From 4b962c9e859de23b461d61f860dbd3f21311e83a Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Sun, 12 Apr 2020 17:42:35 -0300 Subject: 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. --- sysdeps/unix/sysv/linux/opendir.c | 51 ++++++++++++++------------------------- 1 file changed, 18 insertions(+), 33 deletions(-) (limited to 'sysdeps/unix') diff --git a/sysdeps/unix/sysv/linux/opendir.c b/sysdeps/unix/sysv/linux/opendir.c index e89e09bfc7..2198224588 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 +94,29 @@ __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 = 1048576 }; + + const size_t allocation_size = 32768; + _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 and 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; -- cgit 1.4.1