don't break in the absence of sendmail

If for whatever reason notify child isn't properly spawned, don't die and still
try to launch process in question

Signed-off-by: Michael Krelin <hacker@klever.net>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/process.cc b/src/process.cc
index 6d3b2a2..4807b98 100644
--- a/src/process.cc
+++ b/src/process.cc
@@ -1,297 +1,302 @@
 #include <stdio.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <signal.h>
 #include <pwd.h>
 #include <grp.h>
 #include <dirent.h>
 #include <sys/wait.h>
 #include <syslog.h>
 #include <errno.h>
 #include <iostream>
 #include <fstream>
 #include <sstream>
 #include <stdexcept>
 #include <string>
 #include <vector>
 using namespace std;
 #include "process.h"
 #include "configuration.h"
 
 static multimap<string,pid_t> procpids;
 
 void process::check() const {
     if(!pidfile.empty()) {
         signal(0);
     }else if(!process_name.empty()) {
         if(procpids.empty())
             gather_proc_info();
         if(procpids.find(process_name)==procpids.end())
             throw runtime_error("no such process");
     } // XXX: or else?
 }
 void process::check(const string& id,configuration& config) {
     try {
         check();
         patience = 0;
     }catch(exception& e) {
         if(patience>60) { // TODO: configurable
             patience = 0;
         }else{
             if(patience<10) { // TODO: configurable
                 syslog(LOG_NOTICE,"The process '%s' is down, trying to launch.",id.c_str());
                 do_notify(id,"Starting up",
                         "The named process seems to be down. Dudki will try\n"
                         "to revive it by running the specified command.\n",
                         config);
                 try {
                     launch(id,config);
                 }catch(exception& e) {
                     syslog(LOG_ERR,"Error trying to launch process '%s': %s",id.c_str(),e.what());
                 }
             }else if(patience==10){ // TODO: configurable like the above
                 syslog(LOG_NOTICE,"Giving up on process '%s' for a while",id.c_str());
                 do_notify(id,"Giving up",
                         "After a number of attempts to relaunch the named process\n"
                         "It still seems to be down. Dudki is giving up attempts\n"
                         "to revive the process for a while.\n",
                         config);
             }
             patience++;
         }
     }
 }
 
 void process::launch(const string& id,configuration& config) {
     uid_t uid = (uid_t)-1;
     gid_t gid = (gid_t)-1;
     if(!user.empty()) {
         struct passwd *ptmp = getpwnam(user.c_str());
         if(ptmp) {
             uid = ptmp->pw_uid;
             gid = ptmp->pw_gid;
         }else{
             errno=0;
             uid = strtol(user.c_str(),NULL,0);
             if(errno)
                 throw runtime_error("Failed to resolve User value to uid");
         }
     }
     if(!group.empty()) {
         struct group *gtmp = getgrnam(group.c_str());
         if(gtmp) {
             gid = gtmp->gr_gid;
         }else{
             errno = 0;
             gid = strtol(group.c_str(),NULL,0);
             if(errno)
                 throw runtime_error("Failed to reslove Group value to gid");
         }
     }
     pid_t p = fork();
     if(p<0)
         throw runtime_error(string(__PRETTY_FUNCTION__)+": failed to fork()");
     if(!p) {
         // child
         try {
             setsid();
             if(!group.empty()) {
                 if(user.empty()) {
                     if((getgid()!=gid) && setgid(gid))
                         throw runtime_error(string(__PRETTY_FUNCTION__)+": failed to setgid()");
                 }else{
                     if(initgroups(user.c_str(),gid))
                         throw runtime_error(string(__PRETTY_FUNCTION__)+": failed to initgroups()");
                 }
             }
             if(!chroot.empty()) {
                 if(::chroot(chroot.c_str()))
                     throw runtime_error(string(__PRETTY_FUNCTION__)+": failed to chroot()");
             }
             if(!user.empty()) {
                 if((getuid()!=uid) && setuid(uid))
                     throw runtime_error(string(__PRETTY_FUNCTION__)+": failed to setuid()");
             }
             char *argv[] = { "/bin/sh", "-c", (char*)restart_cmd.c_str(), NULL };
             close(0); close(1); close(2);
             execv("/bin/sh",argv);
         }catch(exception& e) {
             syslog(LOG_ERR,"Error trying to launch process '%s': %s",id.c_str(),e.what());
         }
         _exit(-1);
     }
     // parent
     int rv;
     if(waitpid(p,&rv,0)<0)
         throw runtime_error(string(__PRETTY_FUNCTION__)+": failed to waitpid()");
 }
 
 void process::do_notify(const string& id,const string& event,const string& description,configuration& config) {
     string the_notify;
     if(!notify.empty())
         the_notify=notify;
     else if(!config.notify.empty())
         the_notify=config.notify;
     else
         return;
     try {
         string::size_type colon = the_notify.find(':');
         if(colon==string::npos)
             throw runtime_error("invalid notify action specification");
         string nschema = the_notify.substr(0,colon);
         string ntarget = the_notify.substr(colon+1);
         if(nschema=="mailto") {
             notify_mailto(ntarget,id,event,description,config);
         }else
             throw runtime_error("unrecognized notification schema");
     }catch(exception& e) {
         syslog(LOG_ERR,"Notification error: %s",e.what());
     }
 }
 
 void process::notify_mailto(const string& email,const string& id,const string& event,const string& description,configuration& config) {
     int files[2];
     if(pipe(files))
         throw runtime_error("Failed to pipe()");
     pid_t pid = vfork();
     if(pid==-1) {
         close(files[0]);
         close(files[1]);
         throw runtime_error("Failed to vfork()");
     }
     if(!pid) {
         // child
         if(dup2(files[0],0)!=0)
             _exit(-1);
         close(1);
         close(files[0]);
         close(files[1]);
         execl("/usr/sbin/sendmail","usr/sbin/sendmail","-i",email.c_str(),NULL);
         _exit(-1);
     }
     // parent
+    int status;
+    if(waitpid(pid,&status,WNOHANG)) {
+        close(files[0]);
+        close(files[1]);
+        throw runtime_error("vfork()ed sendmail child exited unexpectedly");
+    }
     close(files[0]);
     FILE *mta = fdopen(files[1],"w");
     for(headers_t::const_iterator i=mailto_headers.begin();i!=mailto_headers.end();++i) {
         fprintf(mta,"%s: %s\n",i->first.c_str(),i->second.c_str());
     }
     for(headers_t::const_iterator i=config.mailto_headers.begin();i!=config.mailto_headers.end();++i) {
         if(mailto_headers.find(i->first)!=mailto_headers.end())
             continue;
         fprintf(mta,"%s: %s\n",i->first.c_str(),i->second.c_str());
     }
     fprintf(mta,
             "Subject: [%s] %s\n\n"
             "%s\n"
             "---\n"
             "This message was sent automatically by the 'dudki' daemon\n",
             id.c_str(), event.c_str(),
             description.c_str() );
     fclose(mta);
-    int status;
     waitpid(pid,&status,0);
     // TODO: check the return code
 }
 
 void process::signal(int signum) const {
     if(!pidfile.empty()) {
         ifstream pids(pidfile.c_str(),ios::in);
         if(!pids)
             throw runtime_error("no pidfile found");
         pid_t pid = 0;
         pids >> pid;
         pids.close();
         if(!pid)
             throw runtime_error("no pid in pidfile");
         if(kill(pid,signum))
             throw runtime_error("failed to signal process");
     }else if(!process_name.empty()) {
         if(procpids.empty())
             gather_proc_info();
         pair<multimap<string,pid_t>::const_iterator,multimap<string,pid_t>::const_iterator> range = procpids.equal_range(process_name);
         int count = 0;
         for(multimap<string,pid_t>::const_iterator i=range.first;i!=range.second;++i) {
             pid_t pid = i->second;
             if(kill(i->second,signum))
                 throw runtime_error("failed to signal process");
             count++;
         }
         if(!count)
             throw runtime_error("no running instance detected");
     }else
         throw runtime_error("nothing is known about the process");
 }
 
 void process::prepare_herd() {
     procpids.clear();
 }
 void process::unprepare_herd() {
     procpids.clear();
 }
 void process::gather_proc_info() {
     vector<pid_t> allpids;
     DIR *pd = opendir("/proc");
     if(!pd)
         throw runtime_error("failed to open /proc");
     struct dirent *pde;
     pid_t selfpid = getpid();
     while(pde=readdir(pd)) {
         errno=0;
         pid_t pid = atoi(pde->d_name);
         if((!pid) || pid==selfpid)
             continue;
         allpids.push_back(pid);
     }
     closedir(pd);
     char s[256];
     procpids.clear();
     for(vector<pid_t>::const_iterator i=allpids.begin();i!=allpids.end();++i) {
         int r = snprintf(s,sizeof(s),"/proc/%d/stat",*i);
         if(r>=sizeof(s) || r<1)
             continue;
         string cmd;
         ifstream ss(s,ios::in);
         if(ss) {
             getline(ss,cmd);
             string::size_type op = cmd.find('(');
             if(op==string::npos)
                 continue;
             cmd.erase(0,op+1);
             string::size_type cp = cmd.find(')');
             if(cp==string::npos)
                 continue;
             cmd.erase(cp);
         }else{
             r = snprintf(s,sizeof(s),"/proc/%d/status",*i);
             if(r>=sizeof(s) || r<1)
                 continue;
             ifstream ss(s,ios::in);
             if(!ss)
                 continue;
             ss >> cmd;
             if(cmd.empty())
                 continue;
         }
         r = snprintf(s,sizeof(s),"/proc/%d/cmdline",*i);
         if(r>=sizeof(s) || r<1)
             continue;
         ifstream cs(s,ios::binary);
         if(!cs)
             continue;
         string command;
         while(cs) {
             string cl;
             getline(cs,cl,(char)0);
             string::size_type lsl = cl.rfind('/');
             if(lsl!=string::npos)
                 cl.erase(0,lsl+1);
             if(cl.substr(0,cmd.length())==cmd) {
                 command = cl;
                 break;
             }
         }
         procpids.insert(pair<string,pid_t>(cmd,*i));
         if((!command.empty()) && cmd!=command)
             procpids.insert(pair<string,pid_t>(command,*i));
     }
 }