From 2a47dd786386d77d970e3abd8be72e2ae586b06f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marc=20W=C3=A4ckerlin?= <marc@mrw.sh>
Date: Fri, 17 Dec 2004 16:28:51 +0000
Subject: [PATCH] stable implementation with select for both executes

---
 mrw/exec.cpp | 78 ++++++++++++++++++++++++++++------------------------
 1 file changed, 42 insertions(+), 36 deletions(-)

diff --git a/mrw/exec.cpp b/mrw/exec.cpp
index 7eec02a..6d4a2d7 100644
--- a/mrw/exec.cpp
+++ b/mrw/exec.cpp
@@ -9,6 +9,9 @@
     @license LGPL, see file <a href="license.html">COPYING</a>
 
     $Log$
+    Revision 1.6  2004/12/17 16:28:51  marc
+    stable implementation with select for both executes
+
     Revision 1.5  2004/12/14 20:30:09  marc
     added possibility to pass string to stdin of child process
 
@@ -137,25 +140,40 @@ mrw::Exec& mrw::Exec::execute(bool exc) throw(std::exception) {
     stdErr.close_out();
     if (!stdOut || !stdErr)
       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||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
-        || num1==-1 || num2==-1) {
-      if (exc) {
-        throw ExecutionFailedExc("execution failed", *_cmd);
-      } else {
-        _success = false;
-        return *this;
-      }
+    ssize_t num1(-1), num2(-1);
+    fd_set readfds;
+    char buf[4096];
+    int res(0), s(0);
+    while (num1||num2) try { // not all end of file
+      if (!res && (res=waitpid(pid, &s, WNOHANG)))
+        if (res!=pid || WIFEXITED(s)!=0 && WEXITSTATUS(s)!=0)
+          throw ExecutionFailedExc("execution failed", *_cmd);
+      // select...
+      FD_ZERO(&readfds);
+      if (num1) FD_SET(stdOut.istream(), &readfds);
+      if (num2) FD_SET(stdErr.istream(), &readfds);
+      int n(mrw::max((num1?stdOut.istream():0),
+                     (num2?stdErr.istream():0)));
+      timeval tm = {0, 10000};
+      int num = select(n, &readfds, 0, 0, &tm);
+      if (num<0) throw ExecutionFailedExc("select failed", *_cmd);
+      if (num==0 && res==pid) break; // process ended, no data left
+      // 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;
     }
   } else { // child
     stdOut.close_in();
@@ -198,26 +216,24 @@ mrw::Exec& mrw::Exec::execute(const std::string& input, bool exc)
     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))) {
+    int res(0), s(0);
+    while (num0||num1||num2) try { // not all end of file
+      if (!res && (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))));
+      timeval tm = {0, 10000};
       int num = select(n, &readfds, &writefds, 0, &tm);
       if (num<0) throw ExecutionFailedExc("select failed", *_cmd);
+      if (num==0 && res==pid) break; // process ended, no data left
       // check and handle stdin
       if (num0 && num>0
           && FD_ISSET(stdIn.ostream(), &writefds))
@@ -245,16 +261,6 @@ mrw::Exec& mrw::Exec::execute(const std::string& input, bool exc)
       _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();