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//************************************************************
// locks.C - source file for creation and removal of port
// locks
//************************************************************
#include "incall.h"
Locks::Locks()
{
PortLocked = 0;
LockFileName = NULL;
}
Locks::~Locks()
{
if (LockFileName)
{
RemoveLockFile();
delete LockFileName;
}
}
void Locks::Init(ConfigInfo* conf)
{
int i;
LockFileName = new char[strlen(conf->LockPath) +
7 + strlen(conf->SerialPort)];
strcpy(LockFileName, conf->LockPath);
strcat(LockFileName, "/LCK..");
for (i=strlen(conf->SerialPort)-1; i > 0 && conf->SerialPort[i]!='/'; i--);
i++;
strcat(LockFileName, &(conf->SerialPort[i]));
}
// Attempts to create a lock file for the specified ttyS.
// returns:
// 1 - success
// 0 - device is locked by another process
// -1 - Something is really screwed (permissions?)
int Locks::MakeLockFile()
{
char LockBuf[MAXPATHLEN];
int fd, procID;
if (PortLocked) return 1;
// If you use NFS, see man open for different implementation,
// I'm toooooo lazy to do it the RIGHT way. Sorry.
fd = open( LockFileName, O_WRONLY | O_CREAT | O_EXCL,
S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
if (fd == -1)
{
// Something did not work
if (errno != EEXIST)
return -1; // Go, figure....
// File exists, the port may be locked by another process
// Check if the process exist...
fd = open( LockFileName, O_RDONLY );
if (fd == -1) return 0;
if (read( fd, LockBuf, sizeof(LockBuf)) <= 0)
{
close(fd);
return 0;
}
close(fd);
if (sscanf(LockBuf, "%d", &procID) != 1)
{
return 0;
}
if (-1 != kill(procID, 0) || errno != ESRCH )
return 0;
syslog(LOG_WARNING,"Removing stale lock file.");
unlink( LockFileName );
// Yet another retry
fd = open( LockFileName, O_WRONLY | O_CREAT | O_EXCL,
S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
// Oh, I give up
if (fd == -1) return 0;
}
sprintf( LockBuf, "%d", getpid());
write(fd, LockBuf, strlen(LockBuf)+1);
close(fd);
PortLocked = 1;
return 1;
}
// Checks for existance of the lock file
// returns:
// 1 - No lock file
// 0 - device is locked by another process
int Locks::CheckLockFile()
{
int fd;
if (PortLocked) return 1;
// If you use NFS, see man open for different implementation,
// I'm toooooo lazy to do it the RIGHT way. Sorry.
fd = open( LockFileName, O_RDONLY );
if (fd == -1)
{
return 1; // No lock file...
}
close(fd);
return 0;
}
// The name sez it all.
void Locks::RemoveLockFile()
{
FILE* fp;
int pid;
syslog(LOG_DEBUG,"Removing lock file name: %s",LockFileName);
fp = fopen(LockFileName, "r");
if (fp)
{
fscanf(fp, "%d", &pid);
fclose(fp);
if (pid == getpid())
unlink( LockFileName );
else
syslog(LOG_ERR,
"The lock file belongs to another process. Could not remove");
}
PortLocked = 0;
};
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