add --block-notify to monerod and --tx-notify to monero-wallet-{cli,rpc}

Those take a command line of the form "A [B]", with A being the
name (and optional path, if not in the caller's CWD, but fully
qualified path is recommended, avoids possible security issues)
to a program, and optional arguments. Any occurence of the two
character string "%s" will be replaced by the hash of the block
or transaction which triggered the notification.

Tokenization is barebones. If you want things like pipes, calls
to paths with spaces, etc, then use a script (though exec time
will suffer).

block-notify is called when a new block is added onto the chain.

tx-notify is called when a new transaction happens with the
wallet as source and/or destination.

It is the notification program's responsibility to determine what
to do in those cases.

Note that this is asynchronous, so it is very possible that:
- the notification programs will be run out of order
- several events happen before the notification for the first one

A Windows port would be nice if someone wants to make one.

5 files changed, 238 insertions, 0 deletions

diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index e89dbbc24..9b83f149f 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -34,9 +34,11 @@ set(common_sources
   dns_utils.cpp
   download.cpp
   error.cpp
+  exec.cpp
   expect.cpp
   util.cpp
   i18n.cpp
+  notify.cpp
   password.cpp
   perf_timer.cpp
   threadpool.cpp
@@ -58,9 +60,11 @@ set(common_private_headers
   dns_utils.h
   download.h
   error.h
+  exec.h
   expect.h
   http_connection.h
   int-util.h
+  notify.h
   pod-class.h
   rpc_client.h
   scoped_message_writer.h
diff --git a/src/common/exec.cpp b/src/common/exec.cpp
new file mode 100644
index 000000000..41b8f1378
--- /dev/null
+++ b/src/common/exec.cpp
@@ -0,0 +1,88 @@
+// Copyright (c) 2018, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <errno.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "misc_log_ex.h"
+#include "exec.h"
+
+namespace tools
+{
+
+int exec(const char *filename, char * const argv[], bool wait)
+{
+  pid_t pid = fork();
+  if (pid < 0)
+  {
+    MERROR("Error forking: " << strerror(errno));
+    return -1;
+  }
+
+  // child
+  if (pid == 0)
+  {
+    char *envp[] = {NULL};
+    execve(filename, argv, envp);
+    MERROR("Failed to execve: " << strerror(errno));
+    return -1;
+  }
+
+  // parent
+  if (pid > 0)
+  {
+    if (!wait)
+      return 0;
+
+    while (1)
+    {
+      int wstatus = 0;
+      pid_t w = waitpid(pid, &wstatus, WUNTRACED | WCONTINUED);
+      if (w  < 0) {
+        MERROR("Error waiting for child: " << strerror(errno));
+        return -1;
+      }
+      if (WIFEXITED(wstatus))
+      {
+        MINFO("Child exited with " << WEXITSTATUS(wstatus));
+        return WEXITSTATUS(wstatus);
+      }
+      if (WIFSIGNALED(wstatus))
+      {
+        MINFO("Child killed by " << WEXITSTATUS(wstatus));
+        return WEXITSTATUS(wstatus);
+      }
+    }
+  }
+  MERROR("Secret passage found");
+  return -1;
+}
+
+}
diff --git a/src/common/exec.h b/src/common/exec.h
new file mode 100644
index 000000000..4d2037798
--- /dev/null
+++ b/src/common/exec.h
@@ -0,0 +1,36 @@
+// Copyright (c) 2018, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#pragma once 
+
+namespace tools
+{
+
+int exec(const char *filename, char * const argv[], bool wait);
+
+}
diff --git a/src/common/notify.cpp b/src/common/notify.cpp
new file mode 100644
index 000000000..b7869ad84
--- /dev/null
+++ b/src/common/notify.cpp
@@ -0,0 +1,61 @@
+// Copyright (c) 2018, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include <boost/algorithm/string.hpp>
+#include "misc_log_ex.h"
+#include "file_io_utils.h"
+#include "exec.h"
+#include "notify.h"
+
+namespace tools
+{
+
+Notify::Notify(const char *spec)
+{
+  CHECK_AND_ASSERT_THROW_MES(spec, "Null spec");
+
+  boost::split(args, spec, boost::is_any_of(" "));
+  CHECK_AND_ASSERT_THROW_MES(args.size() > 0, "Failed to parse spec");
+  filename = args[0];
+  CHECK_AND_ASSERT_THROW_MES(epee::file_io_utils::is_file_exist(filename), "File not found: " << filename);
+}
+
+int Notify::notify(const char *parameter)
+{
+  std::vector<std::string> margs = args;
+  for (std::string &s: margs)
+    boost::replace_all(s, "%s", parameter);
+
+  char **cargs = (char**)alloca(sizeof(char*) * (margs.size() + 1));
+  for (size_t n = 0; n < margs.size(); ++n)
+    cargs[n] = (char*)margs[n].c_str();
+  cargs[margs.size()] = NULL;
+  return tools::exec(filename.c_str(), cargs, false);
+}
+
+}
diff --git a/src/common/notify.h b/src/common/notify.h
new file mode 100644
index 000000000..81aacebb0
--- /dev/null
+++ b/src/common/notify.h
@@ -0,0 +1,49 @@
+// Copyright (c) 2018, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#pragma once 
+
+#include <string>
+#include <vector>
+
+namespace tools
+{
+
+class Notify
+{
+public:
+  Notify(const char *spec);
+
+  int notify(const char *parameter);
+
+private:
+  std::string filename;
+  std::vector<std::string> args;
+};
+
+}