Question

We’ve discovered our complex iPhone app (ObjC, C++, JavaScript/WebKit) is leaking file descriptors under unusual circumstances.

I need to know which files (by file path) we are leaving open.

I want something like the BSD command “lsof”, which, of course, isn’t available in iOS 4, at least not to me. Ideally a C or ObjC function. Or a tool, like shark or Instruments. Just need the files for our running app, not (as with lsof) for all apps/processes.

We do all sorts of things with files, and the code that is failing with “Too many open files” hasn’t changed in ages, and since the circumstances are unusual, this could have crept in months ago. So there’s no need to remind me to look at code that opens files and make sure I close them. I know that already. Would be nice to narrow it down with something lsof-esque. Thanks.

Answer 1

#import <sys/types.h>  
#import <fcntl.h>
#import <errno.h>
#import <sys/param.h>

+(void) lsof
{
    int flags;
    int fd;
    char buf[MAXPATHLEN+1] ;
    int n = 1 ;

    for (fd = 0; fd < (int) FD_SETSIZE; fd++) {
        errno = 0;
        flags = fcntl(fd, F_GETFD, 0);
        if (flags == -1 && errno) {
            if (errno != EBADF) {
                return ;
            }
            else
                continue;
        }
        fcntl(fd , F_GETPATH, buf ) ; 
        NSLog( @"File Descriptor %d number %d in use for: %s",fd,n , buf ) ;
        ++n ; 
    }
}