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Diffstat (limited to 'sysdeps/unix/sysv/linux/getdents.c')
-rw-r--r--sysdeps/unix/sysv/linux/getdents.c105
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)