System-dependent functions

src/system.c

@@ -0,0 +1,633 @@
+/* System-dependent calls for tar.
+
+   Copyright (C) 2003 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by the
+   Free Software Foundation; either version 2, or (at your option) any later
+   version.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General
+   Public License for more details.
+
+   You should have received a copy of the GNU General Public License along
+   with this program; if not, write to the Free Software Foundation, Inc.,
+   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+#include "system.h"
+
+#include "common.h"
+#include "rmt.h"
+
+#if MSDOS
+
+bool
+sys_get_archive_stat ()
+{
+  return 0;
+}
+
+bool
+sys_file_is_archive (struct tar_stat_info *p)
+{
+  return false;
+}
+
+void
+sys_save_archive_dev_ino ()
+{
+}
+
+void
+sys_detect_dev_null_output ()
+{
+  static char const dev_null[] = "nul";
+
+  dev_null_output = (strcmp (archive_name_array[0], dev_null) == 0
+		     || (! _isrmt (archive)));
+}
+
+void
+sys_drain_input_pipe ()
+{
+}
+
+void
+sys_wait_for_child (pid_t child_pid)
+{
+}
+
+void
+sys_spawn_shell ()
+{
+  spawnl (P_WAIT, getenv ("COMSPEC"), "-", 0);
+}
+
+void
+sys_compare_uid_gid (struct stat *a, struct stat *b)
+{
+  /* stat() in djgpp's C library gives a constant number of 42 as the
+     uid and gid of a file.  So, comparing an FTP'ed archive just after
+     unpack would fail on MSDOS.  */
+}
+
+void
+sys_compare_links (struct stat *link_data, struct stat *stat_data)
+{
+}
+
+int
+sys_truncate (int fd)
+{
+  return write (fd, "", 0);
+}
+
+void
+sys_reset_uid_gid ()
+{
+}
+
+ssize_t
+sys_write_archive_buffer (void)
+{
+  ssize_t status;
+  ssize_t written = 0;
+
+  while (0 <= (status = full_write (archive, record_start->buffer + written,
+				    record_size - written)))
+    {
+      written += status;
+      if (written == record_size)
+        break;
+    }
+
+  return written ? written : status;
+}
+
+/* Set ARCHIVE for writing, then compressing an archive.  */
+void
+sys_child_open_for_compress (void)
+{
+  FATAL_ERROR ((0, 0, _("Cannot use compressed or remote archives")));
+}
+
+/* Set ARCHIVE for uncompressing, then reading an archive.  */
+void
+sys_child_open_for_uncompress (void)
+{
+  FATAL_ERROR ((0, 0, _("Cannot use compressed or remote archives")));
+}
+
+#else
+
+extern union block *record_start; /* FIXME */
+
+static struct stat archive_stat; /* stat block for archive file */
+
+bool
+sys_get_archive_stat ()
+{
+  return fstat (archive, &archive_stat) == 0;
+}
+    
+bool
+sys_file_is_archive (struct tar_stat_info *p)
+{
+  return (ar_dev && p->stat.st_dev == ar_dev && p->stat.st_ino == ar_ino);
+}
+
+/* Save archive file inode and device numbers */
+void
+sys_save_archive_dev_ino ()
+{
+  if (!_isrmt (archive) && S_ISREG (archive_stat.st_mode))
+    {
+      ar_dev = archive_stat.st_dev;
+      ar_ino = archive_stat.st_ino;
+    }
+  else
+    ar_dev = 0;
+}
+
+/* Detect if outputting to "/dev/null".  */
+void
+sys_detect_dev_null_output ()
+{
+  static char const dev_null[] = "/dev/null";
+  struct stat dev_null_stat;
+
+  dev_null_output = (strcmp (archive_name_array[0], dev_null) == 0
+		     || (! _isrmt (archive)
+			 && S_ISCHR (archive_stat.st_mode)
+			 && stat (dev_null, &dev_null_stat) == 0
+			 && archive_stat.st_dev == dev_null_stat.st_dev
+			 && archive_stat.st_ino == dev_null_stat.st_ino));
+}
+
+/* Manage to fully drain a pipe we might be reading, so to not break it on
+   the producer after the EOF block.  FIXME: one of these days, GNU tar
+   might become clever enough to just stop working, once there is no more
+   work to do, we might have to revise this area in such time.  */
+
+void
+sys_drain_input_pipe ()
+{
+  if (access_mode == ACCESS_READ
+      && ! _isrmt (archive)
+      && (S_ISFIFO (archive_stat.st_mode) || S_ISSOCK (archive_stat.st_mode)))
+    while (rmtread (archive, record_start->buffer, record_size) > 0)
+      continue;
+}
+
+void
+sys_wait_for_child (pid_t child_pid)
+{
+  if (child_pid)
+    {
+      int wait_status;
+
+      while (waitpid (child_pid, &wait_status, 0) == -1)
+	if (errno != EINTR)
+	  {
+	    waitpid_error (use_compress_program_option);
+	    break;
+	  }
+
+      if (WIFSIGNALED (wait_status))
+	ERROR ((0, 0, _("Child died with signal %d"),
+		WTERMSIG (wait_status)));
+      else if (WEXITSTATUS (wait_status) != 0)
+	ERROR ((0, 0, _("Child returned status %d"),
+		WEXITSTATUS (wait_status)));
+    }
+}
+
+void
+sys_spawn_shell ()
+{
+  pid_t child;
+  const char *shell = getenv ("SHELL");
+  if (! shell)
+    shell = "/bin/sh";
+  child = xfork ();
+  if (child == 0)
+    {
+      execlp (shell, "-sh", "-i", 0);
+      exec_fatal (shell);
+    }
+  else
+    {
+      int wait_status;
+      while (waitpid (child, &wait_status, 0) == -1)
+	if (errno != EINTR)
+	  {
+	    waitpid_error (shell);
+	    break;
+	  }
+    }
+}
+
+void
+sys_compare_uid_gid (struct stat *a, struct stat *b)
+{
+  if (a->st_uid != b->st_uid)
+    report_difference (_("Uid differs"));
+  if (a->st_gid != b->st_gid)
+    report_difference (_("Gid differs"));
+}
+
+void
+sys_compare_links (struct stat *link_data, struct stat *stat_data)
+{
+  if (stat_data->st_dev != link_data->st_dev
+      || stat_data->st_ino != link_data->st_ino)
+    {
+      report_difference (_("Not linked to %s"),
+			 quote (current_stat_info.link_name));
+    }
+}
+
+int
+sys_truncate (int fd)
+{
+  off_t pos = lseek (fd, (off_t) 0, SEEK_CUR);
+  return pos < 0 ? -1 : ftruncate (fd, pos);
+}
+
+void
+sys_reset_uid_gid ()
+{
+  setuid (getuid ());
+  setgid (getgid ());
+}
+
+/* Return nonzero if NAME is the name of a regular file, or if the file
+   does not exist (so it would be created as a regular file).  */
+static int
+is_regular_file (const char *name)
+{
+  struct stat stbuf;
+
+  if (stat (name, &stbuf) == 0)
+    return S_ISREG (stbuf.st_mode);
+  else
+    return errno == ENOENT;
+}
+
+ssize_t
+sys_write_archive_buffer (void)
+{
+  ssize_t status;
+  ssize_t written = 0;
+
+  while (0 <= (status = rmtwrite (archive, record_start->buffer + written,
+				  record_size - written)))
+    {
+      written += status;
+      if (written == record_size
+	  || _isrmt (archive)
+	  || ! (S_ISFIFO (archive_stat.st_mode)
+		|| S_ISSOCK (archive_stat.st_mode)))
+	break;
+    }
+
+  return written ? written : status;
+}
+
+#define	PREAD 0			/* read file descriptor from pipe() */
+#define	PWRITE 1		/* write file descriptor from pipe() */
+
+/* Duplicate file descriptor FROM into becoming INTO.
+   INTO is closed first and has to be the next available slot.  */
+static void
+xdup2 (int from, int into)
+{
+  if (from != into)
+    {
+      int status = close (into);
+
+      if (status != 0 && errno != EBADF)
+	{
+	  int e = errno;
+	  FATAL_ERROR ((0, e, _("Cannot close")));
+	}
+      status = dup (from);
+      if (status != into)
+	{
+	  if (status < 0)
+	    {
+	      int e = errno;
+	      FATAL_ERROR ((0, e, _("Cannot dup")));
+	    }
+	  abort ();
+	}
+      xclose (from);
+    }
+}
+
+/* Set ARCHIVE for writing, then compressing an archive.  */
+pid_t
+sys_child_open_for_compress (void)
+{
+  int parent_pipe[2];
+  int child_pipe[2];
+  pid_t grandchild_pid;
+  pid_t child_pid;
+  int wait_status;
+
+  xpipe (parent_pipe);
+  child_pid = xfork ();
+
+  if (child_pid > 0)
+    {
+      /* The parent tar is still here!  Just clean up.  */
+
+      archive = parent_pipe[PWRITE];
+      xclose (parent_pipe[PREAD]);
+      return child_pid;
+    }
+
+  /* The new born child tar is here!  */
+
+  program_name = _("tar (child)");
+
+  xdup2 (parent_pipe[PREAD], STDIN_FILENO);
+  xclose (parent_pipe[PWRITE]);
+
+  /* Check if we need a grandchild tar.  This happens only if either:
+     a) we are writing stdout: to force reblocking;
+     b) the file is to be accessed by rmt: compressor doesn't know how;
+     c) the file is not a plain file.  */
+
+  if (strcmp (archive_name_array[0], "-") != 0
+      && !_remdev (archive_name_array[0])
+      && is_regular_file (archive_name_array[0]))
+    {
+      if (backup_option)
+	maybe_backup_file (archive_name_array[0], 1);
+
+      /* We don't need a grandchild tar.  Open the archive and launch the
+	 compressor.  */
+
+      archive = creat (archive_name_array[0], MODE_RW);
+      if (archive < 0)
+	{
+	  int saved_errno = errno;
+
+	  if (backup_option)
+	    undo_last_backup ();
+	  errno = saved_errno;
+	  open_fatal (archive_name_array[0]);
+	}
+      xdup2 (archive, STDOUT_FILENO);
+      execlp (use_compress_program_option, use_compress_program_option,
+	      (char *) 0);
+      exec_fatal (use_compress_program_option);
+    }
+
+  /* We do need a grandchild tar.  */
+
+  xpipe (child_pipe);
+  grandchild_pid = xfork ();
+
+  if (grandchild_pid == 0)
+    {
+      /* The newborn grandchild tar is here!  Launch the compressor.  */
+
+      program_name = _("tar (grandchild)");
+
+      xdup2 (child_pipe[PWRITE], STDOUT_FILENO);
+      xclose (child_pipe[PREAD]);
+      execlp (use_compress_program_option, use_compress_program_option,
+	      (char *) 0);
+      exec_fatal (use_compress_program_option);
+    }
+
+  /* The child tar is still here!  */
+
+  /* Prepare for reblocking the data from the compressor into the archive.  */
+
+  xdup2 (child_pipe[PREAD], STDIN_FILENO);
+  xclose (child_pipe[PWRITE]);
+
+  if (strcmp (archive_name_array[0], "-") == 0)
+    archive = STDOUT_FILENO;
+  else
+    {
+      archive = rmtcreat (archive_name_array[0], MODE_RW, rsh_command_option);
+      if (archive < 0)
+	open_fatal (archive_name_array[0]);
+    }
+
+  /* Let's read out of the stdin pipe and write an archive.  */
+
+  while (1)
+    {
+      ssize_t status = 0;
+      char *cursor;
+      size_t length;
+
+      /* Assemble a record.  */
+
+      for (length = 0, cursor = record_start->buffer;
+	   length < record_size;
+	   length += status, cursor += status)
+	{
+	  size_t size = record_size - length;
+
+	  status = safe_read (STDIN_FILENO, cursor, size);
+	  if (status <= 0)
+	    break;
+	}
+
+      if (status < 0)
+	read_fatal (use_compress_program_option);
+
+      /* Copy the record.  */
+
+      if (status == 0)
+	{
+	  /* We hit the end of the file.  Write last record at
+	     full length, as the only role of the grandchild is
+	     doing proper reblocking.  */
+
+	  if (length > 0)
+	    {
+	      memset (record_start->buffer + length, 0, record_size - length);
+	      status = sys_write_archive_buffer ();
+	      if (status != record_size)
+		archive_write_error (status);
+	    }
+
+	  /* There is nothing else to read, break out.  */
+	  break;
+	}
+
+      status = sys_write_archive_buffer ();
+      if (status != record_size)
+	archive_write_error (status);
+    }
+
+  /* Propagate any failure of the grandchild back to the parent.  */
+
+  while (waitpid (grandchild_pid, &wait_status, 0) == -1)
+    if (errno != EINTR)
+      {
+	waitpid_error (use_compress_program_option);
+	break;
+      }
+
+  if (WIFSIGNALED (wait_status))
+    {
+      kill (child_pid, WTERMSIG (wait_status));
+      exit_status = TAREXIT_FAILURE;
+    }
+  else if (WEXITSTATUS (wait_status) != 0)
+    exit_status = WEXITSTATUS (wait_status);
+
+  exit (exit_status);
+}
+
+/* Set ARCHIVE for uncompressing, then reading an archive.  */
+pid_t
+sys_child_open_for_uncompress (void)
+{
+  int parent_pipe[2];
+  int child_pipe[2];
+  pid_t grandchild_pid;
+  pid_t child_pid;
+  int wait_status;
+
+  xpipe (parent_pipe);
+  child_pid = xfork ();
+
+  if (child_pid > 0)
+    {
+      /* The parent tar is still here!  Just clean up.  */
+
+      read_full_records_option = 1;
+      archive = parent_pipe[PREAD];
+      xclose (parent_pipe[PWRITE]);
+      return child_pid;
+    }
+
+  /* The newborn child tar is here!  */
+
+  program_name = _("tar (child)");
+
+  xdup2 (parent_pipe[PWRITE], STDOUT_FILENO);
+  xclose (parent_pipe[PREAD]);
+
+  /* Check if we need a grandchild tar.  This happens only if either:
+     a) we're reading stdin: to force unblocking;
+     b) the file is to be accessed by rmt: compressor doesn't know how;
+     c) the file is not a plain file.  */
+
+  if (strcmp (archive_name_array[0], "-") != 0
+      && !_remdev (archive_name_array[0])
+      && is_regular_file (archive_name_array[0]))
+    {
+      /* We don't need a grandchild tar.  Open the archive and lauch the
+	 uncompressor.  */
+
+      archive = open (archive_name_array[0], O_RDONLY | O_BINARY, MODE_RW);
+      if (archive < 0)
+	open_fatal (archive_name_array[0]);
+      xdup2 (archive, STDIN_FILENO);
+      execlp (use_compress_program_option, use_compress_program_option,
+	      "-d", (char *) 0);
+      exec_fatal (use_compress_program_option);
+    }
+
+  /* We do need a grandchild tar.  */
+
+  xpipe (child_pipe);
+  grandchild_pid = xfork ();
+
+  if (grandchild_pid == 0)
+    {
+      /* The newborn grandchild tar is here!  Launch the uncompressor.  */
+
+      program_name = _("tar (grandchild)");
+
+      xdup2 (child_pipe[PREAD], STDIN_FILENO);
+      xclose (child_pipe[PWRITE]);
+      execlp (use_compress_program_option, use_compress_program_option,
+	      "-d", (char *) 0);
+      exec_fatal (use_compress_program_option);
+    }
+
+  /* The child tar is still here!  */
+
+  /* Prepare for unblocking the data from the archive into the
+     uncompressor.  */
+
+  xdup2 (child_pipe[PWRITE], STDOUT_FILENO);
+  xclose (child_pipe[PREAD]);
+
+  if (strcmp (archive_name_array[0], "-") == 0)
+    archive = STDIN_FILENO;
+  else
+    archive = rmtopen (archive_name_array[0], O_RDONLY | O_BINARY,
+		       MODE_RW, rsh_command_option);
+  if (archive < 0)
+    open_fatal (archive_name_array[0]);
+
+  /* Let's read the archive and pipe it into stdout.  */
+
+  while (1)
+    {
+      char *cursor;
+      size_t maximum;
+      size_t count;
+      ssize_t status;
+
+      clear_read_error_count ();
+
+    error_loop:
+      status = rmtread (archive, record_start->buffer, record_size);
+      if (status < 0)
+	{
+	  archive_read_error ();
+	  goto error_loop;
+	}
+      if (status == 0)
+	break;
+      cursor = record_start->buffer;
+      maximum = status;
+      while (maximum)
+	{
+	  count = maximum < BLOCKSIZE ? maximum : BLOCKSIZE;
+	  if (full_write (STDOUT_FILENO, cursor, count) != count)
+	    write_error (use_compress_program_option);
+	  cursor += count;
+	  maximum -= count;
+	}
+    }
+
+  xclose (STDOUT_FILENO);
+
+  /* Propagate any failure of the grandchild back to the parent.  */
+
+  while (waitpid (grandchild_pid, &wait_status, 0) == -1)
+    if (errno != EINTR)
+      {
+	waitpid_error (use_compress_program_option);
+	break;
+      }
+
+  if (WIFSIGNALED (wait_status))
+    {
+      kill (child_pid, WTERMSIG (wait_status));
+      exit_status = TAREXIT_FAILURE;
+    }
+  else if (WEXITSTATUS (wait_status) != 0)
+    exit_status = WEXITSTATUS (wait_status);
+
+  exit (exit_status);
+}
+
+#endif /* not MSDOS */
+