/* $Id: file_utils.c,v 1.2 2002/01/11 08:44:55 fors Exp $
 * ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 * COPYRIGHT (c) 2001 European Southern Observatory
 * LICENSE: GNU General Public License version 2 or later
 *
 * PROJECT:   VLT Data Flow System
 * AUTHOR:    Ralf Palsa -- ESO/DMD/DPG
 * SUBSYSTEM: Instrument pipelines
 *
 * PURPOSE:
 * DESCRIPTION:
 *
 * $Name: fsmosaic-1_0 $
 * $Revision: 1.2 $
 * ----------------------------------------------------------------------------
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>


/**
 * @memo
 *   Copy a file.
 *
 * @return The function returns 0 if no error occurred, otherwise -1 is
 *    returned and errno is set appropriately.
 *
 * @param srcpath  Source file name.
 * @param dstpath  Destination file name.
 *
 * @doc
 *   The function provides a very basic way to copy the source file 
 *   \textbf{srcpath} to a destination file \textbf{dstpath}.
 *   The implementation just uses \textbf{read()} and \textbf{write()}
 *   to do the job. It is by far not comparable with the \textbf{cp}
 *   shell command. Actually it just writes the source file contents into
 *   a new file with the appropriate output name.
 *
 *   If an error occurs the destination file is removed before the function
 *   returns.
 *
 * @author R. Palsa
 */

int copy(const char *srcpath, const char *dstpath)
{

  int src, dst;
  struct stat sb, db;
  char *buf;
  ssize_t rbytes = 0, wbytes = 0, blksize = 4096;


  if ((src = open(srcpath, O_RDONLY)) == -1)
    return -1;
  else {
    if (fstat(src, &sb) == -1 || !S_ISREG(sb.st_mode)) {
      close(src);
      return -1;
    }

    if ((dst = open(dstpath, O_CREAT | O_WRONLY | O_TRUNC,
		    sb.st_mode)) == -1) {
      close(src);
      return -1;
    }
    else 
      if (fstat(dst, &db) == -1 || !S_ISREG(db.st_mode)) {
	close(src);
	close(dst);
	unlink(dstpath);
	return -1;
      }
  }

#ifdef HAVE_ST_BLOCKS
  blksize = db.st_blksize;
#else
#ifdef DEV_BSIZE
  blksize = DEV_BSIZE;
#endif
#endif

  if ((buf = (char *)malloc(blksize)) == NULL) {
    close(src);
    close(dst);
    unlink(dstpath);
    return -1;
  }

  while ((rbytes = read(src, buf, blksize)) > 0)
    if ((wbytes = write(dst, buf, rbytes)) != rbytes) {
      wbytes = -1;
      break;
    }

  close(src);
  close(dst);
  free(buf);
  
  if (rbytes == -1 || wbytes == -1) {
    unlink(dstpath);
    return -1;
  }
  
  return 0;

}


/*
 * @memo
 *   Strip non-directory suffix from a filename.
 *
 * @return Pointer to the stripped filename, or #NULL# in case an error
 *    occurred.
 *
 * @param filename  Path to the file.
 *
 * @doc
 *   The function removes the trailing directory component from
 *   \textbf{filename}. If filename does not contain any slashes the
 *   result is the current working directory. The input string must
 *    not contain more than PATHNAME_MAX characters.
 *
 *   The result is stored in a static, internal buffer, i.e. it is
 *   overwritten by the next call to \textbf{dir_name()}.
 *
 * @author R. Palsa
 */

char *dir_name(const char *filename)
{

  static char dirname[PATHNAME_MAX + 1];

  size_t sz;

  char *s;


  /*
   * Is there any slash?
   */

  if (!(s = strrchr(filename, '/'))) {
    if (!getcwd(dirname, PATHNAME_MAX))
      return NULL;
  }
  else {
    if ((sz = s - filename) > PATHNAME_MAX)
      return NULL;
    else {
      strncpy(dirname, filename, sz);
      dirname[sz + 1] = '\0';
    }
  }

  return dirname;

}


/*@}*/