From 041f0af3668e037f465d0e80ea5561fb3fbaa7d0 Mon Sep 17 00:00:00 2001 From: Heinrich Schuchardt Date: Thu, 21 Jan 2021 00:23:33 +0100 Subject: [PATCH] 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 --- fs/fat/fat.c | 32 ++++++++++++++++---------------- fs/fat/fat_write.c | 20 +++++++++----------- include/fat.h | 7 ++++++- 3 files changed, 31 insertions(+), 28 deletions(-) diff --git a/fs/fat/fat.c b/fs/fat/fat.c index 157dad60a4..fb6ce094ac 100644 --- 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 2f4391e86f..0132ef9b42 100644 --- 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 b9f273f381..bd8e450b33 100644 --- 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 */ -- 2.39.5