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Description of problem: On [Linux 2.4.20-2.48bigmem #1 SMP Thu Feb 13 11:31:10 EST 2003 i686 i686 i386 GNU/Linux] in a threaded application, when calling malloc, sometimes errno is set to EINVAL. The malloc function does seem to return a valid pointer, as apposed to NULL which is supposed to be returned on an actual error. According to the man page, error codes of only 0 or ENOMEM are expected. The man pages on other platforms suggest that EINVAL may be set if malloc(0) is called. We are not calling malloc with an argument of 0. Version-Release number of selected component (if applicable): gcc version 3.2.1 20030202 (Red Hat Linux 8.0 3.2.1-7)
Setting the environment variable MALLOC_CHECK_ = 1 or 2 eliminates this problem. I don't know why, as MALLOC_CHECK_ is only supposed to be a debugging aid and is not supposed to effect the behavior of the actual malloc function call. However, obviously it does, as malloc is no longer setting errno to EINVAL.
You mean that malloc returns non-NULL and sets errno to EINVAL? That is completely legal. With the exception of a few routines named in the standards (I remember ATM only some math functions, there are a few others I think), errno has defined value only after function fails (typically returns -1, in the case of malloc NULL). So, unless malloc returns NULL, you shouldn't look what value errno has, it can have any.