Harden test suite against silent-skip patterns

Makefile

@@ -1,4 +1,4 @@
-# elfuse — aarch64-linux ELF executor on macOS Apple Silicon
+# elfuse -- aarch64-linux ELF executor on macOS Apple Silicon
 #
 # Copyright 2026 elfuse contributors
 # SPDX-License-Identifier: Apache-2.0
@@ -8,7 +8,7 @@
 #
 # Example: make elfuse
 #          make test-hello
-#          make V=1 elfuse    (verbose — show full commands)
+#          make V=1 elfuse    (verbose -- show full commands)
 
 .DEFAULT_GOAL := help
 .DELETE_ON_ERROR:
@@ -90,7 +90,7 @@ define link-and-sign
 	mv "$$tmp" "$1"
 endef
 
-# ── Main executable ──────────────────────────────────────────────
+# Main executable
 .PHONY: all elfuse
 .PHONY: gen-syscall-dispatch check-syscall-dispatch
 
@@ -119,7 +119,7 @@ elfuse: $(ELFUSE_BIN)
 $(ELFUSE_BIN): $(OBJS) | $(BUILD_DIR)
 	$(call link-and-sign,$@,$(OBJS))
 
-# ── Native test binaries (macOS, Hypervisor.framework) ───────────
+# Native test binaries (macOS, Hypervisor.framework)
 
 ## Build the multi-vCPU HVF validation test (native macOS binary)
 $(BUILD_DIR)/test-multi-vcpu: $(BUILD_DIR)/test-multi-vcpu.o | $(BUILD_DIR)
@@ -129,7 +129,16 @@ $(BUILD_DIR)/test-multi-vcpu: $(BUILD_DIR)/test-multi-vcpu.o | $(BUILD_DIR)
 $(BUILD_DIR)/test-rwx: $(BUILD_DIR)/test-rwx.o | $(BUILD_DIR)
 	$(call link-and-sign,$@,$<)
 
-# ── Guest test binaries (cross-compiled, aarch64-linux) ──────────
+## Build the proctitle argv-tail regression test (native macOS binary)
+# Links against the project-built proctitle.o so the exact in-tree code is
+# exercised; no HVF entitlement is needed because the test only manipulates
+# mmap and PROT_NONE. The codesign step is skipped for the same reason.
+$(BUILD_DIR)/test-proctitle-host: $(BUILD_DIR)/test-proctitle-host.o \
+		$(BUILD_DIR)/runtime/proctitle.o | $(BUILD_DIR)
+	@echo "  LD      $@"
+	$(Q)$(CC) $(CFLAGS) -o $@ $^
+
+# Guest test binaries (cross-compiled, aarch64-linux)
 # Only used when GUEST_TEST_BINARIES is not set.
 
 ifndef GUEST_TEST_BINARIES

mk/tests.mk

@@ -7,7 +7,7 @@
         test-matrix test-matrix-elfuse-aarch64 test-matrix-qemu-aarch64 \
         test-full test-multi-vcpu test-rwx test-sysroot-rename \
         test-case-collision test-case-collision-fallback test-sysroot-create-paths \
-        test-proctitle-low-stack \
+        test-proctitle-host test-proctitle-low-stack \
         test-sysroot-procfs-exec test-timeout-disable test-fuse-alpine \
         test-sysroot-nofollow test-sysroot-chdir perf
 
@@ -23,6 +23,8 @@ check-syscall-coverage:
 ## Run the unit test suite plus busybox applet validation
 check: $(ELFUSE_BIN) $(TEST_DEPS) check-syscall-coverage
 	@bash tests/driver.sh -e $(ELFUSE_BIN) -d $(TEST_DIR) -v
+	@printf "\n$(BLUE)━━━ proctitle argv-tail regression ━━━$(RESET)\n"
+	@$(MAKE) --no-print-directory test-proctitle-host
 	@printf "\n$(BLUE)━━━ proctitle low-stack regression ━━━$(RESET)\n"
 	@$(MAKE) --no-print-directory test-proctitle-low-stack
 	@printf "\n$(BLUE)━━━ busybox applet validation ━━━$(RESET)\n"
@@ -35,7 +37,8 @@ check: $(ELFUSE_BIN) $(TEST_DEPS) check-syscall-coverage
 	@$(MAKE) --no-print-directory test-timeout-disable
 
 test-sysroot-rename: $(ELFUSE_BIN) $(BUILD_DIR)/test-sysroot-rename
-	@tmpdir=$$(mktemp -d); \
+	@set -e; \
+	tmpdir=$$(mktemp -d); \
 	trap 'rm -rf "$$tmpdir"; rm -f /tmp/elfuse-sysroot-rename-dst.txt' EXIT; \
 	mkdir -p "$$tmpdir/tmp"; \
 	printf 'inside-sysroot\n' > "$$tmpdir/tmp/elfuse-sysroot-rename-src.txt"; \
@@ -74,7 +77,8 @@ test-case-collision-fallback: $(ELFUSE_BIN) $(BUILD_DIR)/test-case-collision
 	$(ELFUSE_BIN) --sysroot "$$tmpdir" $(BUILD_DIR)/test-case-collision
 
 test-sysroot-create-paths: $(ELFUSE_BIN) $(BUILD_DIR)/test-sysroot-create-paths
-	@tmpdir=$$(mktemp -d); \
+	@set -e; \
+	tmpdir=$$(mktemp -d); \
 	guest_tmp="/tmp/elfuse-sysroot-create-paths/file.txt"; \
 	mounted_tmp="$$tmpdir/case-sysroot/tmp/elfuse-sysroot-create-paths/file.txt"; \
 	host_out_dir="$$tmpdir/host-out"; \
@@ -113,8 +117,7 @@ test-gdbstub: $(ELFUSE_BIN) $(TEST_DIR)/test-hello
 ## Alias for check (backward compat)
 test-all: check
 
-# ── Coreutils integration test ───────────────────────────────────
-
+# Coreutils integration test
 FIXTURES_DIR ?= $(CURDIR)/externals/test-fixtures
 
 ifeq ($(origin GUEST_COREUTILS), undefined)
@@ -171,8 +174,7 @@ test-coreutils: $(ELFUSE_BIN)
 		bash tests/test-coreutils.sh $(ELFUSE_BIN) $(COREUTILS_BIN); \
 	fi
 
-# ── Busybox integration test ─────────────────────────────────────
-
+# Busybox integration test
 ifneq ($(wildcard $(BUILD_DIR)/busybox),)
   BUSYBOX_BIN ?= $(BUILD_DIR)/busybox
 else ifdef GUEST_BUSYBOX
@@ -256,8 +258,7 @@ test-proctitle-low-stack: $(ELFUSE_BIN) $(BUSYBOX_DEPS)
 	fi
 	@bash tests/test-proctitle-low-stack.sh $(ELFUSE_BIN) $(BUSYBOX_BIN)
 
-# ── Static binary integration tests ──────────────────────────────
-
+# Static binary integration tests
 ifdef GUEST_STATIC_BINS
   ifneq ($(wildcard $(GUEST_STATIC_BINS)/bin),)
     STATIC_BINS_DIR ?= $(GUEST_STATIC_BINS)/bin
@@ -278,8 +279,7 @@ test-static-bins: $(ELFUSE_BIN)
 		bash tests/test-static-bins.sh $(ELFUSE_BIN) $(STATIC_BINS_DIR); \
 	fi
 
-# ── Dynamic linking tests ────────────────────────────────────────
-
+# Dynamic linking tests
 # Musl sysroot with dynamic linker + libc.so.
 SYSROOT_DIR ?= $(GUEST_SYSROOT)
 ifdef GUEST_DYNAMIC_COREUTILS
@@ -299,13 +299,24 @@ test-dynamic: $(ELFUSE_BIN)
 	@printf "$(BLUE)▸ Running$(RESET) dynamic hello-dynamic (--sysroot)\n"
 	$(ELFUSE_BIN) --sysroot $(SYSROOT_DIR) $(GUEST_DYNAMIC_TESTS)/bin/hello-dynamic
 
-## Run guest FUSE validation against the Alpine musl sysroot
+## Run guest FUSE validation
+# test-fuse-basic is statically linked and accesses exactly one host path:
+# /mnt/fuse (open + access). /dev/fuse is intercepted by elfuse internally.
+# A minimal sysroot under build/ that contains only /mnt/fuse is therefore
+# sufficient coverage; the earlier dependency on the full Alpine fixture
+# tree was incidental and broke `make distclean && make check` whenever
+# the Alpine CDN pruned a pinned package version.
+#
+# An explicit SYSROOT_DIR override is still honored for users who want
+# the test to run against their own sysroot (e.g. the Alpine fixtures
+# fetched separately for the broader matrix runner).
 test-fuse-alpine: $(ELFUSE_BIN) $(BUILD_DIR)/test-fuse-basic
-	@if [ -z "$(SYSROOT_DIR)" ] || [ ! -d "$(SYSROOT_DIR)" ]; then \
-		printf "$(YELLOW)SKIP$(RESET) Alpine sysroot not found. Set SYSROOT_DIR=/path/to/sysroot or run tests/fetch-fixtures.sh.\n"; \
-		exit 0; \
-	fi
-	@bash tests/test-fuse-alpine.sh $(ELFUSE_BIN) $(SYSROOT_DIR) $(BUILD_DIR)/test-fuse-basic
+	@sysroot="$(SYSROOT_DIR)"; \
+	if [ -z "$$sysroot" ] || [ ! -d "$$sysroot" ]; then \
+		sysroot="$(BUILD_DIR)/fuse-scratch-sysroot"; \
+		mkdir -p "$$sysroot/mnt/fuse"; \
+	fi; \
+	bash tests/test-fuse-alpine.sh $(ELFUSE_BIN) "$$sysroot" $(BUILD_DIR)/test-fuse-basic
 
 ## Run dynamically-linked coreutils tests (--sysroot)
 test-dynamic-coreutils: $(ELFUSE_BIN)
@@ -323,8 +334,7 @@ test-dynamic-coreutils: $(ELFUSE_BIN)
 		bash tests/test-dynamic-coreutils.sh $(ELFUSE_BIN) $(SYSROOT_DIR) $(DYNAMIC_COREUTILS_BIN); \
 	fi
 
-# ── glibc dynamic linking tests ───────────────────────────────────
-
+# glibc dynamic linking tests
 # glibc sysroot with dynamic linker + libc.so.
 GLIBC_SYSROOT_DIR ?= $(GUEST_GLIBC_SYSROOT)
 ifdef GUEST_GLIBC_DYNAMIC_COREUTILS
@@ -358,8 +368,7 @@ test-glibc-coreutils: $(ELFUSE_BIN)
 	    SUITE_SUMMARY="glibc results" \
 	    bash tests/test-dynamic-coreutils.sh $(ELFUSE_BIN) $(GLIBC_SYSROOT_DIR) $(GLIBC_DYNAMIC_COREUTILS_BIN)
 
-# ── Performance benchmark ─────────────────────────────────────────
-
+# Performance benchmark
 ifneq ($(wildcard $(BUILD_DIR)/busybox),)
   PERF_BIN ?= $(BUILD_DIR)/perf-bin
   PERF_DEPS := $(addprefix $(PERF_BIN)/,grep wc cat sort)
@@ -385,8 +394,7 @@ test-perf: $(ELFUSE_BIN) $(PERF_DEPS)
 ## Alias for test-perf
 perf: test-perf
 
-# ── Test matrix (elfuse + qemu, aarch64) ────────────────────────────────
-
+# Test matrix (elfuse + qemu, aarch64)
 ## Run full test matrix (all modes: elfuse + qemu, aarch64)
 test-matrix: $(ELFUSE_BIN) $(TEST_DEPS)
 	@bash tests/test-matrix.sh all
@@ -399,8 +407,7 @@ test-matrix-elfuse-aarch64: $(ELFUSE_BIN) $(TEST_DEPS)
 test-matrix-qemu-aarch64: $(ELFUSE_BIN) $(TEST_DEPS)
 	@bash tests/test-matrix.sh qemu-aarch64
 
-# ── Full test suite ──────────────────────────────────────────────────
-
+# Full test suite
 ## Run the complete test suite (aarch64: unit + busybox + gdbstub + coreutils + static + dynamic)
 test-full: $(ELFUSE_BIN)
 	@printf "\n$(CYAN)╔══════════════════════════════════════════════════════╗$(RESET)\n"
@@ -438,15 +445,19 @@ test-full: $(ELFUSE_BIN)
 	printf "$(CYAN)╚══════════════════════════════════════════════════════╝$(RESET)\n"; \
 	[ "$$fail" -eq 0 ]
 
-# ── Multi-vCPU validation test ─────────────────────────────────────
+# Multi-vCPU validation test
 # Build rules in top-level Makefile; these are just run targets.
 
 ## Run multi-vCPU validation tests (5 tests)
 test-multi-vcpu: $(BUILD_DIR)/test-multi-vcpu
 	$(BUILD_DIR)/test-multi-vcpu
 
-# ── RWX page table entry test ───────────────────────────────────
-
+# RWX page table entry test
 ## Run RWX page table entry test (does HVF allow W+X?)
 test-rwx: $(BUILD_DIR)/test-rwx
 	$(BUILD_DIR)/test-rwx
+
+# Proctitle argv-tail regression
+## Run the deterministic argv-tail overshoot guard test
+test-proctitle-host: $(BUILD_DIR)/test-proctitle-host
+	$(BUILD_DIR)/test-proctitle-host

src/syscall/fd.c

@@ -1028,7 +1028,7 @@ int64_t signalfd_read(int guest_fd,
             if (written == 0) {
                 /* No bytes transferred: surface EFAULT, leave the queue
                  * untouched so the signal is not lost. Matches the elfuse
-                 * promise locked in by tests/test-tier-b's
+                 * promise locked in by tests/test-fd-family's
                  * test_signalfd_efault_preserves_pending.
                  */
                 if (pending != pending_stack)

tests/driver.sh

@@ -27,7 +27,14 @@ FILTER=""
 LIST_ONLY=0
 VERBOSE=0
 TAP=0
-ALLOW_MISSING_BINARIES="${ALLOW_MISSING_BINARIES:-auto}"
+# Three values: 0 (strict, default), 1 (skip missing), auto (legacy).
+# In strict mode any missing test binary is a FAIL. The legacy "auto"
+# value flips to skip when TESTDIR is not the canonical build/ or
+# build/bin tree, which used to silently turn a partial out-of-tree
+# fixture set into a wall of green skips. Callers that genuinely want
+# permissive-skip-mode behavior should set ALLOW_MISSING_BINARIES=1
+# explicitly.
+ALLOW_MISSING_BINARIES="${ALLOW_MISSING_BINARIES:-0}"
 
 usage()
 {
@@ -230,15 +237,21 @@ evaluate_result()
     if [ "$rc" -eq 124 ]; then
         return 1
     fi
-    if [ "$rc" -eq 0 ] || {
-        [ -n "$expected" ] && [ "$rc" -eq "$expected" ]
-    }; then
-        if [ -n "$stdout_pat" ] && ! grep -qE "$stdout_pat" <<< "$output"; then
+    # When the manifest declares expected_rc=N, only that exact rc passes.
+    # Without this guard, a test that mistakenly exits 0 instead of its
+    # declared non-zero code (e.g. test-complex with expected_rc=42)
+    # would be reported PASS because rc=0 short-circuited the OR clause.
+    if [ -n "$expected" ]; then
+        if [ "$rc" -ne "$expected" ]; then
             return 1
         fi
-        return 0
+    elif [ "$rc" -ne 0 ]; then
+        return 1
+    fi
+    if [ -n "$stdout_pat" ] && ! grep -qE "$stdout_pat" <<< "$output"; then
+        return 1
     fi
-    return 1
+    return 0
 }
 
 report_case()

tests/lib/coreutils-suite.sh

@@ -47,30 +47,24 @@ coreutils_suite_extended_text()
 coreutils_suite_basic_encoding()
 {
     coreutils_print_section "Encoding / hashing"
-    if [ -e "$BIN/base32" ]; then
-        run_check base32 "NBSWY" "$TMPDIR/hello.txt"
-    fi
+    # Optional binaries (base32/basenc/sha224sum/sha384sum/b2sum/sum) are
+    # gated by test_skip_missing_tool inside run_check: when the wrapper
+    # sets TEST_SKIP_MISSING_TOOLS=1 they report SKIP with accounting,
+    # otherwise the missing binary surfaces as a hard FAIL. The previous
+    # raw "if [ -e ... ]; then" blocks bypassed both paths, silently
+    # erasing assertions whenever the binary was absent.
+    run_check base32 "NBSWY" "$TMPDIR/hello.txt"
     run_check base64 "aGVsbG8" "$TMPDIR/hello.txt"
-    if [ -e "$BIN/basenc" ]; then
-        run_check basenc "aGVsbG8" "--base64" "$TMPDIR/hello.txt"
-    fi
+    run_check basenc "aGVsbG8" "--base64" "$TMPDIR/hello.txt"
     run_check md5sum "hello.txt" "$TMPDIR/hello.txt"
     run_check sha1sum "hello.txt" "$TMPDIR/hello.txt"
-    if [ -e "$BIN/sha224sum" ]; then
-        run_check sha224sum "95041d" "$TMPDIR/hello.txt"
-    fi
+    run_check sha224sum "95041d" "$TMPDIR/hello.txt"
     run_check sha256sum "hello.txt" "$TMPDIR/hello.txt"
-    if [ -e "$BIN/sha384sum" ]; then
-        run_check sha384sum "6b3b69" "$TMPDIR/hello.txt"
-    fi
+    run_check sha384sum "6b3b69" "$TMPDIR/hello.txt"
     run_check sha512sum "hello.txt" "$TMPDIR/hello.txt"
-    if [ -e "$BIN/b2sum" ]; then
-        run_check b2sum "hello.txt" "$TMPDIR/hello.txt"
-    fi
+    run_check b2sum "hello.txt" "$TMPDIR/hello.txt"
     run_check cksum "hello.txt" "$TMPDIR/hello.txt"
-    if [ -e "$BIN/sum" ]; then
-        run_check sum "[0-9]" "$TMPDIR/hello.txt"
-    fi
+    run_check sum "[0-9]" "$TMPDIR/hello.txt"
 }
 
 coreutils_suite_basic_files()
@@ -164,9 +158,10 @@ coreutils_suite_basic_math()
     run_check seq "5" "1" "5"
     run_check expr "3" "1" "+" "2"
     run_check factor "2 2 3" "12"
-    if [ -e "$BIN/numfmt" ]; then
-        run_check numfmt "1\\.0[kK]" "--to=si" "1000"
-    fi
+    # numfmt is optional in some packages; rely on test_skip_missing_tool
+    # so absence becomes a SKIP under TEST_SKIP_MISSING_TOOLS=1 and a FAIL
+    # otherwise, rather than a silent omission.
+    run_check numfmt "1\\.0[kK]" "--to=si" "1000"
 }
 
 coreutils_suite_basic_sysinfo()