add shell-free pipestream

[libi2ncommon] / src / pipestream.cpp

 /*
The software in this package is distributed under the GNU General
Public License version 2 (with a special exception described below).

A copy of GNU General Public License (GPL) is included in this distribution,
in the file COPYING.GPL.

As a special exception, if other files instantiate templates or use macros
or inline functions from this file, or you compile this file and link it
with other works to produce a work based on this file, this file
does not by itself cause the resulting work to be covered
by the GNU General Public License.

However the source code for this file must still be made available
in accordance with section (3) of the GNU General Public License.

This exception does not invalidate any other reasons why a work based
on this file might be covered by the GNU General Public License.
*/
/***************************************************************************
              inpipestream.cpp  -  C++ streambuffer wrapper 
                             -------------------
    begin                : Thu Dec 27 2001
    copyright            : (C) 2001 by Intra2net AG
 ***************************************************************************/

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/wait.h>
#include <unistd.h>

#include <streambuf>
#include <istream>
#include <ostream>
#include <cstdio>
#include <boost/foreach.hpp>
#include <boost/shared_array.hpp>

#include "exception.hxx"
#include "stringfunc.hxx"
#include "pipestream.hxx"

/** @brief runs command and returns it's output as string
 *  @param command the full command with all parameters
 *  @param rescode struct containing the return code, if the program exited normally and so on
 *  @returns the output (stdout) of the called program
 */
template <typename CmdT>
std::string capture_exec(CmdT command, ExecResult &rescode)
{
    std::string output;

    bool exit_set = false;
    int exit_status_waitpid;

    // set the results to false until we are sure we have proper values
    rescode.normal_exit = false;
    rescode.terminated_by_signal = false;

    try
    {
        {
            inpipestream ips(command);

            ips.store_exit_status(&exit_set, &exit_status_waitpid);

            char buffer[2048];
            while (ips.good())
            {
                ips.read(buffer, sizeof(buffer));
                output.append(buffer, ips.gcount());
            }
        }

        // exit_status_waitpid only valid after destruction of the inpipestream

        if (exit_set)
        {
            rescode.normal_exit = WIFEXITED(exit_status_waitpid);
            if (rescode.normal_exit)
                rescode.return_code = WEXITSTATUS(exit_status_waitpid);

            rescode.terminated_by_signal = WIFSIGNALED(exit_status_waitpid);
            if (rescode.terminated_by_signal)
                rescode.signal = WTERMSIG(exit_status_waitpid);
        }
    }
    catch (pipestream_error &e)
    {
        rescode.error_message = e.what();
    }

    return output;
}

std::string capture_exec (const std::string &command, ExecResult &res)
{ return capture_exec<const std::string &>(command, res); }

std::string capture_exec (const char *const *command, ExecResult &res)
{ return capture_exec<const char *const *>(command, res); }

#define PIPE_CTOR_FAIL(where) \
    do { \
        throw EXCEPTION (pipestream_error, \
                         std::string (where) + ": error " \
                         + I2n::to_string (errno) \
                         + " (" + std::string (strerror (errno)) + ")"); \
    } while (0)

static boost::shared_array <char *>
mk_argv (const std::vector<std::string> &command)
{
    char **ret = NULL;

    try {
        ret = new char *[command.size () * sizeof (ret[0]) + 1];
    } catch (std::bad_alloc &) {
        return boost::shared_array<char *> ();
    }

    size_t cur = 0;
    BOOST_FOREACH(const std::string &arg, command) {
        /*
         * Casting away constness is safe since the data is always
         * kept alive until after exec().
         */
        ret [cur++] = const_cast<char *> (arg.c_str ());
    }

    ret [cur] = NULL;

    return boost::shared_array<char *> (ret);
}


FILE *
inpipebuf::init_without_shell (const char *const *argv) const
{
    FILE *pipeobj = NULL;
    int pipefd [2];

    errno = 0;
    if (::pipe (pipefd) == -1) {
        PIPE_CTOR_FAIL("pipe");
    }

    errno = 0;
    pid_t childpid = fork ();
    switch (childpid) {
        case -1: {
            PIPE_CTOR_FAIL("fork");
            break;
        }
        case 0: {
            close (pipefd [0]);

            if (dup2 (pipefd[1], STDOUT_FILENO) == -1) {
                PIPE_CTOR_FAIL("dup2");
            }

            if (dup2 (pipefd[1], STDERR_FILENO) == -1) {
                PIPE_CTOR_FAIL("dup2");
            }

            errno = 0;
            if (execve (argv [0], const_cast <char *const *>(argv), NULL) == -1) {
                PIPE_CTOR_FAIL("exec");
            }
            break;
        }
        default: {
            close (pipefd [1]);

            errno = 0;
            if ((pipeobj = fdopen (pipefd [0], "r")) == NULL) {
                PIPE_CTOR_FAIL("fdopen");
            }
            break;
        }
    }

    return pipeobj;
}

inpipebuf::inpipebuf(const char *const *command)
    : pipe (NULL) /* brr: shadowing global ident */
    , status_set (NULL)
    , exit_status (NULL)
{
    if (command == NULL || command [0] == NULL) {
        PIPE_CTOR_FAIL("command");
    }

    this->pipe = this->init_without_shell (command);

    setg (&buffer, &buffer, &buffer);
}

inpipebuf::inpipebuf(const std::string& command)
{
    status_set = NULL;
    exit_status = NULL;

    pipe = popen (command.c_str(), "r");
    if (pipe == NULL)
        throw EXCEPTION (pipestream_error, "can't open program or permission denied");

    // force underflow
    setg (&buffer, &buffer, &buffer);
}

inpipebuf::~inpipebuf()
{
    if (pipe != NULL) {
        int pclose_exit = pclose (pipe);

        if (exit_status && pclose_exit != -1)
        {
            if (status_set)
                *status_set = true;
            *exit_status = pclose_exit;
        }

        pipe = NULL;
    }
}

/** note: exit status only available after destruction */
void inpipebuf::store_exit_status(bool *_status_set, int *_exit_status)
{ 
    status_set = _status_set; 
    exit_status = _exit_status; 
}

inpipebuf::int_type inpipebuf::underflow()
{
    if (gptr() < egptr())
        return traits_type::to_int_type(*gptr());

    buffer = fgetc (pipe);
    if (feof (pipe))
    {
        // ERROR or EOF
        return EOF;
    }

    setg (&buffer, &buffer, &buffer+sizeof(char));

    return traits_type::to_int_type(*gptr());
}

outpipebuf::outpipebuf(const std::string& command)
{
    status_set = NULL;
    exit_status = NULL;

    pipe = popen (command.c_str(), "w");
    if (pipe == NULL)
        throw EXCEPTION (pipestream_error, "can't open program or permission denied");
}

outpipebuf::~outpipebuf()
{
    if (pipe != NULL) {
        int pclose_exit = pclose (pipe);

        if (exit_status && pclose_exit != -1)
        {
            if (status_set)
                *status_set = true;
            *exit_status = pclose_exit;
        }

        pipe = NULL;
    }
}

/** note: exit status only available after destruction */
void outpipebuf::store_exit_status(bool *_status_set, int *_exit_status)
{ 
    status_set = _status_set; 
    exit_status = _exit_status; 
}

outpipebuf::int_type outpipebuf::overflow(int_type c)
{
    if (c != EOF)
    {
        if (fputc(c,pipe)==EOF)
            return EOF;
    }
    return c;
}

std::streamsize outpipebuf::xsputn(const char* s, std::streamsize num)
{
    return fwrite(s,num,1,pipe);
}