From a5aee8e0e844f9f9cf8df0a41e67cddf8de7540f Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Tue, 20 Oct 2020 16:00:43 -0300 Subject: [PATCH 12/14] linux: Use getdents64 on readdir64 compat implementation 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 510a586859..92481526c5 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 - -# if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2) -# include -# include - -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 00c84b9521..68aafd7c02 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 9a0b7ab4c4..df40b0a64e 100644 --- a/sysdeps/unix/sysv/linux/opendir.c +++ b/sysdeps/unix/sysv/linux/opendir.c @@ -23,6 +23,11 @@ #include +#include +#if SHLIB_COMPAT(libc, GLIBC_2_1, GLIBC_2_2) +# include +#endif + enum { opendir_oflags = O_RDONLY|O_NDELAY|O_DIRECTORY|O_LARGEFILE|O_CLOEXEC }; @@ -128,7 +133,15 @@ __alloc_dir (int fd, bool close_fd, int flags, 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 dbf6a8c54d..4b41299c6c 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 +/* 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 -- 2.34.1