Implement cmp

1 files changed, 97 insertions, 0 deletions

diff --git a/toys/cmp.c b/toys/cmp.c
new file mode 100644
index 00000000..f1e980e7
--- /dev/null
+++ b/toys/cmp.c
@@ -0,0 +1,97 @@
+/* vi: set sw=4 ts=4:
+ *
+ * cmp.c - Compare two files.
+ *
+ * Copyright 2012 Timothy Elliott <tle@holymonkey.com>
+ *
+ * See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/cmp.html
+
+USE_CMP(NEWTOY(cmp, "<2>2ls", TOYFLAG_USR|TOYFLAG_BIN))
+
+config CMP
+	bool "cmp"
+	default y
+	help
+	  usage: cmp [-l] [-s] FILE1 FILE2
+
+	  Compare the contents of two files.
+
+	  -l show all differing bytes
+	  -s silent
+*/
+
+#include "toys.h"
+
+#define FLAG_s	1
+#define FLAG_l	2
+
+int get_fd(char *file)
+{
+	int fd;
+
+	if (!strcmp(file,"-")) fd=0;
+	else if (0>(fd = open(file, O_RDONLY, 0))) {
+		perror_exit("%s", file);
+	}
+	return fd;
+}
+
+void do_cmp(int fd1, int fd2, char *file1, char *file2, char *buf1, char *buf2,
+	size_t size) {
+	int i, len1, len2, min_len;
+	size_t byte_no = 1, line_no = 1;
+
+	for (;;) {
+		len1 = read(fd1, buf1, size);
+		len2 = read(fd2, buf2, size);
+
+		min_len = len1 < len2 ? len1 : len2;
+		for (i=0; i<min_len; i++) {
+			if (buf1[i] != buf2[i]) {
+				toys.exitval = 1;
+				if (toys.optflags & FLAG_l) {
+					printf("%d %o %o\n", byte_no, buf1[i],
+						buf2[i]);
+				}
+				else {
+					if (!(toys.optflags & FLAG_s)) {
+						printf("%s %s differ: char %d, line %d\n",
+							file1, file2, byte_no,
+							line_no);
+					}
+					return;
+				}
+
+			}
+			byte_no++;
+			if (buf1[i] == '\n') line_no++;
+		}
+		if (len1 != len2) {
+			if (!(toys.optflags & FLAG_s)) {
+				fdprintf(2, "cmp: EOF on %s\n",
+					len1 < len2 ? file1 : file2);
+			}
+			toys.exitval = 1;
+			break;
+		}
+		if (len1 < 1) break;
+	}
+}
+
+void cmp_main(void)
+{
+	char *file1 = toys.optargs[0];
+	char *file2 = toys.optargs[1];
+	int fd1, fd2, size=sizeof(toybuf);
+	char *toybuf2 = xmalloc(size);
+
+	fd1 = get_fd(file1);
+	fd2 = get_fd(file2);
+
+	do_cmp(fd1, fd2, file1, file2, toybuf, toybuf2, size);
+
+	close(fd1);
+	close(fd2);
+	free(toybuf2);
+}
+