file/fat: add utime function

This emulates the traditional utime function from UNIX clones to allow
for manual updates of the modification timestamp on files and directories.

This should only prove useful for non-native targets as those usually
have a libc version of utime.

Change-Id: Iea8a1d328e78b92c400d3354ee80689c7cf53af8

1 files changed, 35 insertions, 0 deletions

diff --git a/firmware/drivers/fat.c b/firmware/drivers/fat.c
index cc9735d0f7..28d4eb1987 100644
--- a/firmware/drivers/fat.c
+++ b/firmware/drivers/fat.c
@@ -2276,6 +2276,41 @@ fat_error:
     return rc;
 }
 
+int fat_utime(struct fat_file *parent, struct fat_file *file,
+              const struct utimbuf *times)
+{
+    struct bpb * const fat_bpb = FAT_BPB(parent->volume);
+
+    if (!fat_bpb)
+        return -1;
+
+    int rc;
+
+    struct fat_filestr parentstr;
+    fat_filestr_init(&parentstr, parent);
+
+    dc_lock_cache();
+
+    union raw_dirent *ent = cache_direntry(fat_bpb, &parentstr, file->e.entry);
+    if (!ent)
+        FAT_ERROR(-2);
+
+    uint16_t date;
+    uint16_t time;
+    dostime_localtime(times->modtime, &date, &time);
+
+    ent->wrttime    = htole16(time);
+    ent->wrtdate    = htole16(date);
+    ent->lstaccdate = htole16(date);
+
+    dc_dirty_buf(ent);
+
+    rc = 0;
+fat_error:
+    dc_unlock_cache();
+    cache_commit(fat_bpb);
+    return rc;
+}
 
 /** File stream functions **/