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#ifndef IFDNBUF_H_
#define IFDNBUF_H_
#include <unistd.h>
#include <streambuf>
#include <cstring>
//CLASS
class IFdNStreambuf: public std::streambuf
{
protected:
int d_fd = -1;
size_t d_bufsize = 0;
char* d_buffer = 0;
public:
IFdNStreambuf() = default;
IFdNStreambuf(int fd, size_t bufsize = 1);
~IFdNStreambuf() override;
void open(int fd, size_t bufsize = 1);
private:
int underflow() override;
std::streamsize xsgetn(char *dest, std::streamsize n) override;
};
//=
//CONS
inline IFdNStreambuf::IFdNStreambuf(int fd, size_t bufsize)
{
open(fd, bufsize);
}
//=
// In real applications, the following members should be defined in
// source files. Headers should not have external linkage.
//DESTR
IFdNStreambuf::~IFdNStreambuf()
{
if (d_bufsize)
{
close(d_fd);
delete[] d_buffer;
}
}
//=
//OPEN
void IFdNStreambuf::open(int fd, size_t bufsize)
{
d_fd = fd;
d_bufsize = bufsize == 0 ? 1 : bufsize;
delete[] d_buffer;
d_buffer = new char[d_bufsize];
setg(d_buffer, d_buffer + d_bufsize, d_buffer + d_bufsize);
}
//=
//UFLOW
int IFdNStreambuf::underflow()
{
if (gptr() < egptr())
return *gptr();
int nread = read(d_fd, d_buffer, d_bufsize);
if (nread <= 0)
return EOF;
setg(d_buffer, d_buffer, d_buffer + nread);
return static_cast<unsigned char>(*gptr());
}
//=
//XSGETN
std::streamsize IFdNStreambuf::xsgetn(char *dest, std::streamsize n)
{
int nread = 0;
while (n)
{
if (!in_avail())
{
if (underflow() == EOF)
break;
}
int avail = in_avail();
if (avail > n)
avail = n;
memcpy(dest + nread, gptr(), avail);
gbump(avail);
nread += avail;
n -= avail;
}
return nread;
}
//=
#endif
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