Add test_variable_data framework that reuses the snippets

Most of these snippets are likely to have some env var that causes the
data to hold constant, while the data will otherwise be likely to vary
over time.

This framework offers a way to test those snippets, by dropping the
variable and an example value in the test/snippets/FOO.variable
one-line file.

Note that the test/snippets/syscall.c snippet is *not* expected to
vary over time (or to differ when any given variable is set), so we
simply don't add any test/snippets/syscall.variable file to avoid it
being tested in this way.

.gitignore

@@ -4,6 +4,7 @@ timetest
 test/getrandom_test
 test/lib*.so
 test/use_lib_*
+test/run_*
 test/repeat_random
 test/getentropy_test
 test/syscall_test

test/Makefile

@@ -7,6 +7,7 @@ SRC = timetest.c
 OBJ = ${SRC:.c=.o}
 
 TESTFUNCS = $(notdir $(basename $(wildcard snippets/*.c)))
+EXPECTATIONS= $(notdir $(basename $(wildcard snippets/*.variable)))
 
 all: timetest test
 
@@ -37,6 +38,14 @@ syscalltest: syscall_test
 	./syscalltest.sh
 
 
+## test variables
+
+test_variable_data: test_variable_data.sh $(foreach f,${EXPECTATIONS},run_${f})
+	./test_variable_data.sh ${EXPECTATIONS}
+
+run_%: _run_test.c snippets/%.c
+	sed s/FUNC_NAME/$*/g < _run_test.c | ${CC} -o $@ ${CFLAGS} -x c - 
+
 ## testing when interception points get called in library constructors:
 
 test_library_constructors: test_constructors.sh $(foreach f,${TESTFUNCS},use_lib_${f} lib${f}.so)
@@ -52,7 +61,7 @@ use_lib_%: _use_lib_test.c snippets/%.c lib%.so
 ## cleanup and metainformation
 
 clean:
-	@rm -f ${OBJ} timetest getrandom_test syscall_test $(foreach f,${TESTFUNCS},use_lib_${f} lib${f}.so)
+	@rm -f ${OBJ} timetest getrandom_test syscall_test $(foreach f,${TESTFUNCS},use_lib_${f} lib${f}.so run_${f})
 
 distclean: clean
 	@echo

test/_run_test.c

@@ -0,0 +1,5 @@
+#include "snippets/include_headers.h"
+#define where "direct"
+int main() {
+#include "snippets/FUNC_NAME.c"
+}

test/snippets/README

@@ -15,10 +15,13 @@ 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 output of the snippet is expected to be stable when the
+associated variable (e.g. FAKETIME, FAKETIME_FAKEPID, or
+FAKERANDOM_SEED) is set, and is likely to vary otherwise, especially
+across a delay of a second or more, add a single-line file
+FOO.variable that contains the name of the variable separated by a
+space and then the value of the variable.
 
 If the snippet needs to additional #include headers, please add them
 in include_headers.h. These #includes will be used by every snippet,
@@ -28,5 +31,5 @@ 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.
+uses each snippet.  See test_variable_data or
+test_library_constructors in ../Makefile for an example.

test/snippets/getpid.variable

@@ -0,0 +1 @@
+FAKETIME_FAKEPID 1

test/snippets/getrandom.variable

@@ -0,0 +1 @@
+FAKERANDOM_SEED 0xDEADBEEFDEADBEEF

test/test_variable_data.sh

@@ -0,0 +1,54 @@
+#!/bin/bash
+
+set -e
+
+FTPL="${FAKETIME_TESTLIB:-../src/libfaketime.so.1}"
+DELAY="${DELAY:-2}"
+
+declare -A firstunset first second delayed delayedunset
+
+err=0
+for func in "$@"; do
+    if ! [ -x "./run_$func" ]; then
+        printf >&2 '%s does not exist, failing\n' "./run_$func"
+        exit 1
+    fi
+    read varname value < "snippets/$func.variable"
+    unset $varname
+    firstunset[$func]="$(env LD_PRELOAD="$FTPL" "./run_$func")"
+    first[$func]="$(env LD_PRELOAD="$FTPL" "$varname=$value" "./run_$func")"
+    second[$func]="$(env LD_PRELOAD="$FTPL" "$varname=$value" "./run_$func")"
+    if [ "${first[$func]}" != "${second[$func]}" ]; then
+        printf >&2 '[%s] Set %s="%s", but got two different outputs:\n - %s\n - %s\n' "$func" "$varname" "$value" "${first[$func]}" "${second[$func]}"
+        err=$(( $err + 1 ))
+    fi
+    if [ "${first[$func]}" == "${firstunset[$func]}" ]; then
+        printf >&2 '[%s] Same answer when %s="%s" and when unset:\n -   set: %s\n - unset: %s\n' "$func" "$varname" "$value" "${first[$func]}" "${firstunset[$func]}"
+        err=$(( $err + 1 ))
+    fi
+done
+
+printf "Sleeping %d seconds..." "$DELAY"
+sleep "$DELAY"
+printf 'done\n'
+
+for func in "$@"; do
+    read varname value < "snippets/$func.variable"
+    unset $varname
+    delayed[$func]="$(env LD_PRELOAD="$FTPL" "$varname=$value" "./run_$func")"
+    delayedunset[$func]="$(LD_PRELOAD="$FTPL" "./run_$func")"
+    if [ "${first[$func]}" != "${delayed[$func]}" ]; then
+        printf >&2 '[%s] Vary across delay of %d seconds (%s="%s"):\n - before: %s\n -  after: %s\n' "$func" "$DELAY" "$varname" "$value" "${first[$func]}" "${delayed[$func]}"
+        err=$(( $err + 1 ))
+    fi
+    if [ "${firstunset[$func]}" == "${delayedunset[$func]}" ]; then
+        printf >&2 '[%s] Same answer when unset across delay of %d seconds:\n - before: %s\n -  after: %s\n' "$func" "$DELAY" "${firstunset[$func]}" "${delayedunset[$func]}"
+        err=$(( $err + 1 ))
+    fi
+done
+
+if [ "$err" -gt 0 ]; then
+    printf >&2 'Got %d errors, failing\n' "$err"
+    exit 1
+fi
+exit 0