Add memfd fexecve zipos support (#752)

libc/calls/fexecve.c

@@ -30,6 +30,7 @@
 #include "libc/fmt/itoa.h"
 #include "libc/intrin/asan.internal.h"
 #include "libc/intrin/describeflags.internal.h"
+#include "libc/intrin/safemacros.internal.h"
 #include "libc/intrin/strace.internal.h"
 #include "libc/intrin/weaken.h"
 #include "libc/str/str.h"
@@ -125,9 +126,6 @@ static int fd_to_mem_fd(const int infd, char *path) {
   int fd;
   if (IsLinux()) {
     fd = sys_memfd_create(__func__, MFD_CLOEXEC);
-    if ((fd != -1) && path) {
-      FormatInt32(stpcpy(path, "/proc/self/fd/"), fd);
-    }
   } else if (IsFreebsd()) {
     fd = sys_shm_open(SHM_ANON, O_CREAT | O_RDWR, 0);
   } else {
@@ -144,10 +142,22 @@ static int fd_to_mem_fd(const int infd, char *path) {
     readRc = pread(infd, space, st.st_size, 0);
     bool success = readRc != -1;
     if (success && (st.st_size > 8) && IsAPEMagic(space)) {
-      success = ape_to_elf(space, st.st_size);
+      int flags = fcntl(fd, F_GETFD);
+      if (success = (flags != -1) &&
+                    (fcntl(fd, F_SETFD, flags & (~FD_CLOEXEC)) != -1) &&
+                    ape_to_elf(space, st.st_size)) {
+        const int newfd = fcntl(fd, F_DUPFD, 9001);
+        if (newfd != -1) {
+          close(fd);
+          fd = newfd;
+        }
+      }
     }
     const int e = errno;
     if ((_weaken(munmap)(space, st.st_size) != -1) && success) {
+      if (path) {
+        FormatInt32(stpcpy(path, "COSMOPOLITAN_INIT_ZIPOS="), fd);
+      }
       _unassert(readRc == st.st_size);
       return fd;
     } else if (!success) {
@@ -182,6 +192,7 @@ int fexecve(int fd, char *const argv[], char *const envp[]) {
   } else {
     STRACE("fexecve(%d, %s, %s) → ...", fd, DescribeStringList(argv),
            DescribeStringList(envp));
+    int savedErr = 0;
     do {
       if (!IsLinux() && !IsFreebsd()) {
         rc = enosys();
@@ -200,33 +211,36 @@ int fexecve(int fd, char *const argv[], char *const envp[]) {
         if (rc == -1) {
           break;
         } else if (!memfdReq) {
-          rc = fexecve_impl(fd, argv, envp);
+          fexecve_impl(fd, argv, envp);
           if (errno != ENOEXEC) {
             break;
           }
+          savedErr = ENOEXEC;
         }
       }
       int newfd;
+      char *path = alloca(PATH_MAX);
       BEGIN_CANCELLATION_POINT;
       BLOCK_SIGNALS;
       strace_enabled(-1);
-      newfd = fd_to_mem_fd(fd, NULL);
+      newfd = fd_to_mem_fd(fd, path);
       strace_enabled(+1);
       ALLOW_SIGNALS;
       END_CANCELLATION_POINT;
       if (newfd == -1) {
-        if (rc == -1) {
-          errno = ENOEXEC;
-        }
-        rc = -1;
         break;
       }
-      fexecve_impl(newfd, argv, envp);
+      size_t numenvs;
-      if (rc == -1) {
+      for (numenvs = 0; envp[numenvs];) ++numenvs;
-        errno = ENOEXEC;
+      const size_t desenvs = min(500, max(numenvs + 1, 2));
+      static _Thread_local char *envs[500];
+      memcpy(envs, envp, numenvs * sizeof(char *));
+      envs[numenvs] = path;
+      envs[numenvs + 1] = NULL;
+      fexecve_impl(newfd, argv, envs);
+      if (!savedErr) {
+        savedErr = errno;
       }
-      rc = -1;
-      const int savedErr = errno;
       BEGIN_CANCELLATION_POINT;
       BLOCK_SIGNALS;
       strace_enabled(-1);
@@ -234,8 +248,11 @@ int fexecve(int fd, char *const argv[], char *const envp[]) {
       strace_enabled(+1);
       ALLOW_SIGNALS;
       END_CANCELLATION_POINT;
-      errno = savedErr;
     } while (0);
+    if (savedErr) {
+      errno = savedErr;
+    }
+    rc = -1;
   }
   STRACE("fexecve(%d) failed %d% m", fd, rc);
   return rc;

libc/zipos/get.c

@@ -18,6 +18,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
 #include "libc/calls/metalfile.internal.h"
+#include "libc/fmt/conv.h"
 #include "libc/intrin/cmpxchg.h"
 #include "libc/intrin/promises.internal.h"
 #include "libc/intrin/strace.internal.h"
@@ -59,7 +60,7 @@ static void __zipos_munmap_unneeded(const uint8_t *base, const uint8_t *cdir,
  * @threadsafe
  */
 struct Zipos *__zipos_get(void) {
-  int fd;
+  int fd = -1;
   ssize_t size;
   const char *msg;
   static bool once;
@@ -67,10 +68,17 @@ struct Zipos *__zipos_get(void) {
   const char *progpath;
   static struct Zipos zipos;
   uint8_t *map, *base, *cdir;
-  if (!once && PLEDGED(RPATH)) {
+  progpath = getenv("COSMOPOLITAN_INIT_ZIPOS");
+  if (progpath) {
+    fd = atoi(progpath);
+  }
+  if (!once && ((fd != -1) || PLEDGED(RPATH))) {
     __zipos_lock();
-    progpath = GetProgramExecutableName();
+    if (fd == -1) {
-    if ((fd = open(progpath, O_RDONLY)) != -1) {
+      progpath = GetProgramExecutableName();
+      fd = open(progpath, O_RDONLY);
+    }
+    if (fd != -1) {
       if ((size = getfiledescriptorsize(fd)) != -1ul &&
           (map = mmap(0, size, PROT_READ, MAP_SHARED, fd, 0)) != MAP_FAILED) {
         if ((base = FindEmbeddedApe(map, size))) {

test/libc/calls/fexecve_test.c

@@ -128,3 +128,14 @@ TEST(fexecve, ziposAPE) {
   EXITS(42);
   close(fd);
 }
+
+TEST(fexecve, ziposAPEHasZipos) {
+  if (!IsLinux() && !IsFreebsd()) return;
+  int fd = open("/zip/zipread.com", O_RDONLY);
+  SPAWN(fork);
+  ASSERT_NE(-1, fd);
+  if (fd == -1 && errno == ENOSYS) _Exit(42);
+  fexecve(fd, (char *const[]){0}, (char *const[]){0});
+  EXITS(42);
+  close(fd);
+}

test/libc/calls/test.mk

@@ -19,7 +19,8 @@ TEST_LIBC_CALLS_BINS =							\
 	$(TEST_LIBC_CALLS_COMS)						\
 	$(TEST_LIBC_CALLS_COMS:%=%.dbg)					\
 	o/$(MODE)/test/libc/calls/life-nomod.com			\
-	o/$(MODE)/test/libc/calls/life-classic.com
+	o/$(MODE)/test/libc/calls/life-classic.com			\
+	o/$(MODE)/test/libc/calls/zipread.com
 
 TEST_LIBC_CALLS_TESTS =							\
 	$(TEST_LIBC_CALLS_SRCS_TEST:%.c=o/$(MODE)/%.com.ok)
@@ -95,6 +96,7 @@ o/$(MODE)/test/libc/calls/fexecve_test.com.dbg:				\
 		o/$(MODE)/test/libc/mem/prog/life.elf.zip.o		\
 		o/$(MODE)/tool/build/echo.zip.o				\
 		o/$(MODE)/test/libc/calls/life-nomod.com.zip.o		\
+		o/$(MODE)/test/libc/calls/zipread.com.zip.o		\
 		$(LIBC_TESTMAIN)					\
 		$(CRT)							\
 		$(APE_NO_MODIFY_SELF)
@@ -102,7 +104,8 @@ o/$(MODE)/test/libc/calls/fexecve_test.com.dbg:				\
 
 o/$(MODE)/test/libc/calls/tiny64.elf.zip.o				\
 o/$(MODE)/test/libc/calls/life-nomod.com.zip.o				\
-o/$(MODE)/test/libc/calls/life-classic.com.zip.o: private		\
+o/$(MODE)/test/libc/calls/life-classic.com.zip.o			\
+o/$(MODE)/test/libc/calls/zipread.com.zip.o: private			\
 		ZIPOBJ_FLAGS +=						\
 			-B
 

test/libc/calls/zipread.c

@@ -0,0 +1,41 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2023 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/str/str.h"
+#include "libc/sysv/consts/o.h"
+
+STATIC_YOINK("zip_uri_support");
+
+int main(int argc, char *argv[]) {
+  int fd = open("/zip/life.elf", O_RDONLY);
+  if (fd != -1) {
+    uint8_t buf[4] = {0};
+    ssize_t readres = read(fd, buf, sizeof(buf));
+    if (readres == sizeof(buf)) {
+      if (memcmp(buf,
+                 "\x7F"
+                 "ELF",
+                 sizeof(buf)) == 0) {
+        return 42;
+      }
+    }
+    close(fd);
+  }
+  return 1;
+}