diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/getdents.c')
| -rw-r--r-- | sysdeps/unix/sysv/linux/getdents.c | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/sysdeps/unix/sysv/linux/getdents.c b/sysdeps/unix/sysv/linux/getdents.c new file mode 100644 index 0000000000..0504393e67 --- /dev/null +++ b/sysdeps/unix/sysv/linux/getdents.c @@ -0,0 +1,105 @@ +/* Copyright (C) 1993, 1995, 1996, 1997 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <dirent.h> +#include <stddef.h> +#include <string.h> +#include <unistd.h> +#include <sys/types.h> + +#include <linux/posix_types.h> + +#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) + + +extern int __getdents __P ((int fd, char *buf, size_t nbytes)); + +/* For Linux we need a special version of this file since the + definition of `struct dirent' is not the same for the kernel and + the libc. There is one additional field which might be introduced + in the kernel structure in the future. + + He is the kernel definition of `struct dirent' as of 2.1.20: */ + +struct kernel_dirent + { + long int d_ino; + __kernel_off_t d_off; + unsigned short int d_reclen; + char d_name[256]; + }; + + +/* The problem here is that we cannot simply read the next NBYTES + bytes. We need to take the additional field into account. We use + some heuristic. Assume the directory contains names with at least + 3 characters we can compute a maximum number of entries which fit + in the buffer. Taking this number allows us to specify a correct + number of bytes to read. If we should be wrong, we can reset the + file descriptor. */ +int __getdirentries __P ((int fd, char *buf, size_t nbytes, off_t *basep)); +int +__getdirentries (fd, buf, nbytes, basep) + int fd; + char *buf; + size_t nbytes; + off_t *basep; +{ + off_t base = __lseek (fd, (off_t) 0, SEEK_CUR); + size_t red_nbytes; + struct kernel_dirent *kdp; + struct dirent *dp; + int retval; + + red_nbytes = nbytes - (nbytes / (offsetof (struct dirent, d_name) + 3)); + + dp = (struct dirent *) buf; + kdp = (struct kernel_dirent *) (buf + (nbytes - red_nbytes)); + + retval = __getdents (fd, (char *) kdp, red_nbytes); + + while ((char *) kdp < buf + (nbytes - red_nbytes) + retval) + { + dp->d_ino = kdp->d_ino; + dp->d_off = kdp->d_off; + dp->d_reclen = (kdp->d_reclen + + (offsetof (struct dirent, d_name) + - offsetof (struct kernel_dirent, d_name))); + dp->d_type = DT_UNKNOWN; + memmove (dp->d_name, kdp->d_name, + kdp->d_reclen - offsetof (struct kernel_dirent, d_name)); + + dp = (struct dirent *) (((char *) dp) + dp->d_reclen); + kdp = (struct kernel_dirent *) (((char *) kdp) + kdp->d_reclen); + + if ((char *) dp >= (char *) kdp) + { + /* Our heuristic failed. We read too many entries. Reset + the stream. */ + off_t used = ((char *) kdp - (char *) buf) - (nbytes - red_nbytes); + base = __lseek (fd, retval - used, SEEK_CUR); + } + } + + if (basep) + *basep = base; + + return (char *) dp - (char *) buf; +} + +weak_alias (__getdirentries, getdirentries) |