dirfd (dirp) ((dirp)->dd_fd)

Description

get directory stream file descriptor

Parameters

dirp

DTF_HIDEW 0x0001

Description

flags for opendir2. hide whiteout entries.

DTF_NODUP 0x0002

Description

flags for opendir2. don't return duplicate names.

DTF_REWIND 0x0004

Description

flags for opendir2. rewind after reading union stack.

__DTF_READALL 0x0008

Description

flags for opendir2. everything has been read.

Interface status:

externallyDefinedApi

typedef struct _dirdesc DIR;

Description

defines DIR data type through typedef. A type representing a directory stream.

Interface status:

externallyDefinedApi

IMPORT_C int alphasort(const void *, const void *);

Description

Parameters

const void * const void * Refer to scandir(const char *,struct dirent ***,int(*)(struct dirent *),int(*)(const void *, const void *))scandir(const char *,struct dirent ***,int(*)(struct dirent *),int(*)(const void *, const void *)) for the documentation

Return value

int

See also:

• malloc(size_t)
• malloc(size_t)
• qsort(void *,size_t,size_t,int(*)(const void *, const void *))

Interface status:

externallyDefinedApi

IMPORT_C int getdirentries(int, char *, int, long *);

Description

getdirentries(int,char *,int,long *)getdirentries(int,char *,int,long *) The getdirentries system call reads directory entries from the directory referenced by the file descriptor x into the buffer pointed to by ptr, in a file system independent format. Up to y of data will be transferred. The y argument must be greater than or equal to the block size associated with the file, see stat. Some file systems may not support these system calls with buffers smaller than this size.

The data in the buffer is a series of dirent

structures each containing the following entries: u_int32_t d_fileno;
u_int16_t d_reclen;
u_int8_t  d_type;
u_int8_t  d_namlen;
char  d_name[MAXNAMELEN + 1];/* see below */

The d_fileno entry is a number which is unique for each distinct file in the file system. Files that are linked by hard links (see link ) have the same d_fileno. The d_reclen entry is the length, in bytes, of the directory record. The d_type entry is the type of the file pointed to by the directory record. The file type values are defined in <sys/dirent.h>. Presently, however, file type is not supported and d_type is set to 0. The d_name entry contains a null terminated file name. The d_namlen entry specifies the length of the file name excluding the null byte. Thus the actual size of d_name may vary from 1 to MAXNAMELEN + 1.

Entries may be separated by extra space. The d_reclen entry may be used as an offset from the start of a dirent structure to the next structure, if any.

The actual number of bytes transferred is returned. The current position pointer associated with x is set to point to the next block of entries. The pointer may not advance by the number of bytes returned by getdirentries . A value of zero is returned when the end of the directory has been reached.

The getdirentries system call writes the position of the block read into the location pointed to by lptr. Alternatively, the current position pointer may be set and retrieved by lseek. The current position pointer should only be set to a value returned by lseek, a value returned in the location pointed to by basep ( (getdirentries); only) or zero.

Examples:

/* reading directory stream using getdirenttries */ 
/* considering directory c:    emp already exists */
# 52 "d:/EPOC/release/9.4/common/generic/openenv/core/include/dirent.dosc" 2
int main()
{
        int retval;
        long basep=(off_t) 0;
        char buf[1024];
        struct dirent * d;
        char * dname="C:\       emp\
        char * fname="C:\       emp\input.txt";
        int fd,fd1;
        fd1=open(fname,O_WRONLY|O_CREAT);
        if(fd==-1)
                {
                printf("file creation failed");
                return -1;
                }
        fd=open(dname,O_RDONLY);
        if(fd==-1)
                {
                printf("directory opening failed");
                return -1;
                }
        retval = getdirentries (fd, buf,(unsigned int)sizeof (buf),&basep);
        if(retval == -1)
        {
                printf("getdirentries call failed");
                return -1;
        }               
       
        d=(struct dirent *)buf;
        
        printf("name of the file in the newly created directory is \"%s\",d-d_name);
        
        close(fd1);
        close(fd);
        return 0;
}

Output

name of the file in the newly created directory is "input.txt"

Parameters

int char * int long *

Return value

int If successful, the number of bytes actually transferred is returned. Otherwise, -1 is returned and the global variable errno is set to indicate the error.

See also:

• lseek(int,off_t,int)
• lseek(int,off_t,int)...

Interface status:

externallyDefinedApi

IMPORT_C DIR* opendir(const char *);

Description

The opendir function opens the directory named by _path , associates a directory stream with it and returns a pointer to be used to identify the directory stream in subsequent operations. The pointer NULL is returned if filename cannot be accessed, or if it cannot malloc enough memory to hold the whole thing.

The readdir function returns a pointer to the next directory entry. It returns NULL upon reaching the end of the directory or detecting an invalid seekdir operation.

The readdir_r function provides the same functionality as readdir , but the caller must provide a directory entry buffer to store the results in. If the read succeeds, result is pointed at the entry ; upon reaching the end of the directory result is set to NULL . The readdir_r function returns 0 on success or an error number to indicate failure.

The telldir function returns the current location associated with the named directory stream . Values returned by telldir are good only for the lifetime of the DIR pointer, dirp , from which they are derived. If the directory is closed and then reopened, prior values returned by telldir will no longer be valid.

The seekdir function sets the position of the next readdir operation on the directory stream . The new position reverts to the one associated with the directory stream when the telldir operation was performed.

The rewinddir function resets the position of the named directory stream to the beginning of the directory.

The closedir function closes the named directory stream and frees the structure associated with the dirp pointer, returning 0 on success. On failure, -1 is returned and the global variable errno is set to indicate the error.

The dirfd function returns the integer file descriptor associated with the named directory stream , see open .

 Sample code which searches a directory for entry ‘‘name’’ is: len = strlen(name);
dirp = opendir(".");
while ((dp = readdir(dirp)) != NULL)
        if (dp->d_namlen == len && !strcmp(dp->d_name, name)) {
                (void)closedir(dirp);
                return FOUND;
        }
(void)closedir(dirp);
return NOT_FOUND;

Examples:

/* Detailed description: This test code demonstrates usage of opendir system call, open directory name test.
 Preconditions: Expects Test directory to be present in the current working directory.
*/
 #include <sys/types.h>
 #include <dirent.h>
int main()
{
  DIR *DirHandle;
  if(!(DirHandle = opendir("Test") ) ) 
  {
     printf("Failed to open directory Test\n");
     return -1;
  }
  printf("Directory Test opened \n");
  return 0;
}

Output 
Directory Test opened

Limitations:

The filename parameter of the opendir(const char *)opendir(const char *) function should not exceed 256 characters in length.

Parameters

const char * Note: This description also covers the following functions - readdir(DIR *)readdir(DIR *) readdir_r() telldir(DIR *)telldir(DIR *) seekdir(DIR *,long)seekdir(DIR *,long) rewinddir(DIR *)rewinddir(DIR *) closedir(DIR *)closedir(DIR *) dirfd

Return value

_dirdesc * closedir function returns 0 on success or -1 on failure.

See also:

• lseek(int,off_t,int)
• lseek(int,off_t,int)...

Interface status:

externallyDefinedApi

IMPORT_C struct dirent* readdir(DIR *);

Description

Parameters

_dirdesc * Refer to opendir(const char *)opendir(const char *) for the documentation

Return value

struct direntdirent *

See also:

• lseek(int,off_t,int)
• lseek(int,off_t,int)...

Interface status:

externallyDefinedApi

IMPORT_C void rewinddir(DIR *);

Description

Parameters

_dirdesc * Refer to opendir(const char *)opendir(const char *) for the documentation

See also:

• lseek(int,off_t,int)
• lseek(int,off_t,int)...

Interface status:

externallyDefinedApi

IMPORT_C int scandir(const char *, struct dirent ***, int(*)(struct dirent *), int(*)(const void *, const void *));

Description

The scandir function reads the directory dirname and builds an array of pointers to directory entries using malloc It returns the number of entries in the array. A pointer to the array of directory entries is stored in the location referenced by namelist.

The select argument is a pointer to a user supplied subroutine which is called by scandir to select which entries are to be included in the array. The select routine is passed a pointer to a directory entry and should return a non-zero value if the directory entry is to be included in the array. If select is null, then all the directory entries will be included.

The compar argument is a pointer to a user supplied subroutine which is passed to qsort to sort the completed array. If this pointer is null, the array is not sorted.

The alphasort function is a routine which can be used for the compar argument to sort the array alphabetically.

The memory allocated for the array can be deallocated with free , by freeing each pointer in the array and then the array itself.

Examples:

//Illustrates how to use scandir API.
#include <dirent.h>
Void  scandirTest()
    {
       struct dirent **namelist;
       int n;
       // Function call to get the dir entries into the namelist.
       n = scandir("\home\manjus\GETTEXT", &namelist;, 0, 0);
      
       if(n > 0) // if scandir is successful it retuns the number of entries greater than 0
       {
             // print all the entries in the directory.
        while(n--)
        {
                printf("dir name @ pos %d is %s",n,namelist[n]->d_name);
        }
       }
     }

Diagnostics: Returns -1 if the directory cannot be opened for reading or if malloc cannot allocate enough memory to hold all the data structures.

Limitations:

The dirname parameter in scandir(const char *,struct dirent ***,int(*)(struct dirent *),int(*)(const void *, const void *))scandir(const char *,struct dirent ***,int(*)(struct dirent *),int(*)(const void *, const void *)) should not exceed 256 characters in length.

Parameters

const char * struct direntdirent *** Note: This description also covers the following functions - alphasort(const void *,const void *)alphasort(const void *,const void *) int(*)(struct direntdirent *) int(*)(const void *, const void *)

Return value

int

See also:

• malloc(size_t)
• malloc(size_t)
• qsort(void *,size_t,size_t,int(*)(const void *, const void *))

Interface status:

externallyDefinedApi

IMPORT_C void seekdir(DIR *, long);

Description

Parameters

_dirdesc * long Refer to opendir(const char *)opendir(const char *) for the documentation

See also:

• lseek(int,off_t,int)
• lseek(int,off_t,int)...

Interface status:

externallyDefinedApi

IMPORT_C long telldir(DIR *);

Description

Parameters

_dirdesc * Refer to opendir(const char *)opendir(const char *) for the documentation

Return value

long

See also:

• lseek(int,off_t,int)
• lseek(int,off_t,int)...

Interface status:

externallyDefinedApi

IMPORT_C int closedir(DIR *);

Description

Parameters

_dirdesc * Refer to opendir(const char *)opendir(const char *) for the documentation

Return value

int

See also:

• lseek(int,off_t,int)
• lseek(int,off_t,int)...