ref: d42f32137f5a59e229b6b0e086e9b2502f5c729d
dir: /lib/bio/bio.myr/
use std
pkg bio =
type mode = int
const Rd : mode = 1
const Wr : mode = 2
const Rw : mode = 1 | 2
type file = struct
/* backing fd */
fd : std.fd
mode : mode
/* read buffer */
rbuf : byte[:]
rstart : std.size
rend : std.size
/* write buffer */
wbuf : byte[:]
wend : std.size
;;
/* creation */
const mkfile : (fd : std.fd, mode : mode -> file#)
const open : (path : byte[:], mode : mode -> std.result(file#, byte[:]))
const dial : (srv : byte[:], mode : mode -> std.result(file#, byte[:]))
const create : (path : byte[:], mode : mode, perm : int -> std.result(file#, byte[:]))
const close : (f : file# -> bool)
const free : (f : file# -> void)
/* basic i/o. Returns sub-buffer when applicable. */
const write : (f : file#, src : byte[:] -> std.size)
const read : (f : file#, dst : byte[:] -> std.option(byte[:]))
const flush : (f : file# -> bool)
/* seeking */
/* single unit operations */
const putb : (f : file#, b : byte -> std.size)
const putc : (f : file#, c : char -> std.size)
const getb : (f : file# -> std.option(byte))
const getc : (f : file# -> std.option(char))
/* peeking */
const peekb : (f : file# -> std.option(byte))
const peekc : (f : file# -> std.option(char))
/* delimited read; returns freshly allocated buffer. */
const readln : (f : file# -> std.option(byte[:]))
const readto : (f : file#, delim : byte[:] -> std.option(byte[:]))
const skipto : (f : file#, delim : byte[:] -> bool)
/* formatted i/o */
const put : (f : file#, fmt : byte[:], args : ... -> std.size)
/* pkg funcs */
pkglocal const ensureread : (f : file#, n : std.size -> bool)
pkglocal const ensurewrite : (f : file#, n : std.size -> bool)
;;
const Bufsz = 16*std.KiB
const Small = 512
/* Creates a file from an fd, opened in the given mode. */
const mkfile = {fd, mode
var f
f = std.alloc()
f.fd = fd
f.mode = mode
if mode & Rd != 0
f.rbuf = std.slalloc(Bufsz)
f.rstart = 0
f.rend = 0
;;
if mode & Wr != 0
f.wbuf = std.slalloc(Bufsz)
f.wend = 0
;;
-> f
}
/* Opens a file with mode provided. */
const open = {path, mode
-> sysopen(path, mode, sysmode(mode), 0o777)
}
/*
Creates a file for the provided path, with opened in
the requested mode, with the requested permissions
*/
const create = {path, mode, perm
-> sysopen(path, mode, sysmode(mode) | std.Ocreat | std.Otrunc, perm)
}
/* dial the server, and open a file using the returned fd */
const dial = {srv, mode
match std.dial(srv)
| `std.Ok sock: -> `std.Ok mkfile(sock, mode)
| `std.Fail m: -> `std.Fail m
;;
}
/* map from the bio modes to the unix open modes */
const sysmode = {mode
match mode
| Rd: -> std.Ordonly
| Wr: -> std.Owronly
| Rw: -> std.Ordwr
| _: std.fatal("bio: bad file mode")
;;
-> 0
}
/* open the file, and return it */
const sysopen = {path, mode, openmode, perm
var fd
fd = std.openmode(path, openmode, perm castto(int64))
if fd < 0
-> `std.Fail "could not open fd"
else
-> `std.Ok mkfile(fd, mode)
;;
}
/* closes a file, flushing it to the output fd */
const close = {f
var fd
fd = f.fd
free(f)
-> std.close(fd) == 0
}
const free = {f
flush(f)
if f.mode & Rd != 0
std.slfree(f.rbuf)
;;
if f.mode & Wr != 0
std.slfree(f.wbuf)
;;
std.free(f)
}
/*
writes to as much from `src` as possible to a file,
returning the number of bytes written.
*/
const write = {f, src
std.assert(f.mode & Wr != 0, "File is not in write mode")
/*
Tack small writes onto the buffer end. Big ones
flush the buffer and then go right to kernel.
*/
if src.len < (f.wbuf.len - f.wend)
std.slcp(f.wbuf[f.wend:f.wend+src.len], src)
f.wend += src.len
-> src.len
else
flush(f)
-> writebuf(f.fd, src)
;;
}
/*
reads as much into 'dst' as possible, up to the size of 'dst',
returning the number of bytes read.
*/
const read = {f, dst
var n
var d
var count
std.assert(f.mode & Rd != 0, "File is not in read mode")
/*
* small reads should try to fill, so we don't have to make a
* syscall for every read
*/
if dst.len < Small
fill(f, f.rbuf.len - f.rend)
;;
/* Read as much as we can from the buffer */
count = std.min(dst.len, f.rend - f.rstart)
std.slcp(dst[:count], f.rbuf[f.rstart:f.rstart+count])
f.rstart += count
/* if we drained the buffer, reset it */
if f.rstart == f.rend
f.rstart = 0
f.rend = 0
;;
/* Read the rest directly from the fd */
d = dst[count:]
while dst.len > 0
n = std.read(f.fd, d)
if n <= 0
goto readdone
;;
count += n
d = d[n:]
;;
:readdone
if count > 0
-> `std.Some dst[:count]
else
-> `std.None
;;
}
/* flushes f out to the backing fd */
const flush = {f
var ret
ret = true
if f.mode & Wr != 0
ret = (writebuf(f.fd, f.wbuf[:f.wend]) == f.wend)
f.wend = 0
;;
-> ret
}
/* writes a single byte to the output stream */
const putb = {f, b
ensurewrite(f, 1)
f.wbuf[f.wend++] = b
-> 1
}
/* writes a single character to the output stream, encoded in utf8 */
const putc = {f, c
var sz
sz = std.charlen(c)
ensurewrite(f, sz)
std.encode(f.wbuf[f.wend:], c)
f.wend += sz
-> sz
}
/* reads a single byte from the input stream */
const getb = {f
if ensureread(f, 1)
-> `std.Some f.rbuf[f.rstart++]
;;
-> `std.None
}
/* reads a single character from the input stream, encoded in utf8 */
const getc = {f
var c
if ensurecodepoint(f)
c = std.decode(f.rbuf[f.rstart:f.rend])
f.rstart += std.charlen(c)
-> `std.Some c
;;
-> `std.None
}
/* ensures we have enough to read a single codepoint in the buffer */
const ensurecodepoint = {f
var b
var len
if !ensureread(f, 1)
-> false
;;
b = f.rbuf[f.rstart]
if b & 0x80 == 0 /* 0b0xxx_xxxx */
len = 1
elif b & 0xe0 == 0xc0 /* 0b110x_xxxx */
len = 2
elif b & 0xf0 == 0xe0 /* 0b1110_xxxx */
len = 3
elif b & 0xf8 == 0xf0 /* 0b1111_0xxx */
len = 4
else
len = 1 /* invalid unicode char */
;;
-> ensureread(f, len)
}
/*
writes a single integer-like value to the output stream, in
little endian format
*/
generic putle = {f, v : @a::(numeric,integral)
var i
for i = 0; i < sizeof(@a); i++
putb(f, (v & 0xff) castto(byte))
v >>= 8
;;
-> sizeof(@a)
}
/*
writes a single integer-like value to the output stream, in
big endian format
*/
generic putbe = {f, v : @a::(numeric,integral)
var i
for i = sizeof(@a); i != 0; i--
putb(f, ((v >> ((i-1)*8)) & 0xff) castto(byte))
;;
-> sizeof(@a)
}
/* peeks a single byte from an input stream */
const peekb = {f
if !ensureread(f, 1)
-> `std.None
else
-> `std.Some f.rbuf[f.rstart]
;;
}
/* peeks a single character from a utf8 encoded input stream */
const peekc = {f
if !ensurecodepoint(f)
-> `std.None
else
-> `std.Some std.decode(f.rbuf[f.rstart:f.rend])
;;
}
/*
reads up to a single character delimiter. drops the delimiter
from the input stream. EOF always counts as a delimiter.
Eg, with the input "foo,bar\n"
bio.readto(f, ',') -> "foo"
bio.readto(f, ',') -> "bar\n"
*/
const readto = {f, delim
-> readdelim(f, delim, false)
}
/* same as readto, but drops the read data. */
const skipto = {f, delim
match readdelim(f, delim, true)
| `std.Some ret: -> true
| `std.None: -> false
;;
}
/* Same as readto, but the delimiter is always a '\n' */
const readln = {f
-> readto(f, "\n")
}
const readdelim = {f, delim, drop
var ret
var i, j
ret = [][:]
while true
if !ensureread(f, delim.len)
if !drop
ret = readinto(f, ret, f.rend - f.rstart)
;;
if ret.len > 0
-> `std.Some ret
else
-> `std.None
;;
;;
for i = f.rstart; i < f.rend; i++
if f.rbuf[i] == delim[0]
for j = 0; j < delim.len; j++
if f.rbuf[i + j] != delim[j]
goto nextiterread
;;
;;
if !drop
ret = readinto(f, ret, i - f.rstart)
;;
f.rstart += delim.len
-> `std.Some ret
;;
:nextiterread
;;
if !drop
ret = readinto(f, ret, f.rend - f.rstart)
;;
;;
std.die("unreachable")
}
/*
Same as std.put, but buffered. Returns the number of bytes written.
FIXME: depends on std.fmt() having a flush buffer API. Until then,
we're stuck with a small static buffer.
*/
const put = {f, fmt, args
var sl, ap, n
ap = std.vastart(&args)
sl = std.fmtv(fmt, &ap)
n = write(f, sl)
std.slfree(sl)
-> n
}
/*
reads n bytes from the read buffer onto the heap-allocated slice
provided.
*/
const readinto = {f, buf, n
var ret
std.assert(f.rstart + n <= f.rend, "Reading too much from buffer")
ret = std.sljoin(buf, f.rbuf[f.rstart:f.rstart + n])
f.rstart += n
-> ret
}
/* makes sure we can bufferedly write at least n bytes */
const ensurewrite = {f, n
std.assert(n < f.wbuf.len, "ensured write capacity > buffer size")
if n > f.wbuf.len - f.wend
-> flush(f)
;;
-> true
}
/*
makes sure we have at least n bytes buffered. returns true if we succeed
in buffering n bytes, false if we fail.
*/
const ensureread = {f, n
var held
var cap
std.assert(n < f.rbuf.len, "ensured read capacity > buffer size")
held = f.rend - f.rstart
if n > held
/* if we need to shift the slice down to the start, do it */
cap = f.rend - f.rstart
if n > (cap + held)
std.slcp(f.rbuf[:cap], f.rbuf[f.rstart:f.rend])
f.rstart = 0
f.rend = cap
;;
-> fill(f, n) > n
else
-> true
;;
}
/* blats a buffer to an fd */
const writebuf = {fd, src
var n
var count
count = 0
while src.len != 0
n = std.write(fd, src)
if n <= 0
goto writedone
;;
count += n
src = src[n:]
;;
:writedone
-> count
}
/*
Reads as many bytes as possible from the file into
the read buffer.
*/
const fill = {f, min
var n
var count
count = 0
while count < min
n = std.read(f.fd, f.rbuf[f.rend:])
if n <= 0
goto filldone
;;
count += n
f.rend += n
;;
:filldone
-> count
}