fs: fat: generate unique short names

File names must be unique within their directory. So before assigning a
short name we must check that it is unique.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 716b6a6..59cffef 100644 (file)
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -20,6 +20,8 @@
 #include <linux/math64.h>
 #include "fat.c"
 
+static dir_entry *find_directory_entry(fat_itr *itr, char *filename);
+
 /* Characters that may only be used in long file names */
 static const char LONG_ONLY_CHARS[] = "+,;=[]";
 
@@ -64,6 +66,27 @@ static int str2fat(char *dest, char *src, int length)
 }
 
 /**
+ * fat_move_to_cluster() - position to first directory entry in cluster
+ *
+ * @itr:       directory iterator
+ * @cluster    cluster
+ * Return:     0 for success, -EIO on error
+ */
+static int fat_move_to_cluster(fat_itr *itr, unsigned int cluster)
+{
+       unsigned int nbytes;
+
+       /* position to the start of the directory */
+       itr->next_clust = cluster;
+       itr->last_cluster = 0;
+       if (!fat_next_cluster(itr, &nbytes))
+               return -EIO;
+       itr->dent = (dir_entry *)itr->block;
+       itr->remaining = nbytes / sizeof(dir_entry) - 1;
+       return 0;
+}
+
+/**
  * set_name() - set short name in directory entry
  *
  * The function determines if the @filename is a valid short name.
@@ -71,11 +94,12 @@ static int str2fat(char *dest, char *src, int length)
  *
  * If a long name is needed, a short name is constructed.
  *
+ * @itr:       directory iterator
  * @filename:  long file name
  * @shortname: buffer of 11 bytes to receive chosen short name and extension
  * Return:     number of directory entries needed, negative on error
  */
-static int set_name(const char *filename, char *shortname)
+static int set_name(fat_itr *itr, const char *filename, char *shortname)
 {
        char *period;
        char *pos;
@@ -144,9 +168,16 @@ static int set_name(const char *filename, char *shortname)
                else
                        sprintf(buf, "%.*s", suffix_start + suffix_len,
                                dirent.name);
-               debug("short name: %s\n", buf);
-               /* TODO: Check that the short name does not exist yet. */
+               debug("generated short name: %s\n", buf);
+
+               /* Check that the short name does not exist yet. */
+               ret = fat_move_to_cluster(itr, itr->start_clust);
+               if (ret)
+                       return ret;
+               if (find_directory_entry(itr, buf))
+                       continue;
 
+               debug("chosen short name: %s\n", buf);
                /* Each long name directory entry takes 13 characters. */
                ret = (strlen(filename) + 25) / 13;
                goto out;
@@ -1261,7 +1292,7 @@ int file_fat_write_at(const char *filename, loff_t pos, void *buffer,
                }
 
                /* Check if long name is needed */
-               ret = set_name(filename, shortname);
+               ret = set_name(itr, filename, shortname);
                if (ret < 0)
                        goto exit;
                if (ret > 1) {
@@ -1523,7 +1554,7 @@ int fat_mkdir(const char *new_dirname)
                }
 
                /* Check if long name is needed */
-               ret = set_name(dirname, shortname);
+               ret = set_name(itr, dirname, shortname);
                if (ret < 0)
                        goto exit;
                if (ret > 1) {