From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1791) id 32BF53870850; Fri, 2 Oct 2020 13:53:21 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 32BF53870850 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Adhemerval Zanella To: glibc-cvs@sourceware.org Subject: [glibc/azanella/bz23960] linux: Simplify opendir buffer allocation X-Act-Checkin: glibc X-Git-Author: Adhemerval Zanella X-Git-Refname: refs/heads/azanella/bz23960 X-Git-Oldrev: 1aa7d361a6b317bfa6f571609097c106914ad8a5 X-Git-Newrev: c66e52bf76415c26b10b46dbc5660db9b00972e2 Message-Id: <20201002135321.32BF53870850@sourceware.org> Date: Fri, 2 Oct 2020 13:53:21 +0000 (GMT) X-BeenThere: glibc-cvs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Glibc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 02 Oct 2020 13:53:21 -0000 https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=c66e52bf76415c26b10b46dbc5660db9b00972e2 commit c66e52bf76415c26b10b46dbc5660db9b00972e2 Author: Adhemerval Zanella Date: Sun Apr 12 17:42:35 2020 -0300 linux: Simplify opendir buffer allocation The fallback allocation is removed, so the possible size constraint should be analyzed just once; __alloc_dir assumes that 'statp' argument is non-null, and the max_buffer_size move to close its used. Checked on x86_64-linux-gnu and i686-linux-gnu. Diff: --- include/dirent.h | 3 ++- sysdeps/unix/sysv/linux/opendir.c | 52 ++++++++++++++------------------------- 2 files changed, 21 insertions(+), 34 deletions(-) diff --git a/include/dirent.h b/include/dirent.h index 2b1cdcf8bd..fdf4c4a2f1 100644 --- a/include/dirent.h +++ b/include/dirent.h @@ -48,7 +48,8 @@ extern int __versionsort64 (const struct dirent64 **a, const struct dirent64 **b) __attribute_pure__; extern DIR *__alloc_dir (int fd, bool close_fd, int flags, - const struct stat64 *statp) attribute_hidden; + const struct stat64 *statp) + __nonnull (4) attribute_hidden; extern __typeof (rewinddir) __rewinddir; extern __typeof (seekdir) __seekdir; extern __typeof (dirfd) __dirfd; diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c index e89e09bfc7..4e8d108821 100644 --- a/sysdeps/unix/sysv/linux/opendir.c +++ b/sysdeps/unix/sysv/linux/opendir.c @@ -23,12 +23,6 @@ #include -/* The st_blksize value of the directory is used as a hint for the - size of the buffer which receives struct dirent values from the - kernel. st_blksize is limited to MAX_DIR_BUFFER_SIZE, in case the - file system provides a bogus value. */ -#define MAX_DIR_BUFFER_SIZE 1048576U - enum { opendir_oflags = O_RDONLY|O_NDELAY|O_DIRECTORY|O_LARGEFILE|O_CLOEXEC }; @@ -100,38 +94,30 @@ __alloc_dir (int fd, bool close_fd, int flags, const struct stat64 *statp) file descriptor. */ if (!close_fd && __glibc_unlikely (__fcntl64_nocancel (fd, F_SETFD, FD_CLOEXEC) < 0)) - goto lose; - - const size_t default_allocation = (4 * BUFSIZ < sizeof (struct dirent64) - ? sizeof (struct dirent64) : 4 * BUFSIZ); - const size_t small_allocation = (BUFSIZ < sizeof (struct dirent64) - ? sizeof (struct dirent64) : BUFSIZ); - size_t allocation = default_allocation; -#ifdef _STATBUF_ST_BLKSIZE + return NULL; + + /* The st_blksize value of the directory is used as a hint for the + size of the buffer which receives struct dirent values from the + kernel. st_blksize is limited to max_buffer_size, in case the + file system provides a bogus value. */ + enum { max_buffer_size = 1U << 20 }; + + const size_t allocation_size = 4 * BUFSIZ; + _Static_assert (allocation_size >= sizeof (struct dirent64), + "allocation_size < sizeof (struct dirent64)"); + /* Increase allocation if requested, but not if the value appears to - be bogus. */ - if (statp != NULL) - allocation = MIN (MAX ((size_t) statp->st_blksize, default_allocation), - MAX_DIR_BUFFER_SIZE); -#endif + be bogus. It will be between 32Kb (for blocksizes smaller than BUFSIZ) + up to 1Mb. */ + size_t allocation = MIN (MAX ((size_t) statp->st_blksize, allocation_size), + max_buffer_size); DIR *dirp = (DIR *) malloc (sizeof (DIR) + allocation); if (dirp == NULL) { - allocation = small_allocation; - dirp = (DIR *) malloc (sizeof (DIR) + allocation); - - if (dirp == NULL) - lose: - { - if (close_fd) - { - int save_errno = errno; - __close_nocancel_nostatus (fd); - __set_errno (save_errno); - } - return NULL; - } + if (close_fd) + __close_nocancel_nostatus (fd); + return NULL; } dirp->fd = fd;