[PATCH v2 048/113] commands: time: refactor into new strjoin

[Ahmad Fatoum]

time concatenates all its remaining arguments with a space in-between
and then passes that to the command executor. This can be useful
elsewhere as well, so factor it out into a new strjoin function.

No functional change.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
v1 -> v2:
  - swapped order with previous commit (Sascha)

Originally posted at: https://lore.barebox.org/barebox/20221027073334.GS6702@pengutronix.de/

Changes:
  - remove if statemnt in loop (Sascha)
---
 commands/time.c  | 17 +++--------------
 include/string.h |  2 ++
 lib/string.c     | 28 ++++++++++++++++++++++++++++
 3 files changed, 33 insertions(+), 14 deletions(-)

diff --git a/commands/time.c b/commands/time.c
index 0a38db61845d..a3f270407122 100644
--- a/commands/time.c
+++ b/commands/time.c
@@ -9,11 +9,10 @@
 
 static int do_time(int argc, char *argv[])
 {
-	int i, opt;
-	unsigned char *buf, *p;
+	int opt;
+	unsigned char *buf;
 	u64 start, end, diff64;
 	bool nanoseconds = false;
-	int len = 1; /* '\0' */
 
 	while ((opt = getopt(argc, argv, "+n")) > 0) {
 		switch (opt) {
@@ -31,17 +30,7 @@ static int do_time(int argc, char *argv[])
 	if (argc < 1)
 		return COMMAND_ERROR_USAGE;
 
-	for (i = 0; i < argc; i++)
-		len += strlen(argv[i]) + 1;
-
-	p = buf = xmalloc(len);
-
-	for (i = 0; i < argc - 1; i++) {
-		p = stpcpy(p, argv[i]);
-		p = mempcpy(p, " ", strlen(" "));
-	}
-
-	stpcpy(p, argv[i]);
+	buf = strjoin(" ", argv, argc);
 
 	start = get_time_ns();
 
diff --git a/include/string.h b/include/string.h
index 71810180b5ba..2f2af85b554f 100644
--- a/include/string.h
+++ b/include/string.h
@@ -21,6 +21,8 @@ char *parse_assignment(char *str);
 
 int strverscmp(const char *a, const char *b);
 
+char *strjoin(const char *separator, char **array, size_t len);
+
 static inline int strcmp_ptr(const char *a, const char *b)
 {
 	return a && b ? strcmp(a, b) : compare3(a, b);
diff --git a/lib/string.c b/lib/string.c
index bf0f0455ab3f..695e50bc8fc1 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -1000,3 +1000,31 @@ char *parse_assignment(char *str)
 
 	return value;
 }
+
+char *strjoin(const char *separator, char **arr, size_t arrlen)
+{
+	size_t separatorlen;
+	int len = 1; /* '\0' */
+	char *buf, *p;
+	int i;
+
+	separatorlen = strlen(separator);
+
+	for (i = 0; i < arrlen; i++)
+		len += strlen(arr[i]) + separatorlen;
+
+	if (!arrlen)
+		return xzalloc(1);
+
+	p = buf = xmalloc(len);
+
+	for (i = 0; i < arrlen - 1; i++) {
+		p = stpcpy(p, arr[i]);
+		p = mempcpy(p, separator, separatorlen);
+	}
+
+	stpcpy(p, arr[i]);
+
+	return buf;
+}
+EXPORT_SYMBOL(strjoin);
-- 
2.39.2