cygwin_conv_path
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## Name

cygwin_conv_path

## Synopsis

    #include <sys/cygwin.h>

`ssize_t cygwin_conv_path(`cygwin_conv_path_t what, const void * from, void * to, size_t size`)`;

## Description

Use this function to convert NUL-terminated POSIX paths in `from` to NUL-terminated Win32 paths in `to` or, vice versa, NUL-terminated Win32 paths in `from` to NUL-terminated POSIX paths in `to`. `what` defines the direction of this conversion and can be any of the below values.

      CCP_POSIX_TO_WIN_A      /* from is char *posix, to is char *win32       */
      CCP_POSIX_TO_WIN_W,     /* from is char *posix, to is wchar_t *win32    */
      CCP_WIN_A_TO_POSIX,     /* from is char *win32, to is char *posix       */
      CCP_WIN_W_TO_POSIX,     /* from is wchar_t *win32, to is char *posix    */

You can additionally or the following values to `what`, to define whether you want the resulting path in `to` to be absolute or if you want to keep relative paths in relative notation. Creating absolute paths is the default.

      CCP_ABSOLUTE = 0,         /* Request absolute path (default).             */
      CCP_RELATIVE = 0x100      /* Request to keep path relative.               */
      CCP_PROC_CYGDRIVE = 0x200 /* Request to return /proc/cygdrive path
                                   (only with CCP_*_TO_POSIX).                  */

`size` is the size of the buffer pointed to by `to` in bytes. If `size` is 0, `to` may be NULL and `cygwin_conv_path` just returns the required buffer size in bytes. Otherwise, it returns 0 on success, or -1 on error and errno is set to one of the below values.

        EINVAL        what has an invalid value or from is NULL.
        EFAULT        from or to point into nirvana.
        ENAMETOOLONG  the resulting path is longer than 32K, or, in case
                      of what == CCP_POSIX_TO_WIN_A, longer than MAX_PATH.
        ENOSPC        size is less than required for the conversion.

In the event of an error, the memory at `to` is not modified unless the error is `EFAULT` writing to the memory at `to`, which may happen if `size` is incorrectly specified.

## Example

Example 2.1. Example use of cygwin_conv_path

    #include <sys/cygwin.h>

    /* Conversion from incoming Win32 path given as wchar_t *win32 to POSIX path.
       If incoming path is a relative path, stick to it.  First ask how big
       the output buffer has to be and allocate space dynamically. */
    ssize_t size;
    char *posix;
    size = cygwin_conv_path (CCP_WIN_W_TO_POSIX | CCP_RELATIVE, win32, NULL, 0);
    if (size < 0)
      perror ("cygwin_conv_path");
    else
      {
        posix = (char *) malloc (size);
        if (cygwin_conv_path (CCP_WIN_W_TO_POSIX | CCP_RELATIVE, win32,
                              posix, size))
          perror ("cygwin_conv_path");
      }

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