I think I see a flaw with this... Goetz Babin-Ebell wrote: > > I did something that way: > > FILE *DoOpen(const char *cpFile, long bAppend) > { > FILE *spNew; > FILE *spTest; > struct stat sStat; > > spTest = fopen(cpFile,"a"); > if (!spTest) > { > Log("ERR FILE OPEN",cpFile); > return NULL; > } > if (lstat(cpFile,&sStat)) > { > Log("ERR STAT",cpFile); > return NULL; > } > if ((sStat.st_mode & S_IFMT) == S_IFLNK) > { > fclose(spTest); > Log("ERR ISLINK",cpFile); > return NULL; > } > if (bAppend) > spNew = spTest; > else > { > spNew = freopen(cpFile,"w",spTest); > fclose(spTest); > } > if (!spNew) > { > Log("ERR FILE OPEN",cpFile); > return NULL; > } > return spFile; > } > In my tired state, I get the feeling that you open yourself up to an inverted race situation here. In this situation, the file that you open may be a link, but before it is stat()ed, it may be deleted (yes you can do this even though it is open) and replaced with a normal file, so that stat() won't complain. I'd suggest that you don't stat the file by name, but rather by the file descriptor that you already have (_fstat()?); this way you know that you are stat()ing the same file that you actually opened (I hope!). Oh, and the freopen() call opens you up to another race situation (I think). AFAIK, freopen() is just a shorthand for fclose() followed by fopen(), so that leaves room for a race situation. (I might be talking out of my arse here tho) If it were me, I'd move the file pointer to 0 and set the file length to 0; this way the file remains open all the time, and you still get the desired effect. <flame shield> I'm _REALLY_ tired Just so you know :-) </flame shield> /Mike -- Mikael Olsson, EnterNet Sweden AB, Box 393, S-891 28 ÖRNSKÖLDSVIK Phone: +46-(0)660-105 50 Fax: +46-(0)660-122 50 Mobile: +46-(0)70-248 00 33 WWW: http://www.enternet.se E-mail: mikael.olssonat_private
This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 15:26:22 PDT