Lazarus

Programming => Operating Systems => macOS / Mac OS X => Topic started by: inferno on November 26, 2019, 02:18:55 pm

Title: converting C headers to pas files
Post by: inferno on November 26, 2019, 02:18:55 pm

Hi all,
I'm trying to convert C headers with the structures as follow:

Code: C  [Select][+][-]

1. typedef struct {
2. #define KAUTH_GUID_SIZE 16      /* 128-bit identifier */
3.         unsigned char g_guid[KAUTH_GUID_SIZE];
4. } guid_t;
5.  
6. struct _acl_entry {
7.         u_int32_t       ae_magic;
8. #define _ACL_ENTRY_MAGIC        0xac1ac101
9.         u_int32_t       ae_tag;
10.         guid_t          ae_applicable;
11.         u_int32_t       ae_flags;
12.         u_int32_t       ae_perms;
13. };
14.  
15. struct _acl {
16.         u_int32_t       a_magic;
17. #define _ACL_ACL_MAGIC          0xac1ac102
18.         unsigned        a_entries;
19.         int             a_last_get;
20.         u_int32_t       a_flags;
21.         struct _acl_entry a_ace[ACL_MAX_ENTRIES];
22. };

The pascal versions below. I don't know what to do with const values and also not sure about types conversion...

Code: Pascal  [Select][+][-]

1. guid_t = packed record
2.     KAUTH_GUID_SIZE: Integer; //const = 16
3.     g_guid: array[0..(KAUTH_GUID_SIZE)-1] of byte;
4. end;
5.  
6. _acl_entry = packed record
7.     ae_magic: dword;
8.     _ACL_ENTRY_MAGIC: Cardinal; //const = $ac1ac101
9.     ae_tag: dword;
10.     ae_applicable: guid_t;
11.     ae_flags: dword;
12.     ae_perms: dword;
13.  end;
14.  
15.  _acl = packed record
16.     a_magic: dword;
17.     _ACL_ENTRY_MAGIC: Cardinal; //const = $ac1ac102
18.     a_entries: Cardinal;
19.     a_last_get: Integer;
20.     a_flags: dword;
21.     a_ace: array[0..(ACL_MAX_ENTRIES)-1] of _acl_entry;
22.  end;

Any suggestions?

Best regards,
Inferno

Title: Re: converting C headers to pas files
Post by: 440bx on November 26, 2019, 02:38:42 pm

Quote from: inferno on November 26, 2019, 02:18:55 pm

I don't know what to do with const values and also not sure about types conversion...

All you need to do is convert the #define(s) to Pascal const(s), for those you showed:

Code: C  [Select][+][-]

1. #define KAUTH_GUID_SIZE 16      /* 128-bit identifier */
2. #define _ACL_ENTRY_MAGIC        0xac1ac101
3. #define _ACL_ACL_MAGIC          0xac1ac102
4.  

the equivalent Pascal version is:

Code: Pascal  [Select][+][-]

1. const
2.   KAUTH_GUID_SIZE   = 16;
3.   _ACL_ENTRY_MAGIC  = $ac1ac101;
4.   _ACL_ACL_MAGIC    = $ac1ac102;
5.  

That's all there is to it.

Also, get rid of the declarations you currently have for those #define(s).  The way you have them now makes them fields of the record and they are _not_ fields of those records, they are simply constant declarations.

HTH.

Title: Re: converting C headers to pas files
Post by: inferno on November 26, 2019, 05:45:21 pm

Thank you 440bx! How about type conversions - are they correct (u_int32_t -> dword, unsigned -> cardinal, int -> integer)?

Best regards,
Inferno

Title: Re: converting C headers to pas files
Post by: lucamar on November 26, 2019, 06:38:42 pm

Quote from: inferno on November 26, 2019, 05:45:21 pm

How about type conversions - are they correct (u_int32_t -> dword, unsigned -> cardinal, int -> integer)?

They are correct but note that there are aliases in the system unit which were added, IIRC, precisely to ease this kind of conversions: Int8, UInt8, Int16, UInt16, Int32, UInt32, Int64, UInt64, an its corresponding pointers: PInt8, PUInt8, PInt16, etc.

They are described in the help for that unit (in the RTL help).

Title: Re: converting C headers to pas files
Post by: marcov on November 26, 2019, 08:02:29 pm

Somewhat older is unit ctypes, it defines many C types for use in headers, prefixed with a "C"

https://www.freepascal.org/docs-html/current/rtl/ctypes/index-3.html

Title: Re: converting C headers to pas files
Post by: inferno on December 02, 2019, 03:26:55 pm

Thanks lucamar and marcov! I got it working. On macOS there is the useful unit MacTypes - maybe it will be useful for somebody.

Best regards,
Inferno