Overwriting an empty file not created by U-Boot did not work, and it could even corrupt the FAT. Moreover, creating empty files or emptying existing files allocated a cluster, which is not standard.
Fix this by always keeping empty files clusterless as specified by Microsoft (the start cluster must be set to 0 in the directory entry in that case), and by supporting overwriting such files.
Signed-off-by: Benoît Thébaudeau benoit@wsystem.com --- fs/fat/fat_write.c | 85 ++++++++++++++++++++++++++++++++++++++++-------------- 1 file changed, 64 insertions(+), 21 deletions(-)
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c index 2d032ee..af828d0 100644 --- a/fs/fat/fat_write.c +++ b/fs/fat/fat_write.c @@ -710,6 +710,14 @@ set_contents(fsdata *mydata, dir_entry *dentptr, __u8 *buffer,
debug("%llu bytes\n", filesize);
+ if (!curclust) { + if (filesize) { + debug("error: nonempty clusterless file!\n"); + return -1; + } + return 0; + } + actsize = bytesperclust; endclust = curclust; do { @@ -765,15 +773,24 @@ getit: }
/* - * Fill dir_entry + * Set start cluster in directory entry */ -static void fill_dentry(fsdata *mydata, dir_entry *dentptr, - const char *filename, __u32 start_cluster, __u32 size, __u8 attr) +static void set_start_cluster(const fsdata *mydata, dir_entry *dentptr, + __u32 start_cluster) { if (mydata->fatsize == 32) dentptr->starthi = cpu_to_le16((start_cluster & 0xffff0000) >> 16); dentptr->start = cpu_to_le16(start_cluster & 0xffff); +} + +/* + * Fill dir_entry + */ +static void fill_dentry(fsdata *mydata, dir_entry *dentptr, + const char *filename, __u32 start_cluster, __u32 size, __u8 attr) +{ + set_start_cluster(mydata, dentptr, start_cluster); dentptr->size = cpu_to_le32(size);
dentptr->attr = attr; @@ -1030,32 +1047,58 @@ static int do_fat_write(const char *filename, void *buffer, loff_t size, retdent->size = cpu_to_le32(size); start_cluster = START(retdent);
- ret = check_overflow(mydata, start_cluster, size); - if (ret) { - printf("Error: %llu overflow\n", size); - goto exit; - } + if (start_cluster) { + if (size) { + ret = check_overflow(mydata, start_cluster, + size); + if (ret) { + printf("Error: %llu overflow\n", size); + goto exit; + } + }
- ret = clear_fatent(mydata, start_cluster); - if (ret) { - printf("Error: clearing FAT entries\n"); - goto exit; + ret = clear_fatent(mydata, start_cluster); + if (ret) { + printf("Error: clearing FAT entries\n"); + goto exit; + } + + if (!size) + set_start_cluster(mydata, retdent, 0); + } else if (size) { + ret = start_cluster = find_empty_cluster(mydata); + if (ret < 0) { + printf("Error: finding empty cluster\n"); + goto exit; + } + + ret = check_overflow(mydata, start_cluster, size); + if (ret) { + printf("Error: %llu overflow\n", size); + goto exit; + } + + set_start_cluster(mydata, retdent, start_cluster); } } else { /* Set short name to set alias checksum field in dir_slot */ set_name(empty_dentptr, filename); fill_dir_slot(mydata, &empty_dentptr, filename);
- ret = start_cluster = find_empty_cluster(mydata); - if (ret < 0) { - printf("Error: finding empty cluster\n"); - goto exit; - } + if (size) { + ret = start_cluster = find_empty_cluster(mydata); + if (ret < 0) { + printf("Error: finding empty cluster\n"); + goto exit; + }
- ret = check_overflow(mydata, start_cluster, size); - if (ret) { - printf("Error: %llu overflow\n", size); - goto exit; + ret = check_overflow(mydata, start_cluster, size); + if (ret) { + printf("Error: %llu overflow\n", size); + goto exit; + } + } else { + start_cluster = 0; }
/* Set attribute as archieve for regular file */