Dr. Dobb's Journal - May 2008 - (Page 42)

d05gor_p3db 3/13/08 9:17 AM Page 42 C/C++ header ﬁle user-mode API speciﬁcation eXtremeDB-KM Interface Compiler __api_km.h api km.c Kernal side ﬁles __api_um.h api um.c User-mode side ﬁles translations from kernel-address space to user-address space. The ioctl interface provides user-mode applications with access to the kernel-mode database. The user-level application creates a userlevel database access API exposed by the database module via the ioctl interface. This API lets user-mode processes (such as administrative applications) interact with eXtremeDB-KM. Figure 3: eXtremeDB-KM interface compiler. /* calculate page aligned address */ mem_ptr = (char*) ( ((unsigned long)mem_ua_ptr+PAGE_SIZE-1) & PAGE_MASK ); /* lock pages */ for ( va=(unsigned long)mem_ptr; va<(unsigned long)(&(mem_ptr[mem_size/sizeof(int)])); va+=PAGE_SIZE) { SetPageReserved(vmalloc_to_page((void *)(((unsigned long)va)))); } Example 3: Locking virtual memory pages. #ifndef __EX_DB_API_H #define __EX_DB_API_H typedef struct tagFile { unsigned char result; char name[100]; unsigned int inode; unsigned int device; unsigned int owner; unsigned int defaccess; }File_t, *File_h; typedef char* zstring /*sero-terminated string*/; typedef unsigned int* pint; int exdb_init_database ( unsigned long mem_size ); int exdb_shutdown_database( ); int exdb_add_file (zstring file_name, unsigned int inode, unsigned int device, unsigned int owner, unsigned int defaccess ); int exdb_remove_file( zstring file_name ); int exdb_find_file( zstring file_name, /*out*/ pint pinode, /*out*/ pint pdevice, /*out*/ pint powner, /*out*/ pint pdefaccess ); int exdb_authorize_file( zstring file_name, unsigned int uid, unsigned int access ); #endif /* __EX_DB_API_H */ Example 4: Interface definition header file. (a) if ( 0 != (i = exdb_find_file( name, &inode, &device, &owner, &access ))) { printf("exdb_find_file(\"%s\")==%d\n", name, i ); return (0); }; (b) if ( 0 != (i = exdb_find_file( name,&inode,&device,&owner,&access ))) { pr_info(DEV_NAME" exdb_find_file(\"%s\")==%d\n", name, i ); return (0); }; Example 5: Initialization. (a) User mode; (b) Kernel mode. static int __init eACmod_init( void ) { if (!sys_call_table) { return -1; } if ( (major = register_chrdev( 0, DEV_NAME, &eACmod_fops )) < 0 ) { return -EIO; }; eACm_api_Init(); intercept_syscalls(); return 0; }; Example 6: Registering file access. http://www.leadtools.com/dobbs http://www.leadtools.com/dobbs

Table of Contents Feed for the Digital Edition of Dr. Dobb's Journal - May 2008

Dr. Dobb's Journal - May 2008 Contents Friday Night Fish Fry Alia Vox Developer Diaries Software Development Goes to the Movies Cat: A Functional Stack-Based Little Language Mojax: Mobile Ajax Framework Kernel-Mode Databases Getting Better Search Results Effective Concurrency The Agile Edge

Dr. Dobb's Journal - May 2008

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