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author | Paul Eggert <eggert@cs.ucla.edu> | 2019-09-17 03:54:41 -0700 |
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committer | Paul Eggert <eggert@cs.ucla.edu> | 2019-09-17 03:55:12 -0700 |
commit | c108d8ecc65c8e9626ce782213764d5d12508b43 (patch) | |
tree | 488a4d0e82aa6869a38606df598de552bde2501e | |
parent | d27fb533ffe8aa40285daecd8e3eab0ca0b7484e (diff) | |
download | emacs-c108d8ecc65c8e9626ce782213764d5d12508b43.tar.gz |
Don’t round file-system-info counts
* src/fileio.c (blocks_to_bytes): Convert the byte count to an
integer, since we have bignums now. This avoids possible rounding
errors for file systems containing more than 8 PiB or so.
-rw-r--r-- | src/fileio.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/src/fileio.c b/src/fileio.c index c129f19872e..81c29ca0cca 100644 --- a/src/fileio.c +++ b/src/fileio.c @@ -6081,16 +6081,18 @@ effect except for flushing STREAM's data. */) #ifndef DOS_NT -/* Yield a Lisp float as close as possible to BLOCKSIZE * BLOCKS, with - the result negated if NEGATE. */ +/* Yield a Lisp number equal to BLOCKSIZE * BLOCKS, with the result + negated if NEGATE. */ static Lisp_Object blocks_to_bytes (uintmax_t blocksize, uintmax_t blocks, bool negate) { - /* On typical platforms the following code is accurate to 53 bits, - which is close enough. BLOCKSIZE is invariably a power of 2, so - converting it to double does not lose information. */ - double bs = blocksize; - return make_float (negate ? -bs * -blocks : bs * blocks); + intmax_t n; + if (!INT_MULTIPLY_WRAPV (blocksize, blocks, &n)) + return make_int (negate ? -n : n); + Lisp_Object bs = make_uint (blocksize); + if (negate) + bs = CALLN (Fminus, bs); + return CALLN (Ftimes, bs, make_uint (blocks)); } DEFUN ("file-system-info", Ffile_system_info, Sfile_system_info, 1, 1, 0, |