From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: libc-alpha@sourceware.org, Florian Weimer <fweimer@redhat.com>
Cc: Dave Flogeras <dflogeras2@gmail.com>,
James Clarke <jrtc27@debian.org>,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Subject: [PATCH v3 6/7] linux: Use getdents64 on readdir64 compat implementation
Date: Wed, 21 Oct 2020 11:15:41 -0300 [thread overview]
Message-ID: <20201021141542.2003377-7-adhemerval.zanella@linaro.org> (raw)
In-Reply-To: <20201021141542.2003377-1-adhemerval.zanella@linaro.org>
It uses a similar strategy from the non-LFS readdir that also
uses getdents64 internally and uses a translation buffer to return
the compat readdir64 entry.
It allows to remove __old_getdents64.
Checked on i686-linux-gnu.
---
sysdeps/unix/sysv/linux/getdents64.c | 93 ------------------------
sysdeps/unix/sysv/linux/olddirent.h | 2 -
sysdeps/unix/sysv/linux/opendir.c | 15 +++-
sysdeps/unix/sysv/linux/readdir64.c | 104 +++++++++++++++++----------
4 files changed, 79 insertions(+), 135 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/getdents64.c b/sysdeps/unix/sysv/linux/getdents64.c
index 75892c2823..b8682c3472 100644
--- a/sysdeps/unix/sysv/linux/getdents64.c
+++ b/sysdeps/unix/sysv/linux/getdents64.c
@@ -36,97 +36,4 @@ weak_alias (__getdents64, getdents64)
#if _DIRENT_MATCHES_DIRENT64
strong_alias (__getdents64, __getdents)
-#else
-# include <shlib-compat.h>
-
-# if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
-# include <olddirent.h>
-# include <unistd.h>
-
-static ssize_t
-handle_overflow (int fd, __off64_t offset, ssize_t count)
-{
- /* If this is the first entry in the buffer, we can report the
- error. */
- if (offset == 0)
- {
- __set_errno (EOVERFLOW);
- return -1;
- }
-
- /* Otherwise, seek to the overflowing entry, so that the next call
- will report the error, and return the data read so far. */
- if (__lseek64 (fd, offset, SEEK_SET) != 0)
- return -1;
- return count;
-}
-
-ssize_t
-__old_getdents64 (int fd, char *buf, size_t nbytes)
-{
- /* We do not move the individual directory entries. This is only
- possible if the target type (struct __old_dirent64) is smaller
- than the source type. */
- _Static_assert (offsetof (struct __old_dirent64, d_name)
- <= offsetof (struct dirent64, d_name),
- "__old_dirent64 is larger than dirent64");
- _Static_assert (__alignof__ (struct __old_dirent64)
- <= __alignof__ (struct dirent64),
- "alignment of __old_dirent64 is larger than dirent64");
-
- ssize_t retval = INLINE_SYSCALL_CALL (getdents64, fd, buf, nbytes);
- if (retval > 0)
- {
- /* This is the marker for the first entry. Offset 0 is reserved
- for the first entry (see rewinddir). Here, we use it as a
- marker for the first entry in the buffer. We never actually
- seek to offset 0 because handle_overflow reports the error
- directly, so it does not matter that the offset is incorrect
- if entries have been read from the descriptor before (so that
- the descriptor is not actually at offset 0). */
- __off64_t previous_offset = 0;
-
- char *p = buf;
- char *end = buf + retval;
- while (p < end)
- {
- struct dirent64 *source = (struct dirent64 *) p;
-
- /* Copy out the fixed-size data. */
- __ino_t ino = source->d_ino;
- __off64_t offset = source->d_off;
- unsigned int reclen = source->d_reclen;
- unsigned char type = source->d_type;
-
- /* Check for ino_t overflow. */
- if (__glibc_unlikely (ino != source->d_ino))
- return handle_overflow (fd, previous_offset, p - buf);
-
- /* Convert to the target layout. Use a separate struct and
- memcpy to side-step aliasing issues. */
- struct __old_dirent64 result;
- result.d_ino = ino;
- result.d_off = offset;
- result.d_reclen = reclen;
- result.d_type = type;
-
- /* Write the fixed-sized part of the result to the
- buffer. */
- size_t result_name_offset = offsetof (struct __old_dirent64, d_name);
- memcpy (p, &result, result_name_offset);
-
- /* Adjust the position of the name if necessary. Copy
- everything until the end of the record, including the
- terminating NUL byte. */
- if (result_name_offset != offsetof (struct dirent64, d_name))
- memmove (p + result_name_offset, source->d_name,
- reclen - offsetof (struct dirent64, d_name));
-
- p += reclen;
- previous_offset = offset;
- }
- }
- return retval;
-}
-# endif /* SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2) */
#endif /* _DIRENT_MATCHES_DIRENT64 */
diff --git a/sysdeps/unix/sysv/linux/olddirent.h b/sysdeps/unix/sysv/linux/olddirent.h
index b118b0ef96..63d8e97868 100644
--- a/sysdeps/unix/sysv/linux/olddirent.h
+++ b/sysdeps/unix/sysv/linux/olddirent.h
@@ -36,8 +36,6 @@ extern struct __old_dirent64 *__old_readdir64_unlocked (DIR *__dirp)
attribute_hidden;
extern int __old_readdir64_r (DIR *__dirp, struct __old_dirent64 *__entry,
struct __old_dirent64 **__result);
-extern __ssize_t __old_getdents64 (int __fd, char *__buf, size_t __nbytes)
- attribute_hidden;
int __old_scandir64 (const char * __dir,
struct __old_dirent64 *** __namelist,
int (*__selector) (const struct __old_dirent64 *),
diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c
index 28fd55341e..3a08b76c0a 100644
--- a/sysdeps/unix/sysv/linux/opendir.c
+++ b/sysdeps/unix/sysv/linux/opendir.c
@@ -23,6 +23,11 @@
#include <not-cancel.h>
+#include <shlib-compat.h>
+#if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
+# include <olddirent.h>
+#endif
+
enum {
opendir_oflags = O_RDONLY|O_NDELAY|O_DIRECTORY|O_LARGEFILE|O_CLOEXEC
};
@@ -127,7 +132,15 @@ __alloc_dir (int fd, bool close_fd, int flags, const struct stat64 *statp)
expand the buffer if required. */
enum
{
- tbuffer_size = sizeof (struct dirent) + NAME_MAX + 1
+ tbuffer_size =
+# if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
+ /* This is used on compat readdir64. */
+ MAX (sizeof (struct dirent),
+ sizeof (struct __old_dirent64))
+# else
+ sizeof (struct dirent)
+# endif
+ + NAME_MAX + 1
};
dirp->tbuffer = malloc (tbuffer_size);
if (dirp->tbuffer == NULL)
diff --git a/sysdeps/unix/sysv/linux/readdir64.c b/sysdeps/unix/sysv/linux/readdir64.c
index acd190733c..799708174a 100644
--- a/sysdeps/unix/sysv/linux/readdir64.c
+++ b/sysdeps/unix/sysv/linux/readdir64.c
@@ -99,57 +99,83 @@ versioned_symbol (libc, __readdir64, readdir64, GLIBC_2_2);
# if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2)
# include <olddirent.h>
+/* Translate the DP64 entry to the old LFS one in the translation buffer
+ at dirstream DS. Return true is the translation was possible or
+ false if either an internal fields can be represented in the non-LFS
+ entry or if the translation can not be resized. */
+static bool
+dirstream_old_entry (struct __dirstream *ds, const struct dirent64 *dp64)
+{
+ /* Check for overflow. */
+ ino_t d_ino = dp64->d_ino;
+ if (d_ino != dp64->d_ino)
+ return false;
+
+ /* Expand the translation buffer to hold the new namesize. */
+ size_t d_reclen = sizeof (struct __old_dirent64)
+ + dp64->d_reclen - offsetof (struct dirent64, d_name);
+ if (d_reclen > ds->tbuffer_size)
+ {
+ char *newbuffer = realloc (ds->tbuffer, d_reclen);
+ if (newbuffer == NULL)
+ return false;
+ ds->tbuffer = newbuffer;
+ ds->tbuffer_size = d_reclen;
+ }
+
+ struct __old_dirent64 *olddp64 = (struct __old_dirent64 *) ds->tbuffer;
+
+ olddp64->d_off = dp64->d_off;
+ olddp64->d_ino = dp64->d_ino;
+ olddp64->d_reclen = dp64->d_reclen;
+ olddp64->d_type = dp64->d_type;
+ memcpy (olddp64->d_name, dp64->d_name,
+ dp64->d_reclen - offsetof (struct dirent64, d_name));
+
+ return true;
+}
+
attribute_compat_text_section
struct __old_dirent64 *
__old_readdir64_unlocked (DIR *dirp)
{
- struct __old_dirent64 *dp;
- int saved_errno = errno;
+ const int saved_errno = errno;
- do
+ if (dirp->offset >= dirp->size)
{
- size_t reclen;
-
- if (dirp->offset >= dirp->size)
+ /* We've emptied out our buffer. Refill it. */
+ ssize_t bytes = __getdents64 (dirp->fd, dirp->data, dirp->allocation);
+ if (bytes <= 0)
{
- /* We've emptied out our buffer. Refill it. */
-
- size_t maxread = dirp->allocation;
- ssize_t bytes;
-
- bytes = __old_getdents64 (dirp->fd, dirp->data, maxread);
- if (bytes <= 0)
- {
- /* On some systems getdents fails with ENOENT when the
- open directory has been rmdir'd already. POSIX.1
- requires that we treat this condition like normal EOF. */
- if (bytes < 0 && errno == ENOENT)
- bytes = 0;
-
- /* Don't modifiy errno when reaching EOF. */
- if (bytes == 0)
- __set_errno (saved_errno);
- dp = NULL;
- break;
- }
- dirp->size = (size_t) bytes;
-
- /* Reset the offset into the buffer. */
- dirp->offset = 0;
- }
-
- dp = (struct __old_dirent64 *) &dirp->data[dirp->offset];
+ /* On some systems getdents fails with ENOENT when the
+ open directory has been rmdir'd already. POSIX.1
+ requires that we treat this condition like normal EOF. */
+ if (bytes < 0 && errno == ENOENT)
+ bytes = 0;
- reclen = dp->d_reclen;
+ /* Don't modifiy errno when reaching EOF. */
+ if (bytes == 0)
+ __set_errno (saved_errno);
+ return NULL;
+ }
+ dirp->size = bytes;
- dirp->offset += reclen;
+ /* Reset the offset into the buffer. */
+ dirp->offset = 0;
+ }
- dirp->filepos = dp->d_off;
+ struct dirent64 *dp64 = (struct dirent64 *) &dirp->data[dirp->offset];
+ dirp->offset += dp64->d_reclen;
- /* Skip deleted files. */
- } while (dp->d_ino == 0);
+ /* Skip entries which might overflow d_ino or for memory allocation failure
+ in case of large file names. */
+ if (dirstream_old_entry (dirp, dp64))
+ {
+ dirp->filepos = dp64->d_off;
+ return (struct __old_dirent64 *) dirp->tbuffer;
+ }
- return dp;
+ return NULL;
}
attribute_compat_text_section
--
2.25.1
next prev parent reply other threads:[~2020-10-21 14:16 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-21 14:15 [PATCH v3 0/7] Fix getdents{64} regression on some FS Adhemerval Zanella
2020-10-21 14:15 ` [PATCH v3 1/7] linux: Do not skip entries with zero d_ino values [BZ #12165] Adhemerval Zanella
2020-10-21 14:15 ` [PATCH v3 2/7] linux: Use getdents64 on non-LFS readdir Adhemerval Zanella
2020-10-21 14:15 ` [PATCH v3 3/7] linux: Set internal DIR filepos as off64_t [BZ #23960, BZ #24050] Adhemerval Zanella
2020-10-21 14:15 ` [PATCH v3 4/7] linux: Add __readdir64_unlocked Adhemerval Zanella
2020-10-21 14:15 ` [PATCH v3 5/7] linux: Add __old_readdir64_unlocked Adhemerval Zanella
2020-10-21 14:15 ` Adhemerval Zanella [this message]
2020-10-21 14:15 ` [PATCH v3 7/7] dirent: Deprecate getdirentries Adhemerval Zanella
2022-01-06 21:48 ` John Paul Adrian Glaubitz
2022-01-06 21:59 ` Sam James
2022-01-06 22:01 ` John Paul Adrian Glaubitz
2022-05-10 19:30 ` John Paul Adrian Glaubitz
2022-05-12 15:40 ` Adhemerval Zanella
2021-07-22 8:28 ` [PATCH v3 0/7] Fix getdents{64} regression on some FS John Paul Adrian Glaubitz
2021-08-19 16:07 ` John Paul Adrian Glaubitz
2021-08-19 16:19 ` Adhemerval Zanella
2021-08-19 16:50 ` John Paul Adrian Glaubitz
2021-08-19 16:52 ` Adhemerval Zanella
2021-08-19 17:02 ` John Paul Adrian Glaubitz
2021-08-19 17:15 ` Florian Weimer
2021-08-19 20:30 ` John Paul Adrian Glaubitz
2021-08-20 10:34 ` Dave Flogeras
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