DCMTK: OFFile Class Reference

DCMTK Version 3.7.0 OFFIS DICOM Toolkit

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Public Member Functions | Private Member Functions | Private Attributes | List of all members
OFFile Class Reference

this class provides a simple C++ encapsulation layer for stdio FILE pointers. More...

## Public Member Functions
| OFFile ()
| default constructor, creates an object that is not associated with any file.
| OFFile (FILE *f)
| create object for given stdio FILE
| ~OFFile ()
| destructor. Closes file if still open.
OFBool | fopen (const char *filename, const char *modes)
| opens the file whose name is the string pointed to by path and associates a stream with it.
OFBool | wfopen (const wchar_t *filename, const wchar_t *modes)
| opens the file whose name is the wide character string pointed to by path and associates a stream with it.
OFBool | fopen (const OFFilename &filename, const char *modes)
| opens the file whose name is a conventional or wide character string pointed to by path and associates.
OFBool | fdopen (int fd, const char *modes)
| associates a stream with the existing file descriptor 'fd'.
OFBool | popen (const char *command, const char *modes)
| opens a process by creating a pipe, forking, and invoking the shell.
OFBool | freopen (const char *filename, const char *modes)
| opens the file whose name is the string pointed to by path and associates the stream pointed maintained by this object with it.
OFBool | tmpfile ()
| generates a unique temporary filename.
int | fclose ()
| dissociates the named stream from its underlying file or set of functions.
int | pclose ()
| waits for the associated process (created with popen) to terminate and returns the exit status of the command as returned by wait4.
size_t | fwrite (const void *ptr, size_t size, size_t n)
| writes n elements of data, each size bytes long, to the stream, obtaining them from the location given by ptr.
size_t | fread (void *ptr, size_t size, size_t n)
| reads n elements of data, each size bytes long, from the stream, storing them at the location given by ptr.
int | fflush ()
| forces a write of all user-space buffered data for the given output or update stream via the stream's underlying write function.
int | fgetc ()
| reads the next character from stream and returns it as an unsigned char cast to an int, or EOF on end of file or error.
void | setlinebuf ()
| The three types of buffering available are unbuffered, block buffered, and line buffered.
void | rewind ()
| sets the file position indicator for the stream pointed to by stream to the beginning of the file.
void | clearerr ()
| clears the end-of-file and error indicators for the stream
int | eof () const
| tests the end-of-file indicator for the stream, returning non-zero if it is set.
int | error ()
| tests the error indicator for the stream, returning non-zero if it is set.
int | fileNo ()
| returns the low-level file descriptor associated with the stream.
void | setbuf (char *buf)
| The three types of buffering available are unbuffered, block buffered, and line buffered.
int | setvbuf (char *buf, int modes, size_t n)
| The three types of buffering available are unbuffered, block buffered, and line buffered.
void | setbuffer (char *buf, size_t size)
| The three types of buffering available are unbuffered, block buffered, and line buffered.
int | fputc (int c)
| writes the character c, cast to an unsigned char, to stream.
char * | fgets (char *s, int n)
| reads in at most one less than n characters from stream and stores them into the buffer pointed to by s.
int | fputs (const char *s)
| writes the string s to stream, without its trailing '\0'.
int | ungetc (int c)
| pushes c back to stream, cast to unsigned char, where it is available for subsequent read operations.
int | fseek (offile_off_t off, int whence)
| sets the file position indicator for the stream pointed to by stream.
offile_off_t | ftell ()
| obtains the current value of the file position indicator for the stream pointed to by the stream.
int | fgetpos (offile_fpos_t *pos)
| alternate interface equivalent to ftell, storing the current value of the file offset into the object referenced by pos.
int | fsetpos (offile_fpos_t *pos)
| alternate interface equivalent to fseek (with whence set to SEEK_SET), setting the current value of the file offset from the object referenced by pos.
int | fprintf (const char *format,...)
| print formatted string into stream, see printf(3)
int | vfprintf (const char *format, va_list arg)
| print formatted string into stream, see printf(3)
FILE * | file ()
| return FILE pointer managed by this object.
OFBool | open () const
| return true if this object is currently associated with a stream, false otherwise
offile_errno_t | getLastError () const
| return last error code for this stream
void | getLastErrorString (OFString &s) const
| return string describing last error code for this stream
int | fwide (int mode)
| When mode is zero, the fwide function determines the current orientation of stream.
wint_t | fgetwc ()
| reads a wide character from stream and returns it.
wint_t | fputwc (wchar_t wc)
| writes the wide character wc to stream.
wint_t | ungetwc (wint_t wc)
| pushes back a wide character onto stream and returns it.
int | fwprintf (const wchar_t *format,...)
| print formatted wide string into stream, see wprintf(3)
int | vfwprintf (const wchar_t *format, va_list arg)
| print formatted wide string into stream, see printf(3)

## Private Member Functions
void | storeLastError ()
| store last error code. For now we simply store the content of errno.

## Private Attributes
FILE * | file_
| the file maintained by this object
OFBool | popened_
| a flag indicating whether or not this object was created with popen().
offile_errno_t | lasterror_
| the last error code for operations of this stream

## Detailed Description

this class provides a simple C++ encapsulation layer for stdio FILE pointers.

All stdio functions on files are directly mapped into member functions. The handling of large files (64 bit file systems) is transparent. Instead of type off_t, fseek() and ftell() use offile_off_t which is a 64 bit type if available on the underlying platform. Similarly, getpos() and setpos() use type offile_fpos_t, which is defined appropriately. This class provides both fclose() and pclose(), but these are equivalent - the code always closes pipes with pclose() and files with fclose(). Finally, an abstraction for errno is provided. Error codes should always be retrieves using methods getLastError() and getLastErrorString() which on Unix platforms are based on errno and strerror/strerror_r, but may be based on other mechanisms on platforms where errno does not exist.

## Constructor & Destructor Documentation

## ◆ OFFile()

OFFile::OFFile | ( | FILE * | f | ) |
| inline

create object for given stdio FILE

Parameters

  f | stdio FILE

References file_, lasterror_, and popened_.

## Member Function Documentation

## ◆ eof()

int OFFile::eof | ( |  | ) | const
| inline

tests the end-of-file indicator for the stream, returning non-zero if it is set.

The end-of-file indicator can only be cleared by the function clearerr. This method is called eof, not feof, because feof() is a macro on some systems and, therefore, cannot be used as a method name.

Returns
  non-zero if EOF, zero otherwise

References file_.

## ◆ error()

int OFFile::error | ( |  | ) |
| inline

tests the error indicator for the stream, returning non-zero if it is set.

This method is named error, not ferror, because ferror() is a macro on some systems and, therefore, cannot be used as a method name. The error indicator can only be reset by the clearerr function.

Returns
  non-zero if error flag is set, zero otherwise

References file_.

## ◆ fclose()

int OFFile::fclose | ( |  | ) |

dissociates the named stream from its underlying file or set of functions.

If the stream was being used for output, any buffered data is written first, using fflush. Independent of the return value of this method, any further access (including another call to fclose()) to the stream maintained by this object results in undefined behaviour.

Returns
  0 upon success, EOF otherwise, in which case the error code is set.

Referenced by ~OFFile(), fdopen(), fopen(), pclose(), tmpfile(), and wfopen().

## ◆ fdopen()

OFBool OFFile::fdopen | ( | int | fd,
|  | const char * | modes )
| inline

associates a stream with the existing file descriptor 'fd'.

The mode of the stream (one of the values "r", "r+", "w", "w+", "a", "a+") must be compatible with the mode of the file descriptor. The file position indicator of the new stream is set to that belonging to 'fd', and the error and end-of-file indicators are cleared. Modes "w" or "w+" do not cause truncation of the file. The file descriptor is not dup'ed, and will be closed when the stream created by fdopen is closed. The result of applying fdopen to a shared memory object is undefined.

Parameters

  fd | file descriptor
  modes | "r", "w" or "a" with possible modifiers "+", "b"

Returns
  true if stream was successfully created, false otherwise, in which case the error code is set.

References fclose(), file_, popened_, and storeLastError().

## ◆ fflush()

int OFFile::fflush | ( |  | ) |
| inline

forces a write of all user-space buffered data for the given output or update stream via the stream's underlying write function.

The open status of the stream is unaffected.

Returns
  0 upon success, EOF otherwise, in which case the error code is set.

References file_, and storeLastError().

## ◆ fgetc()

int OFFile::fgetc | ( |  | ) |
| inline

reads the next character from stream and returns it as an unsigned char cast to an int, or EOF on end of file or error.

Returns
  next character from stream or EOF

References file_.

## ◆ fgetpos()

int OFFile::fgetpos | ( | offile_fpos_t * | pos | ) |
| inline

alternate interface equivalent to ftell, storing the current value of the file offset into the object referenced by pos.

On some non-UNIX systems an fpos_t object may be a complex object and these routines may be the only way to portably reposition a text stream.

Parameters

  pos | pointer to offile_fpos_t structure

Returns
  0 upon success, -1 otherwise in which case the error code is set.

References file_, and storeLastError().

Referenced by fseek(), and ftell().

## ◆ fgets()

char * OFFile::fgets | ( | char * | s,
|  | int | n )
| inline

reads in at most one less than n characters from stream and stores them into the buffer pointed to by s.

Reading stops after an EOF or a newline. If a newline is read, it is stored into the buffer. A '\0' is stored after the last character in the buffer.

Parameters

  s | pointer to buffer of size n
  n | buffer size

Returns
  pointer to string

References file_.

## ◆ fgetwc()

wint_t OFFile::fgetwc | ( |  | ) |
| inline

reads a wide character from stream and returns it.

If the end of stream is reached, or if ferror(stream) becomes true, it returns WEOF. If a wide character conversion error occurs, it sets the error code to EILSEQ and returns WEOF.

Returns
  next character from stream or WEOF

References file_, and storeLastError().

## ◆ file()

FILE * OFFile::file | ( |  | ) |
| inline

return FILE pointer managed by this object.

This allows the user to call some stdio functions that are not encapsulated in this class (but possibly should be).

Returns
  pointer to FILE structure managed by this object

References file_.

## ◆ fileNo()

int OFFile::fileNo | ( |  | ) |
| inline

returns the low-level file descriptor associated with the stream.

The spelling of this member function is different from stdio fileno() because on some systems (such as MinGW) fileno() is a macro and, therefore, cannot be used as a method name.

Returns
  low-level file descriptor associated with stream

References file_.

## ◆ fopen() [1/2]

OFBool OFFile::fopen | ( | const char * | filename,
|  | const char * | modes )
| inline

opens the file whose name is the string pointed to by path and associates a stream with it.

Parameters

  filename | path to file
  modes | "r", "w" or "a" with possible modifiers "+", "b"

Returns
  true if stream was successfully created, false otherwise, in which case the error code is set.

References fclose(), file_, popened_, and storeLastError().

Referenced by fopen().

## ◆ fopen() [2/2]

OFBool OFFile::fopen | ( | const OFFilename & | filename,
|  | const char * | modes )
| inline

opens the file whose name is a conventional or wide character string pointed to by path and associates.

The wide character support is currently Windows-specific.

Parameters

  filename | object containing the filename path to file
  modes | "r", "w" or "a" with possible modifiers "+", "b"

Returns
  true if stream was successfully created, false otherwise, in which case the error code is set.

References fopen(), OFFilename::getCharPointer(), OFFilename::getWideCharPointer(), OFFilename::usesWideChars(), and wfopen().

## ◆ fprintf()

int OFFile::fprintf | ( | const char * | format,
|  |  | ... )
| inline

print formatted string into stream, see printf(3)

Parameters

  format | format string
  ... | further parameters according to format string

Returns
  number of characters printed

References file_.

## ◆ fputc()

int OFFile::fputc | ( | int | c | ) |
| inline

writes the character c, cast to an unsigned char, to stream.

Parameters

  c | character

Returns
  the character written as an unsigned char cast to an int or EOF on error

References file_.

## ◆ fputs()

int OFFile::fputs | ( | const char * | s | ) |
| inline

writes the string s to stream, without its trailing '\0'.

Parameters

  s | string to be written

Returns
  a non-negative number on success, or EOF on error.

References file_.

## ◆ fputwc()

wint_t OFFile::fputwc | ( | wchar_t | wc | ) |
| inline

writes the wide character wc to stream.

If ferror(stream) becomes true, it returns WEOF. If a wide character conversion error occurs, it sets the error code to EILSEQ and returns WEOF. Otherwise it returns wc.

Parameters

  wc | wide character to write to stream

Returns
  character written or WEOF

References file_, and storeLastError().

## ◆ fread()

size_t OFFile::fread | ( | void * | ptr,
|  | size_t | size,
|  | size_t | n )
| inline

reads n elements of data, each size bytes long, from the stream, storing them at the location given by ptr.

Returns the number of items successfully read (i.e., not the number of characters). If an error occurs, or the end-of-file is reached, the return value is a short item count (or zero). fread does not distinguish between end-of-file and error, and callers must use feof and ferror to determine which occurred.

Parameters

  ptr | pointer to buffer
  size | size of item
  n | number of items

Returns
  number of items read

References file_.

## ◆ freopen()

OFBool OFFile::freopen | ( | const char * | filename,
|  | const char * | modes )
| inline

opens the file whose name is the string pointed to by path and associates the stream pointed maintained by this object with it.

The original stream (if it exists) is closed. The mode argument is used just as in the fopen function. The primary use of the freopen function is to change the file associated with a standard text stream (stderr, stdin, or stdout).

Parameters

  filename | path to file
  modes | "r", "w" or "a" with possible modifiers "+", "b"

Returns
  true if stream was successfully created, false otherwise, in which case the error code is set.

References file_, popened_, and storeLastError().

## ◆ fseek()

int OFFile::fseek | ( | offile_off_t | off,
|  | int | whence )
| inline

sets the file position indicator for the stream pointed to by stream.

The new position, measured in bytes, is obtained by adding offset bytes to the position specified by whence. If whence is set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to the start of the file, the current position indicator, or end-of-file, respectively. A successful call to the fseek function clears the end-of- file indicator for the stream and undoes any effects of the ungetc function on the same stream.

Parameters

  off | offset to seek to
  whence | SEEK_SET, SEEK_CUR, or SEEK_END

Returns
  0 upon success, -1 otherwise in which case the error code is set.

References fgetpos(), file_, fsetpos(), and storeLastError().

Referenced by rewind().

## ◆ fsetpos()

int OFFile::fsetpos | ( | offile_fpos_t * | pos | ) |
| inline

alternate interface equivalent to fseek (with whence set to SEEK_SET), setting the current value of the file offset from the object referenced by pos.

On some non-UNIX systems an fpos_t object may be a complex object and these routines may be the only way to portably reposition a text stream.

Parameters

  pos | pointer to offile_fpos_t structure

Returns
  0 upon success, -1 otherwise in which case the error code is set.

References file_, and storeLastError().

Referenced by fseek().

## ◆ ftell()

offile_off_t OFFile::ftell | ( |  | ) |
| inline

obtains the current value of the file position indicator for the stream pointed to by the stream.

Returns
  current file position

References fgetpos(), file_, and storeLastError().

## ◆ fwide()

int OFFile::fwide | ( | int | mode | ) |
| inline

When mode is zero, the fwide function determines the current orientation of stream.

It returns a value > 0 if stream is wide-character oriented, i.e. if wide character I/O is permitted but char I/O is disallowed. It returns a value < 0 if stream is byte oriented, i.e. if char I/O is permitted but wide character I/O is disallowed. It returns zero if stream has no orientation yet; in this case the next I/O operation might change the orientation (to byte oriented if it is a char I/O operation, or to wide-character oriented if it is a wide character I/O operation). Once a stream has an orientation, it cannot be changed and persists until the stream is closed. When mode is non-zero, the fwide function first attempts to set stream's orientation (to wide-character oriented if mode > 0, or to byte oriented if mode < 0). It then returns a value denoting the current orientation, as above.

Parameters

  mode | mode of operation for fwide

Returns
  orientation of stream

References file_.

## ◆ fwprintf()

int OFFile::fwprintf | ( | const wchar_t * | format,
|  |  | ... )
| inline

print formatted wide string into stream, see wprintf(3)

Parameters

  format | format string
  ... | further parameters according to format string

Returns
  number of characters printed

References file_.

## ◆ fwrite()

size_t OFFile::fwrite | ( | const void * | ptr,
|  | size_t | size,
|  | size_t | n )
| inline

writes n elements of data, each size bytes long, to the stream, obtaining them from the location given by ptr.

Returns the number of items successfully written (i.e., not the number of characters). If an error occurs the return value is a short item count (or zero).

Parameters

  ptr | pointer to buffer
  size | size of item
  n | number of items

Returns
  number of items written

References file_.

## ◆ getLastError()

offile_errno_t OFFile::getLastError | ( |  | ) | const
| inline

return last error code for this stream

Returns
  last error code for this stream

References lasterror_.

## ◆ getLastErrorString()

void OFFile::getLastErrorString | ( | OFString & | s | ) | const
| inline

return string describing last error code for this stream

Parameters

  s | string describing last error code for this stream returned in this parameter

References lasterror_, and OFStandard::strerror().

## ◆ open()

OFBool OFFile::open | ( |  | ) | const
| inline

return true if this object is currently associated with a stream, false otherwise

Returns
  true if this object is currently associated with a stream, false otherwise

References file_.

## ◆ pclose()

int OFFile::pclose | ( |  | ) |
| inline

waits for the associated process (created with popen) to terminate and returns the exit status of the command as returned by wait4.

In this implementation, fclose and pclose can be used synonymously.

Returns
  process ID of the child which exited, or -1 on error, in which case the error code is set

References fclose().

## ◆ popen()

OFBool OFFile::popen | ( | const char * | command,
|  | const char * | modes )

opens a process by creating a pipe, forking, and invoking the shell.

Since a pipe is by definition unidirectional, the type argument may specify only reading or writing, not both; the resulting stream is correspondingly read-only or write-only. If the object was already associated with another file or pipe, that one is closed.

Parameters

  command | shell command line
  modes | "r" or "w"

Returns
  true if pipe was successfully created, false otherwise

## ◆ rewind()

void OFFile::rewind | ( |  | ) |
| inline

sets the file position indicator for the stream pointed to by stream to the beginning of the file.

This is equivalent to fseek(0, SEEK_SET) except that the error indicator for the stream is also cleared.

References file_, and fseek().

## ◆ setbuf()

void OFFile::setbuf | ( | char * | buf | ) |
| inline

The three types of buffering available are unbuffered, block buffered, and line buffered.

When an output stream is unbuffered, information appears on the destination file or terminal as soon as written; when it is block buffered many characters are saved up and written as a block; when it is line buffered characters are saved up until a newline is output or input is read from any stream attached to a terminal device (typically stdin). Normally all files are block buffered. if a stream refers to a terminal (as stdout normally does) it is line buffered. The standard error stream stderr is always unbuffered by default. This function allows to set the mode of the stream to unbuffered (if buf is NULL) or block buffered.

Parameters

  buf | pointer to buffer of size BUFSIZ as declared in cstdio, or NULL

Returns
  0 upon success, nonzero otherwise, in which case the error code may be set

References file_.

## ◆ setbuffer()

void OFFile::setbuffer | ( | char * | buf,
|  | size_t | size )
| inline

The three types of buffering available are unbuffered, block buffered, and line buffered.

When an output stream is unbuffered, information appears on the destination file or terminal as soon as written; when it is block buffered many characters are saved up and written as a block; when it is line buffered characters are saved up until a newline is output or input is read from any stream attached to a terminal device (typically stdin). Normally all files are block buffered. if a stream refers to a terminal (as stdout normally does) it is line buffered. The standard error stream stderr is always unbuffered by default. This function allows to set the mode of the stream to unbuffered (if buf is NULL) or block buffered.

Parameters

  buf | pointer to buffer
  size | size of buffer, in bytes

Returns
  0 upon success, nonzero otherwise, in which case the error code may be set

References file_, and setvbuf().

## ◆ setlinebuf()

void OFFile::setlinebuf | ( |  | ) |
| inline

The three types of buffering available are unbuffered, block buffered, and line buffered.

When an output stream is unbuffered, information appears on the destination file or terminal as soon as written; when it is block buffered many characters are saved up and written as a block; when it is line buffered characters are saved up until a newline is output or input is read from any stream attached to a terminal device (typically stdin). Normally all files are block buffered. if a stream refers to a terminal (as stdout normally does) it is line buffered. The standard error stream stderr is always unbuffered by default. this function allows to set the mode of the stream to line buffered.

Returns
  0 upon success, nonzero otherwise, in which case the error code may be set

References file_, and setvbuf().

## ◆ setvbuf()

int OFFile::setvbuf | ( | char * | buf,
|  | int | modes,
|  | size_t | n )
| inline

The three types of buffering available are unbuffered, block buffered, and line buffered.

When an output stream is unbuffered, information appears on the destination file or terminal as soon as written; when it is block buffered many characters are saved up and written as a block; when it is line buffered characters are saved up until a newline is output or input is read from any stream attached to a terminal device (typically stdin). Normally all files are block buffered. if a stream refers to a terminal (as stdout normally does) it is line buffered. The standard error stream stderr is always unbuffered by default. This function allows to set the stream mode.

Parameters

  buf | pointer to buffer, may be NULL
  modes | _IONBF (unbuffered) _IOLBF (line buffered) or _IOFBF (fully buffered)
  n | size of buffer, in bytes

Returns
  0 upon success, nonzero otherwise, in which case the error code may be set

References file_, and storeLastError().

Referenced by setbuffer(), and setlinebuf().

## ◆ tmpfile()

OFBool OFFile::tmpfile | ( |  | ) |
| inline

generates a unique temporary filename.

The temporary file is then opened in binary read/write (w+b) mode. The file will be automatically deleted when it is closed or the program terminates normally.

Returns
  true if stream was successfully created, false otherwise, in which case the error code is set.

References fclose(), file_, popened_, and storeLastError().

## ◆ ungetc()

int OFFile::ungetc | ( | int | c | ) |
| inline

pushes c back to stream, cast to unsigned char, where it is available for subsequent read operations.

Pushed - back characters will be returned in reverse order; only one pushback is guaranteed.

Parameters

  c | character to push back

Returns
  c on success, or EOF on error.

References file_.

## ◆ ungetwc()

wint_t OFFile::ungetwc | ( | wint_t | wc | ) |
| inline

pushes back a wide character onto stream and returns it.

If wc is WEOF, it returns WEOF. If wc is an invalid wide character, it sets errno to EILSEQ and returns WEOF. If wc is a valid wide character, it is pushed back onto the stream and thus becomes available for future wide character read operations. The file-position indicator is decremented by one or more. The end-of-file indicator is cleared. The backing storage of the file is not affected. Note: wc need not be the last wide character read from the stream; it can be any other valid wide character. If the implementation supports multiple push-back operations in a row, the pushed-back wide characters will be read in reverse order; however, only one level of push-back is guaranteed.

Parameters

  wc | wide character to put back to stream

Returns
  character put back or WEOF

References file_, and storeLastError().

## ◆ vfprintf()

int OFFile::vfprintf | ( | const char * | format,
|  | va_list | arg )
| inline

print formatted string into stream, see printf(3)

Parameters

  format | format string
  arg | list of further parameters according to format string

Returns
  number of characters printed

References file_.

## ◆ vfwprintf()

int OFFile::vfwprintf | ( | const wchar_t * | format,
|  | va_list | arg )
| inline

print formatted wide string into stream, see printf(3)

Parameters

  format | format string
  arg | list of further parameters according to format string

Returns
  number of characters printed

References file_.

## ◆ wfopen()

OFBool OFFile::wfopen | ( | const wchar_t * | filename,
|  | const wchar_t * | modes )
| inline

opens the file whose name is the wide character string pointed to by path and associates a stream with it.

Remarks
  This member is only available if DCMTK is compiled on Windows Operating Systems with wide chars enabled (defining _WIN32 as well as WIDE_CHAR_FILE_IO_FUNCTIONS).

Parameters

  filename | Unicode filename path to file
  modes | "r", "w" or "a" with possible modifiers "+", "b", as a wide character string

Returns
  true if stream was successfully created, false otherwise, in which case the error code is set.

References fclose(), file_, popened_, and storeLastError().

Referenced by fopen().

The documentation for this class was generated from the following file:

- ofstd/include/dcmtk/ofstd/offile.h

Generated on for DCMTK Version 3.7.0 by Doxygen 1.16.1