libassa
3.5.1
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#include <Streambuf.h>
Public Member Functions | |
virtual | ~Streambuf () |
Streambuf * | pubsetbuf (char *s_, int n_) |
Set buffer. More... | |
int | pubsync () |
int | in_avail () |
This function returns the number of characters immediately available in the get area. More... | |
int | snextc () |
This function moves the get pointer forward one position, then returns the character after the get pointer's new position. More... | |
int | sbumpc () |
This function should probably have been called `‘sgetc’'. More... | |
int | sgetc () |
This function returns the character after the get pointer, or EOF if the get pointer is at the end of the sequence. More... | |
int | sgetn (char *b_, int len_) |
This function gets the next len_ characters following the get pointer, copying them to the char array pointed to by b_; it advances the get pointer past the last character fetched. More... | |
int | sputc (char c_) |
This function stores c just after the put pointer, and advances the pointer one position, possibly extending the sequence. More... | |
int | sputn (char *b_, int len_) |
From the location pointed to by ptr, stores exactly len characters after the put pointer, advancing the put pointer just past the last character. More... | |
void | unbuffered (int i_) |
If i_ is non-zero, then all IO operations are buffered. More... | |
int | unbuffered () |
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io_ptrs () | |
void | dump () const |
Static Public Attributes | |
static const int | MAXTCPFRAMESZ = 65536 |
Size of the internal input/output buffer. More... | |
Protected Member Functions | |
Streambuf () | |
The default constructor is protected for class Streambuf to asssure that only objects for classes derived from this class may be constructed. More... | |
Streambuf (const Streambuf &) | |
Streambuf & | operator= (const Streambuf &) |
char * | base () const |
Returns the lowest possible value for gptr() - the beginning of the get area. More... | |
char * | gptr () const |
Returns a pointer to the beginning of the get area, and thus to the next character to be fetched (if there are any). More... | |
char * | egptr () const |
Returns a pointer just past the end of the get area, the maximum possible value for gptr(). More... | |
void | setg (char *gbeg_, char *gnext_, char *gend_) |
Set get area pointers. More... | |
char * | pbase () const |
Returns a pointer to the beginning fo the space available for the put area, the lowest possible value for pptr(). More... | |
char * | pptr () const |
Returns a pointer to the beginning of the put area, and thus to the location of the next character that is stored (if possible). More... | |
char * | epptr () const |
Returns a pointer just past the end of the put area, the maximum possible value for pptr(). More... | |
void | setp (char *pbeg_, char *pend_) |
Set put area pointers. More... | |
void | pbump (int n_) |
Advances the next pointer for the output sequence by n_. More... | |
void | setb (char *b_, char *eb_, int del_) |
Establish the reserve area (buffer). More... | |
void | init () |
virtual Streambuf * | setbuf (char *p_, int len_) |
Performs an operation that is defined separately for each class derived from Streambuf. More... | |
virtual int | sync () |
This function synchronizes the streambuf with its actual stream of characters. More... | |
virtual int | showmanyc () |
The morphemes of showmanyc are "es-how-many-see", not "show-man-ic". More... | |
virtual int | xsgetn (char *b_, int len_) |
Assigns up to len_ characters to successive elements of the array whose first element is designated by b_. More... | |
virtual int | underflow () |
This function is called to supply characters for input (from some source) when the get area is empty, although it may be called at other times. More... | |
virtual int | uflow () |
Reads the characters from the input sequence, if possible, and moves the stream position past it, as follows: More... | |
virtual int | xsputn (const char *b_, int len_) |
Writes up to len_ characters to the output sequence as if by repeated calls to sputc (c). More... | |
virtual int | overflow (int c=EOF) |
This function is called to consume characters (flush them to output), typically when the put area is full and an attempt is made to store another character. More... | |
virtual int | doallocate () |
This function is called by allocate when unbuffered() is zero and base() is zero. More... | |
Additional Inherited Members | |
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enum | { USER_BUF = 1 , UNBUFFERED = 2 , EOF_SEEN = 4 , ERR_SEEN = 8 } |
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char * | m_read_base |
char * | m_read_ptr |
char * | m_read_end |
char * | m_write_base |
char * | m_write_ptr |
char * | m_write_end |
char * | m_buf_base |
char * | m_buf_end |
int | m_flags |
char | m_shortbuf [1] |
Streambuf class.
Streambuf class is based on Standard C++ iostream streambuf class.
Extending std::streambuf is always pain due to the obscurity and complexity of its interface, and in general, lack of the source code needed to efficiently understand its implementation.
I wrote my own Streambuf that implements a subset of std::streambuf functions - a bare minimum to get by for Socket buffering.
The buffer of a Streambuf may be considered to have three parts: the get area, the put area, and the reserve area (which is the same as the buffer area).
The get area contains the characters immediately available for input.
The put area holds characters stored for output but not yet consumed by (flushed to) their ultimate destination. The get and put areas may be disjoint or may overlap (in my implementation they are two disjoined buffers). The reserve area is the entire buffer, overlapped by the get and put areas (in my implementation, reserve area covers get area only).
The get and put areas may expand into the remainder of the reserve area. In the course of input and output operations, the sizes of the get and put areas expand and shrink, always bounded by the total buffer size.
Definition at line 90 of file Streambuf.h.
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inlinevirtual |
Definition at line 451 of file Streambuf.h.
References ASSA::io_ptrs::m_buf_base, ASSA::io_ptrs::m_buf_end, ASSA::io_ptrs::m_flags, ASSA::STRMBUFTRACE, trace_with_mask, and ASSA::io_ptrs::USER_BUF.
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inlineprotected |
The default constructor is protected for class Streambuf to asssure that only objects for classes derived from this class may be constructed.
Definition at line 428 of file Streambuf.h.
References init(), ASSA::STRMBUFTRACE, and trace_with_mask.
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protected |
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inlineprotected |
Returns the lowest possible value for gptr() - the beginning of the get area.
Definition at line 463 of file Streambuf.h.
References ASSA::io_ptrs::m_read_base, ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by ASSA::Socketbuf::underflow().
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protectedvirtual |
This function is called by allocate when unbuffered() is zero and base() is zero.
It attempts to make a buffer of suitable size available. On success it must call setb to establish the reserve area, then return a value greater than zero. On failure it returns EOF. The default behavior is to allocate a buffer using new.
Reimplemented in ASSA::Socketbuf.
Definition at line 234 of file Streambuf.cpp.
References setb(), ASSA::STRMBUFTRACE, and trace_with_mask.
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inlineprotected |
Returns a pointer just past the end of the get area, the maximum possible value for gptr().
Definition at line 481 of file Streambuf.h.
References ASSA::io_ptrs::m_read_end, ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by ASSA::Socketbuf::underflow().
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inlineprotected |
Returns a pointer just past the end of the put area, the maximum possible value for pptr().
The space from pptr() through epptr() is immediately available for storing characters without a flush operation.
Definition at line 506 of file Streambuf.h.
References ASSA::io_ptrs::m_write_end, ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by ASSA::Socketbuf::flush_output(), and ASSA::Socketbuf::overflow().
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inlineprotected |
Returns a pointer to the beginning of the get area, and thus to the next character to be fetched (if there are any).
The characters immediately available are from gptr() through egptr()-1. If egptr()<=gptr(), no char- acters are available.
Definition at line 472 of file Streambuf.h.
References ASSA::io_ptrs::m_read_ptr, ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by ASSA::Socketbuf::underflow().
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inline |
This function returns the number of characters
immediately available in the get area.
It is certain that i characters may be fetched without error, and without accessing any external device.
Definition at line 398 of file Streambuf.h.
References ASSA::io_ptrs::m_read_end, ASSA::io_ptrs::m_read_ptr, ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by ASSA::IPv4Socket::clone(), ASSA::IPv4Socket::close(), ASSA::Socket::getBytesAvail(), and ASSA::IPv4Socket::in_avail().
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inlineprotected |
Definition at line 437 of file Streambuf.h.
References ASSA::io_ptrs::m_buf_base, ASSA::io_ptrs::m_buf_end, ASSA::io_ptrs::m_flags, ASSA::io_ptrs::m_read_base, ASSA::io_ptrs::m_read_end, ASSA::io_ptrs::m_read_ptr, ASSA::io_ptrs::m_shortbuf, ASSA::io_ptrs::m_write_base, ASSA::io_ptrs::m_write_end, ASSA::io_ptrs::m_write_ptr, ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by Streambuf().
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inlineprotectedvirtual |
This function is called to consume characters (flush them to output), typically when the put area is full and an attempt is made to store another character.
If c is not EOF, overflow must either store or consume the character, following those already in the put area. It returns EOF on error, any other value on success. The default behavior of the base class version is undefined, so each derived class must define its own overflow. The normal action for a derived class version is to consume the characters in the put area (those between pbase() and pptr()), call setp() to set up a new put area, then store c (using sputc()) if it is not EOF.
Reimplemented in ASSA::Socketbuf.
Definition at line 606 of file Streambuf.h.
References ASSA::STRMBUFTRACE, and trace_with_mask.
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inlineprotected |
Returns a pointer to the beginning fo the space available for the put area, the lowest possible value for pptr().
The area from pbase() through pptr()-1 represents characters which have been stored int the buffer but not yet consumed.
Definition at line 490 of file Streambuf.h.
References ASSA::io_ptrs::m_write_base, ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by ASSA::Socketbuf::flush_output(), and ASSA::Socketbuf::overflow().
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inlineprotected |
Advances the next pointer for the output sequence by n_.
Definition at line 514 of file Streambuf.h.
References ASSA::io_ptrs::m_write_ptr, ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by ASSA::Socketbuf::flush_output(), and ASSA::Socketbuf::xput_char().
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inlineprotected |
Returns a pointer to the beginning of the put area, and thus to the location of the next character that is stored (if possible).
Definition at line 498 of file Streambuf.h.
References ASSA::io_ptrs::m_write_ptr, ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by ASSA::Socketbuf::flush_output(), ASSA::Socketbuf::overflow(), and ASSA::Socketbuf::xput_char().
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inline |
Set buffer.
Definition at line 380 of file Streambuf.h.
References setbuf(), ASSA::STRMBUFTRACE, and trace_with_mask.
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inline |
Definition at line 389 of file Streambuf.h.
References ASSA::STRMBUFTRACE, sync(), and trace_with_mask.
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inline |
This function should probably have been called `‘sgetc’'.
It moves the get pointer forward one posi- tion and returns the character it moved past. If the get pointer is currently at the end of the sequence, this function returns EOF.
Definition at line 538 of file Streambuf.h.
References ASSA::io_ptrs::m_read_end, ASSA::io_ptrs::m_read_ptr, ASSA::STRMBUFTRACE, trace_with_mask, and uflow().
Referenced by ASSA::IPv4Socket::close(), and ASSA::IPv4Socket::read().
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protected |
Establish the reserve area (buffer).
Set base() to b_, ebuf() to eb_. If del_ is non-zero, the buffer will be deleted whenever base() is changed by another call to setb(), or when Streambuf destructor is invoked. If del_ is zero, the buffer will not be deleted automatically.
b_ | pointer to the buffer's first byte |
eb_ | pointer to the byte one past the buffer's last byte |
del_ | 0 - external memory management, 1 - delete on swap/destruction |
Definition at line 79 of file Streambuf.cpp.
References ASSA::io_ptrs::dump(), ASSA::io_ptrs::m_buf_base, ASSA::io_ptrs::m_buf_end, ASSA::io_ptrs::m_flags, ASSA::STRMBUFTRACE, trace_with_mask, and ASSA::io_ptrs::USER_BUF.
Referenced by ASSA::Socketbuf::doallocate(), doallocate(), and setbuf().
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protectedvirtual |
Performs an operation that is defined separately for each class derived from Streambuf.
Default behavior is to set internal buffer to p_. If p_ is NULL or len_ is 0, then unbuffered I/O (one byte at a time) is assumed.
p_ | buffer to use |
len_ | length of the buffer |
Definition at line 99 of file Streambuf.cpp.
References DL, setb(), setg(), setp(), ASSA::STRMBUF, ASSA::STRMBUFTRACE, sync(), trace_with_mask, and unbuffered().
Referenced by pubsetbuf().
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protected |
Set get area pointers.
Definition at line 68 of file Streambuf.cpp.
References ASSA::io_ptrs::m_read_base, ASSA::io_ptrs::m_read_end, ASSA::io_ptrs::m_read_ptr, ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by ASSA::Socketbuf::doallocate(), setbuf(), and ASSA::Socketbuf::underflow().
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inlineprotected |
Set put area pointers.
Definition at line 587 of file Streambuf.h.
References ASSA::io_ptrs::m_write_base, ASSA::io_ptrs::m_write_end, ASSA::io_ptrs::m_write_ptr, ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by ASSA::Socketbuf::doallocate(), ASSA::Socketbuf::flush_output(), and setbuf().
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inline |
This function returns the character after the get pointer, or EOF if the get pointer is at the end of the sequence.
Despite its name, this function does NOT move the get pointer.
Definition at line 548 of file Streambuf.h.
References ASSA::io_ptrs::m_read_end, ASSA::io_ptrs::m_read_ptr, ASSA::STRMBUFTRACE, trace_with_mask, and underflow().
Referenced by snextc().
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inline |
This function gets the next len_ characters following the get pointer, copying them to the char array pointed to by b_; it advances the get pointer past the last character fetched.
If fewer than len characters are left, it gets as many as are available.
Definition at line 558 of file Streambuf.h.
References ASSA::STRMBUFTRACE, trace_with_mask, and xsgetn().
Referenced by ASSA::IPv4Socket::read().
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inlineprotectedvirtual |
The morphemes of showmanyc are "es-how-many-see",
not "show-man-ic".
Return an estimate of the number of characters available in the sequence, or -1. If it returns a positive value,
then successive calls to underflow() will not return EOF until at least that number of characters have been supplied.
If showmanyc() returns -1, then calls to underflow() or uflow() will fail. The intention is not only that these calls will not return EOF, but that they will return `‘immediately.’'
Reimplemented in ASSA::Socketbuf.
Definition at line 530 of file Streambuf.h.
References ASSA::STRMBUFTRACE, and trace_with_mask.
int Streambuf::snextc | ( | ) |
This function moves the get pointer forward one
position, then returns the character after the get pointer's new position.
If the get pointer is at the end of the sequence before or after the call to this function (no character is available), this function returns EOF. Example: Suppose the input buffer looks like this: abc|def where ‘|’ marks the position of the get pointer. This function will advance the get pointer and return ‘e’.
Definition at line 56 of file Streambuf.cpp.
References ASSA::io_ptrs::m_read_end, ASSA::io_ptrs::m_read_ptr, sgetc(), ASSA::STRMBUFTRACE, trace_with_mask, and underflow().
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inline |
This function stores c just after the put pointer, and advances the pointer one position, possibly extending the sequence.
It returns c, or EOF on error. What constitutes an error depends on the actual derived buffer class.
Definition at line 567 of file Streambuf.h.
References ASSA::io_ptrs::m_write_end, ASSA::io_ptrs::m_write_ptr, overflow(), ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by ASSA::IPv4Socket::write().
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inline |
From the location pointed to by ptr, stores exactly len characters after the put pointer, advancing the put pointer just past the last character.
It returns the number of characters stored, which ought to be len. Fewer than len characters stored indicates some sort of error.
Definition at line 578 of file Streambuf.h.
References ASSA::STRMBUFTRACE, trace_with_mask, and xsputn().
Referenced by ASSA::IPv4Socket::write().
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inlineprotectedvirtual |
This function synchronizes the streambuf with its actual stream of characters.
The derived class version should flush any characters in the put area to their final destination, and if possible give back any characters in the input buffer to their source. It should return EOF on any error, zero on success. The default behavior of the base class version is to return zero if there are no pending input or output characters (in_avail() and out_waiting() are both zero), and return EOF otherwise.
Reimplemented in ASSA::Socketbuf.
Definition at line 522 of file Streambuf.h.
References ASSA::STRMBUFTRACE, and trace_with_mask.
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protectedvirtual |
Reads the characters from the input sequence, if possible, and moves the stream position past it, as follows:
1) If the input sequence has a read position available the function signals success by returning (unsigned char)*gnext++.
2) Otherwise, if the function can read the character x directly from the associated input sequence, it signals succes by returning (unsigned char) x. If the function makes a read position available, it also assigns x to *gnext.
The default behavior is to call underflow () and, if that function returns EOF or fails to make a read position available, return EOF. Otherwise, the function signals success by returning (unsigned char)*gnext++.
Definition at line 171 of file Streambuf.cpp.
References ASSA::io_ptrs::dump(), ASSA::io_ptrs::m_read_ptr, ASSA::STRMBUFTRACE, trace_with_mask, and underflow().
Referenced by sbumpc().
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inline |
Definition at line 407 of file Streambuf.h.
References ASSA::io_ptrs::m_flags, ASSA::STRMBUFTRACE, trace_with_mask, and ASSA::io_ptrs::UNBUFFERED.
Referenced by ASSA::Socketbuf::flush_output(), ASSA::Socketbuf::overflow(), setbuf(), ASSA::Socketbuf::Socketbuf(), and ASSA::Socketbuf::underflow().
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inline |
If i_ is non-zero, then all IO operations are buffered.
If i_ is zero, then unbuffered IO is performed (one character at a time.
Definition at line 416 of file Streambuf.h.
References ASSA::io_ptrs::m_flags, ASSA::STRMBUFTRACE, trace_with_mask, and ASSA::io_ptrs::UNBUFFERED.
Referenced by ASSA::IPv4Socket::read(), and ASSA::IPv4Socket::write().
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inlineprotectedvirtual |
This function is called to supply characters for input (from some source) when the get area is empty, although it may be called at other times.
If the get area is not empty, it should just return the first character (without advancing the get pointer). If the get area is empty, it should establish a new get area, aquire new input, and return the first character, if any. If no input characters are available, it should leave an empty get area and return EOF. The default behavior of the base class version is undefined, so each derived class must define its own underflow.
Reimplemented in ASSA::Socketbuf.
Definition at line 597 of file Streambuf.h.
References ASSA::STRMBUFTRACE, and trace_with_mask.
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protectedvirtual |
Assigns up to len_ characters to successive elements of the array whose first element is designated by b_.
The characters assigned are read from the input sequence as if by repeated calls to sbumpc(). Assigning stops when either len_ characters have been assigned or a call to sbumpc() would return EOF.
Definition at line 127 of file Streambuf.cpp.
References DL, ASSA::io_ptrs::m_read_end, ASSA::io_ptrs::m_read_ptr, ASSA::STRMBUFTRACE, trace_with_mask, and underflow().
Referenced by sgetn().
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protectedvirtual |
Writes up to len_ characters to the output sequence as if by repeated calls to sputc (c).
The characters written are obtained from successive elements of the array whose first element is designated by b_. Writing stops when either len_ characters have been written or a call to sputc(c) would return EOF.
Definition at line 183 of file Streambuf.cpp.
References ASSA::io_ptrs::m_write_end, ASSA::io_ptrs::m_write_ptr, overflow(), ASSA::STRMBUFTRACE, and trace_with_mask.
Referenced by sputn().
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static |
Size of the internal input/output buffer.
You can use this constant to do application code read/writes to the socket.
Definition at line 106 of file Streambuf.h.
Referenced by ASSA::Socketbuf::doallocate(), ASSA::Socketbuf::flush_output(), and ASSA::Socketbuf::underflow().