Set errno to ENOENT when files does not exist, not EACCES

.github/workflows/ci.yml

@@ -4,7 +4,6 @@ on:
   push:
     branches:
       - '*'
-  pull_request:
 
 jobs:
   check:
@@ -15,7 +14,7 @@ jobs:
       - uses: nttld/setup-ndk@v1
         id: setup-ndk
         with:
-          ndk-version: r26d
+          ndk-version: r28c
           link-to-sdk: true
       - run: brew install clang-format
       - run: make CC="${ANDROID_NDK_HOME}"/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android30-clang
@@ -24,7 +23,13 @@ jobs:
       - run: make check CLANG_TIDY="${ANDROID_NDK_HOME}/toolchains/llvm/prebuilt/linux-x86_64/bin/clang-tidy --extra-arg=--target=aarch64-linux-android29"
         env:
           ANDROID_NDK_HOME: ${{ steps.setup-ndk.outputs.ndk-path }}
+
+  host-build-tests:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
       - run: make unit-test CC=clang HOST_BUILD=1
+      - run: make on-normal-linux-tests CC=clang HOST_BUILD=1
 
   actionlint:
     runs-on: ubuntu-latest

.gitignore

@@ -5,6 +5,8 @@
 *.swp
 *.deb
 test-binary
+tests/execl
+tests/exec-directory
 tests/fexecve
 tests/popen
 tests/system-uname

Makefile

@@ -1,9 +1,10 @@
 CC ?= clang
 TERMUX_BASE_DIR ?= /data/data/com.termux/files
-CFLAGS += -Wall -Wextra -Werror -Wshadow -fvisibility=hidden -std=c17
+CFLAGS += -Wall -Wextra -Werror -Wshadow -fvisibility=hidden -std=c23 -D__USE_GNU
 C_SOURCE := src/termux-exec.c src/exec-variants.c src/termux-readlink.c
 CLANG_FORMAT := clang-format --sort-includes --style="{ColumnLimit: 120}" $(C_SOURCE) tests/fexecve.c tests/system-uname.c tests/print-argv0.c tests/popen.c
 CLANG_TIDY ?= clang-tidy
+TEST_BINARIES = tests/execl tests/exec-directory tests/fexecve tests/popen tests/system-uname tests/readlink-proc-self-exe
 
 ifeq ($(SANITIZE),1)
   CFLAGS += -O1 -g -fsanitize=address -fno-omit-frame-pointer
@@ -13,11 +14,19 @@ endif
 
 ifeq ($(HOST_BUILD),1)
   CFLAGS += -Wno-error=tautological-pointer-compare
+else
+  TEST_BINARIES += $(TERMUX_BASE_DIR)/usr/bin/termux-exec-test-print-argv0
 endif
 
 libtermux-exec.so: $(C_SOURCE)
 	$(CC) $(CFLAGS) $(LDFLAGS) $(C_SOURCE) -DTERMUX_PREFIX=\"$(TERMUX_PREFIX)\" -DTERMUX_BASE_DIR=\"$(TERMUX_BASE_DIR)\" -shared -fPIC -o libtermux-exec.so
 
+tests/execl: tests/execl.c
+	$(CC) $(CFLAGS) -DTERMUX_BASE_DIR=\"$(TERMUX_BASE_DIR)\" $< -o $@
+
+tests/exec-directory: tests/exec-directory.c
+	$(CC) $(CFLAGS) -DTERMUX_BASE_DIR=\"$(TERMUX_BASE_DIR)\" $< -o $@
+
 tests/fexecve: tests/fexecve.c
 	$(CC) $(CFLAGS) -DTERMUX_BASE_DIR=\"$(TERMUX_BASE_DIR)\" $< -o $@
 
@@ -34,7 +43,7 @@ $(TERMUX_BASE_DIR)/usr/bin/termux-exec-test-print-argv0: tests/print-argv0.c
 	$(CC) $(CFLAGS) $< -o $@
 
 clean:
-	rm -f libtermux-exec.so tests/*-actual test-binary $(TERMUX_BASE_DIR)/usr/bin/termux-exec-test-print-argv0
+	rm -f libtermux-exec.so tests/*-actual $(TEST_BINARIES)
 
 install: libtermux-exec.so
 	install libtermux-exec.so $(DESTDIR)$(PREFIX)/lib/libtermux-exec.so
@@ -46,9 +55,12 @@ on-device-tests:
 	make clean
 	ASAN_OPTIONS=symbolize=0,detect_leaks=0 make on-device-tests-internal
 
-on-device-tests-internal: libtermux-exec.so tests/fexecve tests/popen tests/system-uname tests/readlink-proc-self-exe $(TERMUX_BASE_DIR)/usr/bin/termux-exec-test-print-argv0
+on-device-tests-internal: libtermux-exec.so $(TEST_BINARIES)
 	@LD_PRELOAD=${CURDIR}/libtermux-exec.so ./run-tests.sh
 
+on-normal-linux-tests: $(TEST_BINARIES)
+	./run-tests.sh
+
 format:
 	$(CLANG_FORMAT) -i $(C_SOURCE) tests/*.c
 

run-tests.sh

@@ -1,8 +1,18 @@
-#!/data/data/com.termux/files/usr/bin/bash
+#!/bin/bash
 
 set -u
 
+UNAME_OS=$(uname -o)
+EXIT_CODE=0
+
 for f in tests/*.sh; do
+	if [ "$UNAME_OS" != Android ]; then
+		if [ "$f" = tests/call-system-bin-sh.sh ] || [ "$f" = tests/print-argv0.sh ] || [ "$f" = tests/fexecve.sh ] ; then
+			echo "Skipping $f..."
+			continue
+		fi
+	fi
+
 	printf "Running $f..."
 
 	EXPECTED_FILE=$f-expected
@@ -14,7 +24,14 @@ for f in tests/*.sh; do
 	if cmp --silent $ACTUAL_FILE $EXPECTED_FILE; then
 		printf " OK\n"
 	else
-		printf " FAILED - compare expected $EXPECTED_FILE with ${ACTUAL_FILE}\n"
+		printf " FAILED - compare expected ${EXPECTED_FILE} with ${ACTUAL_FILE}\n"
+		echo "### Expected:"
+		cat "$EXPECTED_FILE"
+		echo "### Actual:"
+		cat "$ACTUAL_FILE"
+		echo "###"
+		EXIT_CODE=1
 	fi
 done
 
+exit $EXIT_CODE

src/termux-exec.c

@@ -10,6 +10,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sys/stat.h>
 #include <sys/syscall.h>
 #include <unistd.h>
 
@@ -284,9 +285,19 @@ __attribute__((visibility("default"))) int execve(const char *executable_path, c
     fprintf(stderr, LOG_PREFIX "Rewritten path: '%s'\n", executable_path);
   }
 
+  char normalized_path_buffer[PATH_MAX];
+  executable_path = normalize_path(executable_path, normalized_path_buffer);
+
   if (access(executable_path, X_OK) != 0) {
-    // Error out if the file is not executable:
-    errno = EACCES;
+    // Error out if the file is not executable.
+    struct stat stat_buffer;
+    if (stat(executable_path, &stat_buffer) == 0) {
+      // File exists but is executable:
+      errno = EACCES;
+    } else {
+      // File does not exist:
+      errno = ENOENT;
+    }
     return -1;
   }
 
@@ -315,6 +326,13 @@ __attribute__((visibility("default"))) int execve(const char *executable_path, c
   // We use one more byte since inspect_file_header() will null terminate the buffer.
   char header[256];
   ssize_t read_bytes = read(fd, header, sizeof(header) - 1);
+  if (read_bytes < 0) {
+    if (errno == EISDIR) {
+      // execve() should error with EACCES if file is directory.
+      errno = EACCES;
+    }
+    return -1;
+  }
   close(fd);
 
   struct file_header_info info = {
@@ -338,9 +356,6 @@ __attribute__((visibility("default"))) int execve(const char *executable_path, c
     }
   }
 
-  char normalized_path_buffer[PATH_MAX];
-  executable_path = normalize_path(executable_path, normalized_path_buffer);
-
   char **new_allocated_envp = NULL;
   char *termux_self_exe = NULL;
 

tests/exec-directory.c

@@ -0,0 +1,11 @@
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+
+int main(int, char **argv, char **env) {
+  execve(".", argv, env);
+  printf("errno = %d\n", errno);
+  execve("/", argv, env);
+  printf("errno = %d\n", errno);
+  return 0;
+}

tests/exec-directory.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+set -e -u
+
+./tests/exec-directory

tests/exec-directory.sh-expected

@@ -0,0 +1,2 @@
+errno = 13
+errno = 13

tests/execl.c

@@ -0,0 +1,22 @@
+#include <errno.h>
+#include <stdio.h>
+#include <unistd.h>
+
+void exec_debug(char *path) {
+  int ret = execl(path, "--arg", (char *)NULL);
+  if (ret != -1) {
+    fprintf(stderr, "Unexpected return value when execl():ing non-existing file: %d\n", ret);
+  } else {
+    printf("errno = %d\n", errno);
+  }
+}
+
+int main(int argc, char **argv) {
+  if (argc != 2) {
+    fprintf(stderr, "Unexpected argc=%d\n", argc);
+    return 1;
+  }
+  exec_debug("/this-file-does-not-exist");
+  exec_debug(argv[1]);
+  return 0;
+}

tests/execl.sh

@@ -0,0 +1,10 @@
+#!/bin/sh
+set -e -u
+
+# Make TMPFILE an existing but non-executable file:
+TMPFILE=$(mktemp)
+echo "1" > $TMPFILE
+
+./tests/execl $TMPFILE
+
+rm $TMPFILE

tests/execl.sh-expected

@@ -0,0 +1,2 @@
+errno = 2
+errno = 13

tests/fexecve.c

@@ -1,5 +1,6 @@
 #include <fcntl.h>
 #include <stdio.h>
+#define __USE_XOPEN2K8
 #include <unistd.h>
 
 int main() {

tests/not-executable.sh-expected

@@ -1 +1 @@
-./run-tests.sh: line 12: tests/not-executable.sh: Permission denied
+./run-tests.sh: line 22: tests/not-executable.sh: Permission denied

tests/popen.c

@@ -1,3 +1,4 @@
+#define _POSIX_C_SOURCE 2
 #include <stdio.h>
 
 int main() {

tests/readlink-proc-self-exe.c

@@ -1,4 +1,6 @@
 #define _DEFAULT_SOURCE
+#define __USE_XOPEN2K8
+#include <fcntl.h>
 #include <linux/limits.h>
 #include <stdio.h>
 #include <string.h>