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authorEric Andersen <andersen@codepoet.org>2000-10-30 08:25:20 +0000
committerEric Andersen <andersen@codepoet.org>2000-10-30 08:25:20 +0000
commit79a09cdaaec661c701080108a73f93d5ca71a006 (patch)
tree72e22a39992bab1c0eaebbecf1a52ea06da47c44 /libc/sysdeps
parent31a8f5cb0e06061181d4a6ed8b154abec561f981 (diff)
First pass at fixing readdir by adding a getdents wrapper...
Diffstat (limited to 'libc/sysdeps')
-rw-r--r--libc/sysdeps/linux/common/Makefile2
-rw-r--r--libc/sysdeps/linux/common/getdents.c114
-rw-r--r--libc/sysdeps/linux/common/syscalls.c9
3 files changed, 120 insertions, 5 deletions
diff --git a/libc/sysdeps/linux/common/Makefile b/libc/sysdeps/linux/common/Makefile
index b08230be2..0c361ba48 100644
--- a/libc/sysdeps/linux/common/Makefile
+++ b/libc/sysdeps/linux/common/Makefile
@@ -26,7 +26,7 @@ include $(TOPDIR)Rules.mak
LIBC=$(TOPDIR)libc.a
-CSRC =closedir.o dirfd.o getdnnm.o gethstnm.o getpagesize.o \
+CSRC =closedir.o dirfd.o getdents.o getdnnm.o gethstnm.o getpagesize.o \
isatty.o kernel_version.o mkfifo.o opendir.o readdir.o rewinddir.o \
seekdir.o setegid.o seteuid.o setpgrp.o statfix.o tcgetatr.o tell.o \
telldir.o wait.o wait3.o _xmknod.o _fxstat.o _lxstat.o _xstat.o
diff --git a/libc/sysdeps/linux/common/getdents.c b/libc/sysdeps/linux/common/getdents.c
new file mode 100644
index 000000000..940532da2
--- /dev/null
+++ b/libc/sysdeps/linux/common/getdents.c
@@ -0,0 +1,114 @@
+/* Copyright (C) 1993, 95, 96, 97, 98, 99 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 <stdlib.h>
+#include <errno.h>
+#include <dirent.h>
+#include <stddef.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/param.h>
+#include <sys/types.h>
+
+#include <sysdep.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.
+ */
+#define dirent kernel_dirent
+#include <linux/dirent.h>
+#undef dirent
+
+
+#ifdef GETDENTS64
+# define __getdents __getdents64
+# define dirent dirent64
+#endif
+
+/* 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. Assuming the directory contains names with 14
+ characters on average we can compute an estimated number of entries
+ which fit in the buffer. Taking this number allows us to specify a
+ reasonable number of bytes to read. If we should be wrong, we can
+ reset the file descriptor. In practice the kernel is limiting the
+ amount of data returned much more then the reduced buffer size. */
+ssize_t getdents (int fd, char *buf, size_t nbytes)
+{
+ off_t last_offset = 0;
+ 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 = malloc (red_nbytes);
+
+ retval = _getdents(fd, (char *) kdp, red_nbytes);
+
+ if (retval == -1)
+ return -1;
+
+ 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. `last_offset' contains the last known
+ position. If it is zero this is the first record we are
+ reading. In this case do a relative search. */
+ if (last_offset == 0)
+ lseek (fd, -retval, SEEK_CUR);
+ else
+ 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);
+ }
+
+ return (char *) dp - buf;
+}
diff --git a/libc/sysdeps/linux/common/syscalls.c b/libc/sysdeps/linux/common/syscalls.c
index f83932458..c7d4343be 100644
--- a/libc/sysdeps/linux/common/syscalls.c
+++ b/libc/sysdeps/linux/common/syscalls.c
@@ -867,7 +867,7 @@ SYSCALL__(setfsuid, 1)
#endif
//#define __NR__llseek 140
#ifdef L__llseek
- _syscall5(int, _llseek, int, fd, off_t, hoff, off_t, loff, loff_t *, res,
+_syscall5(int, _llseek, int, fd, off_t, hoff, off_t, loff, loff_t *, res,
int, whence);
loff_t llseek(int fd, loff_t offset, int whence)
@@ -883,16 +883,17 @@ loff_t llseek(int fd, loff_t offset, int whence)
#endif
//#define __NR_getdents 141
-#ifdef L_getdents
+#ifdef L__getdents
+#define __NR__getdents __NR_getdents
#include <unistd.h>
#include <dirent.h>
-_syscall3(int, getdents, unsigned int, fd, struct dirent *, dirp, unsigned int, count);
+_syscall3(int, _getdents, int, fd, char *, dirp, size_t, count);
#endif
//#define __NR__newselect 142
#ifdef L__newselect
#include <unistd.h>
- _syscall5(int, _newselect, int, n, fd_set *, readfds, fd_set *, writefds,
+_syscall5(int, _newselect, int, n, fd_set *, readfds, fd_set *, writefds,
fd_set *, exceptfds, struct timeval *, timeout);
int select(int n, fd_set * readfds, fd_set * writefds, fd_set * exceptfds,