Back to index

glibc  2.9
Classes | Defines | Functions
getdents.c File Reference
#include <alloca.h>
#include <dirent.h>
#include <stddef.h>
#include <string.h>
#include <unistd.h>
#include <sys/param.h>
#include <sys/types.h>

Go to the source code of this file.

Classes

struct  kernel_dirent

Defines

#define offsetof(TYPE, MEMBER)   ((size_t) &((TYPE *)0)->MEMBER)

Functions

int __getdents (int fd, char *buf, size_t nbytes)
ssize_t __getdirentries (int fd, char *buf, size_t nbytes, off_t *basep)

Class Documentation

struct kernel_dirent

Definition at line 39 of file getdents.c.

Class Members
ino_t d_ino
long int d_ino
char d_name
off_t d_off
__kernel_off_t d_off
unsigned short int d_reclen

Define Documentation

#define offsetof (   TYPE,
  MEMBER 
)    ((size_t) &((TYPE *)0)->MEMBER)

Definition at line 27 of file getdents.c.


Function Documentation

int __getdents ( int  fd,
char *  buf,
size_t  nbytes 
)

Definition at line 25 of file getdents.c.

{
  return getdirent (fd, buf, count);
}
ssize_t __getdirentries ( int  fd,
char *  buf,
size_t  nbytes,
off_t basep 
)

Definition at line 60 of file getdents.c.

{
  off_t base = __lseek (fd, (off_t) 0, SEEK_CUR);
  off_t last_offset = base;
  size_t red_nbytes;
  struct kernel_dirent *skdp, *kdp;
  struct dirent *dp;
  int retval;
  const size_t size_diff = (offsetof (struct dirent, d_name)
                         - offsetof (struct kernel_dirent, d_name));

  red_nbytes = nbytes - ((nbytes / (offsetof (struct dirent, d_name) + 14))
                      * size_diff);

  dp = (struct dirent *) buf;
  skdp = kdp = __alloca (red_nbytes);

  retval = __getdents (fd, (char *) kdp, red_nbytes);

  while ((char *) kdp < (char *) skdp + retval)
    {
      const size_t alignment = __alignof__ (struct dirent);
      /* Since kdp->d_reclen is already aligned for the kernel structure
        this may compute a value that is bigger than necessary.  */
      size_t new_reclen = ((kdp->d_reclen + size_diff + alignment - 1)
                        & ~(alignment - 1));
      if ((char *) dp + new_reclen > buf + nbytes)
       {
         /* Our heuristic failed.  We read too many entries.  Reset
            the stream.  */
         __lseek (fd, last_offset, SEEK_SET);
         break;
       }

      last_offset = kdp->d_off;
      dp->d_ino = kdp->d_ino;
      dp->d_off = kdp->d_off;
      dp->d_reclen = new_reclen;
      dp->d_type = DT_UNKNOWN;
      memcpy (dp->d_name, kdp->d_name,
             kdp->d_reclen - offsetof (struct kernel_dirent, d_name));

      dp = (struct dirent *) ((char *) dp + new_reclen);
      kdp = (struct kernel_dirent *) (((char *) kdp) + kdp->d_reclen);
    }

  if (basep)
    *basep = base;

  return (char *) dp - buf;
}

Here is the call graph for this function: