--- /dev/null
+/*
+ * 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);
+}
public / FUZIX.git / commitdiff