On Jan 30 08:19, Steven Bardwell wrote: > > On Jan 30 07:25, Steven Bardwell wrote: > > > > > On 29/01/2014 19:12, Corinna Vinschen wrote: > > > > > >On Jan 29 09:00, Steven Bardwell wrote: > > > > > >>My application needs several areas of shared memory, and I am > > getting > > > > an > > > > > >>error ("No such device") on the second call to mmap(). The first > > > > > >>call > > > > works > > > > > >>fine. > > > > > > > > Sorry guys, but it still works fine for me. I tried your testcase on W7 > > > > 32, W7 64 in 32 and 64 bit, and on Windows 8.1 64 in 32 and 64 bit. I > > > > tried it with Cygwin 1.7.27 and with the latest snapshot. I'm always > > > > getting the output "Shared memory initialized" and no error at all. > > > > > > > > > > > > Any chance one of you guys could debug this further, by stepping > > through > > > > the Cygwin mmap64 function, preferredly using the latest snapshot or, > > > > a self-built Cygwin DLL from? > > > > > > > > > > > > Corinna > > > > > > I reinstalled Cygwin, rebooted and the error persisted. Running 'gdb' and > > > stepping through the program showed that the call to mmap() fails for > > /block1 > > > also -- it is returning an invalid address. This simplification of the > > > program > > > shows that error on my machine ('Bus error (core dumped)' ) occurs > > > when it tries to do the memcpy() to the mapped address. > > The reason is that ftruncate is defined with the second argument being > > off_t, which is 8 byte. 524304 is an int (4 byte) only, though. Since > > ftruncate is declared in unistd.h, but you didn't include unistd.h, the > > 2nd parameter to ftruncate is auto-propagated to int, which results in > > an invalid new file length, and which makes ftruncate fail. Since you > > missed to check ftruncate's return value... you get the idea. > > > > > > Corinna > > Thanks so much for wasting your time debugging my program. > > Adding the <unistd.h> fixes the problem in all its iterations -- the original > mmap() > test works (without the call to ftruncate()), as well as the second one.
I'm glad to read that. > You all run a great technical support operation. I'm glad you think that. :) Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
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