From 8db0dc005c98126fb0e6ede59a695e399ad31e01 Mon Sep 17 00:00:00 2001
From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?=
 <jeremie.galarneau@efficios.com>
Date: Mon, 16 Dec 2013 17:15:04 -0500
Subject: [PATCH] Add utils_generate_optstring() to libcommon
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This function generates the optstring argument exepected by getopt_long
from a NULL-terminated struct option array.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Signed-off-by: David Goulet <dgoulet@efficios.com>
---
 src/common/utils.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 src/common/utils.h |  3 +++
 2 files changed, 47 insertions(+)

diff --git a/src/common/utils.c b/src/common/utils.c
index ce25f232d..ea1e5db0e 100644
--- a/src/common/utils.c
+++ b/src/common/utils.c
@@ -1,6 +1,7 @@
 /*
  * Copyright (C) 2012 - David Goulet <dgoulet@efficios.com>
  * Copyright (C) 2013 - Raphaël Beamonte <raphael.beamonte@gmail.com>
+ * Copyright (C) 2013 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License, version 2 only, as
@@ -900,3 +901,46 @@ gid_t utils_get_group_id(const char *name)
 	}
 	return grp->gr_gid;
 }
+
+/*
+ * Return a newly allocated option string. This string is to be used as the
+ * optstring argument of getopt_long(), see GETOPT(3). opt_count is the number
+ * of elements in the long_options array. Returns NULL if the string's
+ * allocation fails.
+ */
+LTTNG_HIDDEN
+char *utils_generate_optstring(const struct option *long_options,
+		size_t opt_count)
+{
+	int i;
+	size_t string_len = opt_count, str_pos = 0;
+	char *optstring;
+
+	/*
+	 * Compute the necessary string length. One letter per option, two when an
+	 * argument is necessary, and a trailing NULL.
+	 */
+	for (i = 0; i < opt_count; i++) {
+		string_len += long_options[i].has_arg ? 1 : 0;
+	}
+
+	optstring = zmalloc(string_len);
+	if (!optstring) {
+		goto end;
+	}
+
+	for (i = 0; i < opt_count; i++) {
+		if (!long_options[i].name) {
+			/* Got to the trailing NULL element */
+			break;
+		}
+
+		optstring[str_pos++] = (char)long_options[i].val;
+		if (long_options[i].has_arg) {
+			optstring[str_pos++] = ':';
+		}
+	}
+
+end:
+	return optstring;
+}
diff --git a/src/common/utils.h b/src/common/utils.h
index c23dfb932..e92ca7006 100644
--- a/src/common/utils.h
+++ b/src/common/utils.h
@@ -21,6 +21,7 @@
 #include <sys/types.h>
 #include <unistd.h>
 #include <stdint.h>
+#include <getopt.h>
 
 #define KIBI_LOG2 10
 #define MEBI_LOG2 20
@@ -47,5 +48,7 @@ int utils_get_count_order_u32(uint32_t x);
 char *utils_get_home_dir(void);
 size_t utils_get_current_time_str(const char *format, char *dst, size_t len);
 gid_t utils_get_group_id(const char *name);
+char *utils_generate_optstring(const struct option *long_options,
+		size_t opt_count);
 
 #endif /* _COMMON_UTILS_H */
-- 
2.34.1