Prepend getcwd to exename early in init (#1048)

libc/calls/getprogramexecutablename.greg.c

@@ -34,6 +34,10 @@
 #include "libc/sysv/consts/at.h"
 #include "libc/sysv/consts/ok.h"
 
+#ifdef __x86_64__
+__static_yoink("_init_program_executable_name");
+#endif
+
 #define CTL_KERN                   1
 #define KERN_PROC                  14
 #define KERN_PROC_PATHNAME_FREEBSD 12
@@ -88,31 +92,37 @@ static int OldApeLoader(char *s) {
          (!strncmp((b = basename(s)), ".ape-", 5) && AllNumDot(b + 5));
 }
 
-// if q exists then turn it into an absolute path. we also try adding
-// a .com suffix since the ape auto-appends it when resolving
-static int TryPath(const char *q, int com) {
-  char c, *p, *e;
-  if (!q) return 0;
-  p = g_prog.u.buf;
-  e = p + sizeof(g_prog.u.buf);
+static char *CopyWithCwd(const char *q, char *p, char *e) {
+  char c;
   if (*q != '/') {
     if (q[0] == '.' && q[1] == '/') {
       q += 2;
     }
-    int got = __getcwd(p, e - p - 1 /* '/' */ - com * 4);
+    int got = __getcwd(p, e - p - 1 /* '/' */);
     if (got != -1) {
       p += got - 1;
       *p++ = '/';
     }
   }
   while ((c = *q++)) {
-    if (p + com * 4 + 1 /* nul */ < e) {
+    if (p + 1 /* nul */ < e) {
       *p++ = c;
     } else {
-      return 0;
+      return NULL;
     }
   }
   *p = 0;
+  return p;
+}
+
+// if q exists then turn it into an absolute path. we also try adding
+// a .com suffix since the ape auto-appends it when resolving
+static int TryPath(const char *q, int com) {
+  char *p;
+  if (!(p = CopyWithCwd(q, g_prog.u.buf,
+                        g_prog.u.buf + sizeof(g_prog.u.buf) - com * 4))) {
+    return 0;
+  }
   if (!sys_faccessat(AT_FDCWD, g_prog.u.buf, F_OK, 0)) return 1;
   if (!com) return 0;
   p = WRITE32LE(p, READ32LE(".com"));
@@ -121,6 +131,16 @@ static int TryPath(const char *q, int com) {
   return 0;
 }
 
+// if the loader passed a relative path, prepend cwd to it.
+// called early in init.
+void __init_program_executable_name(void) {
+  if (__program_executable_name && *__program_executable_name != '/' &&
+      CopyWithCwd(__program_executable_name, g_prog.u.buf,
+                  g_prog.u.buf + sizeof(g_prog.u.buf))) {
+    __program_executable_name = g_prog.u.buf;
+  }
+}
+
 static inline void InitProgramExecutableNameImpl(void) {
   size_t n;
   ssize_t got;
@@ -167,18 +187,6 @@ static inline void InitProgramExecutableNameImpl(void) {
         goto UseEmpty;
       }
     }
-    if (*__program_executable_name == '/') {
-      return;
-    }
-    // loader passed us a relative path; prepend cwd.
-    if (TryPath(__program_executable_name, 0)) {
-      goto UseBuf;
-    }
-    /* if TryPath fails, it probably failed because getcwd() was too long.
-       we are out of options now; KERN_PROC_PATHNAME et al will return the
-       name of the loader not the binary, and argv et al will at best have
-       the same problem. just use the relative path we got from the loader
-       as-is, and accept that if we chdir then things will break. */
     return;
   }
 

libc/calls/program_executable_name_init.S

@@ -0,0 +1,27 @@
+/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8     -*-│
+│ vi: set noet ft=asm ts=8 sw=8 fenc=utf-8                                 :vi │
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2023 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ 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/macros.internal.h"
+
+	.init.start 305,_init_program_executable_name
+	push	%rdi
+	push	%rsi
+	call	__init_program_executable_name
+	pop	%rsi
+	pop	%rdi
+	.init.end 305,_init_program_executable_name

libc/runtime/cosmo2.c

@@ -172,6 +172,9 @@ wontreturn textstartup void cosmo(long *sp, struct Syslib *m1, char *exename,
   // initialize file system
   __init_fds(argc, argv, envp);
 
+  // prepend cwd to executable path
+  __init_program_executable_name();
+
   __enable_tls();
 
 #if 0

libc/runtime/internal.h

@@ -47,6 +47,7 @@ void *__mmap_unlocked(void *, size_t, int, int, int, int64_t);
 int __munmap_unlocked(char *, size_t);
 void __on_arithmetic_overflow(void);
 void __init_fds(int, char **, char **);
+void __init_program_executable_name(void);
 
 COSMOPOLITAN_C_END_
 #endif /* ANSI */

test/libc/calls/getprogramexecutablename_test.c

@@ -18,6 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
 #include "libc/calls/metalfile.internal.h"
+#include "libc/calls/syscall-sysv.internal.h"
 #include "libc/dce.h"
 #include "libc/limits.h"
 #include "libc/runtime/runtime.h"
@@ -57,6 +58,9 @@ void SetUpOnce(void) {
 
 __attribute__((__constructor__)) static void Child(int argc, char *argv[]) {
   if (argc >= 2 && !strcmp(argv[1], "Child")) {
+    if (sys_chdir("/")) {
+      exit(122);
+    }
     if (strcmp(argv[2], GetProgramExecutableName())) {
       exit(123);
     }
@@ -138,4 +142,9 @@ TEST(GetProgramExecutableName, movedSelf) {
   execve(buf, (char *[]){"hello", "Child", buf, "hello", 0}, (char *[]){0});
   abort();
   EXITS(0);
+  SPAWN(fork);
+  execve("./test", (char *[]){"hello", "Child", buf, "hello", 0},
+         (char *[]){0});
+  abort();
+  EXITS(0);
 }