From 1170e634dd2a6fdd541ae2153fd3fd73919da8fc Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Beno=C3=AEt=20Th=C3=A9baudeau?= Date: Tue, 18 Sep 2012 08:14:56 +0000 Subject: FAT: Make it possible to read from any file position MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit When storage devices contain files larger than the embedded RAM, it is useful to be able to read these files by chunks, e.g. for a software update to the embedded NAND Flash from an external storage device (USB stick, SD card, etc.). Hence, this patch makes it possible by adding a new FAT API to read files from a given position. This patch also adds this feature to the fatload command. Signed-off-by: Benoît Thébaudeau Cc: Wolfgang Denk Signed-off-by: Tom Rini --- fs/fat/fat.c | 98 +++++++++++++++++++++++++++++++++++++++++++----------- fs/fat/fat_write.c | 18 +++++----- 2 files changed, 88 insertions(+), 28 deletions(-) (limited to 'fs') diff --git a/fs/fat/fat.c b/fs/fat/fat.c index 19f6a8c0af..41ae15eeb9 100644 --- a/fs/fat/fat.c +++ b/fs/fat/fat.c @@ -328,13 +328,16 @@ get_cluster(fsdata *mydata, __u32 clustnum, __u8 *buffer, unsigned long size) } /* - * Read at most 'maxsize' bytes from the file associated with 'dentptr' + * Read at most 'maxsize' bytes from 'pos' in the file associated with 'dentptr' * into 'buffer'. * Return the number of bytes read or -1 on fatal errors. */ +__u8 get_contents_vfatname_block[MAX_CLUSTSIZE] + __aligned(ARCH_DMA_MINALIGN); + static long -get_contents(fsdata *mydata, dir_entry *dentptr, __u8 *buffer, - unsigned long maxsize) +get_contents(fsdata *mydata, dir_entry *dentptr, unsigned long pos, + __u8 *buffer, unsigned long maxsize) { unsigned long filesize = FAT2CPU32(dentptr->size), gotsize = 0; unsigned int bytesperclust = mydata->clust_size * mydata->sect_size; @@ -344,11 +347,58 @@ get_contents(fsdata *mydata, dir_entry *dentptr, __u8 *buffer, debug("Filesize: %ld bytes\n", filesize); - if (maxsize > 0 && filesize > maxsize) - filesize = maxsize; + if (pos >= filesize) { + debug("Read position past EOF: %lu\n", pos); + return gotsize; + } + + if (maxsize > 0 && filesize > pos + maxsize) + filesize = pos + maxsize; debug("%ld bytes\n", filesize); + actsize = bytesperclust; + + /* go to cluster at pos */ + while (actsize <= pos) { + curclust = get_fatent(mydata, curclust); + if (CHECK_CLUST(curclust, mydata->fatsize)) { + debug("curclust: 0x%x\n", curclust); + debug("Invalid FAT entry\n"); + return gotsize; + } + actsize += bytesperclust; + } + + /* actsize > pos */ + actsize -= bytesperclust; + filesize -= actsize; + pos -= actsize; + + /* align to beginning of next cluster if any */ + if (pos) { + actsize = min(filesize, bytesperclust); + if (get_cluster(mydata, curclust, get_contents_vfatname_block, + (int)actsize) != 0) { + printf("Error reading cluster\n"); + return -1; + } + filesize -= actsize; + actsize -= pos; + memcpy(buffer, get_contents_vfatname_block + pos, actsize); + gotsize += actsize; + if (!filesize) + return gotsize; + buffer += actsize; + + curclust = get_fatent(mydata, curclust); + if (CHECK_CLUST(curclust, mydata->fatsize)) { + debug("curclust: 0x%x\n", curclust); + debug("Invalid FAT entry\n"); + return gotsize; + } + } + actsize = bytesperclust; endclust = curclust; @@ -433,9 +483,6 @@ static int slot2str(dir_slot *slotptr, char *l_name, int *idx) * into 'retdent' * Return 0 on success, -1 otherwise. */ -__u8 get_vfatname_block[MAX_CLUSTSIZE] - __aligned(ARCH_DMA_MINALIGN); - static int get_vfatname(fsdata *mydata, int curclust, __u8 *cluster, dir_entry *retdent, char *l_name) @@ -474,13 +521,13 @@ get_vfatname(fsdata *mydata, int curclust, __u8 *cluster, return -1; } - if (get_cluster(mydata, curclust, get_vfatname_block, + if (get_cluster(mydata, curclust, get_contents_vfatname_block, mydata->clust_size * mydata->sect_size) != 0) { debug("Error: reading directory block\n"); return -1; } - slotptr2 = (dir_slot *)get_vfatname_block; + slotptr2 = (dir_slot *)get_contents_vfatname_block; while (counter > 0) { if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter) @@ -491,7 +538,7 @@ get_vfatname(fsdata *mydata, int curclust, __u8 *cluster, /* Save the real directory entry */ realdent = (dir_entry *)slotptr2; - while ((__u8 *)slotptr2 > get_vfatname_block) { + while ((__u8 *)slotptr2 > get_contents_vfatname_block) { slotptr2--; slot2str(slotptr2, l_name, &idx); } @@ -770,11 +817,12 @@ exit: return ret; } -__u8 do_fat_read_block[MAX_CLUSTSIZE] +__u8 do_fat_read_at_block[MAX_CLUSTSIZE] __aligned(ARCH_DMA_MINALIGN); long -do_fat_read(const char *filename, void *buffer, unsigned long maxsize, int dols) +do_fat_read_at(const char *filename, unsigned long pos, void *buffer, + unsigned long maxsize, int dols) { char fnamecopy[2048]; boot_sector bs; @@ -888,12 +936,12 @@ do_fat_read(const char *filename, void *buffer, unsigned long maxsize, int dols) (mydata->fatsize == 32) ? (mydata->clust_size) : PREFETCH_BLOCKS, - do_fat_read_block) < 0) { + do_fat_read_at_block) < 0) { debug("Error: reading rootdir block\n"); goto exit; } - dentptr = (dir_entry *) do_fat_read_block; + dentptr = (dir_entry *) do_fat_read_at_block; } for (i = 0; i < DIRENTSPERBLOCK; i++) { @@ -913,7 +961,7 @@ do_fat_read(const char *filename, void *buffer, unsigned long maxsize, int dols) get_vfatname(mydata, root_cluster, - do_fat_read_block, + do_fat_read_at_block, dentptr, l_name); if (dols == LS_ROOT) { @@ -1116,7 +1164,7 @@ rootdir_done: subname = nextname; } - ret = get_contents(mydata, dentptr, buffer, maxsize); + ret = get_contents(mydata, dentptr, pos, buffer, maxsize); debug("Size: %d, got: %ld\n", FAT2CPU32(dentptr->size), ret); exit: @@ -1124,6 +1172,12 @@ exit: return ret; } +long +do_fat_read(const char *filename, void *buffer, unsigned long maxsize, int dols) +{ + return do_fat_read_at(filename, 0, buffer, maxsize, dols); +} + int file_fat_detectfs(void) { boot_sector bs; @@ -1192,8 +1246,14 @@ int file_fat_ls(const char *dir) return do_fat_read(dir, NULL, 0, LS_YES); } -long file_fat_read(const char *filename, void *buffer, unsigned long maxsize) +long file_fat_read_at(const char *filename, unsigned long pos, void *buffer, + unsigned long maxsize) { printf("reading %s\n", filename); - return do_fat_read(filename, buffer, maxsize, LS_NO); + return do_fat_read_at(filename, pos, buffer, maxsize, LS_NO); +} + +long file_fat_read(const char *filename, void *buffer, unsigned long maxsize) +{ + return file_fat_read_at(filename, 0, buffer, maxsize); } diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c index a6181e71b5..5829adf1a1 100644 --- a/fs/fat/fat_write.c +++ b/fs/fat/fat_write.c @@ -328,7 +328,7 @@ static void flush_dir_table(fsdata *mydata, dir_entry **dentptr); static void fill_dir_slot(fsdata *mydata, dir_entry **dentptr, const char *l_name) { - dir_slot *slotptr = (dir_slot *)get_vfatname_block; + dir_slot *slotptr = (dir_slot *)get_contents_vfatname_block; __u8 counter = 0, checksum; int idx = 0, ret; char s_name[16]; @@ -373,7 +373,7 @@ static __u32 dir_curclust; * a slot) into 'l_name'. If successful also copy the real directory entry * into 'retdent' * If additional adjacent cluster for directory entries is read into memory, - * then 'get_vfatname_block' is copied into 'get_dentfromdir_block' and + * then 'get_contents_vfatname_block' is copied into 'get_dentfromdir_block' and * the location of the real directory entry is returned by 'retdent' * Return 0 on success, -1 otherwise. */ @@ -416,13 +416,13 @@ get_long_file_name(fsdata *mydata, int curclust, __u8 *cluster, dir_curclust = curclust; - if (get_cluster(mydata, curclust, get_vfatname_block, + if (get_cluster(mydata, curclust, get_contents_vfatname_block, mydata->clust_size * mydata->sect_size) != 0) { debug("Error: reading directory block\n"); return -1; } - slotptr2 = (dir_slot *)get_vfatname_block; + slotptr2 = (dir_slot *)get_contents_vfatname_block; while (counter > 0) { if (((slotptr2->id & ~LAST_LONG_ENTRY_MASK) & 0xff) != counter) @@ -433,7 +433,7 @@ get_long_file_name(fsdata *mydata, int curclust, __u8 *cluster, /* Save the real directory entry */ realdent = (dir_entry *)slotptr2; - while ((__u8 *)slotptr2 > get_vfatname_block) { + while ((__u8 *)slotptr2 > get_contents_vfatname_block) { slotptr2--; slot2str(slotptr2, l_name, &idx); } @@ -459,9 +459,9 @@ get_long_file_name(fsdata *mydata, int curclust, __u8 *cluster, *retdent = realdent; if (slotptr2) { - memcpy(get_dentfromdir_block, get_vfatname_block, + memcpy(get_dentfromdir_block, get_contents_vfatname_block, mydata->clust_size * mydata->sect_size); - cur_position = (__u8 *)realdent - get_vfatname_block; + cur_position = (__u8 *)realdent - get_contents_vfatname_block; *retdent = (dir_entry *) &get_dentfromdir_block[cur_position]; } @@ -980,11 +980,11 @@ static int do_fat_write(const char *filename, void *buffer, if (disk_read(cursect, (mydata->fatsize == 32) ? (mydata->clust_size) : - PREFETCH_BLOCKS, do_fat_read_block) < 0) { + PREFETCH_BLOCKS, do_fat_read_at_block) < 0) { debug("Error: reading rootdir block\n"); goto exit; } - dentptr = (dir_entry *) do_fat_read_block; + dentptr = (dir_entry *) do_fat_read_at_block; name_len = strlen(filename); if (name_len >= VFAT_MAXLEN_BYTES) -- cgit v1.2.1