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fs: fat: structure for name and extension

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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>
This commit is contained in:
Heinrich Schuchardt 2021-01-21 00:23:33 +01:00
parent e97eb638de
commit 041f0af366
3 changed files with 31 additions and 28 deletions
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32
fs/fat/fat.c
View file

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

20
fs/fat/fat_write.c
View file

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

7
include/fat.h
View file

@ -132,8 +132,13 @@ typedef struct volume_info
#define CASE_LOWER_BASE 8 /* base (name) is lower case */ #define CASE_LOWER_BASE 8 /* base (name) is lower case */
#define CASE_LOWER_EXT 16 /* extension is lower case */ #define CASE_LOWER_EXT 16 /* extension is lower case */
struct nameext {
char name[8];
char ext[3];
};
typedef struct dir_entry { typedef struct dir_entry {
char name[8],ext[3]; /* Name and extension */ struct nameext nameext; /* Name and extension */
__u8 attr; /* Attribute bits */ __u8 attr; /* Attribute bits */
__u8 lcase; /* Case for name and ext (CASE_LOWER_x) */ __u8 lcase; /* Case for name and ext (CASE_LOWER_x) */
__u8 ctime_ms; /* Creation time, milliseconds */ __u8 ctime_ms; /* Creation time, milliseconds */