diff options
Diffstat (limited to 'libc')
| -rw-r--r-- | libc/sysdeps/linux/common/Makefile | 2 | ||||
| -rw-r--r-- | libc/sysdeps/linux/common/getdents.c | 114 | ||||
| -rw-r--r-- | libc/sysdeps/linux/common/syscalls.c | 9 |
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, |