diff options
Diffstat (limited to 'ports/sysdeps/unix/sysv/linux/generic/wordsize-32/getdents.c')
| -rw-r--r-- | ports/sysdeps/unix/sysv/linux/generic/wordsize-32/getdents.c | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/ports/sysdeps/unix/sysv/linux/generic/wordsize-32/getdents.c b/ports/sysdeps/unix/sysv/linux/generic/wordsize-32/getdents.c new file mode 100644 index 0000000000..d7d0f04f43 --- /dev/null +++ b/ports/sysdeps/unix/sysv/linux/generic/wordsize-32/getdents.c @@ -0,0 +1,115 @@ +/* Copyright (C) 1993, 1995-2003, 2004, 2006, 2007, 2011 + This file is part of the GNU C Library. + Simplified from sysdeps/unix/sysv/linux/getdents.c. + + 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, see + <http://www.gnu.org/licenses/>. */ + +#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> + +/* Pack the dirent64 struct down into 32-bit offset/inode fields, and + ensure that no overflow occurs. */ +ssize_t +__getdents (int fd, char *buf, size_t nbytes) +{ + union + { + struct dirent64 k; /* Kernel structure. */ + struct dirent u; + char b[1]; + } *kbuf = (void *) buf, *outp, *inp; + size_t kbytes = nbytes; + off64_t last_offset = -1; + ssize_t retval; + + const size_t size_diff = (offsetof (struct dirent64, d_name) + - offsetof (struct dirent, d_name)); + if (nbytes <= sizeof (struct dirent)) + { + kbytes = nbytes + offsetof (struct dirent64, d_name) + - offsetof (struct dirent, d_name); + kbuf = __alloca(kbytes); + } + + retval = INLINE_SYSCALL (getdents64, 3, fd, kbuf, kbytes); + if (retval == -1) + return -1; + + /* These two pointers might alias the same memory buffer. + Standard C requires that we always use the same type for them, + so we must use the union type. */ + inp = kbuf; + outp = (void *) buf; + + while (&inp->b < &kbuf->b + retval) + { + const size_t alignment = __alignof__ (struct dirent); + /* Since inp->k.d_reclen is already aligned for the kernel + structure this may compute a value that is bigger + than necessary. */ + size_t old_reclen = inp->k.d_reclen; + size_t new_reclen = ((old_reclen - size_diff + alignment - 1) + & ~(alignment - 1)); + + /* Copy the data out of the old structure into temporary space. + Then copy the name, which may overlap if BUF == KBUF. */ + const uint64_t d_ino = inp->k.d_ino; + const int64_t d_off = inp->k.d_off; + const uint8_t d_type = inp->k.d_type; + + memmove (outp->u.d_name, inp->k.d_name, + old_reclen - offsetof (struct dirent64, d_name)); + + /* Now we have copied the data from INP and access only OUTP. */ + + outp->u.d_ino = d_ino; + outp->u.d_off = d_off; + if ((sizeof (outp->u.d_ino) != sizeof (inp->k.d_ino) + && outp->u.d_ino != d_ino) + || (sizeof (outp->u.d_off) != sizeof (inp->k.d_off) + && outp->u.d_off != d_off)) + { + /* Overflow. If there was at least one entry before this one, + return them without error, otherwise signal overflow. */ + if (last_offset != -1) + { + __lseek64 (fd, last_offset, SEEK_SET); + return outp->b - buf; + } + __set_errno (EOVERFLOW); + return -1; + } + + last_offset = d_off; + outp->u.d_reclen = new_reclen; + outp->u.d_type = d_type; + + inp = (void *) inp + old_reclen; + outp = (void *) outp + new_reclen; + } + + return outp->b - buf; +} |