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added possibility to pass string to stdin of child process

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master
Marc Wäckerlin 20 years ago
parent d129e4e5b4
commit 0cac265f4d
3 changed files with 245 additions and 16 deletions
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  1. 140
      mrw/exec.cpp
  2. 110
      mrw/exec.hpp
  3. 11
      mrw/exec_test.cpp

140
mrw/exec.cpp
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@ -9,6 +9,9 @@
@license LGPL, see file <a href="license.html">COPYING</a>
$Log$
Revision 1.5 2004/12/14 20:30:09 marc
added possibility to pass string to stdin of child process
Revision 1.4 2004/08/28 16:21:25 marc
mrw-c++-0.92 (mrw)
- new file: version.cpp
@ -26,9 +29,11 @@
#include <mrw/exec.hpp>
#include <mrw/unistd.hpp>
#include <mrw/exception.hpp>
#include <mrw/stdext.hpp> // max
#include <sys/wait.h> // waitpid
#include <unistd.h> // fork, exec
#include <string.h> // memcpy
#include <assert.h> // assert
mrw::ExecutionFailedExc::ExecutionFailedExc(const std::string& w,
const std::string& c)
@ -73,8 +78,13 @@ mrw::Cmd::operator mrw::Exec() const throw(std::bad_exception) {
return mrw::Exec(*this);
}
mrw::Exec mrw::Cmd::execute(bool throwExc) const throw(std::exception) {
return mrw::Exec(*this).execute(throwExc);
mrw::Exec mrw::Cmd::execute(bool exc) const throw(std::exception) {
return mrw::Exec(*this).execute(exc);
}
mrw::Exec mrw::Cmd::execute(const std::string& input, bool exc) const
throw(std::exception) {
return mrw::Exec(*this).execute(input, exc);
}
const char* mrw::Cmd::path() const throw(std::bad_exception) {
@ -109,10 +119,11 @@ mrw::Exec& mrw::Exec::operator=(const mrw::Exec& e) throw(std::bad_exception) {
return *this;
}
mrw::Exec& mrw::Exec::execute(bool throwExc) throw(std::exception) {
mrw::Exec& mrw::Exec::execute(bool exc) throw(std::exception) {
/** This method calls @c fork, sets up a pipe connection to pass @c
stdout and @c stderr from the child process to the parent process
using mrw::Pipe and calls @c execvp to execute the program. */
stdout and @c stderr from the child process to the parent
process using mrw::Pipe and calls @c execvp to execute the
program. */
_success = false;
_res = _err = "";
mrw::Pipe stdOut, stdErr;
@ -128,17 +139,18 @@ mrw::Exec& mrw::Exec::execute(bool throwExc) throw(std::exception) {
throw ExecutionFailedExc("cannot close pipe", *_cmd);
int num1(0), num2(0);
for (char buf1[4096], buf2[4096];
(num1=read(stdOut.istream(), buf1, sizeof(buf1)))>0 ||
num1==-1 && errno==EINTR ||
(num2=read(stdErr.istream(), buf2, sizeof(buf2)))>0 ||
num2==-1 && errno==EINTR;
_res += std::string(buf1, num1), _err += std::string(buf2, num2));
if (num1==-1 || num2==-1)
throw ExecutionFailedExc("cannot_ read pipe", *_cmd);
(num1=read(stdOut.istream(), buf1, sizeof(buf1)))>0
|| num1==-1 && (errno==EINTR||errno==EAGAIN)
|| (num2=read(stdErr.istream(), buf2, sizeof(buf2)))>0
|| num2==-1 && (errno==EINTR||errno==EAGAIN);) {
if (num1>0) _res += std::string(buf1, num1);
if (num2>0) _err += std::string(buf2, num2);
}
// wait for child to get return code
int s(0);
if (waitpid(pid, &s, 0)!=pid || WIFEXITED(s)!=0 && WEXITSTATUS(s)!=0) {
if (throwExc) {
if (waitpid(pid, &s, 0)!=pid || WIFEXITED(s)!=0 && WEXITSTATUS(s)!=0
|| num1==-1 || num2==-1) {
if (exc) {
throw ExecutionFailedExc("execution failed", *_cmd);
} else {
_success = false;
@ -157,6 +169,106 @@ mrw::Exec& mrw::Exec::execute(bool throwExc) throw(std::exception) {
return *this;
}
mrw::Exec& mrw::Exec::execute(const std::string& input, bool exc)
throw(std::exception) {
/// @c input length must be smaller than @c SSIZE_MAX.
/// I'll only add support for longer strings upon request.
assert(input.size()<=SSIZE_MAX &&
"sdin input exeeds C library limit in mrw::Exec "
"please contact the author of the library");
/** This method calls @c fork, sets up a pipe connection to pass @c
stdin, @c stdout and @c stderr from the child process to the
parent process using mrw::Pipe and calls @c execvp to execute
the program. */
_success = false;
_res = _err = "";
mrw::Pipe stdIn(true), // child terminates if stdin is non-blocking
stdOut, stdErr;
if (!stdIn || !stdOut || !stdErr)
throw mrw::ExecutionFailedExc("cannot create pipe", *_cmd);
pid_t pid(fork());
if (pid<0) throw ExecutionFailedExc("cannot fork", *_cmd);
if (pid) { // parent
stdIn.close_in();
stdOut.close_out();
stdErr.close_out();
if (!stdIn || !stdOut || !stdErr)
throw ExecutionFailedExc("cannot close pipes", *_cmd);
ssize_t num0(-1), num1(-1), num2(-1);
std::string in(input);
fd_set writefds, readfds;
char buf[4096];
while (num0 || num1 || num2) try { // no end of file in stdin, -out, -err
int res(0), s(0);
if ((res=waitpid(pid, &s, WNOHANG))) {
if (res!=pid || WIFEXITED(s)!=0 && WEXITSTATUS(s)!=0)
throw ExecutionFailedExc("execution failed", *_cmd);
_success = true;
return *this;
}
// select...
FD_ZERO(&writefds);
FD_ZERO(&readfds);
if (num0) FD_SET(stdIn.ostream(), &writefds);
if (num1) FD_SET(stdOut.istream(), &readfds);
if (num2) FD_SET(stdErr.istream(), &readfds);
timeval tm = {1, 0};
int n(mrw::max((num0?stdIn.ostream():0),
mrw::max((num1?stdOut.istream():0),
(num2?stdErr.istream():0))));
int num = select(n, &readfds, &writefds, 0, &tm);
if (num<0) throw ExecutionFailedExc("select failed", *_cmd);
// check and handle stdin
if (num0 && num>0
&& FD_ISSET(stdIn.ostream(), &writefds))
if ((num0=write(stdIn.ostream(), in.c_str(), in.size()))>0) {
if ((unsigned int)num0<in.size())
in = in.substr(num0);
else if ((unsigned int)num0==in.size())
num0=0, stdIn.close_out();
} else if (num0==-1 && (errno!=EINTR&&errno!=EAGAIN))
throw ExecutionFailedExc("writing stdin", *_cmd);
// check and handle stdout
if (num>0 && FD_ISSET(stdOut.istream(), &readfds))
if ((num1=read(stdOut.istream(), buf, sizeof(buf)))>0)
_res += std::string(buf, num1);
else if (num1==-1 && (errno!=EINTR&&errno!=EAGAIN))
throw ExecutionFailedExc("readin stdout", *_cmd);
// check and handle stderr
if (num>0 && FD_ISSET(stdErr.istream(), &readfds))
if ((num2=read(stdErr.istream(), buf, sizeof(buf)))>0)
_err += std::string(buf, num2);
else if (num2==-1 && (errno!=EINTR&&errno!=EAGAIN))
throw ExecutionFailedExc("readin stderr", *_cmd);
} catch (...) {
if (exc) throw;
_success = false;
return *this;
}
// wait for child to get return code
int s(0);
if (waitpid(pid, &s, 0)!=pid || WIFEXITED(s)!=0 && WEXITSTATUS(s)!=0) {
if (exc) {
throw ExecutionFailedExc("execution failed", *_cmd);
} else {
_success = false;
return *this;
}
}
} else { // child
stdIn.close_out();
stdOut.close_in();
stdErr.close_in();
stdIn.connect_cin();
stdOut.connect_cout(); // if cin is non blocking, child terminates here?!?
stdErr.connect_cerr();
execvp(_cmd->path(), _cmd->args());
exit(1); // execute failed
}
_success = true;
return *this;
}
mrw::Exec& mrw::Exec::operator>>(std::string& res) throw(std::exception) {
execute();
res += _res;

110
mrw/exec.hpp
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@ -9,6 +9,9 @@
@license LGPL, see file <a href="license.html">COPYING</a>
$Log$
Revision 1.5 2004/12/14 20:30:09 marc
added possibility to pass string to stdin of child process
Revision 1.4 2004/10/07 09:27:01 marc
errors in documentation
@ -67,6 +70,18 @@ namespace mrw {
// you can trace x.what() and x.stacktrace()
}
@endcode
It is also possible to pass an @c stdin input argument to the
subprocess called:
@code
try {
mrw::Exec cat = mrw::Cmd("/bin/cat")
.execute("this is passed to stdin");
// "cat" passes all from stdin to stdout, therefore:
assert(cat.result()=="this is passed to stdin");
} catch (...) {} // ignore
@endcode
*/
//@{
@ -99,6 +114,9 @@ namespace mrw {
and returns the two streams @c cout and @c cerr, also known as @c
stderr and @c stdout.
Method @c execute can optionally also take a string parameter
that is passed to @c stdin of the child process.
There are different ways of usage for this class. A simple way,
one line of code, to get only the resulting stream (no error)
is:
@ -146,6 +164,42 @@ namespace mrw {
*/
Exec& execute(bool exc=true) throw(std::exception);
/** @brief Execute the command, pass @c stdin.
@param input Input that is passed to @c stdin of the child process.
@param exc
- @c true throw an exception if return status is not zero
- @c false throw only an exception in case of a fatal error
@throw ExecutionFailedExc is thrown if
- fork fails
- creation or setup of pipes failed
- if given parameter is @c true (the default) also if the
executed program terminates with an error
*/
Exec& execute(const std::string& input, bool exc=true)
throw(std::exception);
/** @brief Execute the command, pass @c stdin.
@param input Input that is passed to @c stdin of the child process.
@param exc
- @c true throw an exception if return status is not zero
- @c false throw only an exception in case of a fatal error
@throw ExecutionFailedExc is thrown if
- fork fails
- creation or setup of pipes failed
- if given parameter is @c true (the default) also if the
executed program terminates with an error
*/
Exec& execute(char const*const input, bool exc=true)
throw(std::exception) {
return execute(std::string(input), exc);
}
/** @brief Executes the command if not done, streams @c stdout into a string
If the command has not yet been executed successfully, it is
@ -220,7 +274,7 @@ namespace mrw {
/** @brief A system command to be executed
@pre #include <mrw/exec.hpp>
This class is used in conjunction with mrw::Exec. It mus be
This class is used in conjunction with mrw::Exec. It must be
initialized with the command name, then the command parameters
are appended either with commas, or by streaming them into the
command, whatever you like.
@ -284,6 +338,60 @@ namespace mrw {
*/
Exec execute(bool exc=true) const throw(std::exception);
/** @brief Create a mrw::Exec and execute the command given an input
Creates a mrw::Exec, executes the command, passes the input
and the flag to mrw::Exec::execute() and returns the created
mrw::Exec. The result of the execution can be retrieved
through the returned mrw::Exec object: The methods
mrw::Exec::success(), mrw::Exec::result() and
mrw::Exec::error() provide the necessary information.
@param input Input that is passed to @c stdin of the child process.
@param exc
- @c true throw an exception if return status is not zero
- @c false throw only an exception in case of a fatal error
@return the mrw::Exec that has executed the command
@throw ExecutionFailedExc is thrown if
- fork fails
- creation or setup of pipes failed
- if given parameter is @c true (the default) also if the
executed program terminates with an error
*/
Exec execute(const std::string& input, bool exc=true) const
throw(std::exception);
/** @brief Create a mrw::Exec and execute the command given an input
Creates a mrw::Exec, executes the command, passes the input
and the flag to mrw::Exec::execute() and returns the created
mrw::Exec. The result of the execution can be retrieved
through the returned mrw::Exec object: The methods
mrw::Exec::success(), mrw::Exec::result() and
mrw::Exec::error() provide the necessary information.
@param input Input that is passed to @c stdin of the child process.
@param exc
- @c true throw an exception if return status is not zero
- @c false throw only an exception in case of a fatal error
@return the mrw::Exec that has executed the command
@throw ExecutionFailedExc is thrown if
- fork fails
- creation or setup of pipes failed
- if given parameter is @c true (the default) also if the
executed program terminates with an error
*/
Exec execute(char const*const input, bool exc=true) const
throw(std::exception) {
return execute(std::string(input), exc);
}
private:
/// Exec is allowed to call @c path() and @c args().
friend class Exec;

11
mrw/exec_test.cpp
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@ -9,6 +9,9 @@
@license LGPL, see file <a href="license.html">COPYING</a>
$Log$
Revision 1.6 2004/12/14 20:30:10 marc
added possibility to pass string to stdin of child process
Revision 1.5 2004/10/13 10:43:11 marc
test for bad exception specification
@ -40,14 +43,20 @@ public:
std::string res = (mrw::Cmd("/bin/ls"), "-l", "..").execute();
CPPUNIT_ASSERT(res.find("COPYING")<res.size());
}
void catTest() {
std::string res =mrw::Cmd("/bin/cat").execute("This is a test");
CPPUNIT_ASSERT(res=="This is a test");
}
void excTest() {
std::string res = (mrw::Cmd("/bin/false")).execute().result();
std::string res1 = (mrw::Cmd("/bin/false")).execute().result();
std::string res2 = (mrw::Cmd("/bin/false")).execute("").result();
}
void unexpectedExc() throw(std::bad_exception) {
std::string res = (mrw::Cmd("/bin/false")).execute().result();
}
CPPUNIT_TEST_SUITE(ExecTest);
CPPUNIT_TEST(lsTest);
CPPUNIT_TEST(catTest);
CPPUNIT_TEST_EXCEPTION(excTest, mrw::ExecutionFailedExc);
CPPUNIT_TEST_EXCEPTION(unexpectedExc, std::bad_exception);
CPPUNIT_TEST_SUITE_END();

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