Ticket #3730: extfs: introduce a command-line tool for parsing file lists.

We introduce 'mc_parse_ls_l', a tool for parsing file-listings in format
similar to that of 'ls -l'. This format is used by the various extfs helpers.

We'll use this tool, in the next commit, to build a tester.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>

configure.ac

@@ -638,6 +638,7 @@ tests/src/Makefile
 tests/src/filemanager/Makefile
 tests/src/editor/Makefile
 tests/src/editor/test-data.txt
+tests/src/extfs-helpers-listcmd/Makefile
 ])
 fi
 

tests/src/Makefile.am

@@ -1,6 +1,6 @@
 PACKAGE_STRING = "/src"
 
-SUBDIRS = . filemanager
+SUBDIRS = . filemanager extfs-helpers-listcmd
 
 if USE_INTERNAL_EDIT
 SUBDIRS += editor

tests/src/extfs-helpers-listcmd/Makefile.am

@@ -0,0 +1,20 @@
+PACKAGE_STRING = "/src/extfs-helpers-listcmd"
+
+AM_CPPFLAGS = $(GLIB_CFLAGS) -I$(top_srcdir)
+
+# This lets mc_parse_ls_l.c override MC's message() without the linker
+# complaining about multiple definitions.
+AM_LDFLAGS = @TESTS_LDFLAGS@
+
+LIBS = $(top_builddir)/lib/libmc.la
+
+# Programs/scripts to build on 'make check'.
+check_PROGRAMS = mc_parse_ls_l
+
+# Tests to run on 'make check'
+TESTS = run
+
+mc_parse_ls_l_SOURCES = \
+	mc_parse_ls_l.c
+
+EXTRA_DIST = run

tests/src/extfs-helpers-listcmd/mc_parse_ls_l.c

@@ -0,0 +1,405 @@
+/*
+   A parser for file-listings formatted like 'ls -l'.
+
+   Copyright (C) 2016
+   Free Software Foundation, Inc.
+
+   This file is part of the Midnight Commander.
+
+   The Midnight Commander is free software: you can redistribute it
+   and/or modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation, either version 3 of the License,
+   or (at your option) any later version.
+
+   The Midnight Commander 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/** \file
+ *  \brief A parser for file-listings formatted like 'ls -l'.
+ *
+ * This program parses file-listings the same way MC does.
+ * It's basically a wrapper around vfs_parse_ls_lga().
+ * You can feed it the output of any of extfs's helpers.
+ *
+ * After parsing, the data is written out to stdout. The output
+ * format can be either YAML or a format similar to 'ls -l'.
+ *
+ * This program is the main tool our tester script is going to use.
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "lib/global.h"
+
+#include "lib/vfs/utilvfs.h"    /* vfs_parse_ls_lga() */
+#include "lib/util.h"           /* string_perm() */
+#include "lib/timefmt.h"        /* FMT_LOCALTIME */
+#include "lib/widget.h"         /* for the prototype of message() only */
+
+/*** global variables ****************************************************************************/
+
+/*** file scope macro definitions ****************************************************************/
+
+/*** file scope type declarations ****************************************************************/
+
+typedef enum
+{
+    FORMAT_YAML,
+    FORMAT_LS
+} output_format_t;
+
+/*** file scope variables ************************************************************************/
+
+/* Command-line options. */
+static gboolean opt_drop_mtime = FALSE;
+static gboolean opt_drop_ids = FALSE;
+static gboolean opt_symbolic_ids = FALSE;
+static output_format_t opt_output_format = FORMAT_LS;
+
+/* Misc. */
+static int error_count = 0;
+
+/* forward declarations */
+static gboolean
+parse_format_name_argument (const gchar * option_name, const gchar * value, gpointer data,
+                            GError ** error);
+
+static GOptionEntry entries[] = {
+    {"drop-mtime", 0, 0, G_OPTION_ARG_NONE, &opt_drop_mtime, "Don't include mtime in the output.",
+     NULL},
+    {"drop-ids", 0, 0, G_OPTION_ARG_NONE, &opt_drop_ids, "Don't include uid/gid in the output.",
+     NULL},
+    {"symbolic-ids", 0, 0, G_OPTION_ARG_NONE, &opt_symbolic_ids,
+     "Print the strings '<<uid>>'/'<<gid>>' instead of the numeric IDs when they match the process' uid/gid.",
+     NULL},
+    {"format", 'f', 0, G_OPTION_ARG_CALLBACK, parse_format_name_argument,
+     "Output format. Default: ls.", "<ls|yaml>"},
+    {NULL, '\0', 0, 0, NULL, NULL, NULL}        /* Make the compiler shut up by initializing everything. */
+};
+
+/*** file scope functions ************************************************************************/
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Command-line handling.
+ */
+/* --------------------------------------------------------------------------------------------- */
+
+static gboolean
+parse_format_name_argument (const gchar * option_name, const gchar * value, gpointer data,
+                            GError ** error)
+{
+    (void) option_name;
+    (void) data;
+
+    if (strcmp (value, "yaml") == 0)
+        opt_output_format = FORMAT_YAML;
+    else if (strcmp (value, "ls") == 0)
+        opt_output_format = FORMAT_LS;
+    else
+    {
+        g_set_error (error, MC_ERROR, G_OPTION_ERROR_FAILED, "unknown output format '%s'", value);
+        return FALSE;
+    }
+
+    return TRUE;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static gboolean
+parse_command_line (int *argc, char **argv[])
+{
+    GError *error = NULL;
+    GOptionContext *context;
+
+    context =
+        g_option_context_new
+        ("- Parses its input, which is expected to be in a format similar to 'ls -l', and writes the result to stdout.");
+    g_option_context_add_main_entries (context, entries, NULL);
+    if (!g_option_context_parse (context, argc, argv, &error))
+    {
+        g_print ("option parsing failed: %s\n", error->message);
+        return FALSE;
+    }
+
+    return TRUE;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Utility functions.
+ */
+/* --------------------------------------------------------------------------------------------- */
+
+static const char *
+my_itoa (int i)
+{
+    static char buf[BUF_SMALL];
+
+    sprintf (buf, "%d", i);
+    return buf;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+/**
+ * Returns the uid as-is, or as "<<uid>>" if the same as current user.
+ */
+static const char *
+symbolic_uid (uid_t uid)
+{
+    return (opt_symbolic_ids && uid == getuid ())? "<<uid>>" : my_itoa ((int) uid);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static const char *
+symbolic_gid (gid_t gid)
+{
+    return (opt_symbolic_ids && gid == getgid ())? "<<gid>>" : my_itoa ((int) gid);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+/**
+ * Cuts off a string's line-end (as in Perl).
+ */
+static void
+chomp (char *s)
+{
+    int i;
+
+    i = strlen (s);
+
+    /* Code taken from vfs_parse_ls_lga(), with modifications. */
+    if ((--i >= 0) && (s[i] == '\r' || s[i] == '\n'))
+        s[i] = '\0';
+    if ((--i >= 0) && (s[i] == '\r' || s[i] == '\n'))
+        s[i] = '\0';
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static const char *
+string_date (time_t time)
+{
+    static char buf[BUF_SMALL];
+
+    /*
+     * If we ever want to be able to re-parse the output of this program,
+     * we'll need to use the American brain-damaged MM-DD-YYYY instead of
+     * YYYY-MM-DD because vfs_parse_ls_lga() doesn't currently recognize
+     * the latter.
+     */
+    FMT_LOCALTIME (buf, sizeof buf, "%Y-%m-%d %H:%M:%S", time);
+    return buf;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+/**
+ * Override MC's message().
+ *
+ * vfs_parse_ls_lga() calls this on error. Since MC's uses tty/widgets, it
+ * will crash us. We replace it with a plain version.
+ */
+void
+message (int flags, const char *title, const char *text, ...)
+{
+    char *p;
+    va_list ap;
+
+    (void) flags;
+    (void) title;
+
+    va_start (ap, text);
+    p = g_strdup_vprintf (text, ap);
+    va_end (ap);
+    printf ("message(): vfs_parse_ls_lga(): parsing error at: %s\n", p);
+    g_free (p);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * YAML output format.
+ */
+/* --------------------------------------------------------------------------------------------- */
+
+static void
+yaml_dump_stbuf (const struct stat *st)
+{
+    /* Various casts and flags here were taken/inspired by info_show_info(). */
+    printf ("  perm: %s\n", string_perm (st->st_mode));
+    if (!opt_drop_ids)
+    {
+        printf ("  uid: %s\n", symbolic_uid (st->st_uid));
+        printf ("  gid: %s\n", symbolic_gid (st->st_gid));
+    }
+    printf ("  size: %" PRIuMAX "\n", (uintmax_t) st->st_size);
+    printf ("  nlink: %d\n", (int) st->st_nlink);
+    if (!opt_drop_mtime)
+        printf ("  mtime: %s\n", string_date (st->st_mtime));
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static void
+yaml_dump_string (const char *name, const char *val)
+{
+    char *q;
+
+    q = g_shell_quote (val);
+    printf ("  %s: %s\n", name, q);
+    g_free (q);
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static void
+yaml_dump_record (gboolean success, const char *input_line, const struct stat *st,
+                  const char *filename, const char *linkname)
+{
+    printf ("-\n");             /* Start new item in the list. */
+
+    if (success)
+    {
+        if (filename != NULL)
+            yaml_dump_string ("name", filename);
+        if (linkname != NULL)
+            yaml_dump_string ("linkname", linkname);
+        yaml_dump_stbuf (st);
+    }
+    else
+    {
+        yaml_dump_string ("cannot parse input line", input_line);
+    }
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * 'ls' output format.
+ */
+/* --------------------------------------------------------------------------------------------- */
+
+static void
+ls_dump_stbuf (const struct stat *st)
+{
+    /* Various casts and flags here were taken/inspired by info_show_info(). */
+    printf ("%s %3d ", string_perm (st->st_mode), (int) st->st_nlink);
+    if (!opt_drop_ids)
+    {
+        printf ("%8s ", symbolic_uid (st->st_uid));
+        printf ("%8s ", symbolic_gid (st->st_gid));
+    }
+    printf ("%10" PRIuMAX " ", (uintmax_t) st->st_size);
+    if (!opt_drop_mtime)
+        printf ("%s ", string_date (st->st_mtime));
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+static void
+ls_dump_record (gboolean success, const char *input_line, const struct stat *st,
+                const char *filename, const char *linkname)
+{
+    if (success)
+    {
+        ls_dump_stbuf (st);
+        if (filename != NULL)
+            printf ("%s", filename);
+        if (linkname != NULL)
+            printf (" -> %s", linkname);
+        printf ("\n");
+    }
+    else
+    {
+        printf ("cannot parse input line: '%s'\n", input_line);
+    }
+}
+
+/* ------------------------------------------------------------------------------ */
+/**
+ * Main code.
+ */
+/* ------------------------------------------------------------------------------ */
+
+static void
+process_ls_line (const char *line)
+{
+    struct stat st;
+    char *filename, *linkname;
+    gboolean success;
+
+    memset (&st, 0, sizeof st);
+    filename = NULL;
+    linkname = NULL;
+
+    success = vfs_parse_ls_lga (line, &st, &filename, &linkname, NULL);
+
+    if (!success)
+        error_count++;
+
+    if (opt_output_format == FORMAT_YAML)
+        yaml_dump_record (success, line, &st, filename, linkname);
+    else
+        ls_dump_record (success, line, &st, filename, linkname);
+
+    g_free (filename);
+    g_free (linkname);
+}
+
+/* ------------------------------------------------------------------------------ */
+
+static void
+process_input (FILE * input)
+{
+    char line[BUF_4K];
+
+    while (fgets (line, sizeof line, input) != NULL)
+    {
+        chomp (line);           /* Not mandatory. Makes error messages nicer. */
+        if (strncmp (line, "total ", 6) == 0)   /* Convenience only: makes 'ls -l' parse cleanly. */
+            continue;
+        process_ls_line (line);
+    }
+}
+
+/* ------------------------------------------------------------------------------ */
+
+int
+main (int argc, char *argv[])
+{
+    FILE *input;
+
+    if (!parse_command_line (&argc, &argv))
+        return EXIT_FAILURE;
+
+    if (argc >= 2)
+    {
+        input = fopen (argv[1], "r");
+        if (input == NULL)
+        {
+            perror (argv[1]);
+            return EXIT_FAILURE;
+        }
+    }
+    else
+    {
+        input = stdin;
+    }
+
+    process_input (input);
+
+    return (error_count > 0) ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+/* ------------------------------------------------------------------------------ */

tests/src/extfs-helpers-listcmd/run

@@ -0,0 +1,15 @@
+#!/bin/sh
+
+echo
+echo "This is a placeholder."
+echo "It will be replaced in the future with a script that does the real"
+echo "work of testing the helpers."
+echo
+echo "Here's a silly test to check whether 'ls', had it been an extfs helper,"
+echo "works properly:"
+echo
+
+LC_ALL=C ls -l | ./mc_parse_ls_l
+
+# (LC_ALL=C is meant to prevent date formats MC can't parse. This might
+# still not be foolproof, but that's just a demonstration.)