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From 3fac92713621f894d33a9f499bacb5b20f0d8ec3 Mon Sep 17 00:00:00 2001
From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Tue, 20 Oct 2020 13:37:15 -0300
Subject: [PATCH 1/3] linux: Use getdents64 on non-LFS readdir
It is similar to what non-LFS getdents do (including overflow check).
Checked on x86_64-linux-gnu and i686-linux-gnu.
---
sysdeps/unix/sysv/linux/readdir.c | 97 +++++++++++++++++++++++--------
1 file changed, 73 insertions(+), 24 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/readdir.c b/sysdeps/unix/sysv/linux/readdir.c
index 33bae4b57d..4e2214f21e 100644
--- a/sysdeps/unix/sysv/linux/readdir.c
+++ b/sysdeps/unix/sysv/linux/readdir.c
@@ -20,43 +20,92 @@
#if !_DIRENT_MATCHES_DIRENT64
#include <dirstream.h>
+#include <unistd.h>
+
+# ifndef DIRENT_SET_DP_INO
+# define DIRENT_SET_DP_INO(dp, value) (dp)->d_ino = (value)
+# endif
/* Read a directory entry from DIRP. */
struct dirent *
__readdir_unlocked (DIR *dirp)
{
- struct dirent *dp;
int saved_errno = errno;
- if (dirp->offset >= dirp->size)
+ while (1)
{
- /* We've emptied out our buffer. Refill it. */
-
- size_t maxread = dirp->allocation;
- ssize_t bytes;
-
- bytes = __getdents (dirp->fd, dirp->data, maxread);
- if (bytes <= 0)
+ if (dirp->offset >= dirp->size)
{
- /* Linux may fail with ENOENT on some file systems if the
- directory inode is marked as dead (deleted). POSIX
- treats this as a regular end-of-directory condition, so
- do not set errno in that case, to indicate success. */
- if (bytes == 0 || errno == ENOENT)
- __set_errno (saved_errno);
+ ssize_t bytes = __getdents64 (dirp->fd, dirp->data,
+ dirp->allocation);
+ if (bytes <= 0)
+ {
+ /* Linux may fail with ENOENT on some file systems if the
+ directory inode is marked as dead (deleted). POSIX
+ treats this as a regular end-of-directory condition, so
+ do not set errno in that case, to indicate success. */
+ if (bytes < 0 && errno == ENOENT)
+ __set_errno (saved_errno);
+ return NULL;
+ }
+ dirp->size = bytes;
+
+ /* Reset the offset into the buffer. */
+ dirp->offset = 0;
+ }
+
+ /* 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. */
+ union
+ {
+ struct dirent64 dp64;
+ struct dirent dp;
+ char *b;
+ } *inp, *outp;
+ inp = (void*) &dirp->data[dirp->offset];
+ outp = (void*) &dirp->data[dirp->offset];
+
+ const size_t size_diff = offsetof (struct dirent64, d_name)
+ - offsetof (struct dirent, d_name);
+
+ /* Since inp->dp64.d_reclen is already aligned for the kernel structure
+ this may compute a value that is bigger than necessary. */
+ size_t old_reclen = inp->dp64.d_reclen;
+ size_t new_reclen = ALIGN_UP (old_reclen - size_diff,
+ _Alignof (struct dirent));
+
+ if (!in_ino_t_range (inp->dp64.d_ino)
+ || !in_off_t_range (inp->dp64.d_off))
+ {
+ /* Overflow. If there was at least one entry before this one,
+ return them without error, otherwise signal overflow. */
+ if (dirp->offset != 0)
+ {
+ __lseek64 (dirp->fd, dirp->offset, SEEK_SET);
+ outp = (void*)(outp->b - dirp->data);
+ return &outp->dp;
+ }
+ __set_errno (EOVERFLOW);
return NULL;
}
- dirp->size = (size_t) bytes;
- /* Reset the offset into the buffer. */
- dirp->offset = 0;
+ /* Copy the data from INP and access only OUTP. */
+ const uint64_t d_ino = inp->dp64.d_ino;
+ const int64_t d_off = inp->dp64.d_off;
+ const uint8_t d_type = inp->dp64.d_type;
+ outp->dp.d_ino = d_ino;
+ outp->dp.d_off = d_off;
+ outp->dp.d_reclen = new_reclen;
+ outp->dp.d_type = d_type;
+ memmove (outp->dp.d_name, inp->dp64.d_name,
+ old_reclen - offsetof (struct dirent64, d_name));
+
+ dirp->filepos = d_off;
+ dirp->offset += old_reclen;
+
+ return &outp->dp;
}
-
- dp = (struct dirent *) &dirp->data[dirp->offset];
- dirp->offset += dp->d_reclen;
- dirp->filepos = dp->d_off;
-
- return dp;
}
struct dirent *
--
2.41.0
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