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Are the posix macros S_ISREG, S_ISDIR etc linux only? I need to find out because i am trying to compile CURL and it is trying to use them on windows
What include file can i use to access them on windows.
This is the offending code
/*we ignore file size for char/block devices, sockets etc*/
if(S_ISREG(fileinfo.st_mode))
   uploadfilesize= fileinfo.st_size;
and it causes an error
error LNK2019: unresolved external symbol _S_ISREG referenced in function _operate file tool_operate.obj
They are referenced in the following questions
How to use S_ISREG() and S_ISDIR() POSIX Macros?
Differentiate between a unix directory and file in C and C++
Problem reading directories in C
Apparently S_ISREG() is part of a bunch of posix macros and is apparently supposed to tell us if a file is a "regular file" but all the examples I found had linux specific include files.  
                "Are the posix macros S_ISREG, S_ISDIR etc linux only?" No, you say it yourself in that question: "posix macros". They are on every POSIX-compliant system.
– Some programmer dude
                Jun 28, 2012 at 6:36
                Wouldn't it be easier to get a pre-compiled Windows version? Shouldn't be too hard to find. Otherwise, how do you configure CURL for building? What environment (Visual Studio, Cygwin, MinGW?)
– Some programmer dude
                Jun 28, 2012 at 6:38
                Funnily enough, nobody seems to have noticed that the link error is about the underscore-prefixed _S_ISREG, which is why curl's #define does not fire: most likely S_ISREG is already defined and references _S_ISREG. My guess is that including <sys/stat.h> would enable it to compile.
– alvherre
                Mar 4, 2016 at 20:32
Currently curl 7.21.5 defines in setup.h this:
#if !defined(S_ISREG) && defined(S_IFMT) && defined(S_IFREG)
#define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
#endif
                In VS2017, I can use MSVC compiler and use S_ISREG using the above code. This should be marked correct answer.
– Arundale Ramanathan
                Jun 17, 2019 at 13:18
                This didn't work for me, but I found a modification of it that did work in VS2017. See my answer below.
– Some Guy
                Jun 14, 2020 at 11:18
After having inspected Microsoft's sys/stat.h, I found that the following modification of @OliverZendel's answer worked for me, with Visual Studio 2017, and hopefully on other compilers as well:
// Windows does not define the S_ISREG and S_ISDIR macros in stat.h, so we do.
// We have to define _CRT_INTERNAL_NONSTDC_NAMES 1 before #including sys/stat.h
// in order for Microsoft's stat.h to define names like S_IFMT, S_IFREG, and S_IFDIR,
// rather than just defining  _S_IFMT, _S_IFREG, and _S_IFDIR as it normally does.
#define _CRT_INTERNAL_NONSTDC_NAMES 1
#include <sys/stat.h>
#if !defined(S_ISREG) && defined(S_IFMT) && defined(S_IFREG)
  #define S_ISREG(m) (((m) & S_IFMT) == S_IFREG)
#endif
#if !defined(S_ISDIR) && defined(S_IFMT) && defined(S_IFDIR)
  #define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
#endif
No such thing on windows, you can use the FindFirstFile, FindNextFile win32 api, the return structure contains something similar but not the same. 
If you use gcc/mingw library they have a stat() simulation. You need to include sys/stat.h for that macro.
                I have the same S_ISREG undefine problem, but I don't understand the answer.  I can see that sys/stat.h is already being included in setup_once.h, which should be included by setup.h already.  Exactly what do I need to do to resolve this?
– M W
                Aug 7, 2012 at 18:45
                MSVC.  I got it to compiled by moving the #include setup_once.h statements right before the S_ISREG definition so it will pick up the S_IFREG defn.  Not sure if it's the right way to fix.
– M W
                Aug 8, 2012 at 15:08
                if you use MSVC, you should use the windows API instead of the unix stat(). e.g.msdn.microsoft.com/en-us/library/windows/desktop/…
– pizza
                Aug 8, 2012 at 19:39
                To be clear, sys/stat.h and the stat function do exist on Windows (at least VS2017). What's missing is the S_ISREG macros (and similar macros like S_ISDIR). However, it is possible to add them yourself. See my answer below. If you can do this in a header file that includes sys/stat.h (e.g. "mystat.h"), then you can use portable code using the stat function in your source files, without having to do an 'ifdef' for operating-system-specific APIs like  FindFirstFile each time you need to check file status. (It is puzzling that Microsoft included sys/stat.h but only some of its contents.)
– Some Guy
                Jun 15, 2020 at 2:27
On windows try adding the underscore (_S_ISREG). In MinGW's lib the S_ISREG macro is also accessible in <sys/stat.h>
Maybe you should just check your configuration macros.
                its not my code. Its part of curl code that generates errors during link step in tool_operate.c .
– Dr Deo
                Jun 28, 2012 at 6:21
                S_ISREG is an emulation of POSIX macro. For Win32 one should use MSVC/MSDN-specified APIs.  I've found the underscore using a text-mode search in all of the MinGW's headers.
– Viktor Latypov
                Mar 14, 2014 at 15:22
                After having inspected Microsoft's sys/stat.h for VS2017, it appears to me that neither S_ISREG nor _S_ISREG will be defined by it. However, enough constants like _S_IFMT and _S_IFREG are defined (and also S_IFMT and S_IFREG if _CRT_INTERNAL_NONSTDC_NAMES is #defined to 1) to allow you to define your own S_ISREG. See my answer below.
– Some Guy
                Jun 14, 2020 at 11:26
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