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authorIlya Dryomov <idryomov@gmail.com>2012-02-03 21:00:17 +0200
committerIlya Dryomov <idryomov@gmail.com>2012-02-03 21:00:17 +0200
commit8b4e3d8b5b9e3cb65b244fec55d93608d1a1e319 (patch)
tree3615c42febac6822dc7cb49ebd900abb1addbb05 /help.c
parent4f268331932819fb5e002e4a88449de6f76bb0b2 (diff)
Btrfs-progs: implement new subcommand parser
This completely replaces the existing subcommand infrastructure, which is not flexible enough to accomodate our needs. Instead of a global command table we now have per-level tables and command group handlers, which allows command-group-specific handling of options and subcommands. The new parser exports a clear interface and gets out of the way - all control over how matching is done is passed to commands and command group handlers. One side effect of this is that command implementors have to check the number of arguments themselves - patch to fix up all existing commands follows. Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Diffstat (limited to 'help.c')
-rw-r--r--help.c207
1 files changed, 207 insertions, 0 deletions
diff --git a/help.c b/help.c
new file mode 100644
index 0000000..932bdf2
--- /dev/null
+++ b/help.c
@@ -0,0 +1,207 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program 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, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "commands.h"
+
+extern char argv0_buf[ARGV0_BUF_SIZE];
+
+#define USAGE_SHORT 1U
+#define USAGE_LONG 2U
+#define USAGE_OPTIONS 4U
+#define USAGE_LISTING 8U
+
+static int do_usage_one_command(const char * const *usagestr,
+ unsigned int flags, FILE *outf)
+{
+ int pad = 4;
+
+ if (!usagestr || !*usagestr)
+ return -1;
+
+ fprintf(outf, "%s%s\n", (flags & USAGE_LISTING) ? " " : "usage: ",
+ *usagestr++);
+
+ /* a short one-line description (mandatory) */
+ if ((flags & USAGE_SHORT) == 0)
+ return 0;
+ else if (!*usagestr)
+ return -2;
+
+ if (flags & USAGE_LISTING)
+ pad = 8;
+ else
+ fputc('\n', outf);
+
+ fprintf(outf, "%*s%s\n", pad, "", *usagestr++);
+
+ /* a long (possibly multi-line) description (optional) */
+ if (!*usagestr || ((flags & USAGE_LONG) == 0))
+ return 0;
+
+ if (**usagestr)
+ fputc('\n', outf);
+ while (*usagestr && **usagestr)
+ fprintf(outf, "%*s%s\n", pad, "", *usagestr++);
+
+ /* options (optional) */
+ if (!*usagestr || ((flags & USAGE_OPTIONS) == 0))
+ return 0;
+
+ /*
+ * options (if present) should always (even if there is no long
+ * description) be prepended with an empty line, skip it
+ */
+ usagestr++;
+
+ fputc('\n', outf);
+ while (*usagestr)
+ fprintf(outf, "%*s%s\n", pad, "", *usagestr++);
+
+ return 0;
+}
+
+static int usage_command_internal(const char * const *usagestr,
+ const char *token, int full, int lst,
+ FILE *outf)
+{
+ unsigned int flags = USAGE_SHORT;
+ int ret;
+
+ if (full)
+ flags |= USAGE_LONG | USAGE_OPTIONS;
+ if (lst)
+ flags |= USAGE_LISTING;
+
+ ret = do_usage_one_command(usagestr, flags, outf);
+ switch (ret) {
+ case -1:
+ fprintf(outf, "No usage for '%s'\n", token);
+ break;
+ case -2:
+ fprintf(outf, "No short description for '%s'\n", token);
+ break;
+ }
+
+ return ret;
+}
+
+static void usage_command_usagestr(const char * const *usagestr,
+ const char *token, int full, int err)
+{
+ FILE *outf = err ? stderr : stdout;
+ int ret;
+
+ ret = usage_command_internal(usagestr, token, full, 0, outf);
+ if (!ret)
+ fputc('\n', outf);
+}
+
+void usage_command(const struct cmd_struct *cmd, int full, int err)
+{
+ usage_command_usagestr(cmd->usagestr, cmd->token, full, err);
+}
+
+void usage(const char * const *usagestr)
+{
+ usage_command_usagestr(usagestr, NULL, 1, 1);
+ exit(129);
+}
+
+static void usage_command_group_internal(const struct cmd_group *grp, int full,
+ FILE *outf)
+{
+ const struct cmd_struct *cmd = grp->commands;
+ int do_sep = 0;
+
+ for (; cmd->token; cmd++) {
+ if (cmd->hidden)
+ continue;
+
+ if (full && cmd != grp->commands)
+ fputc('\n', outf);
+
+ if (!cmd->next) {
+ if (do_sep) {
+ fputc('\n', outf);
+ do_sep = 0;
+ }
+
+ usage_command_internal(cmd->usagestr, cmd->token, full,
+ 1, outf);
+ continue;
+ }
+
+ /* this is an entry point to a nested command group */
+
+ if (!full && cmd != grp->commands)
+ fputc('\n', outf);
+
+ usage_command_group_internal(cmd->next, full, outf);
+
+ if (!full)
+ do_sep = 1;
+ }
+}
+
+void usage_command_group(const struct cmd_group *grp, int full, int err)
+{
+ FILE *outf = err ? stderr : stdout;
+
+ fprintf(outf, "usage: %s\n\n", grp->usagestr);
+ usage_command_group_internal(grp, full, outf);
+ fputc('\n', outf);
+
+ if (grp->infostr)
+ fprintf(outf, "%s\n", grp->infostr);
+}
+
+void help_unknown_token(const char *arg, const struct cmd_group *grp)
+{
+ fprintf(stderr, "%s: unknown token '%s'\n", argv0_buf, arg);
+ usage_command_group(grp, 0, 1);
+ exit(1);
+}
+
+void help_ambiguous_token(const char *arg, const struct cmd_group *grp)
+{
+ const struct cmd_struct *cmd = grp->commands;
+
+ fprintf(stderr, "%s: ambiguous token '%s'\n", argv0_buf, arg);
+ fprintf(stderr, "\nDid you mean one of these ?\n");
+
+ for (; cmd->token; cmd++) {
+ if (!prefixcmp(cmd->token, arg))
+ fprintf(stderr, "\t%s\n", cmd->token);
+ }
+
+ exit(1);
+}
+
+void help_command_group(const struct cmd_group *grp, int argc, char **argv)
+{
+ int full = 0;
+
+ if (argc > 1) {
+ if (!strcmp(argv[1], "--full"))
+ full = 1;
+ }
+
+ usage_command_group(grp, full, 0);
+}