简而言之，是否可能从流类中进行管道的缓冲读取，类似于这个伪例子所描述的内容。
请忽略您看到的任何琐碎问题（如未检查错误等）。我在我的实际代码中处理所有这些问题。这只是一个伪例子，以传达我的问题。
请忽略您看到的任何琐碎问题（如未检查错误等）。我在我的实际代码中处理所有这些问题。这只是一个伪例子，以传达我的问题。
#include <iostream> // or istream, ifstream, strstream, etc; whatever stream could pull this off
#include <unistd.h>
#include <stdlib.h>
#include <sstream>
void myFunc() {
int pipefd[2][2] = {{0,0},{0,0}};
pipe2( pipefd[0], O_NONBLOCK );
pipe2( pipefd[1], O_NONBLOCK );
if( 0 == fork() ) {
close( pipefd[0][1] );
close( pipefd[1][1] );
dup2( pipefd[0][0], stdout );
dup2( pipefd[1][0], stderr );
execv( /* some arbitrary program */ );
} else {
close( pipefd[0][0] );
close( pipefd[1][0] );
/* cloudy bubble here for the 'right thing to do'.
* Obviously this is faulty code; look at the intent,
* not the implementation.
*/
#ifdef RIGHT_THING_TO_DO
for( int ii = 0; ii < 2; ++ii ) {
cin.tie( pipefd[ii][1] );
do {
cin.readline( /* ... */ );
} while( /* ... */ );
}
#else
// This is what I'm doing now; it works, but I'm
// curious whether it can be done more concisely
do {
do {
select( /* ... */ );
for( int ii = 0; ii < 2; ++ii ) {
if( FD_SET( fd[ii][1], &rfds ) ) {
read( fd[ii][1], buff, 4096 );
if( /* read returned a value > 0 */ ) {
myStringStream << buff;
} else {
FD_CLR( fd[ii][1], &rfds );
}
}
}
} while( /* select returned a value > 0 */ );
} while( 0 == waitpid( -1, 0, WNOHANG ) );
#endif
}
}
编辑
下面是一个简单的示例，展示如何使用boost::file_descriptor来处理管道；同样适用于套接字，尽管没有测试过。
这是我编译它的方式：
g++ -m32 -DBOOST_IOSTREAMS_NO_LIB -isystem ${BOOST_PATH}/include \
${BOOST_SRC_PATH}/libs/iostreams/src/file_descriptor.cpp blah.cc -o blah
以下是示例：
#include <fcntl.h>
#include <stdio.h>
#include <boost/iostreams/device/file_descriptor.hpp>
#include <boost/iostreams/stream.hpp>
int main( int argc, char* argv[] ) {
// if you just do 'using namespace...', there's a
// namespace collision with the global 'write'
// function used in the child
namespace io = boost::iostreams;
int pipefd[] = {0,0};
pipe( pipefd, 0 ); // If you use O_NONBLOCK, you'll have to
// add some extra checks to the loop so
// it will wait until the child is finished.
if( 0 == fork() ) {
// child
close( pipefd[0] ); // read handle
dup2( pipefd[1], FILENO_STDOUT );
printf( "This\nis\na\ntest\nto\nmake sure that\nit\nis\working as expected.\n" );
return 0; // ya ya, shoot me ;p
}
// parent
close( pipefd[1] ); // write handle
char *buff = new char[1024];
memset( buff, 0, 1024 );
io::stream<io::file_descriptor_source> fds(
io::file_descriptor_source( pipefd[0], io::never_close_handle ) );
// this should work with std::getline as well
while( fds.getline( buff, 1024 )
&& fds.gcount() > 0 // this condition is not enough if you use
// O_NONBLOCK; it should only bail if this
// is false AND the child has exited
) {
printf( "%s,", buff );
}
printf( "\n" );
}