Fix GetProgramExecutableName() on NetBSD (#1529)

The sysctl parameters for querying KERN_PROC_PATHNAME are different from
FreeBSD. The tests now check the GPEN path using stat instead of strcmp.

libc/calls/getprogramexecutablename.greg.c

@@ -43,6 +43,7 @@ __static_yoink("_init_program_executable_name");
 
 #define CTL_KERN                   1
 #define KERN_PROC                  14
+#define KERN_PROC_ARGS             48
 #define KERN_PROC_PATHNAME_FREEBSD 12
 #define KERN_PROC_PATHNAME_NETBSD  5
 
@@ -173,13 +174,15 @@ static inline void InitProgramExecutableNameImpl(void) {
   if (IsFreebsd() || IsNetbsd()) {
     int cmd[4];
     cmd[0] = CTL_KERN;
-    cmd[1] = KERN_PROC;
     if (IsFreebsd()) {
+      cmd[1] = KERN_PROC;
       cmd[2] = KERN_PROC_PATHNAME_FREEBSD;
+      cmd[3] = -1;  // current process
     } else {
-      cmd[2] = KERN_PROC_PATHNAME_NETBSD;
+      cmd[1] = KERN_PROC_ARGS;
+      cmd[2] = -1;  // current process
+      cmd[3] = KERN_PROC_PATHNAME_NETBSD;
     }
-    cmd[3] = -1;  // current process
     if (sysctl(cmd, ARRAYLEN(cmd), b, &n, 0, 0) != -1) {
       if (!OldApeLoader(b)) {
         goto UseBuf;

test/libc/calls/BUILD.mk

@@ -73,6 +73,7 @@ o/$(MODE)/test/libc/calls/getprogramexecutablename_test.dbg:					\
 		$(TEST_LIBC_CALLS_DEPS)						\
 		o/$(MODE)/test/libc/calls/getprogramexecutablename_test.o	\
 		o/$(MODE)/test/libc/calls/ape.elf.zip.o				\
+		o/$(MODE)/test/libc/calls/gpenchild.elf.zip.o			\
 		o/$(MODE)/test/libc/calls/calls.pkg				\
 		$(LIBC_TESTMAIN)						\
 		$(CRT)								\
@@ -125,14 +126,25 @@ o/$(MODE)/test/libc/calls/life-nomod.dbg:				\
 		$(APE_NO_MODIFY_SELF)
 	@$(APELINK)
 
-o/$(MODE)/test/libc/calls/zipread.dbg:				\
-		$(LIBC_RUNTIME)						\
-		o/$(MODE)/test/libc/calls/zipread.o			\
-		o/$(MODE)/test/libc/mem/prog/life.elf.zip.o		\
-		$(CRT)							\
+o/$(MODE)/test/libc/calls/gpenchild.dbg:			\
+		$(LIBC_RUNTIME)					\
+		o/$(MODE)/test/libc/calls/gpenchild.o		\
+		$(CRT)						\
 		$(APE_NO_MODIFY_SELF)
 	@$(APELINK)
 
+o/$(MODE)/test/libc/calls/gpenchild.elf:				\
+		o/$(MODE)/tool/build/assimilate		\
+		o/$(MODE)/test/libc/calls/gpenchild		\
+		o/$(MODE)/tool/build/cp
+	@$(COMPILE) -wACP -T$@					\
+		o/$(MODE)/tool/build/cp				\
+		o/$(MODE)/test/libc/calls/gpenchild		\
+		o/$(MODE)/test/libc/calls/gpenchild.elf
+	@$(COMPILE) -wAASSIMILATE -T$@				\
+		o/$(MODE)/tool/build/assimilate -bcef	\
+		o/$(MODE)/test/libc/calls/gpenchild.elf
+
 o/$(MODE)/test/libc/calls/ape.elf:			\
 		o/$(MODE)/tool/build/cp		\
 		o/$(MODE)/ape/ape.elf
@@ -142,6 +154,7 @@ o/$(MODE)/test/libc/calls/ape.elf:			\
 		o/$(MODE)/test/libc/calls/ape.elf
 
 o/$(MODE)/test/libc/calls/ape.elf.zip.o					\
+o/$(MODE)/test/libc/calls/gpenchild.elf.zip.o				\
 o/$(MODE)/test/libc/calls/tiny64.elf.zip.o				\
 o/$(MODE)/test/libc/calls/life-nomod.zip.o				\
 o/$(MODE)/test/libc/calls/life-classic.zip.o: private				\

test/libc/calls/getprogramexecutablename_test.c

@@ -19,6 +19,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
 #include "libc/calls/metalfile.internal.h"
+#include "libc/calls/struct/stat.h"
 #include "libc/calls/syscall-nt.internal.h"
 #include "libc/calls/syscall-sysv.internal.h"
 #include "libc/calls/syscall_support-sysv.internal.h"
@@ -70,6 +71,18 @@ void SetUpOnce(void) {
   }
 }
 
+static bool isAbsPath(const char *path) {
+  return strlen(path) >= 2 && path[0] == '/' && path[1] != '/';
+}
+
+static bool isSameFile(const char *a, const char *b) {
+  struct stat st_a, st_b;
+  if (stat(a, &st_a) || stat(b, &st_b)) {
+    return false;
+  }
+  return (st_a.st_dev == st_b.st_dev) && (st_a.st_ino == st_b.st_ino);
+}
+
 __attribute__((__constructor__)) static void Child(int argc, char *argv[]) {
   loaded = !!__program_executable_name;
   if (argc >= 2 && !strcmp(argv[1], "Child")) {
@@ -82,7 +95,8 @@ __attribute__((__constructor__)) static void Child(int argc, char *argv[]) {
     if (rc) {
       exit(122);
     }
-    if (strcmp(argv[2], GetProgramExecutableName())) {
+    const char *path = GetProgramExecutableName();
+    if (!path || !isAbsPath(path) || !isSameFile(argv[2], path)) {
       exit(123);
     }
     if (argc >= 4) {
@@ -192,3 +206,23 @@ TEST(GetProgramExecutableName, nullArgvAPELoader) {
   abort();
   EXITS(0);
 }
+
+TEST(GetProgramExecutableName, elf) {
+  if (skiptests || IsOpenbsd() || IsXnu() || IsWindows() || IsMetal())
+    return;
+  char buf[BUFSIZ];
+  testlib_extract("/zip/gpenchild.elf", "test.elf", 0555);
+  ASSERT_NE(NULL, getcwd(buf, BUFSIZ - 5));
+  stpcpy(buf + strlen(buf), "/test.elf");
+  SPAWN(fork);
+  execve(buf, (char *[]){"hello", "Child", buf, skiparg0 ? 0 : "hello", 0},
+         (char *[]){0});
+  abort();
+  EXITS(0);
+  SPAWN(fork);
+  execve("./test.elf",
+         (char *[]){"hello", "Child", buf, skiparg0 ? 0 : "hello", 0},
+         (char *[]){0});
+  abort();
+  EXITS(0);
+}

test/libc/calls/gpenchild.c

@@ -0,0 +1,63 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8                               :vi │
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2023 Justine Alexandra Roberts Tunney                              │
+│ Copyright 2026 Gavin Arthur Hayes                                            │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/calls/calls.h"
+#include "libc/calls/struct/stat.h"
+#include "libc/calls/syscall-nt.internal.h"
+#include "libc/calls/syscall-sysv.internal.h"
+#include "libc/dce.h"
+#include "libc/runtime/runtime.h"
+#include "libc/str/str.h"
+
+static bool isAbsPath(const char *path) {
+  return strlen(path) >= 2 && path[0] == '/' && path[1] != '/';
+}
+
+static bool isSameFile(const char *a, const char *b) {
+  struct stat st_a, st_b;
+  if (stat(a, &st_a) || stat(b, &st_b)) {
+    return false;
+  }
+  return (st_a.st_dev == st_b.st_dev) && (st_a.st_ino == st_b.st_ino);
+}
+
+int main(int argc, char *argv[]) {
+  if (argc >= 2 && !strcmp(argv[1], "Child")) {
+    int rc;
+    if (!IsWindows()) {
+      rc = sys_chdir("/");
+    } else {
+      rc = sys_chdir_nt("/");
+    }
+    if (rc) {
+      exit(122);
+    }
+    const char *path = GetProgramExecutableName();
+    if (!path || !isAbsPath(path) || !isSameFile(argv[2], path)) {
+      exit(123);
+    }
+    if (argc >= 4) {
+      if (strcmp(argv[3], argv[0])) {
+        exit(124);
+      }
+    }
+    exit(0);
+  }
+  exit(128);
+}