[PATCH v6] ntdll: Add support for EXT4 case folding per directory

[Gabriel Ivăncescu]

This adds support for checking the case-insensitive attribute on ext4 with
newer kernels so that Wine can rely on it for performance.

Signed-off-by: Gabriel Ivăncescu <gabrielopcode(a)gmail.com>
---
 dlls/ntdll/directory.c | 53 ++++++++++++++++++++++++------------------
 1 file changed, 31 insertions(+), 22 deletions(-)

diff --git a/dlls/ntdll/directory.c b/dlls/ntdll/directory.c
index bbdbbe9..b18f56b 100644
--- a/dlls/ntdll/directory.c
+++ b/dlls/ntdll/directory.c
@@ -115,6 +115,8 @@ WINE_DEFAULT_DEBUG_CHANNEL(file);
 
 /* just in case... */
 #undef VFAT_IOCTL_READDIR_BOTH
+#undef EXT2_IOC_GETFLAGS
+#undef EXT4_CASEFOLD_FL
 
 #ifdef linux
 
@@ -130,6 +132,12 @@ typedef struct
 /* Define the VFAT ioctl to get both short and long file names */
 #define VFAT_IOCTL_READDIR_BOTH  _IOR('r', 1, KERNEL_DIRENT [2] )
 
+/* Define the ext2 ioctl for handling extra attributes */
+#define EXT2_IOC_GETFLAGS _IOR('f', 1, long)
+
+/* Case-insensitivity attribute */
+#define EXT4_CASEFOLD_FL 0x40000000
+
 #ifndef O_DIRECTORY
 # define O_DIRECTORY 0200000 /* must be directory */
 #endif
@@ -1113,7 +1121,7 @@ static int get_dir_case_sensitivity_attr( const char *dir )
  *           get_dir_case_sensitivity_stat
  *
  * Checks if the volume containing the specified directory is case
- * sensitive or not. Uses statfs(2) or statvfs(2).
+ * sensitive or not. Uses (f)statfs(2), statvfs(2), fstatat(2), or ioctl(2).
  */
 static BOOLEAN get_dir_case_sensitivity_stat( const char *dir )
 {
@@ -1165,32 +1173,33 @@ static BOOLEAN get_dir_case_sensitivity_stat( const char *dir )
     return FALSE;
 
 #elif defined(__linux__)
+    BOOLEAN sens = TRUE;
     struct statfs stfs;
     struct stat st;
-    char *cifile;
+    int fd, flags;
 
-    /* Only assume CIOPFS is case insensitive. */
-    if (statfs( dir, &stfs ) == -1) return FALSE;
-    if (stfs.f_type != 0x65735546 /* FUSE_SUPER_MAGIC */)
+    if ((fd = open( dir, O_RDONLY | O_NONBLOCK | O_LARGEFILE )) == -1)
         return TRUE;
-    /* Normally, we'd have to parse the mtab to find out exactly what
-     * kind of FUSE FS this is. But, someone on wine-devel suggested
-     * a shortcut. We'll stat a special file in the directory. If it's
-     * there, we'll assume it's a CIOPFS, else not.
-     * This will break if somebody puts a file named ".ciopfs" in a non-
-     * CIOPFS directory.
-     */
-    cifile = RtlAllocateHeap( GetProcessHeap(), 0, strlen( dir )+sizeof("/.ciopfs") );
-    if (!cifile) return TRUE;
-    strcpy( cifile, dir );
-    strcat( cifile, "/.ciopfs" );
-    if (stat( cifile, &st ) == 0)
+
+    if (ioctl( fd, EXT2_IOC_GETFLAGS, &flags ) != -1 && (flags & EXT4_CASEFOLD_FL))
     {
-        RtlFreeHeap( GetProcessHeap(), 0, cifile );
-        return FALSE;
+        sens = FALSE;
     }
-    RtlFreeHeap( GetProcessHeap(), 0, cifile );
-    return TRUE;
+    else
+    {
+        /* Assume CIOPFS is case insensitive. Normally, we'd have to parse
+         * the mtab to find out exactly what kind of FUSE FS this is. But,
+         * someone on wine-devel suggested a shortcut. We'll stat a special
+         * file in the directory. If it's there, we'll assume it's a CIOPFS,
+         * else not. This will break if somebody puts a file named ".ciopfs"
+         * in a non-CIOPFS directory.
+         */
+        if (fstatfs( fd, &stfs ) != -1 && stfs.f_type == 0x65735546 /* FUSE_SUPER_MAGIC */ &&
+            fstatat( fd, ".ciopfs", &st, AT_NO_AUTOMOUNT ) == 0)
+            sens = FALSE;
+    }
+    close( fd );
+    return sens;
 #else
     return TRUE;
 #endif
@@ -1201,7 +1210,7 @@ static BOOLEAN get_dir_case_sensitivity_stat( const char *dir )
  *           get_dir_case_sensitivity
  *
  * Checks if the volume containing the specified directory is case
- * sensitive or not. Uses statfs(2) or statvfs(2).
+ * sensitive or not. Uses multiple methods, depending on platform.
  */
 static BOOLEAN get_dir_case_sensitivity( const char *dir )
 {
-- 
2.21.0

[Huw Davies]

On Thu, Jun 13, 2019 at 06:53:59PM +0300, Gabriel Ivăncescu wrote:
> +    if ((fd = open( dir, O_RDONLY | O_NONBLOCK | O_LARGEFILE )) == -1)
>          return TRUE;
> -    /* Normally, we'd have to parse the mtab to find out exactly what
> -     * kind of FUSE FS this is. But, someone on wine-devel suggested
> -     * a shortcut. We'll stat a special file in the directory. If it's
> -     * there, we'll assume it's a CIOPFS, else not.
> -     * This will break if somebody puts a file named ".ciopfs" in a non-
> -     * CIOPFS directory.
> -     */
> -    cifile = RtlAllocateHeap( GetProcessHeap(), 0, strlen( dir )+sizeof("/.ciopfs") );
> -    if (!cifile) return TRUE;
> -    strcpy( cifile, dir );
> -    strcat( cifile, "/.ciopfs" );
> -    if (stat( cifile, &st ) == 0)
> +
> +    if (ioctl( fd, EXT2_IOC_GETFLAGS, &flags ) != -1 && (flags & EXT4_CASEFOLD_FL))
>      {
> -        RtlFreeHeap( GetProcessHeap(), 0, cifile );
> -        return FALSE;
> +        sens = FALSE;
>      }
> -    RtlFreeHeap( GetProcessHeap(), 0, cifile );
> -    return TRUE;
> +    else
> +    {
> +        /* Assume CIOPFS is case insensitive. Normally, we'd have to parse
> +         * the mtab to find out exactly what kind of FUSE FS this is. But,
> +         * someone on wine-devel suggested a shortcut. We'll stat a special
> +         * file in the directory. If it's there, we'll assume it's a CIOPFS,
> +         * else not. This will break if somebody puts a file named ".ciopfs"
> +         * in a non-CIOPFS directory.
> +         */
> +        if (fstatfs( fd, &stfs ) != -1 && stfs.f_type == 0x65735546 /* FUSE_SUPER_MAGIC */ &&
> +            fstatat( fd, ".ciopfs", &st, AT_NO_AUTOMOUNT ) == 0)
> +            sens = FALSE;
> +    }
> +    close( fd );
> +    return sens;
>  #else
>      return TRUE;
>  #endif

I've sent in a new version with a few changes.  Most notably I've
trimmed the CIOPFS comment right down.  I've also inverted the
return value check of fstatfs() to match that of fstatat().

Huw.