2 files changed, 159 insertions, 0 deletions
diff --git a/lib/save-cwd.c b/lib/save-cwd.c
new file mode 100644
index 000000000..8e0d6dd51
--- /dev/null
+++ b/lib/save-cwd.c
@@ -0,0 +1,136 @@
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <stdio.h>
+
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+#endif
+
+#ifdef HAVE_UNISTD_H
+# include <unistd.h>
+#endif
+
+#ifdef HAVE_FCNTL_H
+# include <fcntl.h>
+#else
+# include <sys/file.h>
+#endif
+
+#include <errno.h>
+# ifndef errno
+extern int errno;
+#endif
+
+#include "save-cwd.h"
+#include "error.h"
+
+char *xgetcwd __P((void));
+
+/* Record the location of the current working directory in CWD so that
+   the program may change to other directories and later use restore_cwd
+   to return to the recorded location.  This function may allocate
+   space using malloc (via xgetcwd) or leave a file descriptor open;
+   use free_cwd to perform the necessary free or close.  Upon failure,
+   no memory is allocated, any locally opened file descriptors are
+   closed;  return non-zero -- in that case, free_cwd need not be
+   called, but doing so is ok.  Otherwise, return zero.  */
+
+int
+save_cwd (cwd)
+     struct saved_cwd *cwd;
+{
+  static int have_working_fchdir = 1;
+
+  cwd->desc = -1;
+  cwd->name = NULL;
+
+  if (have_working_fchdir)
+    {
+#ifdef HAVE_FCHDIR
+      cwd->desc = open (".", O_RDONLY);
+      if (cwd->desc < 0)
+	{
+	  error (0, errno, "cannot open current directory");
+	  return 1;
+	}
+
+# if __sun__ || sun
+      /* On SunOS 4, fchdir returns EINVAL if accounting is enabled,
+	 so we have to fall back to chdir.  */
+      if (fchdir (cwd->desc))
+	{
+	  if (errno == EINVAL)
+	    {
+	      close (cwd->desc);
+	      cwd->desc = -1;
+	      have_working_fchdir = 0;
+	    }
+	  else
+	    {
+	      error (0, errno, "current directory");
+	      close (cwd->desc);
+	      cwd->desc = -1;
+	      return 1;
+	    }
+	}
+# endif /* __sun__ || sun */
+#else
+#define fchdir(x) (abort (), 0)
+      have_working_fchdir = 0;
+#endif
+    }
+
+  if (!have_working_fchdir)
+    {
+      cwd->name = xgetcwd ();
+      if (cwd->name == NULL)
+	{
+	  error (0, errno, "cannot get current directory");
+	  return 1;
+	}
+    }
+  return 0;
+}
+
+/* Change to recorded location, CWD, in directory hierarchy.
+   If "saved working directory", NULL))
+   */
+
+int
+restore_cwd (cwd, dest, from)
+     const struct saved_cwd *cwd;
+     const char *dest;
+     const char *from;
+{
+  int fail = 0;
+  if (cwd->desc >= 0)
+    {
+      if (fchdir (cwd->desc))
+	{
+	  error (0, errno, "cannot return to %s%s%s",
+		 (dest ? dest : "saved working directory"),
+		 (from ? " from " : ""),
+		 (from ? from : ""));
+	  fail = 1;
+	}
+    }
+  else if (chdir (cwd->name) < 0)
+    {
+      error (0, errno, "%s", cwd->name);
+      fail = 1;
+    }
+  return fail;
+}
+
+void
+free_cwd (cwd)
+     struct saved_cwd *cwd;
+{
+  if (cwd->desc >= 0)
+    close (cwd->desc);
+  if (cwd->name)
+    free (cwd->name);
+}
+
diff --git a/lib/save-cwd.h b/lib/save-cwd.h
new file mode 100644
index 000000000..8f9d07def
--- /dev/null
+++ b/lib/save-cwd.h
@@ -0,0 +1,23 @@
+#ifndef SAVE_CWD_H
+#define SAVE_CWD_H 1
+
+struct saved_cwd
+  {
+    int desc;
+    char *name;
+  };
+
+#ifndef __P
+#if defined (__GNUC__) || (defined (__STDC__) && __STDC__)
+#define __P(args) args
+#else
+#define __P(args) ()
+#endif  /* GCC.  */
+#endif  /* Not __P.  */
+
+int save_cwd __P((struct saved_cwd *cwd));
+int restore_cwd __P((const struct saved_cwd *cwd, const char *dest,
+		     const char *from));
+void free_cwd __P((struct saved_cwd *cwd));
+
+#endif /* SAVE_CWD_H */