mozilla code -nspr 文件I/O - 2

文件I/O

#include <prio.h> 

结构体:

PRFileDesc 这个结构体太深奥了.再研究

struct PRFileDesc {    const PRIOMethods *methods;         /* the I/O methods table */ //好像是函数指指的列表,也就是访问的函数的列表    PRFilePrivate *secret;              /* layer dependent data */ //在PR_Open中好像调用了CreateFile,最后在prio.c中fd->secret->md.osfd = osfd这里就是返回的HANDLE    PRFileDesc *lower, *higher;         /* pointers to adjacent layers */ //不清楚    void (PR_CALLBACK *dtor)(PRFileDesc *fd);   /* A destructor function for layer */ //不清楚    PRDescIdentity identity;            /* Identity of this particular layer  */ //特殊的layer的标志};typedef struct PRFileDesc PRFileDesc;

1.PR_Open
//打开or创建一个文件来读OR写OR读写,如果文件成功打开返回PRFileDesc *否则返回NULL；

//成功返回后,在使用完后要用PR_Close.关闭PRFileDesc*

/* Open flags */
#define PR_RDONLY       0x01 //只读打开,与PR_CREATE_FILE一起用时,如果没有文件则可以创建文件
#define PR_WRONLY       0x02 //只写打开,与PR_CREATE_FILE一起用时,如果没有文件则可以创建文件
#define PR_RDWR         0x04 //可读可写打开,与PR_CREATE_FILE一起用时,如果没有文件则可以创建文件
#define PR_CREATE_FILE  0x08 //如果不存在则创建,如果存在没有意义.与其它一起用,如果没有此flags时其它flags会返回NULL
#define PR_APPEND       0x10 //追加打开,打开时指针在最后,与PR_CREATE_FILE一起用时,如果没有文件则可以创建文件
#define PR_TRUNCATE     0x20 //覆盖打开,如果存在文件清零,
#define PR_SYNC         0x40 //写同步
#define PR_EXCL         0x80 //与PR_CREATE_FILE一起用,如果不存在在,则创建,存在则函数返回NULL

/*
** File modes ....
**只针对Ｕｎｉｘ－ｌｉｋｅ系统 -rwxrwxrwx
**当设置了PR_CREATE_FILE,设定相对应的属性
#define PR_IRWXU 00700  /* read, write, execute/search by owner */
#define PR_IRUSR 00400  /* read permission, owner */
#define PR_IWUSR 00200  /* write permission, owner */
#define PR_IXUSR 00100  /* execute/search permission, owner */
#define PR_IRWXG 00070  /* read, write, execute/search by group */
#define PR_IRGRP 00040  /* read permission, group */
#define PR_IWGRP 00020  /* write permission, group */
#define PR_IXGRP 00010  /* execute/search permission, group */
#define PR_IRWXO 00007  /* read, write, execute/search by others */
#define PR_IROTH 00004  /* read permission, others */
#define PR_IWOTH 00002  /* write permission, others */
#define PR_IXOTH 00001  /* execute/search permission, others */
*/

NSPR_API(PRFileDesc*) PR_Open(const char *name, PRIntn flags, PRIntn mode);

NSPR_API(PRFileDesc*) PR_OpenFile( const char *name, PRIntn flags, PRIntn mode);

2.PR_Close
//关闭打开的PRFileDesc *fd (文件或Socket,)
NSPR_API(PRStatus)    PR_Close(PRFileDesc *fd);

3.PR_Delete

//删除指定的文件,成功返回PR_SUCCESS,否则返回PR_FAILURE.

NSPR_API(PRStatus) PR_Delete(const char *name);

4.PR_GetFileInfo 和 PR_GetFileInfo64

见此处

5.PR_Rename

/*
 **************************************************************************
 * FUNCTION: PR_Rename
 * DESCRIPTION:
 *     Rename a file from the old name 'from' to the new name 'to'.
 * INPUTS:
 *     const char *from
 *         The old name of the file to be renamed.
 *     const char *to
 *         The new name of the file.
 * OUTPUTS:
 *     None.
 * RETURN: PRStatus
 **************************************************************************
 */
//重命名一个文件or文件夹(重命名文件夹不一定成功,好像不能移动),成功返回PR_SUCCESS,出错返回PR_FAILURE

//应有出错处理,
NSPR_API(PRStatus)    PR_Rename(const char *from, const char *to);

6. PR_Access

/*
 *************************************************************************
 * FUNCTION: PR_Access
 * DESCRIPTION:
 *     Determine accessibility of a file.
 * INPUTS:
 *     const char *name
 *         path name of the file
 *     PRAccessHow how
 *         specifies which access permission to check for.
 *         It can be one of the following values:
 *             PR_ACCESS_READ_OK       Test for read permission
 *             PR_ACCESS_WRITE_OK      Test for write permission
 *             PR_ACCESS_EXISTS        Check existence of file
 * OUTPUTS:
 *     None.
 * RETURN: PRStatus
 *     PR_SUCCESS is returned if the requested access is permitted.
 *     Otherwise, PR_FAILURE is returned. Additional information
 *     regarding the reason for the failure may be retrieved from
 *     PR_GetError().
 *************************************************************************
 */

typedef enum PRAccessHow {
    PR_ACCESS_EXISTS = 1,
    PR_ACCESS_WRITE_OK = 2,
    PR_ACCESS_READ_OK = 3
} PRAccessHow;

NSPR_API(PRStatus) PR_Access(const char *name, PRAccessHow how);

//例程(vc2008)

#include "nspr.h"

#include <iostream>

#pragma comment(lib,"nspr4.lib")
#pragma comment(lib,"plc4.lib")

using namespace std;
int main(int argc, char* argv[])
{
    
    PR_Init(PR_USER_THREAD, PR_PRIORITY_NORMAL, 0);
    PRErrorCode err_code;
    PRFileDesc* fd;
    if (! (fd = PR_Open("c:\\demo.txt", PR_CREATE_FILE| PR_EXCL, 0)))
    {
        err_code = PR_GetError();
        PR_Cleanup();
        return 0;
    }
    PR_Close(fd);
    PR_Rename("c:\\demo.txt", "c:\\demo_rename.txt");
    PR_MkDir("c:\\dir", 0);//没有写出错处理
    if (PR_SUCCESS == PR_Access("c:\\dir",PR_ACCESS_EXISTS))
    {    
        if (PR_FAILURE == PR_Rename("c:\\dir", "c:\\dir_rename"))
        {
            err_code = PR_GetError();
        }
    }

    PR_Sleep(5000);
    PR_Delete("c:\\demo_rename.txt");
    PR_RmDir("c:\\dir_rename");
    PR_Cleanup();
    return 0;
}