fs: fat: structure for name and extension

The short name and extension of FAT files are stored in adjacent fields of
the directory entry. For some operations like calculating a checksum or
copying both fields it is preferable to treat both as one structure.

Change the definition of the directory entry structure to include a
structure comprising the name and the extension field.

This resolves Coverity CID 316357, CID 316350, CID 316348.

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

diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index 157dad60a48910910ab3b29a53bfa04169f274cd..fb6ce094ac1122b4a1c7d7fda9ce85dce04fb602 100644 (file)
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -123,16 +123,16 @@ static void get_name(dir_entry *dirent, char *s_name)
 {
        char *ptr;
 
-       memcpy(s_name, dirent->name, 8);
+       memcpy(s_name, dirent->nameext.name, 8);
        s_name[8] = '\0';
        ptr = s_name;
        while (*ptr && *ptr != ' ')
                ptr++;
        if (dirent->lcase & CASE_LOWER_BASE)
                downcase(s_name, (unsigned)(ptr - s_name));
-       if (dirent->ext[0] && dirent->ext[0] != ' ') {
+       if (dirent->nameext.ext[0] && dirent->nameext.ext[0] != ' ') {
                *ptr++ = '.';
-               memcpy(ptr, dirent->ext, 3);
+               memcpy(ptr, dirent->nameext.ext, 3);
                if (dirent->lcase & CASE_LOWER_EXT)
                        downcase(ptr, 3);
                ptr[3] = '\0';
@@ -472,16 +472,15 @@ static int slot2str(dir_slot *slotptr, char *l_name, int *idx)
 }
 
 /* Calculate short name checksum */
-static __u8 mkcksum(const char name[8], const char ext[3])
+static __u8 mkcksum(struct nameext *nameext)
 {
        int i;
+       u8 *pos = (void *)nameext;
 
        __u8 ret = 0;
 
-       for (i = 0; i < 8; i++)
-               ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + name[i];
-       for (i = 0; i < 3; i++)
-               ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + ext[i];
+       for (i = 0; i < 11; i++)
+               ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + pos[i];
 
        return ret;
 }
@@ -896,7 +895,7 @@ static dir_entry *next_dent(fat_itr *itr)
        }
 
        /* have we reached the last valid entry? */
-       if (itr->dent->name[0] == 0)
+       if (itr->dent->nameext.name[0] == 0)
                return NULL;
 
        return itr->dent;
@@ -905,7 +904,7 @@ static dir_entry *next_dent(fat_itr *itr)
 static dir_entry *extract_vfat_name(fat_itr *itr)
 {
        struct dir_entry *dent = itr->dent;
-       int seqn = itr->dent->name[0] & ~LAST_LONG_ENTRY_MASK;
+       int seqn = itr->dent->nameext.name[0] & ~LAST_LONG_ENTRY_MASK;
        u8 chksum, alias_checksum = ((dir_slot *)dent)->alias_checksum;
        int n = 0;
 
@@ -932,18 +931,19 @@ static dir_entry *extract_vfat_name(fat_itr *itr)
         * We are now at the short file name entry.
         * If it is marked as deleted, just skip it.
         */
-       if (dent->name[0] == DELETED_FLAG ||
-           dent->name[0] == aRING)
+       if (dent->nameext.name[0] == DELETED_FLAG ||
+           dent->nameext.name[0] == aRING)
                return NULL;
 
        itr->l_name[n] = '\0';
 
-       chksum = mkcksum(dent->name, dent->ext);
+       chksum = mkcksum(&dent->nameext);
 
        /* checksum mismatch could mean deleted file, etc.. skip it: */
        if (chksum != alias_checksum) {
                debug("** chksum=%x, alias_checksum=%x, l_name=%s, s_name=%8s.%3s\n",
-                     chksum, alias_checksum, itr->l_name, dent->name, dent->ext);
+                     chksum, alias_checksum, itr->l_name, dent->nameext.name,
+                     dent->nameext.ext);
                return NULL;
        }
 
@@ -984,12 +984,12 @@ static int fat_itr_next(fat_itr *itr)
                itr->dent_rem = itr->remaining;
                itr->dent_start = itr->dent;
                itr->dent_clust = itr->clust;
-               if (dent->name[0] == DELETED_FLAG)
+               if (dent->nameext.name[0] == DELETED_FLAG)
                        continue;
 
                if (dent->attr & ATTR_VOLUME) {
                        if ((dent->attr & ATTR_VFAT) == ATTR_VFAT &&
-                           (dent->name[0] & LAST_LONG_ENTRY_MASK)) {
+                           (dent->nameext.name[0] & LAST_LONG_ENTRY_MASK)) {
                                /* long file name */
                                dent = extract_vfat_name(itr);
                                /*

diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 2f4391e86f8696b7e8031db2d14e46e8088abe53..0132ef9b42f0b6aff795760371c288507800ab66 100644 (file)
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -275,7 +275,7 @@ static int fat_find_empty_dentries(fat_itr *itr, int count)
                        log_debug("Not enough directory entries available\n");
                        return -ENOSPC;
                }
-               switch (itr->dent->name[0]) {
+               switch (itr->dent->nameext.name[0]) {
                case 0x00:
                case DELETED_FLAG:
                        if (!n) {
@@ -399,7 +399,7 @@ fill_dir_slot(fat_itr *itr, const char *l_name, const char *shortname)
        int idx = 0, ret;
 
        /* Get short file name checksum value */
-       checksum = mkcksum(shortname, shortname + 8);
+       checksum = mkcksum((void *)shortname);
 
        do {
                memset(slotptr, 0x00, sizeof(dir_slot));
@@ -1169,7 +1169,7 @@ static void fill_dentry(fsdata *mydata, dir_entry *dentptr,
 
        dentptr->attr = attr;
 
-       memcpy(dentptr->name, shortname, SHORT_NAME_SIZE);
+       memcpy(&dentptr->nameext, shortname, SHORT_NAME_SIZE);
 }
 
 /**
@@ -1194,7 +1194,7 @@ static dir_entry *find_directory_entry(fat_itr *itr, char *filename)
                if (!match)
                        continue;
 
-               if (itr->dent->name[0] == '\0')
+               if (itr->dent->nameext.name[0] == '\0')
                        return NULL;
                else
                        return itr->dent;
@@ -1470,7 +1470,7 @@ static int delete_single_dentry(fat_itr *itr)
        struct dir_entry *dent = itr->dent;
 
        memset(dent, 0, sizeof(*dent));
-       dent->name[0] = DELETED_FLAG;
+       dent->nameext.name[0] = DELETED_FLAG;
 
        if (!itr->remaining)
                return flush_dir(itr);
@@ -1486,7 +1486,7 @@ static int delete_single_dentry(fat_itr *itr)
 static int delete_long_name(fat_itr *itr)
 {
        struct dir_entry *dent = itr->dent;
-       int seqn = itr->dent->name[0] & ~LAST_LONG_ENTRY_MASK;
+       int seqn = itr->dent->nameext.name[0] & ~LAST_LONG_ENTRY_MASK;
 
        while (seqn--) {
                int ret;
@@ -1531,7 +1531,7 @@ static int delete_dentry_long(fat_itr *itr)
        dent = itr->dent_start;
        /* Delete long name */
        if ((dent->attr & ATTR_VFAT) == ATTR_VFAT &&
-           (dent->name[0] & LAST_LONG_ENTRY_MASK)) {
+           (dent->nameext.name[0] & LAST_LONG_ENTRY_MASK)) {
                int ret;
 
                ret = delete_long_name(itr);
@@ -1712,12 +1712,10 @@ int fat_mkdir(const char *new_dirname)
        }
        memset(dotdent, 0, bytesperclust);
 
-       memcpy(dotdent[0].name, ".       ", 8);
-       memcpy(dotdent[0].ext, "   ", 3);
+       memcpy(&dotdent[0].nameext, ".          ", 11);
        dotdent[0].attr = ATTR_DIR | ATTR_ARCH;
 
-       memcpy(dotdent[1].name, "..      ", 8);
-       memcpy(dotdent[1].ext, "   ", 3);
+       memcpy(&dotdent[1].nameext, "..         ", 11);
        dotdent[1].attr = ATTR_DIR | ATTR_ARCH;
 
        if (itr->is_root)

diff --git a/include/fat.h b/include/fat.h
index b9f273f381f10b6cb5f680c3d771842a268cdfad..bd8e450b33a34216998d6ce492f52dc304e5bc2f 100644 (file)
--- a/include/fat.h
+++ b/include/fat.h
@@ -132,8 +132,13 @@ typedef struct volume_info
 #define CASE_LOWER_BASE        8       /* base (name) is lower case */
 #define CASE_LOWER_EXT 16      /* extension is lower case */
 
+struct nameext {
+       char name[8];
+       char ext[3];
+};
+
 typedef struct dir_entry {
-       char    name[8],ext[3]; /* Name and extension */
+       struct nameext nameext; /* Name and extension */
        __u8    attr;           /* Attribute bits */
        __u8    lcase;          /* Case for name and ext (CASE_LOWER_x) */
        __u8    ctime_ms;       /* Creation time, milliseconds */