auto import from //depot/cupcake/@135843
diff --git a/toolbox/cmp.c b/toolbox/cmp.c
new file mode 100644
index 0000000..9bd2e19
--- /dev/null
+++ b/toolbox/cmp.c
@@ -0,0 +1,90 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <errno.h>
+
+int cmp_main(int argc, char *argv[])
+{
+ int c;
+ int fd1, fd2;
+ char buf1[4096], buf2[4096];
+ int res, res1, res2;
+ int rv = 0;
+ int i;
+ int filepos = 0;
+
+ int show_byte = 0;
+ int show_all = 0;
+ int limit = 0;
+
+ do {
+ c = getopt(argc, argv, "bln:");
+ if (c == EOF)
+ break;
+ switch (c) {
+ case 'b':
+ show_byte = 1;
+ break;
+ case 'l':
+ show_all = 1;
+ break;
+ case 'n':
+ limit = atoi(optarg);
+ break;
+ case '?':
+ fprintf(stderr, "%s: invalid option -%c\n",
+ argv[0], optopt);
+ exit(1);
+ }
+ } while (1);
+
+ if (optind + 2 != argc) {
+ fprintf(stderr, "Usage: %s [-b] [-l] [-n count] file1 file2\n", argv[0]);
+ exit(1);
+ }
+
+ fd1 = open(argv[optind], O_RDONLY);
+ if(fd1 < 0) {
+ fprintf(stderr, "could not open %s, %s\n", argv[optind], strerror(errno));
+ return 1;
+ }
+
+ fd2 = open(argv[optind+1], O_RDONLY);
+ if(fd2 < 0) {
+ fprintf(stderr, "could not open %s, %s\n", argv[optind+1], strerror(errno));
+ return 1;
+ }
+
+ while(1) {
+ res1 = read(fd1, &buf1, sizeof(buf1));
+ res2 = read(fd2, &buf2, sizeof(buf2));
+ res = res1 < res2 ? res1 : res2;
+ if(res1 == 0 && res2 == 0) {
+ return rv;
+ }
+ for(i = 0; i < res; i++) {
+ if(buf1[i] != buf2[i]) {
+ printf("%s %s differ byte %d", argv[optind], argv[optind+1], filepos + i);
+ if(show_byte)
+ printf(" 0x%02x 0x%02x", buf1[i], buf2[i]);
+ printf("\n");
+ if(!show_all)
+ return 1;
+ rv = 1;
+ }
+ if(limit) {
+ limit--;
+ if(limit == 0)
+ return rv;
+ }
+ }
+ if(res1 != res2 || res < 0) {
+ printf("%s on %s\n", res < 0 ? "Read error" : "EOF", res1 < res2 ? argv[optind] : argv[optind+1]);
+ return 1;
+ }
+ filepos += res;
+ }
+}