tools lib: Move argv_{split,free} from tools/perf/util/

This came from the kernel lib/argv_split.c, so move it to
tools/lib/argv_split.c, to get it closer to the kernel structure.

We need to audit the usage of argv_split() to figure out if it is really
necessary to do have one allocation per argv[] entry, looking at one of
its users I guess that is not the case and we probably are even leaking
those allocations by not using argv_free() judiciously, for later.

With this we further remove stuff from tools/perf/util/, reducing the
perf specific codebase and encouraging other tools/ code to use these
routines so as to keep the style and constructs used with the kernel.

Cc: Adrian Hunter <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Namhyung Kim <[email protected]>
Link: https://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

tools/lib/argv_split.c

@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Helper function for splitting a string into an argv-like array.
+ */
+
+#include <stdlib.h>
+#include <linux/kernel.h>
+#include <linux/ctype.h>
+#include <linux/string.h>
+
+static const char *skip_arg(const char *cp)
+{
+	while (*cp && !isspace(*cp))
+		cp++;
+
+	return cp;
+}
+
+static int count_argc(const char *str)
+{
+	int count = 0;
+
+	while (*str) {
+		str = skip_spaces(str);
+		if (*str) {
+			count++;
+			str = skip_arg(str);
+		}
+	}
+
+	return count;
+}
+
+/**
+ * argv_free - free an argv
+ * @argv - the argument vector to be freed
+ *
+ * Frees an argv and the strings it points to.
+ */
+void argv_free(char **argv)
+{
+	char **p;
+	for (p = argv; *p; p++) {
+		free(*p);
+		*p = NULL;
+	}
+
+	free(argv);
+}
+
+/**
+ * argv_split - split a string at whitespace, returning an argv
+ * @str: the string to be split
+ * @argcp: returned argument count
+ *
+ * Returns an array of pointers to strings which are split out from
+ * @str.  This is performed by strictly splitting on white-space; no
+ * quote processing is performed.  Multiple whitespace characters are
+ * considered to be a single argument separator.  The returned array
+ * is always NULL-terminated.  Returns NULL on memory allocation
+ * failure.
+ */
+char **argv_split(const char *str, int *argcp)
+{
+	int argc = count_argc(str);
+	char **argv = calloc(argc + 1, sizeof(*argv));
+	char **argvp;
+
+	if (argv == NULL)
+		goto out;
+
+	if (argcp)
+		*argcp = argc;
+
+	argvp = argv;
+
+	while (*str) {
+		str = skip_spaces(str);
+
+		if (*str) {
+			const char *p = str;
+			char *t;
+
+			str = skip_arg(str);
+
+			t = strndup(p, str-p);
+			if (t == NULL)
+				goto fail;
+			*argvp++ = t;
+		}
+	}
+	*argvp = NULL;
+
+out:
+	return argv;
+
+fail:
+	argv_free(argv);
+	return NULL;
+}