Bug#535695: std::ifstream uses a block size of 8191 bytes ..

Package: libstdc++6-4.3-dev
Version: 4.3.3-13

The program below reads the input file in blocks of 8191 bytes (as
shown by strace). There's probably a mistake somewhere because it
should use 8192 byte blocks. (8191 byte blocks tend to maximize
misalignment.)

Recompiling with g++-4.4 doesn't change this. Using the
in.rdbuf()->sgetc() and friends exhibits the same behavior, too.

#include <iostream>
#include <fstream>

static int usage(const char* progname);

int
main(int argc, const char** argv)
{
if (argc != 2) {
return usage(argv[0]);
}

const char* filename = argv[1];
std::ifstream in(filename);

std::string l;
while (in) {
std::getline(in, l);
}

if (in.eof()) {
return 0;
} else {
std::cerr << "error: reading from: " << filename << std::endl;
return 1;
}
}

static int
usage(const char* progname)
{
std::cerr << "usage: " << progname << " FILE\n";
return 1;
}




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