How to know if malloc.h is available?



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How to know if malloc.h is available?

Postby fogli_beppe » Fri, 21 Nov 2008 05:40:48 GMT

is there a way to know if the header file malloc.h is available?
I mean, is there some cpp macro to test, like for example
macros defined in standards or specifications like SVID, XPG,
or unix flavour like __sun?
I have this piece of code:

#if defined (__sun) || defined (__i386) || defined (__ia64)
#include <malloc.h>

It compiles on linux (x86, x86_64 and itanium) and on Solaris (SPARC)
but it doesn't compile on Mac OS X (x86), where the compiler (gcc from
XCode 3.1.1) can't find malloc.h .
Now, I'm pretty new with Mac but I think the test above should make
use of "more portable" macros.

Thanks for your help.

Re: How to know if malloc.h is available?

Postby Lew Pitcher » Fri, 21 Nov 2008 06:10:12 GMT

On November 19, 2008 15:40, in comp.unix.programmer,  XXXX@XXXXX.COM 


Well, that's the cannonical test for whether or not malloc.h is available to
the compiler.

Now, two things:
1) For the compiler to be /complete/, it /must/ include a malloc.h header.
So, go back and check the install for the compiler to see if it missed

2) While there is no /requirement/ (at the C compiler level) that <malloc.h> 
actually be a file in your filesystem, most Unixish systems populate
the /usr/include directory with flat files for all the standard (C and
POSIX) headers. If there is a file for malloc.h, you'd find it there.

Lew Pitcher

Master Codewright & JOAT-in-training | Registered Linux User #112576
 http://www.**--****.com/ | GPG public key available by request
----------      Slackware - Because I know what I'm doing.          ------

Re: How to know if malloc.h is available?

Postby Lew Pitcher » Fri, 21 Nov 2008 06:17:00 GMT

On November 19, 2008 16:10, in comp.unix.programmer, Lew Pitcher

Oops... let me correct that. 
For the compiler to be complete, it must include malloc() and friends. The
header for the malloc() family of functions is <stdlib.h>, not <malloc.h>. 

Lew Pitcher

Master Codewright & JOAT-in-training | Registered Linux User #112576
 http://www.**--****.com/ | GPG public key available by request
----------      Slackware - Because I know what I'm doing.          ------

Re: How to know if malloc.h is available?

Postby Doug McIntyre » Fri, 21 Nov 2008 06:31:31 GMT

Lew Pitcher < XXXX@XXXXX.COM > writes:

And Darwin (MacOSX) does have malloc() defined in stdlib.h, and also
has a /usr/include/malloc/malloc.h header file. 

Probably a throwback to its Mach roots. 

Re: How to know if malloc.h is available?

Postby gordonb.1mzml » Fri, 21 Nov 2008 08:37:28 GMT

>1) For the compiler to be /complete/, it /must/ include a malloc.h header.

Incorrect.  Standard C makes no mention of such a header.
The correct header for malloc() and related functions is <stdlib.h>.

FreeBSD has an interesting <malloc.h> header, which suggests that
it's probably a bad idea to use <malloc.h>, and an even worse idea
to assume that its presence implies the existence of mallinfo():

/* $FreeBSD: src/include/malloc.h,v 1.5 2001/11/07 23:14:31 obrien Exp $ */
#if __STDC__
#error "<malloc.h> has been replaced by <stdlib.h>"
#include <stdlib.h>

Re: How to know if malloc.h is available?

Postby fogli_beppe » Sat, 22 Nov 2008 01:35:37 GMT

Thanks to everyone for the answers.
Probably I've been a little too short in my first message.

On the Mac OS X I installed all of the package XCode 3.1.1 from Apple
which provides
gcc 4.2 beside a lots of other development tools.
I think this is a /complete/ installation of the compiler and so of
the standard headers too.
The malloc.h is not an ISO C standard header so it's not part of the
I think it should be provided by the system, for example the GNU C
Library provide a
malloc.h containing mallinfo . I can't find a usable malloc.h on the
Mac even though
there are 2 malloc.h in /usr/include (malloc/malloc.h and sys/
malloc.h) none
containing mallinfo.

Searching a bit on the net I found that mallinfo should be provided by
compliant systems (GNU Lib C malloc.h and manual).
Under Solaris 8 mallinfo is in malloc.h and the man page for mallinfo
says that
prototypes for malloc(), calloc(), realloc() and free() are also
provided in malloc.h
for compatibility with old applications, but new application should
<stdlib.h> which has no mallinfo.
The SVID 4th edition ( http://www.**--****.com/ ) says
that it's use
is deprecated because it would be removed in later version of the
definition (probably
for ISO C compatibility).
I'm not an expert about unix standards and definitions but I'm
wondering if
there exist some ccp macro like _XOPEN_*, _XPG_*, _POSIX_* or the like
to test for checking the availability of malloc.h/mallinfo .

Re: How to know if malloc.h is available?

Postby Nate Eldredge » Sat, 22 Nov 2008 04:55:12 GMT

reformatted your paragraphs to make them easier to read.


Let's step back for a minute.

malloc() and free() are ISO standard C and should exist everywhere. In
pre-ISO days, some systems put their prototypes in malloc.h, but the
correct place for them according to ISO C is stdlib.h, and all modern
systems should comply with this, Mac OS X included. The ISO standard
does not mention malloc.h at all.

mallinfo() is a non-ISO function which provides some statistics about
memory allocations. On SYSV-derived systems (to which SVID applies),
its prototype is located in the non-ISO malloc.h header.

But Mac OS X is based on BSD, so I wouldn't expect it to comply with
SVID. I suspect it doesn't provide mallinfo() at all, and it may not
have a malloc.h header either. This is not a deficiency in the
compiler; you're trying to hold it to a standard that it doesn't claim
to support.

I'm not aware of a standard predefined macro to test for mallinfo() or
malloc.h. It appears that Solaris defines __SVR4 which might be good
enough, since any system that defines it is claiming to be SYSV like,
and should thus have mallinfo(). However, the usual way to handle this
sort of thing is to test for it in a configuration stage before starting
to compile. A tool like GNU autoconf is typical; its configure script
could check for headers like malloc.h and the existence of functions
like mallinfo, then create a header file containing macros like
HAVE_MALLINFO that indicate whether they exist.

So in short: your system probably doesn't have mallinfo() or malloc.h,
so you're going to have to alter the code not to use it in your case.
(This should be easy since the values it returns are purely
informational.) If you want to automatically detect whether a system
has these features, you'll have to deal with that yourself, but there
exist tools that can help.

Re: How to know if malloc.h is available?

Postby Arch Stanton » Sat, 22 Nov 2008 07:01:59 GMT

The one platform where you need malloc.h is Windows (yes, I know the 
name of this newsgroup but still, many people need Windows portability). 
So I would think that

#ifdef _WIN32
#include <malloc.h>

would be sufficient and appropriate. That's what I do.

Regarding mallinfo, that's more complex. Maybe you could just declare it 


Re: How to know if malloc.h is available?

Postby fogli_beppe » Sat, 22 Nov 2008 07:05:23 GMT

Thanks a lot!

OK, this was clear to me. My previous message can be confusing,
I wrote it in a hurry... I apologize.

This is the point! I'm looking for a cpp macro that can detect
whether the system is SVID compliant or, the other way round,
that can detect a system based on BSD like Mac OS X, which
is supposed not to have malloc.h/mallinfo.
I'm not looking necessarily for a macro specific to malloc.h/mallinfo.
This was what I meant with "more portable" in my first message.
The way it is now seems not to work with system based on BSD
on i386/ia64 platforms.

Thanks for the hints about __SVR4. I'm going to investigate if
it is what I need.

I agree! Tools like autoconf really simplify your life,
but the code I'm talking about doesn't use such tools.
Believe me or not, it hasn't even a makefile!
It's a single monolitic source file, 1.6 MB - 60000 lines
of C code!

I already bypassed the problem and compiled the program, simply
commenting out the inclusion of malloc.h and the definition
of HAVE_MALLINFO. It works fine.
But I'm looking for a definitive solution to give some feedback to the

Thanks a lot again!

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