diff options
| -rw-r--r-- | buf.c | 24 | ||||
| -rw-r--r-- | tests/018/streams.tl | 29 | ||||
| -rw-r--r-- | txr.1 | 16 |
3 files changed, 66 insertions, 3 deletions
@@ -1213,24 +1213,42 @@ static val buf_strm_seek(val stream, val offset, enum strm_whence whence) npos = plus(s->pos, offset); break; case strm_end: - npos = minus(b->len, offset); + npos = plus(b->len, offset); break; default: internal_error("invalid whence value"); } + if (minusp(npos)) - uw_throwf(error_s, lit("~a: cannot seek to negative position ~s"), + uw_throwf(file_error_s, lit("~a: cannot seek to negative position ~s"), self, npos, nao); + if (gt(npos, b->len)) + buf_set_length(s->buf, npos, zero); + s->pos = npos; return t; } static val buf_strm_truncate(val stream, val len) { + val self = lit("truncate-stream"); struct buf_strm *s = coerce(struct buf_strm *, stream->co.handle); - buf_set_length(s->buf, len, zero); + struct buf *b = us_buf_handle(s->buf); + + if (ge(len, s->pos)) { + buf_set_length(s->buf, len, zero); + } else if (minusp(len)) { + uw_throwf(file_error_s, lit("~a: negative length~s specified"), + self, len, nao); + } else { + cnum p = c_num(s->pos, self); + cnum l = c_num(len, self); + buf_set_length(s->buf, s->pos, zero); + memset(b->data + l, 0, p - l); + } + return t; } diff --git a/tests/018/streams.tl b/tests/018/streams.tl index 9475d4f7..4c4bde7d 100644 --- a/tests/018/streams.tl +++ b/tests/018/streams.tl @@ -194,3 +194,32 @@ (truncate-stream s 2) :error (seek-stream s 0 :from-current) :error (put-string "X" s) :error)) + +(with-in-buf-stream (s (make-buf 16)) + (mtest + (put-char #\A s) t + (get-buf-from-stream s) #b'41000000000000000000000000000000' + (put-string "BCD" s) t + (get-buf-from-stream s) #b'41424344000000000000000000000000' + (truncate-stream s -1) :error + (seek-stream s -1 :from-start) :error + (seek-stream s 0 :from-start) t + (put-char #\X s) t + (get-buf-from-stream s) #b'58424344000000000000000000000000' + (put-buf #b'AABBCCDDEEFF11' 0 s) 7 + (get-buf-from-stream s) #b'58AABBCCDDEEFF110000000000000000' + (put-buf #b'AABBCCDDEEFF1122' 0 s) 8 + (get-buf-from-stream s) #b'58AABBCCDDEEFF11AABBCCDDEEFF1122' + (truncate-stream s 16) t + (get-buf-from-stream s) #b'58AABBCCDDEEFF11AABBCCDDEEFF1122' + (truncate-stream s 18) t + (get-buf-from-stream s) #b'58AABBCCDDEEFF11AABBCCDDEEFF11220000' + (truncate-stream s 8) t + (get-buf-from-stream s) #b'58AABBCCDDEEFF110000000000000000' + (seek-stream s 0 :from-current) 16 + (truncate-stream s 0) t + (get-buf-from-stream s) #b'00000000000000000000000000000000' + (seek-stream s -16 :from-end) t + (seek-stream s 0 :from-current) 0 + (truncate-stream s 0) t + (get-buf-from-stream s) #b'')) @@ -70441,6 +70441,22 @@ object. The stream is then associated with this object. If the argument is omitted, a buffer of length zero is created and associated with the stream. +Buffer streams support byte and character input and output. + +They support the +.code seek-stream +and +.code truncate-stream +operations. The latter may make be used to make the buffer +larger or smaller. Enlargement causes the newly created space to be +filled with zero bytes. +When +.code truncate-stream +is used to specify a length which is below the current position, +the buffer is not truncated to that length, but rather to the +current position. The interval between the truncation length +and the current position is then obliterated with zeros. + .coNP Function @ get-buf-from-stream .synb .mets (get-buf-from-stream << buf-stream ) |