added possibility to pass string to stdin of child process

mrw/exec.cpp

@@ -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) {
+mrw::Exec mrw::Cmd::execute(bool exc) const throw(std::exception) {
-  return mrw::Exec(*this).execute(throwExc);
+  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
+      stdout and @c stderr from the child process to the parent
-      using mrw::Pipe and calls @c execvp to execute the program. */
+      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=read(stdOut.istream(), buf1, sizeof(buf1)))>0
-           num1==-1 && errno==EINTR ||
+           || num1==-1 && (errno==EINTR||errno==EAGAIN)
-           (num2=read(stdErr.istream(), buf2, sizeof(buf2)))>0 ||
+           || (num2=read(stdErr.istream(), buf2, sizeof(buf2)))>0
-           num2==-1 && errno==EINTR;
+           || num2==-1 && (errno==EINTR||errno==EAGAIN);) {
-         _res += std::string(buf1, num1), _err += std::string(buf2, num2));
+      if (num1>0) _res += std::string(buf1, num1);
-    if (num1==-1 || num2==-1)
+      if (num2>0) _err += std::string(buf2, num2);
-      throw ExecutionFailedExc("cannot_ read pipe", *_cmd);
+    }
     // wait for child to get return code
     int s(0);
-    if (waitpid(pid, &s, 0)!=pid || WIFEXITED(s)!=0 && WEXITSTATUS(s)!=0) {
+    if (waitpid(pid, &s, 0)!=pid || WIFEXITED(s)!=0 && WEXITSTATUS(s)!=0
-      if (throwExc) {
+        || 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;

mrw/exec.hpp

@@ -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;

mrw/exec_test.cpp

@@ -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();