Thanks. Yes, I believe this is a bug. The implementation of MPI_Info_get in MPICH passes valuelen to the internal copy routine, yet it is clear that the definition in the standard for MPI_Info_get, it should pass valuelen+1 (it should also check for the error return code from the internal routine and return a value MPI error code if the buffer is too small. Bill On Feb 1, 2015, at 12:13 AM, Hajime Fujita <[email protected]> wrote:

Hello,

I came across some question about a behavior of MPI_Info_get in MPICH.

If I knew the size of the value, what should I pass to MPI_Info_get as `valuelen`? Suppose I have 3-byte value in the info object, and I allocate 4-byte buffer including a space for null-termination. Then I think I should specify 3 as valuelen to retrieve the whole value, as the MPI-3 specifications says "In C, valuelen should be one less than the amount of allocated space to allow for the null terminator.”

However, when I run the attached program in MPICH 3.1.1, I get: $ ./test key found: vaule=va # The last character ‘l’ is missing

If I specify `sizeof(buff)` as valuelen, it shows “val” correctly.

So apparently MPICH thinks valuelen includes null terminator. Am I missing anything, or any misunderstanding here?

Thank you in advance, Hajime

-- Hajime Fujita Postdoctoral Scholar, Large-Scale Systems Group Department of Computer Science, The University of Chicago http://www.cs.uchicago.edu/people/hfujita _______________________________________________ discuss mailing list [email protected] To manage subscription options or unsubscribe: https://lists.mpich.org/mailman/listinfo/discuss <test.c>

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