diff options
Diffstat (limited to 'kernel/fs.rv')
| -rw-r--r-- | kernel/fs.rv | 83 |
1 files changed, 61 insertions, 22 deletions
diff --git a/kernel/fs.rv b/kernel/fs.rv index adb317c..5d72bc1 100644 --- a/kernel/fs.rv +++ b/kernel/fs.rv @@ -5,10 +5,7 @@ # sectors 1..8 directory, 128 entries of 32 bytes (16 per sector) # sectors 9..136 fat, one 2 byte entry per sector on the whole disk # sectors 137.. file data, one block == one sector -# -# a fat entry is the next block in a files chain, 0 means free, END means last -# block of a chain. a file just stores its first block + byte size in its dir -# entry and we walk the chain from there +# a fat entry points at the next block in a files chain, 0 is free, END is the last const SB_LBA = 0 const DIR_LBA = 1 @@ -66,12 +63,7 @@ end fn dir_lba(i) DIR_LBA + (i shr 4) fn dir_off(i) (i band 15) * 32 -# entry byte layout: base is fs.buf + dir_off(i) after loading the sector -# +0 used (0/1) -# +1 name length -# +2 first block (2) -# +4 size (4) -# +8 name bytes (up to NAME_MAX) +# dir entry, 32 bytes: +0 used, +1 name len, +2 first block, +4 size, +8 name bytes fn name_at(base, len) do let out = "" for k in 0..len do out = out ~ string.of_ascii(mem_read(base + 8 + k, 1)) end @@ -108,13 +100,19 @@ fn fs_init() do fs.buf = frame_alloc() fs.fat = frame_alloc() fs.total = disk_sectors() - if disk_present() == 0 do fs.ready = :false return :nil end + if fs.total == 0 do fs.ready = :false return :nil end disk_read(SB_LBA, fs.buf) fs.ready = if mem_read(fs.buf, 4) == MAGIC :true else :false end +fn fs_ready() do + if fs.ready return :true + puts("no filesystem, run mkfs first\n") + :false +end + fn fs_format() do - if disk_present() == 0 do puts("mkfs: no disk\n") return :nil end + if disk_sectors() == 0 do puts("mkfs: no disk\n") return :nil end mem_zero(fs.buf, BLOCK) mem_write(fs.buf, MAGIC, 4) mem_write(fs.buf + 4, fs.total, 4) @@ -126,10 +124,10 @@ fn fs_format() do puts("formatted " ~ fs.total ~ " sectors, " ~ (fs.total shr 1) ~ " KiB\n") end -# write a file, gee i wonder what a function called `fs_write` does -fn fs_write(name, text) do - if fs.ready == :false do puts("no filesystem, run mkfs first\n") return :nil end - if name:len() > NAME_MAX do puts("name too long (max " ~ NAME_MAX ~ ")\n") return :nil end +# silent core of fs_write, global so the bridge can reach it via getGlobal +global fs_store = fn(name, text) do + if fs_ready() == :false return 0 + if name:len() > NAME_MAX do puts("name too long (max " ~ NAME_MAX ~ ")\n") return 0 end let idx = fs_find(name) if idx >= 0 do disk_read(dir_lba(idx), fs.buf) @@ -137,7 +135,7 @@ fn fs_write(name, text) do end else do idx = dir_alloc() - if idx < 0 do puts("directory full\n") return :nil end + if idx < 0 do puts("directory full\n") return 0 end end const size = text:len() @@ -146,7 +144,7 @@ fn fs_write(name, text) do let written = 0 while written < size do const block = fat_alloc() - if block == 0 do puts("disk full\n") return :nil end + if block == 0 do puts("disk full\n") return 0 end fat_set(block, END) # reserve if first == 0 do first = block end else do fat_set(prev, block) end @@ -169,11 +167,52 @@ fn fs_write(name, text) do mem_write(base + 4, size, 4) for k in 0..name:len() do mem_write(base + 8 + k, name[k]:ascii(), 1) end disk_write(dir_lba(idx), fs.buf) - puts("wrote " ~ name ~ " (" ~ size ~ " bytes)\n") + return 1 +end + +# write a file, gee i wonder what a function called `fs_write` does +fn fs_write(name, text) do + if fs_store(name, text) == 1 puts("wrote " ~ name ~ " (" ~ text:len() ~ " bytes)\n") +end + +global fs_size = fn(name) do + const idx = fs_find(name) + if idx < 0 return -1 + disk_read(dir_lba(idx), fs.buf) + return mem_read(fs.buf + dir_off(idx) + 4, 4) +end + +# read up to len bytes from offset, returned as a string (shorter at eof) +global fs_read_bytes = fn(name, offset, len) do + const idx = fs_find(name) + if idx < 0 return "" + disk_read(dir_lba(idx), fs.buf) + const base = fs.buf + dir_off(idx) + let block = mem_read(base + 2, 2) + const size = mem_read(base + 4, 4) + let stop = offset + len + if stop > size do stop = size end + let pos = 0 + let out = "" + while (block != 0 and block != END and pos < stop) do + const nxt = fat_get(block) + if (pos + BLOCK > offset and pos < stop) do + disk_read(block, fs.buf) + let k = 0 + while (k < BLOCK) do + const abs = pos + k + if (abs >= offset and abs < stop) do out = out ~ string.of_ascii(mem_read(fs.buf + k, 1)) end + k += 1 + end + end + pos += BLOCK + block = nxt + end + return out end fn fs_cat(name) do - if fs.ready == :false do puts("no filesystem, run mkfs first\n") return :nil end + if fs_ready() == :false return :nil const idx = fs_find(name) if idx < 0 do puts("cat: " ~ name ~ ": no such file\n") return :nil end disk_read(dir_lba(idx), fs.buf) @@ -194,7 +233,7 @@ fn fs_cat(name) do end fn fs_ls() do - if fs.ready == :false do puts("no filesystem, run mkfs first\n") return :nil end + if fs_ready() == :false return :nil let count = 0 for i in 0..DIR_ENTRIES do disk_read(dir_lba(i), fs.buf) @@ -208,7 +247,7 @@ fn fs_ls() do end fn fs_rm(name) do - if fs.ready == :false do puts("no filesystem, run mkfs first\n") return :nil end + if fs_ready() == :false return :nil const idx = fs_find(name) if idx < 0 do puts("rm: " ~ name ~ ": no such file\n") return :nil end disk_read(dir_lba(idx), fs.buf) |