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Re: [libvirt] [PATCH v3 1/3] vsh: Add API for printing tables.



On Thu, Aug 16, 2018 at 12:56:24PM +0200, Simon Kobyda wrote:
It solves problems with alignment of columns. Width of each column
is calculated by its biggest cell. Should solve unicode bug.
In future, it may be implemented in virsh, virt-admin...

This API has 5 public functions:
- vshTableNew - adds new table and defines its header
- vshTableRowAppend - appends new row (for same number of columns as in
header)
- vshTablePrintToStdout
- vshTablePrintToString
- vshTableFree

https://bugzilla.redhat.com/show_bug.cgi?id=1574624
https://bugzilla.redhat.com/show_bug.cgi?id=1584630

Signed-off-by: Simon Kobyda <skobyda redhat com>
---
tools/Makefile.am |   4 +-
tools/vsh-table.c | 413 ++++++++++++++++++++++++++++++++++++++++++++++
tools/vsh-table.h |  42 +++++
3 files changed, 458 insertions(+), 1 deletion(-)
create mode 100644 tools/vsh-table.c
create mode 100644 tools/vsh-table.h

diff --git a/tools/Makefile.am b/tools/Makefile.am
index 1452d984a0..f069167acc 100644
--- a/tools/Makefile.am
+++ b/tools/Makefile.am
@@ -144,7 +144,9 @@ libvirt_shell_la_LIBADD = \
		$(READLINE_LIBS) \
		../gnulib/lib/libgnu.la \
		$(NULL)
-libvirt_shell_la_SOURCES = vsh.c vsh.h
+libvirt_shell_la_SOURCES = \
+		vsh.c vsh.h \
+		vsh-table.c vsh-table.h

virt_host_validate_SOURCES = \
		virt-host-validate.c \
diff --git a/tools/vsh-table.c b/tools/vsh-table.c
new file mode 100644
index 0000000000..8842e4e4fd
--- /dev/null
+++ b/tools/vsh-table.c
@@ -0,0 +1,413 @@
+/*
+ * vsh-table.c: table printing helper
+ *
+ * Copyright (C) 2018 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 2.1 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, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Authors:
+ *   Simon Kobyda <skobyda redhat com>
+ *
+ */
+
+#include <config.h>
+#include "vsh-table.h"
+
+#include <string.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <wchar.h>
+#include <locale.h>
+
+#include "viralloc.h"
+#include "virbuffer.h"
+#include "virstring.h"
+#include "virsh-util.h"
+
+typedef void (*vshPrintCB)(vshControl *ctl, const char *fmt, ...);
+
+struct _vshTableRow {
+    char **cells;
+    size_t ncells;
+};
+
+struct _vshTable {
+    vshTableRowPtr *rows;
+    size_t nrows;
+};
+
+static void
+vshTableRowFree(vshTableRowPtr row)
+{
+    size_t i;
+
+    if (!row)
+        return;
+
+    for (i = 0; i < row->ncells; i++)
+        VIR_FREE(row->cells[i]);
+
+    VIR_FREE(row->cells);
+    VIR_FREE(row);
+}
+
+void
+vshTableFree(vshTablePtr table)
+{
+    size_t i;
+
+    if (!table)
+        return;
+
+    for (i = 0; i < table->nrows; i++)
+        vshTableRowFree(table->rows[i]);
+    VIR_FREE(table->rows);
+    VIR_FREE(table);
+}
+
+/**
+ * vshTableRowNew:
+ * @arg: the first argument.
+ * @ap: list of variadic arguments
+ *
+ * Create a new row in the table. Each argument passed
+ * represents a cell in the row.
+ * Return: pointer to vshTableRowPtr row or NULL.
+ */
+static vshTableRowPtr
+vshTableRowNew(const char *arg, va_list ap)
+{
+    vshTableRowPtr row = NULL;
+    char *tmp = NULL;
+
+    if (!arg) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                        _("Table row cannot be empty"));
+        goto error;
+    }
+
+    if (VIR_ALLOC(row) < 0)
+        goto error;
+
+    while (arg) {
+        if (VIR_STRDUP(tmp, arg) < 0)
+            goto error;
+
+        if (VIR_APPEND_ELEMENT(row->cells, row->ncells, tmp) < 0)
+            goto error;
+
+        arg = va_arg(ap, const char *);
+    }
+
+    return row;
+
+ error:
+    vshTableRowFree(row);
+    return NULL;
+}
+
+/**
+ * vshTableNew:
+ * @arg: List of column names (NULL terminated)
+ *
+ * Create a new table.
+ *
+ * Returns: pointer to table or NULL.
+ */
+vshTablePtr
+vshTableNew(const char *arg, ...)
+{
+    vshTablePtr table;
+    vshTableRowPtr header = NULL;
+    va_list ap;
+
+    if (VIR_ALLOC(table) < 0)
+        goto error;
+
+    va_start(ap, arg);
+    header = vshTableRowNew(arg, ap);
+    va_end(ap);
+
+    if (!header)
+        goto error;
+
+    if (VIR_APPEND_ELEMENT(table->rows, table->nrows, header) < 0)
+        goto error;
+
+    return table;
+ error:
+    vshTableRowFree(header);
+    vshTableFree(table);
+    return NULL;
+}
+
+/**
+ * vshTableRowAppend:
+ * @table: table to append to
+ * @arg: cells of the row (NULL terminated)
+ *
+ * Append new row into the @table. The number of cells in the row has
+ * to be equal to the number of cells in the table header.
+ *
+ * Returns: 0 if succeeded, -1 if failed.
+ */
+int
+vshTableRowAppend(vshTablePtr table, const char *arg, ...)
+{
+    vshTableRowPtr row = NULL;
+    size_t ncolumns = table->rows[0]->ncells;
+    va_list ap;
+    int ret = -1;
+
+    va_start(ap, arg);
+    row = vshTableRowNew(arg, ap);
+    va_end(ap);
+
+    if (!row)
+        goto cleanup;
+
+    if (ncolumns != row->ncells) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                        _("Incorrect number of cells in a table row"));
+        goto cleanup;
+    }
+
+    if (VIR_APPEND_ELEMENT(table->rows, table->nrows, row) < 0)
+        goto cleanup;
+
+    ret = 0;
+ cleanup:
+    vshTableRowFree(row);
+    return ret;
+}
+
+/**
+ * vshTableGetColumnsWidths:
+ * @table: table
+ * @maxwidths: maximum count of characters for each columns
+ * @widths: count of characters for each cell in the table
+ *
+ * Fill passed @maxwidths and @widths arrays with maximum number
+ * of characters for columns and number of character per each
+ * table cell, respectively.
+ *
+ * Handle unicode strings (user must have multibyte locale)
+ */
+static int
+vshTableGetColumnsWidths(vshTablePtr table,
+                         size_t *maxwidths,
+                         size_t **widths,
+                         bool header)
+{
+    int ret = -1;
+    size_t i = 1;
+    size_t j;
+    size_t len;
+    int tmp;
+    wchar_t *wstr = NULL;
+    size_t wstrlen;
+
+    if (header)
+        i = 0;
+    else
+        i = 1;
+    for (; i < table->nrows; i++) {
+        vshTableRowPtr row = table->rows[i];
+
+        for (j = 0; j < row->ncells; j++) {


+            /* strlen should return maximum possible length needed */
+            wstrlen = strlen(row->cells[j]);
+            VIR_FREE(wstr);
+            if (VIR_ALLOC_N(wstr, wstrlen) < 0)
+                goto cleanup;
+            /* mbstowcs fails if machine is using singlebyte locale
+             * and user tries to convert unicode(multibyte)
+             * */
+            if (mbstowcs(wstr, row->cells[j], wstrlen) ==
+                (size_t) -1) {
+                len = wstrlen;
+            } else {
+                tmp = wcswidth(wstr, wstrlen);
+                if (tmp < 0)
+                    goto cleanup;
+                len = (size_t)((unsigned)tmp);
+            }

Whatever solution you use for converting a multi-byte string to a
maximum count of characters, please put it in a separate function.
That would make this function more readable.

+            widths[i][j] = len;
+            if (len > maxwidths[j])
+                maxwidths[j] = len;
+        }
+    }
+
+    ret = 0;
+ cleanup:
+    VIR_FREE(wstr);
+    return ret;
+}
+
+/**
+ * vshTableRowPrint:
+ * @ctl virtshell control structure
+ * @row: table to append to
+ * @maxwidths: maximum count of characters for each columns
+ * @widths: count of character for each cell in this row
+ * @printCB function for priting table
+ * @buf: buffer to store table (only if @toStdout == true)
+ * @toStdout: whetever print table to Stdout or return in buffer
+ */
+static void
+vshTableRowPrint(vshControl *ctl,
+                 vshTableRowPtr row,
+                 size_t *maxwidths,
+                 size_t *widths,
+                 vshPrintCB printCB,
+                 virBufferPtr buf,
+                 bool toStdout)
+{
+    size_t i;
+    size_t j;
+
+    for (i = 0; i < row->ncells; i++) {
+        if (toStdout)
+            printCB(ctl, " %s", row->cells[i]);
+        else
+            virBufferAsprintf(buf, " %s", row->cells[i]);
+
+        for (j = 0; j < maxwidths[i] - widths[i] + 2; j++) {
+            if (toStdout)
+                printCB(ctl, " ");
+            else
+                virBufferAddStr(buf, " ");
+        }
+    }
+    if (toStdout)
+        printCB(ctl, "\n");
+    else
+        virBufferAddStr(buf, "\n");
+}
+
+/**
+ * vshTablePrint:
+ * @ctl virtshell control structure
+ * @table: table to print
+ * @header: whetever to print to header (true) or not (false)
+ * this argument is relevant only if @ctl == NULL
+ * @toStdout: whetever to print to stdout (true) or return in string
+ *
+ * Print table. To get an alignment of columns right, function
+ * fills 2d array @widths with count of characters in each cell and
+ * array @maxwidths maximum count of character in each column.
+ * Function then prints tables header and content.
+ *
+ * Return string containing table, or NULL if table was printed to
+ * stdout
+ */
+static char *
+vshTablePrint(vshControl *ctl, vshTablePtr table, bool header, bool toStdout)


Rather than having both 'header' and 'toStdout' arguments, I think
having only 'header' and returning the result in a virBuffer would be
nicer than having if (toStdout) before every single print...

+{
+    size_t i;
+    size_t j;
+    size_t *maxwidths;
+    size_t **widths;
+    virBuffer buf = VIR_BUFFER_INITIALIZER;
+    char *ret = NULL;
+
+    if (VIR_ALLOC_N(maxwidths, table->rows[0]->ncells))
+        goto cleanup;
+
+    if (VIR_ALLOC_N(widths, table->nrows))
+        goto cleanup;
+
+    /* retrieve widths of columns */
+    for (i = 0; i < table->nrows; i++) {
+        if (VIR_ALLOC_N(widths[i], table->rows[0]->ncells))
+            goto cleanup;
+    }
+
+    if (vshTableGetColumnsWidths(table, maxwidths, widths, header) < 0)
+        goto cleanup;
+
+    if (header) {
+        /* print header */
+        VIR_WARNINGS_NO_PRINTF
+        vshTableRowPrint(ctl, table->rows[0], maxwidths, widths[0],
+                         vshPrintExtra, &buf, toStdout);
+        VIR_WARNINGS_RESET
+
+        /* print dividing line  */
+        for (i = 0; i < table->rows[0]->ncells; i++) {
+            for (j = 0; j < maxwidths[i] + 3; j++) {
+                if (toStdout)
+                    vshPrintExtra(ctl, "-");
+                else
+                    virBufferAddStr(&buf, "-");
+            }
+        }
+        if (toStdout)
+            vshPrintExtra(ctl, "\n");
+        else
+            virBufferAddStr(&buf, "\n");
+    }
+    /* print content */
+    for (i = 1; i < table->nrows; i++) {
+        VIR_WARNINGS_NO_PRINTF
+        vshTableRowPrint(ctl, table->rows[i], maxwidths, widths[i],
+                         vshPrint, &buf, toStdout);
+        VIR_WARNINGS_RESET
+    }
+
+    if (!toStdout)
+        ret = virBufferContentAndReset(&buf);
+
+ cleanup:
+    VIR_FREE(maxwidths);
+    for (i = 0; i < table->nrows; i++)
+        VIR_FREE(widths[i]);
+    VIR_FREE(widths);
+    return ret;
+}
+
+
+/**
+ * vshTablePrintToStdout:
+ * @table: table to print
+ * @ctl virtshell control structure
+ *
+ * Print table to stdout.
+ *
+ */
+void
+vshTablePrintToStdout(vshTablePtr table, vshControl *ctl)
+{
+    bool header;
+    if (ctl)
+        header = !ctl->quiet;
+    else
+        header = true;

... here you alread set header based on ctl->quiet.

Since vshPrint and vshPrintExtra differ only in whether the extra stuff
gets printed, calling vshTablePrint to get the string, then vshPrint
on that would achieve the same result. (at the expense of extra string
copy, which should not matter in virsh).

Jano

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