Date: Wed, 27 Feb 2008 13:54:46 -0500 From: Garrett Wollman <wollman@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: arch@freebsd.org Subject: Re: Cleaning up FILE in stdio.. Message-ID: <18373.45558.444085.196189@hergotha.csail.mit.edu> In-Reply-To: <200802271134.04166.jhb@freebsd.org> References: <200802262251.m1QMp7bV021709@hergotha.csail.mit.edu> <200802270526.m1R5QQT3024163@hergotha.csail.mit.edu> <200802271134.04166.jhb@freebsd.org>
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<<On Wed, 27 Feb 2008 11:34:04 -0500, John Baldwin <jhb@freebsd.org> said: > I avoided EMFILE in all 3 cases as it struck me as being not really true (an > app would find the rlimit higher than the current fd for example). Also, > EMFILE doesn't really make sense from fdopen() at all. You've already opened > the fd, so you know you can't run out of fd's. [EMFILE] is does not imply that you have run out of fds. POSIX says (for fdopen()): The fdopen( ) function may fail if: [EBADF] The fildes argument is not a valid file descriptor. [EINVAL] The mode argument is not a valid mode. [EMFILE] {FOPEN_MAX} streams are currently open in the calling process. [EMFILE] {STREAM_MAX} streams are currently open in the calling process. [ENOMEM] Insufficient space to allocate a buffer. My change to sysconf() causes {STREAM_MAX} to be clamped at {SHRT_MAX}, so a user calling sysconf(_PC_STREAM_MAX) or $(getconf STREAM_MAX) will see a different value from the resource limit and understand that there is a limit (even if it's not quite on the number of streams). For fopen(), the errors are defined as follows: "shall fail": [EMFILE] {OPEN_MAX} file descriptors are currently open in the calling process. [ENFILE] The maximum allowable number of files is currently open in the system. "may fail": [EINVAL] The value of the mode argument is not valid. [EMFILE] {FOPEN_MAX} streams are currently open in the calling process. [EMFILE] {STREAM_MAX} streams are currently open in the calling process. The other possibility would be [EOVERFLOW], which is defined as: [EOVERFLOW] The named file is a regular file and the size of the file cannot be represented correctly in an object of type off_t. But I truly believe that [EMFILE] is the best option. -GAWollman
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