posix_spawn-internal: Implement for native Windows.

* lib/spawni.c (grow_inheritable_handles, shrink_inheritable_handles,
close_inheritable_handles, memiszero, sigisempty, open_handle, do_open,
do_dup2, do_close): New functions.
(__spawni): Implement on native Windows.
* modules/posix_spawn-internal (Depends-on): Add filename,
concat-filename, findprog-in, malloca, windows-spawn.
* doc/posix-functions/posix_spawn.texi: Update.
* doc/posix-functions/posix_spawnp.texi: Likewise.

1 files changed, 626 insertions, 5 deletions

diff --git a/lib/spawni.c b/lib/spawni.c
index 182d13ff24..2f0d25f38a 100644
--- a/lib/spawni.c
+++ b/lib/spawni.c
@@ -87,16 +87,637 @@
 
 
 #if defined _WIN32 && ! defined __CYGWIN__
-
 /* Native Windows API.  */
+
+/* Get declarations of the native Windows API functions.  */
+# define WIN32_LEAN_AND_MEAN
+# include <windows.h>
+
+# include <stdbool.h>
+# include <stdio.h>
+
+# include "filename.h"
+# include "concat-filename.h"
+# include "findprog.h"
+# include "malloca.h"
+# include "windows-spawn.h"
+
+/* Don't assume that UNICODE is not defined.  */
+# undef CreateFile
+# define CreateFile CreateFileA
+# undef STARTUPINFO
+# define STARTUPINFO STARTUPINFOA
+# undef CreateProcess
+# define CreateProcess CreateProcessA
+
+/* Grows inh_handles->count so that it becomes > newfd.
+   Returns 0 upon success.  In case of failure, -1 is returned, with errno set.
+ */
+static int
+grow_inheritable_handles (struct inheritable_handles *inh_handles, int newfd)
+{
+  if (inh_handles->allocated <= newfd)
+    {
+      size_t new_allocated = 2 * inh_handles->allocated + 1;
+      if (new_allocated <= newfd)
+        new_allocated = newfd + 1;
+      HANDLE *new_handles_array =
+        (HANDLE *)
+        realloc (inh_handles->handles, new_allocated * sizeof (HANDLE));
+      if (new_handles_array == NULL)
+        {
+          errno = ENOMEM;
+          return -1;
+        }
+      unsigned char *new_flags_array =
+        (unsigned char *)
+        realloc (inh_handles->flags, new_allocated * sizeof (unsigned char));
+      if (new_flags_array == NULL)
+        {
+          free (new_handles_array);
+          errno = ENOMEM;
+          return -1;
+        }
+      inh_handles->allocated = new_allocated;
+      inh_handles->handles = new_handles_array;
+      inh_handles->flags = new_flags_array;
+    }
+
+  HANDLE *handles = inh_handles->handles;
+
+  for (; inh_handles->count <= newfd; inh_handles->count++)
+    handles[inh_handles->count] = INVALID_HANDLE_VALUE;
+
+  return 0;
+}
+
+/* Reduces inh_handles->count to the minimum needed.  */
+static void
+shrink_inheritable_handles (struct inheritable_handles *inh_handles)
+{
+  HANDLE *handles = inh_handles->handles;
+
+  while (inh_handles->count > 3
+         && handles[inh_handles->count - 1] == INVALID_HANDLE_VALUE)
+    inh_handles->count--;
+}
+
+/* Closes all handles in inh_handles.  */
+static void
+close_inheritable_handles (struct inheritable_handles *inh_handles)
+{
+  HANDLE *handles = inh_handles->handles;
+  size_t handles_count = inh_handles->count;
+  unsigned int fd;
+
+  for (fd = 0; fd < handles_count; fd++)
+    {
+      HANDLE handle = handles[fd];
+
+      if (handle != INVALID_HANDLE_VALUE)
+        CloseHandle (handle);
+    }
+}
+
+/* Tests whether a memory region, starting at P and N bytes long, contains only
+   zeroes.  */
+static bool
+memiszero (const void *p, size_t n)
+{
+  const char *cp = p;
+  for (; n > 0; cp++, n--)
+    if (*cp != 0)
+      return 0;
+  return 1;
+}
+
+/* Tests whether *S contains no signals.  */
+static bool
+sigisempty (const sigset_t *s)
+{
+  return memiszero (s, sizeof (sigset_t));
+}
+
+/* Opens a HANDLE to a file.
+   Upon failure, returns INVALID_HANDLE_VALUE with errno set.  */
+static HANDLE
+open_handle (const char *name, int flags, mode_t mode)
+{
+  /* To ease portability.  Like in open.c.  */
+  if (strcmp (name, "/dev/null") == 0)
+    name = "NUL";
+
+  /* POSIX <https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_13>
+     specifies: "More than two leading <slash> characters shall be treated as
+     a single <slash> character."  */
+  if (ISSLASH (name[0]) && ISSLASH (name[1]) && ISSLASH (name[2]))
+    {
+      name += 2;
+      while (ISSLASH (name[1]))
+        name++;
+    }
+
+  size_t len = strlen (name);
+  size_t drive_prefix_len = (HAS_DEVICE (name) ? 2 : 0);
+
+  /* Remove trailing slashes (except the very first one, at position
+     drive_prefix_len), but remember their presence.  */
+  size_t rlen;
+  bool check_dir = false;
+
+  rlen = len;
+  while (rlen > drive_prefix_len && ISSLASH (name[rlen-1]))
+    {
+      check_dir = true;
+      if (rlen == drive_prefix_len + 1)
+        break;
+      rlen--;
+    }
+
+  /* Handle '' and 'C:'.  */
+  if (!check_dir && rlen == drive_prefix_len)
+    {
+      errno = ENOENT;
+      return INVALID_HANDLE_VALUE;
+    }
+
+  /* Handle '\\'.  */
+  if (rlen == 1 && ISSLASH (name[0]) && len >= 2)
+    {
+      errno = ENOENT;
+      return INVALID_HANDLE_VALUE;
+    }
+
+  const char *rname;
+  char *malloca_rname;
+  if (rlen == len)
+    {
+      rname = name;
+      malloca_rname = NULL;
+    }
+  else
+    {
+      malloca_rname = malloca (rlen + 1);
+      if (malloca_rname == NULL)
+        {
+          errno = ENOMEM;
+          return INVALID_HANDLE_VALUE;
+        }
+      memcpy (malloca_rname, name, rlen);
+      malloca_rname[rlen] = '\0';
+      rname = malloca_rname;
+    }
+
+  /* For the meaning of the flags, see
+     <https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/open-wopen>  */
+  /* Open a handle to the file.
+     CreateFile
+     <https://docs.microsoft.com/en-us/windows/desktop/api/fileapi/nf-fileapi-createfilea>
+     <https://docs.microsoft.com/en-us/windows/desktop/FileIO/creating-and-opening-files>  */
+  HANDLE handle =
+    CreateFile (rname,
+                ((flags & (O_WRONLY | O_RDWR)) != 0
+                 ? GENERIC_READ | GENERIC_WRITE
+                 : GENERIC_READ),
+                FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+                NULL,
+                ((flags & O_CREAT) != 0
+                 ? ((flags & O_EXCL) != 0
+                    ? CREATE_NEW
+                    : ((flags & O_TRUNC) != 0 ? CREATE_ALWAYS : OPEN_ALWAYS))
+                 : ((flags & O_TRUNC) != 0
+                    ? TRUNCATE_EXISTING
+                    : OPEN_EXISTING)),
+                /* FILE_FLAG_BACKUP_SEMANTICS is useful for opening directories,
+                   which is out-of-scope here.  */
+                /* FILE_FLAG_POSIX_SEMANTICS (treat file names that differ only
+                   in case as different) makes sense only when applied to *all*
+                   filesystem operations.  */
+                /* FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_POSIX_SEMANTICS */
+                FILE_ATTRIBUTE_NORMAL
+                | ((flags & O_TEMPORARY) != 0 ? FILE_FLAG_DELETE_ON_CLOSE : 0)
+                | ((flags & O_SEQUENTIAL ) != 0 ? FILE_FLAG_SEQUENTIAL_SCAN : 0)
+                | ((flags & O_RANDOM) != 0 ? FILE_FLAG_RANDOM_ACCESS : 0),
+                NULL);
+  if (handle == INVALID_HANDLE_VALUE)
+    switch (GetLastError ())
+      {
+      /* Some of these errors probably cannot happen with the specific flags
+         that we pass to CreateFile.  But who knows...  */
+      case ERROR_FILE_NOT_FOUND: /* The last component of rname does not exist.  */
+      case ERROR_PATH_NOT_FOUND: /* Some directory component in rname does not exist.  */
+      case ERROR_BAD_PATHNAME:   /* rname is such as '\\server'.  */
+      case ERROR_BAD_NETPATH:    /* rname is such as '\\nonexistentserver\share'.  */
+      case ERROR_BAD_NET_NAME:   /* rname is such as '\\server\nonexistentshare'.  */
+      case ERROR_INVALID_NAME:   /* rname contains wildcards, misplaced colon, etc.  */
+      case ERROR_DIRECTORY:
+        errno = ENOENT;
+        break;
+
+      case ERROR_ACCESS_DENIED:  /* rname is such as 'C:\System Volume Information\foo'.  */
+      case ERROR_SHARING_VIOLATION: /* rname is such as 'C:\pagefile.sys'.  */
+                                    /* XXX map to EACCES or EPERM? */
+        errno = EACCES;
+        break;
+
+      case ERROR_OUTOFMEMORY:
+        errno = ENOMEM;
+        break;
+
+      case ERROR_WRITE_PROTECT:
+        errno = EROFS;
+        break;
+
+      case ERROR_WRITE_FAULT:
+      case ERROR_READ_FAULT:
+      case ERROR_GEN_FAILURE:
+        errno = EIO;
+        break;
+
+      case ERROR_BUFFER_OVERFLOW:
+      case ERROR_FILENAME_EXCED_RANGE:
+        errno = ENAMETOOLONG;
+        break;
+
+      case ERROR_DELETE_PENDING: /* XXX map to EACCES or EPERM? */
+        errno = EPERM;
+        break;
+
+      default:
+        errno = EINVAL;
+        break;
+      }
+
+  if (malloca_rname != NULL)
+    {
+      int saved_errno = errno;
+      freea (malloca_rname);
+      errno = saved_errno;
+    }
+  return handle;
+}
+
+/* Executes an 'open' action.
+   Returns 0 upon success.  In case of failure, -1 is returned, with errno set.
+ */
+static int
+do_open (struct inheritable_handles *inh_handles, int newfd,
+         const char *filename, const char *directory,
+         int flags, mode_t mode, HANDLE curr_process)
+{
+  if (!(newfd >= 0 && newfd < _getmaxstdio ()))
+    {
+      errno = EBADF;
+      return -1;
+    }
+  if (grow_inheritable_handles (inh_handles, newfd) < 0)
+    return -1;
+  if (inh_handles->handles[newfd] != INVALID_HANDLE_VALUE
+      && !CloseHandle (inh_handles->handles[newfd]))
+    {
+      errno = EIO;
+      return -1;
+    }
+  if (filename == NULL)
+    {
+      errno = EINVAL;
+      return -1;
+    }
+  char *filename_to_free = NULL;
+  if (directory != NULL && IS_RELATIVE_FILE_NAME (filename))
+    {
+      char *real_filename = concatenated_filename (directory, filename, NULL);
+      if (real_filename == NULL)
+        {
+          errno = ENOMEM;
+          return -1;
+        }
+      filename = real_filename;
+      filename_to_free = real_filename;
+    }
+  HANDLE handle = open_handle (filename, flags, mode);
+  if (handle == INVALID_HANDLE_VALUE)
+    {
+      int saved_errno = errno;
+      free (filename_to_free);
+      errno = saved_errno;
+      return -1;
+    }
+  free (filename_to_free);
+  /* Duplicate the handle, so that it becomes inheritable.  */
+  if (!DuplicateHandle (curr_process, handle,
+                        curr_process, &inh_handles->handles[newfd],
+                        0, TRUE,
+                        DUPLICATE_CLOSE_SOURCE | DUPLICATE_SAME_ACCESS))
+    {
+      errno = EBADF; /* arbitrary */
+      return -1;
+    }
+  inh_handles->flags[newfd] = ((flags & O_APPEND) != 0 ? 32 : 0);
+  return 0;
+}
+
+/* Executes a 'dup2' action.
+   Returns 0 upon success.  In case of failure, -1 is returned, with errno set.
+ */
+static int
+do_dup2 (struct inheritable_handles *inh_handles, int oldfd, int newfd,
+         HANDLE curr_process)
+{
+  if (!(oldfd >= 0 && oldfd < inh_handles->count
+        && inh_handles->handles[oldfd] != INVALID_HANDLE_VALUE))
+    {
+      errno = EBADF;
+      return -1;
+    }
+  if (!(newfd >= 0 && newfd < _getmaxstdio ()))
+    {
+      errno = EBADF;
+      return -1;
+    }
+  if (newfd != oldfd)
+    {
+      if (grow_inheritable_handles (inh_handles, newfd) < 0)
+        return -1;
+      if (inh_handles->handles[newfd] != INVALID_HANDLE_VALUE
+          && !CloseHandle (inh_handles->handles[newfd]))
+        {
+          errno = EIO;
+          return -1;
+        }
+      /* Duplicate the handle, so that it a forthcoming do_close action on oldfd
+         has no effect on newfd.  */
+      if (!DuplicateHandle (curr_process, inh_handles->handles[oldfd],
+                            curr_process, &inh_handles->handles[newfd],
+                            0, TRUE, DUPLICATE_SAME_ACCESS))
+        {
+          errno = EBADF; /* arbitrary */
+          return -1;
+        }
+      inh_handles->flags[newfd] = 0;
+    }
+  return 0;
+}
+
+/* Executes a 'close' action.
+   Returns 0 upon success.  In case of failure, -1 is returned, with errno set.
+ */
+static int
+do_close (struct inheritable_handles *inh_handles, int fd)
+{
+  if (!(fd >= 0 && fd < inh_handles->count
+        && inh_handles->handles[fd] != INVALID_HANDLE_VALUE))
+    {
+      errno = EBADF;
+      return -1;
+    }
+  if (!CloseHandle (inh_handles->handles[fd]))
+    {
+      errno = EIO;
+      return -1;
+    }
+  inh_handles->handles[fd] = INVALID_HANDLE_VALUE;
+  return 0;
+}
+
 int
-__spawni (pid_t *pid, const char *file,
+__spawni (pid_t *pid, const char *prog_filename,
           const posix_spawn_file_actions_t *file_actions,
-          const posix_spawnattr_t *attrp, const char *const argv[],
+          const posix_spawnattr_t *attrp, const char *const prog_argv[],
           const char *const envp[], int use_path)
 {
-  /* Not yet implemented.  */
-  return ENOSYS;
+  /* Validate the arguments.  */
+  if (prog_filename == NULL
+      || (attrp != NULL
+          && ((attrp->_flags & ~POSIX_SPAWN_SETPGROUP) != 0
+              || attrp->_pgrp != 0
+              || ! sigisempty (&attrp->_sd)
+              || ! sigisempty (&attrp->_ss)
+              || attrp->_sp.sched_priority != 0
+              || attrp->_policy != 0)))
+    return EINVAL;
+
+  /* Process group handling:
+     Native Windows does not have the concept of process group, but it has the
+     concept of a console attached to a process.
+     So, we interpret the three cases as follows:
+       - Flag POSIX_SPAWN_SETPGROUP not set: Means, the child process is in the
+         same process group as the parent process.  We interpret this as a
+         request to reuse the same console.
+       - Flag POSIX_SPAWN_SETPGROUP set with attrp->_pgrp == 0: Means the child
+         process starts a process group of its own.  See
+         <https://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_spawnattr_getpgroup.html>
+         <https://pubs.opengroup.org/onlinepubs/9699919799/functions/setpgrp.html>
+         We interpret this as a request to detach from the current console.
+       - Flag POSIX_SPAWN_SETPGROUP set with attrp->_pgrp != 0: Means the child
+         process joins another, existing process group.  See
+         <https://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_spawnattr_getpgroup.html>
+         <https://pubs.opengroup.org/onlinepubs/9699919799/functions/setpgid.html>
+         We don't support this case; it produces error EINVAL above.  */
+  /* <https://docs.microsoft.com/en-us/windows/win32/procthread/process-creation-flags>  */
+  DWORD process_creation_flags =
+    (attrp != NULL && (attrp->_flags & POSIX_SPAWN_SETPGROUP) != 0 ? DETACHED_PROCESS : 0);
+
+  char *argv_mem_to_free;
+  const char **argv = prepare_spawn (prog_argv, &argv_mem_to_free);
+  if (argv == NULL)
+    return errno; /* errno is set here */
+  argv++;
+
+  /* Compose the command.  */
+  char *command = compose_command (argv);
+  if (command == NULL)
+    {
+      free (argv_mem_to_free);
+      return ENOMEM;
+    }
+
+  /* Copy *ENVP into a contiguous block of memory.  */
+  char *envblock;
+  if (envp == NULL)
+    envblock = NULL;
+  else
+    {
+      envblock = compose_envblock (envp);
+      if (envblock == NULL)
+        {
+          free (command);
+          free (argv_mem_to_free);
+          return ENOMEM;
+        }
+    }
+
+  /* Set up the array of handles to inherit.
+     Duplicate each handle, so that a spawn_do_close action (below) has no
+     effect on the file descriptors of the current process.  Alternatively,
+     we could store, for each handle, a bit that tells whether it is shared
+     with the current process.  But this is simpler.  */
+  struct inheritable_handles inh_handles;
+  if (init_inheritable_handles (&inh_handles, true) < 0)
+    goto failed_1;
+
+  /* Directory in which to execute the new process.  */
+  const char *directory = NULL;
+
+  /* Execute the file_actions, modifying the inh_handles instead of the
+     file descriptors of the current process.  */
+  if (file_actions != NULL)
+    {
+      HANDLE curr_process = GetCurrentProcess ();
+      int cnt;
+
+      for (cnt = 0; cnt < file_actions->_used; ++cnt)
+        {
+          struct __spawn_action *action = &file_actions->_actions[cnt];
+
+          switch (action->tag)
+            {
+            case spawn_do_close:
+              {
+                int fd = action->action.close_action.fd;
+                if (do_close (&inh_handles, fd) < 0)
+                  goto failed_2;
+              }
+              break;
+
+            case spawn_do_open:
+              {
+                int newfd = action->action.open_action.fd;
+                const char *filename = action->action.open_action.path;
+                int flags = action->action.open_action.oflag;
+                mode_t mode = action->action.open_action.mode;
+                if (do_open (&inh_handles, newfd, filename, directory,
+                             flags, mode, curr_process)
+                    < 0)
+                  goto failed_2;
+              }
+              break;
+
+            case spawn_do_dup2:
+              {
+                int oldfd = action->action.dup2_action.fd;
+                int newfd = action->action.dup2_action.newfd;
+                if (do_dup2 (&inh_handles, oldfd, newfd, curr_process) < 0)
+                  goto failed_2;
+              }
+              break;
+
+            case spawn_do_chdir:
+              {
+                char *newdir = action->action.chdir_action.path;
+                if (directory != NULL && IS_RELATIVE_FILE_NAME (newdir))
+                  {
+                    newdir = concatenated_filename (directory, newdir, NULL);
+                    if (newdir == NULL)
+                      {
+                        errno = ENOMEM;
+                        goto failed_2;
+                      }
+                  }
+                directory = newdir;
+              }
+              break;
+
+            case spawn_do_fchdir:
+              /* Not supported in this implementation.  */
+              errno = EINVAL;
+              goto failed_2;
+            }
+        }
+    }
+
+  /* Reduce inh_handles.count to the minimum needed.  */
+  shrink_inheritable_handles (&inh_handles);
+
+  /* CreateProcess
+     <https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-createprocessa>  */
+  /* STARTUPINFO
+     <https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/ns-processthreadsapi-startupinfoa>  */
+  STARTUPINFO sinfo;
+  sinfo.cb = sizeof (STARTUPINFO);
+  sinfo.lpReserved = NULL;
+  sinfo.lpDesktop = NULL;
+  sinfo.lpTitle = NULL;
+  if (compose_handles_block (&inh_handles, &sinfo) < 0)
+    goto failed_2;
+
+  /* Perform the PATH search now, considering the final DIRECTORY.  */
+  char *resolved_prog_filename_to_free = NULL;
+  {
+    const char *resolved_prog_filename =
+      find_in_given_path (prog_filename, use_path ? getenv ("PATH") : "",
+                          directory, false);
+    if (resolved_prog_filename == NULL)
+      goto failed_3;
+    if (resolved_prog_filename != prog_filename)
+      resolved_prog_filename_to_free = (char *) resolved_prog_filename;
+    prog_filename = resolved_prog_filename;
+  }
+
+  PROCESS_INFORMATION pinfo;
+  if (!CreateProcess (prog_filename, command, NULL, NULL, TRUE,
+                      process_creation_flags, envblock, directory, &sinfo,
+                      &pinfo))
+    {
+      DWORD error = GetLastError ();
+
+      free (resolved_prog_filename_to_free);
+      free (sinfo.lpReserved2);
+      close_inheritable_handles (&inh_handles);
+      free_inheritable_handles (&inh_handles);
+      free (envblock);
+      free (command);
+      free (argv_mem_to_free);
+
+      return convert_CreateProcess_error (error);
+    }
+
+  if (pinfo.hThread)
+    CloseHandle (pinfo.hThread);
+
+  free (resolved_prog_filename_to_free);
+  free (sinfo.lpReserved2);
+  close_inheritable_handles (&inh_handles);
+  free_inheritable_handles (&inh_handles);
+  free (envblock);
+  free (command);
+  free (argv_mem_to_free);
+
+  if (pid != NULL)
+    *pid = (intptr_t) pinfo.hProcess;
+  return 0;
+
+ failed_3:
+  {
+    int saved_errno = errno;
+    free (sinfo.lpReserved2);
+    close_inheritable_handles (&inh_handles);
+    free_inheritable_handles (&inh_handles);
+    free (envblock);
+    free (command);
+    free (argv_mem_to_free);
+    return saved_errno;
+  }
+
+ failed_2:
+  {
+    int saved_errno = errno;
+    close_inheritable_handles (&inh_handles);
+    free_inheritable_handles (&inh_handles);
+    free (envblock);
+    free (command);
+    free (argv_mem_to_free);
+    return saved_errno;
+  }
+
+ failed_1:
+  {
+    int saved_errno = errno;
+    free (envblock);
+    free (command);
+    free (argv_mem_to_free);
+    return saved_errno;
+  }
 }
 
 #else