsigned int targ;
-  ssize_t ret = getrandom(&targ, sizeof(targ), 0);
-  if (ret == sizeof(targ)) {
-    printf("  getrandom() yielded 0x%08x\n", targ);
-  } else {
-    printf("  getrandom() failed with only %zd\n", ret);
-  }
-}

test/librandom.h

@@ -1,6 +0,0 @@
-#ifndef __LIBRANDOM_H__
-#define __LIBRANDOM_H__
-
-extern void func();
-
-#endif

test/randomtest.sh

@@ -35,12 +35,12 @@ for iface in getrandom getentropy; do
 done
 
 printf 'testing shared object with getrandom() in library constructor\n'
-LD_LIBRARY_PATH=. ./use_lib_random
+LD_LIBRARY_PATH=. ./use_lib_getrandom
 printf 'now with LD_PRELOAD and FAKERANDOM_SEED\n'
-FAKERANDOM_SEED=0x0000000000000000 LD_PRELOAD="$FTPL" LD_LIBRARY_PATH=. ./use_lib_random
+FAKERANDOM_SEED=0x0000000000000000 LD_PRELOAD="$FTPL" LD_LIBRARY_PATH=. ./use_lib_getrandom
 # this demonstrates the crasher from https://github.com/wolfcw/libfaketime/issues/295
 printf 'now with LD_PRELOAD without FAKERANDOM_SEED\n'
-LD_PRELOAD="$FTPL" LD_LIBRARY_PATH=. ./use_lib_random
+LD_PRELOAD="$FTPL" LD_LIBRARY_PATH=. ./use_lib_getrandom
 
 
 FAKERANDOM_SEED=0xDEADBEEFDEADBEEF LD_PRELOAD="$FTPL" ./repeat_random 3 5 > repeat3x5 

test/snippets/README

@@ -0,0 +1,32 @@
+Bulk testing of function interception
+=====================================
+
+Faketime intercepts some C library functions.  We want to make it
+easier to apply certain generic tests across many different functions.
+
+Including a new function
+------------------------
+
+To test a function FOO, supply a C snippet in this directory named
+<FOO.c>.  This should be a small bit of code that exercises the
+function FOO.  It should be self-contained, and it should produce some
+kind of description of what happened to stdout.  Take a look at
+getpid.c for a simple example.
+
+The data sent to stdout should include the const char* "where" value
+(which is an indication of which test framework is using the snippet).
+And it should ideally be stable when the associated variable
+(e.g. FAKETIME, FAKETIME_FAKEPID, or FAKERANDOM_SEED) is set, and
+likely to vary otherwise, especially across a delay of a second or
+more.
+
+If the snippet needs to additional #include headers, please add them
+in include_headers.h. These #includes will be used by every snippet,
+so try to keep it minimal.
+
+Testing across functions
+------------------------
+
+If you want to test something systemically, autogenerate code that
+uses each snippet.  See test_library_constructors in ../Makefile for
+an example.

test/snippets/getpid.c

@@ -0,0 +1,2 @@
+pid_t pid = getpid();
+printf("[%s] getpid() yielded %d\n", where, pid);

test/snippets/getrandom.c

@@ -0,0 +1,7 @@
+unsigned int targ;
+ssize_t ret = getrandom(&targ, sizeof(targ), 0);
+if (ret == sizeof(targ)) {
+  printf("[%s] getrandom() yielded 0x%08x\n", where, targ);
+} else {
+  printf("[%s] getrandom() failed with only %zd\n", where, ret);
+}

test/snippets/include_headers.h

@@ -0,0 +1,4 @@
+#include <stdio.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <sys/random.h>

test/test_constructors.sh

@@ -0,0 +1,10 @@
+#!/bin/sh
+
+FTPL="${FAKETIME_TESTLIB:-../src/libfaketime.so.1}"
+
+function="$1"
+
+printf 'Testing library init for %s (no LD_PRELOAD)\n' "$function" 
+LD_LIBRARY_PATH=. "./use_lib_$function"
+printf 'Testing library init for %s (LD_PRELOAD)\n' "$function" 
+LD_LIBRARY_PATH=. LD_PRELOAD="$FTPL" "./use_lib_$function"

test/use_lib_getpid.c

@@ -1,12 +0,0 @@
-#include <stdio.h>
-#include <sys/types.h>
-#include <unistd.h>
-#include "libgetpid.h"
-
-int main() {
-  pid_t pid;
-  getpid_func();
-  pid = getpid();
-  printf(" getpid() -> %d\n", pid);
-  return 0;
-}

test/use_lib_random.c

@@ -1,6 +0,0 @@
-#include "librandom.h"
-
-int main() {
-  func();
-  return 0;
-}