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/// Application instance class implementation
/**
* \file appinst.cpp
*
* Copyright (C) 2007, 2008, 2012 Lukas Jelinek, <lukas@aiken.cz>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of one of the following licenses:
*
* \li 1. X11-style license (see LICENSE-X11)
* \li 2. GNU Lesser General Public License, version 2.1 (see LICENSE-LGPL)
* \li 3. GNU General Public License, version 2 (see LICENSE-GPL)
*
* If you want to help with choosing the best license for you,
* please visit http://www.gnu.org/licenses/license-list.html.
*
* Credits:
* Christian Ruppert (new include to build with GCC 4.4+)
*
*/
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <cstdio>
#include "appinst.h"
/// Lockfile permissions (currently 0644)
#define APPLOCK_PERM (S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH)
AppInstance::AppInstance(const std::string& rName, const std::string& rBase)
: m_fLocked(false)
{
std::string base(rBase);
if (base.empty())
base = APPLOCK_BASEDIR;
if (base[base.length()-1] == '/')
m_path = base + rName + ".pid";
else
m_path = base + "/" + rName + ".pid";
}
AppInstance::~AppInstance()
{
try {
Unlock();
} catch (AppInstException e) {}
}
bool AppInstance::DoLock()
{
int fd = open(m_path.c_str(), O_WRONLY | O_CREAT | O_EXCL, APPLOCK_PERM);
if (fd != -1) {
FILE* f = fdopen(fd, "w");
if (f == NULL) {
AppInstException e(errno);
close(fd);
throw e;
}
if (fprintf(f, "%u", (unsigned) getpid()) <= 0) {
AppInstException e(errno);
fclose(f);
throw e;
}
if (fclose(f) != 0)
throw AppInstException(errno);
m_fLocked = true;
return true;
}
if (errno != EEXIST)
throw AppInstException(errno);
return false;
}
bool AppInstance::Lock()
{
for (int i=0; i<100; i++) {
if (DoLock())
return true;
FILE* f = fopen(m_path.c_str(), "r");
if (f == NULL) {
if (errno != ENOENT)
throw AppInstException(errno);
}
else {
unsigned pid;
ssize_t len = fscanf(f, "%u", &pid);
if (len == -1) {
AppInstException e(errno);
fclose(f);
throw e;
}
else if (len == 0) {
AppInstException e(EIO);
fclose(f);
throw e;
}
fclose(f);
int res = kill((pid_t) pid, 0);
if (res == 0)
return false;
if (errno != ESRCH)
throw AppInstException(errno);
res = unlink(m_path.c_str());
if (res != 0 && errno != ENOENT)
throw AppInstException(errno);
}
}
return false;
}
void AppInstance::Unlock()
{
if (!m_fLocked)
return;
if (unlink(m_path.c_str()) != 0 && errno != ENOENT)
throw AppInstException(errno);
m_fLocked = false;
}
bool AppInstance::Exists() const
{
if (m_fLocked)
return true;
FILE* f = fopen(m_path.c_str(), "r");
if (f == NULL) {
if (errno == ENOENT)
return false;
else
throw AppInstException(errno);
}
bool ok = false;
unsigned pid;
if (fscanf(f, "%u", &pid) == 1) {
if (kill((pid_t) pid, 0) == 0)
ok = true;
else if (errno != ESRCH) {
AppInstException e(errno);
fclose(f);
throw e;
}
}
fclose(f);
return ok;
}
bool AppInstance::SendSignal(int iSigNo) const
{
FILE* f = fopen(m_path.c_str(), "r");
if (f == NULL) {
if (errno == ENOENT)
return false;
else
throw AppInstException(errno);
}
bool ok = false;
unsigned pid;
if (fscanf(f, "%u", &pid) == 1) {
if (pid != (unsigned) getpid()) {
if (kill((pid_t) pid, iSigNo) == 0) {
ok = true;
}
else if (errno != ESRCH) {
AppInstException e(errno);
fclose(f);
throw e;
}
}
}
fclose(f);
return ok;
}
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