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procs: add support for easy redirection to dev null

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Simply set a NULL pointer for a fd, StartPiped will then take care of opening
/dev/null, redirecting fds to it and close it when necessary.
This commit is contained in:
Peter Wu 2012-08-07 17:02:22 +02:00
parent b994bab6d2
commit fa5d27b085
1 changed files with 40 additions and 18 deletions
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58
lib/procs.cpp
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@ -325,9 +325,9 @@ pid_t Util::Procs::Start(std::string name, std::string cmd, std::string cmd2, st
/// \return 0 if process was not started, process PID otherwise.
/// \arg name Name for this process - only used internally.
/// \arg argv Command for this process.
/// \arg fdin Standard input file descriptor. If -1, fd is automatically allocated and written.
/// \arg fdout Standard output file descriptor. If -1, fd is automatically allocated and written.
/// \arg fderr Standard error file descriptor. If -1, fd is automatically allocated and written.
/// \arg fdin Standard input file descriptor. If null, /dev/null is assumed. Otherwise, if arg contains -1, a new fd is automatically allocated and written into this arg. Then the arg will be used as fd.
/// \arg fdout Same as fdin, but for stdout.
/// \arg fdout Same as fdin, but for stderr.
pid_t Util::Procs::StartPiped(std::string name, char * argv[], int * fdin, int * fdout, int * fderr){
if (isActive(name)){return getPid(name);}
pid_t pid;
@ -340,20 +340,20 @@ pid_t Util::Procs::StartPiped(std::string name, char * argv[], int * fdin, int *
sigaction(SIGCHLD, &new_action, NULL);
handler_set = true;
}
if (*fdin == -1 && pipe(pipein) < 0){
if (fdin && *fdin == -1 && pipe(pipein) < 0){
#if DEBUG >= 1
std::cerr << "Pipe (in) creation failed for " << name << std::endl;
#endif
return 0;
}
if (*fdout == -1 && pipe(pipeout) < 0) {
if (fdout && *fdout == -1 && pipe(pipeout) < 0) {
#if DEBUG >= 1
std::cerr << "Pipe (out) creation failed for " << name << std::endl;
#endif
if (*fdin == -1){close(pipein[0]);close(pipein[1]);}
return 0;
}
if (*fderr == -1 && pipe(pipeerr) < 0) {
if (fderr && *fderr == -1 && pipe(pipeerr) < 0) {
#if DEBUG >= 1
std::cerr << "Pipe (err) creation failed for " << name << std::endl;
#endif
@ -361,21 +361,40 @@ pid_t Util::Procs::StartPiped(std::string name, char * argv[], int * fdin, int *
if (*fdout == -1){close(pipeout[0]);close(pipeout[1]);}
return 0;
}
int devnull = -1;
if (!fdin || !fdout || !fderr){
devnull = open("/dev/null", O_RDWR);
if (devnull == -1){
#if DEBUG >= 1
std::cerr << "Could not open /dev/null for " << name << ": " << strerror(errno) << std::endl;
#endif
if (*fdin == -1){close(pipein [0]);close(pipein [1]);}
if (*fdout == -1){close(pipeout[0]);close(pipeout[1]);}
if (*fderr == -1){close(pipeerr[0]);close(pipeerr[1]);}
return 0;
}
}
pid = fork();
if (pid == 0){//child
if (*fdin == -1){
if (!fdin){
dup2(devnull, STDIN_FILENO);
}else if (*fdin == -1){
close(pipein[1]);// close unused write end
dup2(pipein[0], STDIN_FILENO);
}else{
dup2(*fdin, STDIN_FILENO);
}
if (*fdout == -1){
if (!fdout){
dup2(devnull, STDOUT_FILENO);
}else if (*fdout == -1){
close(pipeout[0]);// close unused read end
dup2(pipeout[1], STDOUT_FILENO);
}else{
dup2(*fdout, STDOUT_FILENO);
}
if (*fderr == -1){
if (!fderr){
dup2(devnull, STDERR_FILENO);
}else if (*fderr == -1){
close(pipeerr[0]);// close unused read end
dup2(pipeerr[1], STDERR_FILENO);
}else{
@ -390,27 +409,30 @@ pid_t Util::Procs::StartPiped(std::string name, char * argv[], int * fdin, int *
#if DEBUG >= 1
std::cerr << "Failed to fork for pipe: " << name << std::endl;
#endif
if (*fdin == -1){close(pipein [0]);close(pipein [1]);}
if (*fdout == -1){close(pipeout[0]);close(pipeout[1]);}
if (*fderr == -1){close(pipeerr[0]);close(pipeerr[1]);}
if (fdin && *fdin == -1){close(pipein [0]);close(pipein [1]);}
if (fdout && *fdout == -1){close(pipeout[0]);close(pipeout[1]);}
if (fderr && *fderr == -1){close(pipeerr[0]);close(pipeerr[1]);}
if (devnull != -1){close(devnull);}
return 0;
} else{//parent
#if DEBUG >= 1
std::cerr << "Piped process " << name << " started";
std::cerr << " in=" << (*fdin == -1 ? pipein [1] : *fdin );
std::cerr << " out=" << (*fdout == -1 ? pipeout[0] : *fdout);
std::cerr << " err=" << (*fderr == -1 ? pipeerr[0] : *fderr);
if (fdin ) std::cerr << " in=" << (*fdin == -1 ? pipein [1] : *fdin );
if (fdout) std::cerr << " out=" << (*fdout == -1 ? pipeout[0] : *fdout);
if (fderr) std::cerr << " err=" << (*fderr == -1 ? pipeerr[0] : *fderr);
if (devnull != -1) std::cerr << " null=" << devnull;
std::cerr << ", PID " << pid << ": " << argv[0] << std::endl;
#endif
if (*fdin == -1){
if (devnull != -1){close(devnull);}
if (fdin && *fdin == -1){
close(pipein[0]);// close unused end end
*fdin = pipein[1];
}
if (*fdout == -1){
if (fdout && *fdout == -1){
close(pipeout[1]);// close unused write end
*fdout = pipeout[0];
}
if (*fderr == -1){
if (fderr && *fderr == -1){
close(pipeerr[1]);// close unused write end
*fderr = pipeerr[0];
}