diff options
Diffstat (limited to 'libc/sysdeps/linux/common/getdents64.c')
| -rw-r--r-- | libc/sysdeps/linux/common/getdents64.c | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/common/getdents64.c b/libc/sysdeps/linux/common/getdents64.c new file mode 100644 index 000000000..0fb7336f3 --- /dev/null +++ b/libc/sysdeps/linux/common/getdents64.c @@ -0,0 +1,108 @@ +/* Copyright (C) 1993, 1995-2002 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 Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <features.h> + +#ifdef __UCLIBC_HAS_LFS__ + +#include <alloca.h> +#include <assert.h> +#include <errno.h> +#include <dirent.h> +#include <stddef.h> +#include <stdint.h> +#include <string.h> +#include <unistd.h> +#include <sys/param.h> +#include <sys/types.h> +#include <sysdep.h> +#include <sys/syscall.h> + + +#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER) + +struct kernel_dirent64 +{ + uint64_t d_ino; + int64_t d_off; + unsigned short int d_reclen; + unsigned char d_type; + char d_name[256]; +}; + + +#define __NR___syscall_getdents64 __NR_getdents64 +static inline _syscall3(int, __syscall_getdents64, int, fd, unsigned char *, dirp, size_t, count); + + +ssize_t __getdents64 (int fd, char *buf, size_t nbytes) +{ + struct dirent64 *dp; + off64_t last_offset = -1; + ssize_t retval; + size_t red_nbytes; + struct kernel_dirent64 *skdp, *kdp; + const size_t size_diff = (offsetof (struct dirent64, d_name) + - offsetof (struct kernel_dirent64, d_name)); + + red_nbytes = MIN (nbytes - ((nbytes / + (offsetof (struct dirent64, d_name) + 14)) * size_diff), + nbytes - size_diff); + + dp = (struct dirent64 *) buf; + skdp = kdp = alloca (red_nbytes); + + retval = __syscall_getdents64(fd, (char *)kdp, red_nbytes); + if (retval == -1) + return -1; + + while ((char *) kdp < (char *) skdp + retval) { + const size_t alignment = __alignof__ (struct dirent64); + /* 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. */ + assert (last_offset != -1); + lseek64(fd, last_offset, SEEK_SET); + + if ((char *) dp == buf) { + /* The buffer the user passed in is too small to hold even + one entry. */ + __set_errno (EINVAL); + return -1; + } + 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_dirent64, d_name)); + dp = (struct dirent64 *) ((char *) dp + new_reclen); + kdp = (struct kernel_dirent64 *) (((char *) kdp) + kdp->d_reclen); + } + return (char *) dp - buf; +} +#endif /* __UCLIBC_HAS_LFS__ */ + |