Libc-1353.11.2.tar.gz

[apple/libc.git] / gen / FreeBSD / opendir.c

diff --git a/gen/FreeBSD/opendir.c b/gen/FreeBSD/opendir.c
index 4242906248bb520b4f6974bfc2f94423502d3ef5..844a7e88cbe044f1bbb1fd3f84a48a5b540c3313 100644 (file)
--- a/gen/FreeBSD/opendir.c
+++ b/gen/FreeBSD/opendir.c
@@ -37,6 +37,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/param.h>
 #include <sys/mount.h>
 #include <sys/stat.h>
+#include <sys/sysctl.h>
 
 #include <dirent.h>
 #include <errno.h>
@@ -49,6 +50,32 @@ __FBSDID("$FreeBSD$");
 
 #include "telldir.h"
 
+static bool
+__kernel_supports_unionfs(void)
+{
+       static int8_t kernel_supports_unionfs = -1;
+       if (kernel_supports_unionfs == -1) {
+               int value = 0;
+               size_t len = sizeof(value);
+               sysctlbyname("kern.secure_kernel", &value, &len, NULL, 0);
+               kernel_supports_unionfs = !value;
+       }
+       return kernel_supports_unionfs;
+}
+
+static int
+__fd_is_on_union_mount(int fd)
+{
+       struct statfs stbuf;
+       int rc;
+
+       rc = fstatfs(fd, &stbuf);
+       if (rc < 0) {
+               return rc;
+       }
+       return (stbuf.f_flags & MNT_UNION) != 0;
+}
+
 static DIR * __opendir_common(int, int, bool);
 
 /*
@@ -294,7 +321,6 @@ static DIR *
 __opendir_common(int fd, int flags, bool use_current_pos)
 {
        DIR *dirp;
-       int incr;
        int saved_errno;
        int unionstack;
 
@@ -310,25 +336,13 @@ __opendir_common(int fd, int flags, bool use_current_pos)
        LIST_INIT(&dirp->dd_td->td_locq);
        dirp->dd_td->td_loccnt = 0;
 
-       /*
-        * Use the system page size if that is a multiple of DIRBLKSIZ.
-        * Hopefully this can be a big win someday by allowing page
-        * trades to user space to be done by _getdirentries().
-        */
-       incr = getpagesize();
-       if ((incr % DIRBLKSIZ) != 0) 
-               incr = DIRBLKSIZ;
-
        /*
         * Determine whether this directory is the top of a union stack.
         */
-       if (flags & DTF_NODUP) {
-               struct statfs sfb;
-
-               if (_fstatfs(fd, &sfb) < 0)
+       if ((flags & DTF_NODUP) && __kernel_supports_unionfs()) {
+               unionstack = __fd_is_on_union_mount(fd);
+               if (unionstack < 0)
                        goto fail;
-               unionstack = !strcmp(sfb.f_fstypename, "unionfs")
-                   || (sfb.f_flags & MNT_UNION);
        } else {
                unionstack = 0;
        }
@@ -338,7 +352,14 @@ __opendir_common(int fd, int flags, bool use_current_pos)
                        goto fail;
                dirp->dd_flags |= __DTF_READALL;
        } else {
-               dirp->dd_len = incr;
+               /*
+                * Start with a small-ish size to avoid allocating full pages.
+                * readdir() will allocate a larger buffer if it didn't fit
+                * to stay fast for large directories.
+                */
+               _Static_assert(GETDIRENTRIES64_EXTENDED_BUFSIZE <= READDIR_INITIAL_SIZE,
+                   "Make sure we'll get extended metadata");
+               dirp->dd_len = READDIR_INITIAL_SIZE;
                dirp->dd_buf = malloc(dirp->dd_len);
                if (dirp->dd_buf == NULL)
                        goto fail;
@@ -349,8 +370,26 @@ __opendir_common(int fd, int flags, bool use_current_pos)
                         * fd passed to fdopendir() is a directory.
                         */
 #if __DARWIN_64_BIT_INO_T
+                       /*
+                        * sufficiently recent kernels when the buffer is large enough,
+                        * will use the last bytes of the buffer to return status.
+                        *
+                        * To support older kernels:
+                        * - make sure it's 0 initialized
+                        * - make sure it's past `dd_size` before reading it
+                        */
+                       getdirentries64_flags_t *gdeflags =
+                           (getdirentries64_flags_t *)(dirp->dd_buf + dirp->dd_len -
+                           sizeof(getdirentries64_flags_t));
+                       *gdeflags = 0;
                        dirp->dd_size = (long)__getdirentries64(dirp->dd_fd,
                            dirp->dd_buf, dirp->dd_len, &dirp->dd_td->seekoff);
+                       if (dirp->dd_size >= 0 &&
+                           dirp->dd_size <= dirp->dd_len - sizeof(getdirentries64_flags_t)) {
+                               if (*gdeflags & GETDIRENTRIES64_EOF) {
+                                       dirp->dd_flags |= __DTF_ATEND;
+                               }
+                       }
 #else /* !__DARWIN_64_BIT_INO_T */
                        dirp->dd_size = _getdirentries(dirp->dd_fd,
                            dirp->dd_buf, dirp->dd_len, &dirp->dd_seek);