Re: [Libguestfs] [PATCH nbdinfo 1/2] common/utils: Add function to convert sizes to human-readable

For example 1024 is returned as "1K". This does not attempt to handle decimals or SI units. If the number isn't some multiple of a power of 1024 then it is returned as bytes (a flag is available to indicate this). I looked at both the gnulib and qemu versions of this function. The gnulib version is not under a license which is compatible with libnbd and is also really complicated, although it does handle fractions and SI units. The qemu version is essentially just frexp + sprintf and doesn't attempt to convert to the human-readable version reversibly. --- .gitignore | 1 + common/utils/Makefile.am | 10 +++- common/utils/human-size.c | 54 +++++++++++++++++++++ common/utils/human-size.h | 49 +++++++++++++++++++ common/utils/test-human-size.c | 89 ++++++++++++++++++++++++++++++++++ 5 files changed, 201 insertions(+), 2 deletions(-) diff --git a/.gitignore b/.gitignore index 2aa1fd99..5fc59677 100644 --- a/.gitignore +++ b/.gitignore @@ -31,6 +31,7 @@ Makefile.in /bash/nbdcopy /bash/nbdfuse /bash/nbdinfo +/common/utils/test-human-size /common/utils/test-vector /compile /config.cache diff --git a/common/utils/Makefile.am b/common/utils/Makefile.am index 1ca4a370..b273ada1 100644 --- a/common/utils/Makefile.am +++ b/common/utils/Makefile.am @@ -34,6 +34,8 @@ include $(top_srcdir)/common-rules.mk noinst_LTLIBRARIES = libutils.la libutils_la_SOURCES = \ + human-size.c \ + human-size.h \ vector.c \ vector.h \ version.c \ @@ -50,8 +52,12 @@ libutils_la_LIBADD = \ # Unit tests. -TESTS = test-vector -check_PROGRAMS = test-vector +TESTS = test-human-size test-vector +check_PROGRAMS = test-human-size test-vector + +test_human_size_SOURCES = test-human-size.c human-size.c human-size.h +test_human_size_CPPFLAGS = -I$(srcdir) +test_human_size_CFLAGS = $(WARNINGS_CFLAGS) test_vector_SOURCES = test-vector.c vector.c vector.h test_vector_CPPFLAGS = -I$(srcdir) diff --git a/common/utils/human-size.c b/common/utils/human-size.c new file mode 100644 index 00000000..5cff722b --- /dev/null +++ b/common/utils/human-size.c @@ -0,0 +1,54 @@ +/* nbd client library in userspace + * Copyright (C) 2020-2021 Red Hat Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include <config.h> + +#include <stdio.h> +#include <stdlib.h> +#include <stdbool.h> +#include <stdint.h> +#include <inttypes.h> + +#include "human-size.h" + +char * +human_size (char *buf, uint64_t bytes, bool *human) +{ + static const char *ext[] = { "E", "P", "T", "G", "M", "K", "" }; + size_t i; + + if (buf == NULL) { + buf = malloc (HUMAN_SIZE_LONGEST); + if (buf == NULL) + return NULL; + } + + /* Set to false if we're not going to add a human-readable extension. */ + if (human) + *human = bytes != 0 && (bytes & 1023) == 0; +

+ /* Work out which extension to use, if any. */ + for (i = 6; i >= 0; --i) { + if (bytes == 0 || (bytes & 1023) != 0) + break; + bytes /= 1024; + } +

+ snprintf (buf, HUMAN_SIZE_LONGEST-1, "%" PRIu64 "%s", bytes, ext[i]);