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Subject[patch 4/7] add argv_split()
argv_split() is a helper function which takes a string, splits it at
whitespace, and returns a NULL-terminated argv vector. This is
deliberately simple - it does no quote processing of any kind.

[ Seems to me that this is something which is already being done in
the kernel, but I couldn't find any other implementations, either to
steal or replace. Keep an eye out. ]

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>

---
include/linux/string.h | 3
lib/Makefile | 2
lib/argv_split.c | 159 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 163 insertions(+), 1 deletion(-)
===================================================================
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -108,6 +108,9 @@ extern char *kstrndup(const char *s, siz
extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
extern void *kmemdup(const void *src, size_t len, gfp_t gfp);

+extern char **argv_split(gfp_t gfp, const char *str, int *argcp);
+extern void argv_free(char **argv);
+
#ifdef __cplusplus
}
#endif
===================================================================
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -5,7 +5,7 @@ lib-y := ctype.o string.o vsprintf.o cmd
lib-y := ctype.o string.o vsprintf.o cmdline.o \
rbtree.o radix-tree.o dump_stack.o \
idr.o int_sqrt.o bitmap.o extable.o prio_tree.o \
- sha1.o irq_regs.o reciprocal_div.o
+ sha1.o irq_regs.o reciprocal_div.o argv_split.o

lib-$(CONFIG_MMU) += ioremap.o
lib-$(CONFIG_SMP) += cpumask.o
===================================================================
--- /dev/null
+++ b/lib/argv_split.c
@@ -0,0 +1,159 @@
+/*
+ * Helper function for splitting a string into an argv-like array.
+ */
+
+#ifndef TEST
+#include <linux/kernel.h>
+#include <linux/ctype.h>
+#include <linux/bug.h>
+#endif
+
+static const char *skip_sep(const char *cp)
+{
+ while (*cp && isspace(*cp))
+ cp++;
+
+ return cp;
+}
+
+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_sep(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++)
+ kfree(*p);
+
+ kfree(argv);
+}
+EXPORT_SYMBOL(argv_free);
+
+/**
+ * argv_split - split a string at whitespace, returning an argv
+ * @gfp: the GFP mask used to allocate memory
+ * @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(gfp_t gfp, const char *str, int *argcp)
+{
+ int argc = count_argc(str);
+ char **argv = kzalloc(sizeof(*argv) * (argc+1), gfp);
+ char **argvp;
+
+ if (argv == NULL)
+ goto out;
+
+ *argcp = argc;
+ argvp = argv;
+
+ while (*str) {
+ str = skip_sep(str);
+
+ if (*str) {
+ const char *p = str;
+ char *t;
+
+ str = skip_arg(str);
+
+ t = kstrndup(p, str-p, gfp);
+ if (t == NULL)
+ goto fail;
+ *argvp++ = t;
+ }
+ }
+ *argvp = NULL;
+
+ out:
+ return argv;
+
+ fail:
+ argv_free(argv);
+ return NULL;
+}
+EXPORT_SYMBOL(argv_split);
+
+#ifdef TEST
+#define _GNU_SOURCE
+#include <ctype.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+typedef enum {
+ GFP_KERNEL,
+} gfp_t;
+#define kzalloc(size, x) malloc(size)
+#define kfree(x) free(x)
+#define kstrndup(s, n, gfp) strndup(s, n)
+#define BUG() abort()
+
+int main() {
+ const char *testvec[] = {
+ "",
+ "x",
+ "\"",
+ "\\\0",
+ "\"",
+ "test one two three",
+ "arg\"foo\"bar biff",
+ "one two\\ three four",
+ "one \"two three\" four",
+ NULL,
+ };
+ const char **t;
+
+ for (t = testvec; *t; t++) {
+ char **argv;
+ int argc;
+ char **a;
+
+ printf("%d: test [%s]\n", t-testvec, *t);
+
+ argv = argv_split(GFP_KERNEL, *t, &argc);
+
+ printf("argc=%d vec=", argc);
+ for (a = argv; *a; a++)
+ printf("[%s] ", *a);
+ printf("\n");
+
+ argv_free(argv);
+ }
+
+ return 0;
+}
+#endif
--

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