lockfile.c

来自「用c++包装好的线程库,直接拿来使用,提高效率.」· C语言 代码 · 共 62 行

//
// Implementation of lock for files
//

#include "LockFile.h"

extern void Log(int, char *, ...);
extern void Fatal(char *, ...);

#define _(t)        t

LockFile::LockFile()
{
  isLocked = false;
  name = "";
}

LockFile::~LockFile()
{
  UnLock();
}

bool LockFile::Lock(const char *fname)
{
  FILE *fp;
  const char *dn;
  int n;
  struct stat sbuf;

  Log(LOG_NOTICE, _("Locking file %s"), fname);
  dn = fname;
  if (dn = strrchr(fname, '/'))
    dn++;
  name = LOCK_DIR;
  name += "/LCK..";
  name += dn;
  isLocked = false;
  if (stat(name.c_str(), &sbuf) != -1) {
    Log(LOG_WARNING, _("UUCP Lock file exists"));
    if ((fp = fopen(name.c_str(), "r")) != NULL) {
      fscanf(fp, "%10d\n", &n);
      fclose(fp);
      if (n == getpid())
	return true;
      Log(LOG_ERR, _("Device %s locked by process %d"), dn, n);
    }
    return isLocked;
  }
  Log(LOG_DEBUG, _("Creating uucp lock %s"), name.c_str());
  if ((fp = fopen(name.c_str(), "w")) == NULL)
    Fatal(_("Creating lock file %s"), name.c_str());
  fprintf(fp, "%10d\n", getpid());
  fclose(fp);
  return isLocked = true;
}

void LockFile::UnLock()
{
  Log(LOG_NOTICE, _("Unlocking %s"), name.c_str());
  if (isLocked) unlink(name.c_str());
}