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Diffstat (limited to 'libc/sysdeps/linux/common/getdents.c')
-rw-r--r--libc/sysdeps/linux/common/getdents.c100
1 files changed, 100 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/common/getdents.c b/libc/sysdeps/linux/common/getdents.c
new file mode 100644
index 000000000..47d829454
--- /dev/null
+++ b/libc/sysdeps/linux/common/getdents.c
@@ -0,0 +1,100 @@
+/* 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 <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_dirent
+{
+ long int d_ino;
+ __kernel_off_t d_off;
+ unsigned short int d_reclen;
+ char d_name[256];
+};
+
+#define __NR___syscall_getdents __NR_getdents
+static inline _syscall3(int, __syscall_getdents, int, fd, unsigned char *, kdirp, size_t, count);
+
+
+ssize_t __getdents (int fd, char *buf, size_t nbytes)
+{
+ struct dirent *dp;
+ off_t last_offset = -1;
+ ssize_t retval;
+ size_t red_nbytes;
+ struct kernel_dirent *skdp, *kdp;
+ const size_t size_diff = (offsetof (struct dirent, d_name)
+ - offsetof (struct kernel_dirent, d_name));
+
+ red_nbytes = MIN (nbytes - ((nbytes /
+ (offsetof (struct dirent, d_name) + 14)) * size_diff),
+ nbytes - size_diff);
+
+ dp = (struct dirent *) buf;
+ skdp = kdp = alloca (red_nbytes);
+
+ retval = __syscall_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. */
+ assert (last_offset != -1);
+ lseek(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_dirent, d_name));
+ dp = (struct dirent *) ((char *) dp + new_reclen);
+ kdp = (struct kernel_dirent *) (((char *) kdp) + kdp->d_reclen);
+ }
+ return (char *) dp - buf;
+}