From 3b852d7d9ce6832f2aa9f6526d29a4ba1a80b370 Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@linux.intel.com>
Date: Tue, 30 Dec 2014 11:39:05 +0000
Subject: [PATCH] utils: Add xargs from ELKS

---
 Applications/util/Makefile |   1 +
 Applications/util/xargs.c  | 254 +++++++++++++++++++++++++++++++++++++
 2 files changed, 255 insertions(+)
 create mode 100644 Applications/util/xargs.c

diff --git a/Applications/util/Makefile b/Applications/util/Makefile
index 5cebabad..2614877c 100644
--- a/Applications/util/Makefile
+++ b/Applications/util/Makefile
@@ -89,6 +89,7 @@ SRCS  = banner.c \
 	wc.c \
 	which.c \
 	whoami.c \
+	xargs.c \
 	yes.c
 
 OBJS = $(SRCS:.c=.rel)
diff --git a/Applications/util/xargs.c b/Applications/util/xargs.c
new file mode 100644
index 00000000..e9b13199
--- /dev/null
+++ b/Applications/util/xargs.c
@@ -0,0 +1,254 @@
+/*
+ * xargs.c
+ *
+ * Copyright 2000 Alistair Riddoch
+ * ajr@ecs.soton.ac.uk
+ *
+ * This file may be distributed under the terms of the GNU General Public
+ * License v2, or at your option any later version.
+ */
+
+/*
+ * This is a small version of xargs for use in the ELKS project.
+ * It is not fully functional, and may not be the most efficient
+ * implementation for larger systems. It minimises memory usage and
+ * code size.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#define MAX_ARGS 20
+#define MAX_IARGS 10
+#define MAX_CHARS 255
+
+#define DEFAULT_CMD "/bin/echo"
+
+int max_args = MAX_ARGS;
+int max_chars = MAX_CHARS;	/* Not yet implemented */
+
+char * progname;
+
+/* Command to run if none specified */
+char * default_cmd = DEFAULT_CMD;
+
+/* New arguments for programs */
+int nargc;
+char * nargv[MAX_ARGS + MAX_IARGS + 2];
+
+/*
+ *
+ * usage()
+ *
+ * Display usage information.
+ *
+ */
+
+void usage(char ** argv)
+{
+	fprintf(stderr, "%s [-n max-args] [-s max-chars] [command [initial-arguments]]\n", argv[0]);
+	exit(1);
+}
+
+/*
+ *
+ * do_args()
+ *
+ * Interpret command switches from the command line.
+ *
+ * int argc;		As passed to main().
+ * char ** argv;	As passed to main().
+ *
+ * RETURN		Num of arguments interpreted.
+ *
+ */
+
+
+int do_args(int argc, char ** argv)
+{
+	int i = 1, j, k;
+
+	while(i < argc && argv[i][0] == '-') {
+		k = 0;
+		for(j = 1; j < strlen(argv[i]); j++) {
+			switch (argv[i][j]) {
+				case 'n':
+					k++;
+					if ((i + k) < argc) {
+						max_args = atoi(argv[i+k]);
+					}
+					break;
+				case 's':
+					k++;
+					if ((i + k) < argc) {
+						max_chars = atoi(argv[i+k]);
+					}
+					break;
+				default:
+					usage(argv);
+			}
+		}
+		i += k;
+		i++;
+	}
+	if (max_args > MAX_ARGS) {
+		max_args = MAX_ARGS;
+	}
+	if (max_chars > MAX_CHARS) {
+		max_chars = MAX_CHARS;
+	}
+	return i;
+}
+
+/*
+ *
+ * build_cmd()
+ *
+ * Build the initial portion of the argv array to be used to run
+ * commands from the command line arguments given for xargs.
+ *
+ * int argc;		Number of arguments left.
+ * char ** argv;	Pointer to the first item in main()'s argv for us.
+ *
+ */
+
+void build_cmd(int argc, char ** argv)
+{
+	int i;
+
+	if (argc > (MAX_IARGS + MAX_ARGS - max_args)) {
+		fprintf(stderr, "%s: Too many initial arguments.\n", progname);
+		exit(1);
+	}
+	for(i = 0; i < argc; i++) {
+		nargv[i] = argv[i];
+	}
+	nargc += argc;
+}
+
+#define BSIZE 64
+#define out_of_mem() { perror("malloc"); exit(1); }
+
+/*
+ * next_token()
+ *
+ * Read standard in and get the next argument.
+ * Returns NULL on end of file.
+ *
+ */
+
+char * next_token(void)
+{
+	int size = BSIZE;
+	int tail = 0;
+	char * buf = malloc(BSIZE);
+
+	if (buf == NULL) {
+		out_of_mem();
+	}
+	for(;;) {
+		int inp = fgetc(stdin);
+		switch (inp) {
+			case EOF:
+				if (tail != 0) {
+					buf[tail] = '\0';
+				} else {
+					free(buf);
+					buf = NULL;
+				}
+				return buf;
+				break;
+			case ' ':
+			case '\t':
+			case '\n':
+				if (tail != 0) {
+					buf[tail] = '\0';
+					return buf;
+				}
+				break;
+			default:
+				buf[tail++] = inp;
+				break;
+		}
+		if (tail > size) {
+			size += BSIZE;
+			buf = realloc(buf, size);
+			if (buf == NULL) {
+				out_of_mem();
+			}
+		}
+			
+	}
+}
+
+/*
+ *
+ * run()
+ *
+ * Fork, exec and wait for the commant to complete.
+ *
+ * Parameters are as for execvp.
+ *
+ * We use vfork as this is a good saving under elks.
+ *
+ */
+
+void run(char * argv0, char ** argv)
+{
+	int pid;
+	
+	pid = fork();
+	switch (pid) {
+		case -1:
+			perror("fork");
+			exit(1);
+			break;
+		case 0:
+			break;
+		default:
+			wait(NULL);
+			return;
+	}
+	execvp(argv0, argv);
+	perror("argv0");
+	exit(1);
+}
+
+int main(int argc, char ** argv)
+{
+	int num_args;
+	int new_argc;
+	char * tok = NULL;
+
+	progname = argv[0];
+	num_args = do_args(argc, argv);
+
+	if (num_args >= argc) {
+		build_cmd(1, &default_cmd);
+	} else {
+		build_cmd(argc - num_args, &argv[num_args]);
+	}
+
+	do {
+		int i;
+
+		new_argc = nargc;
+		while(new_argc < (nargc + max_args) &&
+		     (tok = next_token()) != NULL) {
+			nargv[new_argc++] = tok;
+		}
+		nargv[new_argc] = NULL;
+		if (nargc != new_argc) {
+			run(nargv[0], nargv);
+		}
+		for(i = nargc; i < new_argc; i++) {
+			free(nargv[i]);
+		}
+	} while (tok != NULL);
+
+	exit(0);
+}
-- 
2.34.1