mysnprintf.c: Massive rewrite of PyOS_snprintf and PyOS_vsnprintf, to use wrappers on all platforms, to make this as consistent as possible x- platform (in particular, make sure there's at least one \0 byte in the output buffer). Also document more of the truth about what these do. getargs.c, seterror(): Three computations of remaining buffer size were backwards, thus telling PyOS_snprintf the buffer is larger than it actually is. This matters a lot now that PyOS_snprintf ensures there's a trailing \0 byte (because it didn't get the truth about the buffer size, it was storing \0 beyond the true end of the buffer). sysmodule.c, mywrite(): Simplify, now that PyOS_vsnprintf guarantees to produce a \0 byte.