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If errno == EMFILE, the errno = 24. "Too many open files" according to the man page of errno.</div>
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In the else block, errno equals 23 during my run. </div>
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This is ENFILE, and means "Too many open files in system. </div>
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Maximum number of file descriptors allowable on the system has been reached and a request</div>
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for an open cannot be satistfied until at least one has been closed."</div>
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So it turns out that the entire system is simply out of space.</div>
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In another test, I ran</div>
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> fstat | wc -l <br>
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> 249</div>
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openmax.c shows me 4 open files, and fails on #3248 with ENFILE.</div>
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249 + 3247 > 3404, so I'm unsure how the limit of ENFILE is determined.</div>
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I'll look into it later and get back to everyone with what I find.</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> cs631apue-bounces@lists.stevens.edu <cs631apue-bounces@lists.stevens.edu> on behalf of Jan Schaumann <jschauma@stevens.edu><br>
<b>Sent:</b> Monday, September 14, 2020 7:28 PM<br>
<b>To:</b> cs631apue@lists.stevens.edu <cs631apue@lists.stevens.edu><br>
<b>Subject:</b> Re: [cs631apue] Openmax.c fails earlier than expected</font>
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<div class="PlainText">Charles Magyar IV <cmagyar@stevens.edu> wrote:<br>
<br>
> I change the limit to unlimited, and the program starts to throw issues at file # 3249. I had 8 files already open.<br>
> With 8 files open, I would expect it to fail at 3396.<br>
<br>
Ah, I see what's going on here.<br>
<br>
Take a close look at _when_ we generate the error<br>
message, and _what_ the error message is exactly.<br>
<br>
> for (int i = count; i <= num + 1; i++) {<br>
> if ((fd = open("/dev/null", O_RDONLY)) < 0) {<br>
> if (errno == EMFILE) {<br>
> printf("Opened %d additional files, then failed due to limit.\n", i - count);<br>
> break;<br>
<br>
What is 'errno' here, and what is the error message<br>
printed by strerror(errno)?<br>
<br>
> } else {<br>
> fprintf(stdout, "File # %d err\n",i);<br>
> fprintf(stderr, "Unable to open '/dev/null': %s\n",<br>
> strerror(errno));<br>
> }<br>
<br>
And what is 'errno' _here_, and what is the error<br>
message printed by strerror(errno)?<br>
<br>
<br>
I'm sure you can pinpoint the difference - then go one<br>
step further and see if you can find out what the<br>
difference in the numbers you expected and the ones<br>
you observed are.<br>
<br>
-Jan<br>
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