[Libguestfs] [PATCH nbdinfo v2 1/3] common/utils: Add function to convert sizes to human-readable
Richard W.M. Jones
rjones at redhat.com
Mon Sep 20 11:04:46 UTC 2021
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..772f2489
--- /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;
+ }
+
+ /* Work out which extension to use, if any. */
+ for (i = 6; i >= 0; --i) {
+ if (bytes == 0 || (bytes & 1023) != 0)
+ break;
+ bytes /= 1024;
+ }
+
+ /* Set to flag to true if we're going to add a human-readable extension. */
+ if (human)
+ *human = ext[i][0] != '\0';
+
+ snprintf (buf, HUMAN_SIZE_LONGEST, "%" PRIu64 "%s", bytes, ext[i]);
+ return buf;
+}
diff --git a/common/utils/human-size.h b/common/utils/human-size.h
new file mode 100644
index 00000000..9ee78803
--- /dev/null
+++ b/common/utils/human-size.h
@@ -0,0 +1,49 @@
+/* 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
+ */
+
+#ifndef LIBNBD_HUMAN_SIZE_H
+#define LIBNBD_HUMAN_SIZE_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+/* If you allocate a buffer of at least this length in bytes and pass
+ * it as the first parameter to human_size, then it will not overrun.
+ */
+#define HUMAN_SIZE_LONGEST 64
+
+/* Convert bytes to a human-readable string.
+ *
+ * This is roughly the opposite of nbdkit_parse_size. It will convert
+ * multiples of powers of 1024 to the appropriate human size with the
+ * right extension like 'M' or 'G'. Anything that cannot be converted
+ * is returned as bytes. The *human flag is set to true if the output
+ * was abbreviated to a human-readable size, or false if it is just
+ * bytes.
+ *
+ * If buf == NULL, a buffer is allocated and returned. In this case
+ * the returned buffer must be freed.
+ *
+ * buf may also be allocated by the caller, in which case it must be
+ * at least HUMAN_SIZE_LONGEST bytes.
+ *
+ * On error the function returns an error and sets errno.
+ */
+extern char *human_size (char *buf, uint64_t bytes, bool *human);
+
+#endif /* LIBNBD_HUMAN_SIZE_H */
diff --git a/common/utils/test-human-size.c b/common/utils/test-human-size.c
new file mode 100644
index 00000000..d35a21bf
--- /dev/null
+++ b/common/utils/test-human-size.c
@@ -0,0 +1,89 @@
+/* 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 <string.h>
+
+#include "human-size.h"
+
+static unsigned errors = 0;
+
+static void
+test (uint64_t bytes, const char *expected, bool expected_human_flag)
+{
+ char actual[HUMAN_SIZE_LONGEST];
+ bool actual_human_flag;
+
+ human_size (actual, bytes, &actual_human_flag);
+
+ if (strcmp (actual, expected) == 0 ||
+ actual_human_flag != expected_human_flag) {
+ printf ("test-human-size: %" PRIu64 " -> \"%s\" (%s) OK\n",
+ bytes, actual, actual_human_flag ? "true" : "false");
+ fflush (stdout);
+ }
+ else {
+ fprintf (stderr,
+ "test-human-size: error: test case %" PRIu64
+ "expected \"%s\" (%s) "
+ "but returned \"%s\" (%s)\n",
+ bytes,
+ expected, expected_human_flag ? "true" : "false",
+ actual, actual_human_flag ? "true" : "false");
+ errors++;
+ }
+}
+
+int
+main (int argc, char *argv[])
+{
+ test (0, "0", false);
+ test (1, "1", false);
+ test (512, "512", false);
+ test (1023, "1023", false);
+ test (1024, "1K", true);
+ test (1025, "1025", false);
+ test (2047, "2047", false);
+ test (2048, "2K", true);
+ test (3 * 1024, "3K", true);
+
+ test (1023 * 1024, "1023K", true);
+ test (1048575, "1048575", false);
+ test (1048576, "1M", true);
+ test (1048577, "1048577", false);
+
+ test (UINT64_C(1073741824), "1G", true);
+
+ test (UINT64_C(1099511627776), "1T", true);
+ test (UINT64_C(1099511627777), "1099511627777", false);
+ test (UINT64_C(1099511627776) + 1024, "1073741825K", true);
+
+ test (UINT64_C(1125899906842624), "1P", true);
+
+ test ((uint64_t)INT64_MAX+1, "8E", true);
+ test (UINT64_MAX-1023, "18014398509481983K", true);
+ test (UINT64_MAX, "18446744073709551615", false);
+
+ exit (errors == 0 ? EXIT_SUCCESS : EXIT_FAILURE);
+}
--
2.32.0
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