add directory study

study/linux-travel/MINIX-1.5/1.5/Source/commands/cmp.c

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+/* cmp - compare two files	Authors: Paul Polderman & Michiel Huisjes */
+
+/* 90-04-10 Schlenker
+ *	Fixed incorrect handling of flags.
+ *	Reduced buffer size to accommodate 7K pipes (Minix restriction).
+ *	Better trapping of file reading errors.
+ *	Considerable speedup when using -s flag.
+ *	Buffering strategy remains seriously error prone; should be fixed.
+ */
+
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdio.h>
+
+#define BLOCK_SIZE 6144
+
+char *file_1, *file_2;
+char buf1[BLOCK_SIZE];
+char buf2[BLOCK_SIZE];
+char lflag, sflag;
+
+main(argc, argv)
+int argc;
+char *argv[];
+{
+  int fd1, fd2, i, exit_status;
+
+  if (argc < 3 || argc > 4) usage();
+  lflag = 0;
+  sflag = 0;
+
+  i = 1;
+  if (strcmp(argv[i], "-l") == 0) {
+	lflag++;
+	i++;
+  } else
+  if (strcmp(argv[i], "-s") == 0) {
+	sflag++;
+	i++;
+  }
+
+  if (strcmp(argv[i], "-") == 0) {
+	fd1 = 0;
+	file_1 = "<stdin>";
+  } else {
+	if ((fd1 = open(argv[i], O_RDONLY)) < 0)
+		cantopen(argv[i]);
+	file_1 = argv[i];
+  }
+  i++;
+
+  if (i == argc || (fd2 = open(argv[i], O_RDONLY)) < 0)
+	cantopen(argv[i]);
+  file_2 = argv[i];
+
+  exit_status = sflag ? fastcmp(fd1, fd2) : cmp(fd1, fd2);
+
+  close(fd1);
+  close(fd2);
+
+  exit(exit_status);
+}
+
+cmp(fd1, fd2)
+int fd1, fd2;
+{
+  register unsigned long char_cnt, line_cnt;
+  register int i;
+  int n1, n2, n, exit_status;
+
+  char_cnt = 1L;
+  line_cnt = 1L;
+  exit_status = 0;
+  do {
+	n1 = read(fd1, buf1, BLOCK_SIZE);
+	n2 = read(fd2, buf2, BLOCK_SIZE);
+	n = (n1 < n2) ? n1 : n2;
+	if (n < 0) {
+		printf("cmp: Error on %s\n", (n1 < 0) ? file_1 : file_2);
+		return(1);
+	}
+	for (i = 0; i < n; i++) {	/* Check buffers for equality */
+		if (buf1[i] != buf2[i]) {
+			if (!lflag) {
+				printf("%s %s differ: char %ld, line %ld\n",
+				file_1, file_2, char_cnt, line_cnt);
+				return(1);
+			}
+			printf("%10lu %03o %03o\n",
+			       char_cnt, buf1[i] & 0377, buf2[i] & 0377);
+			exit_status = 1;
+		}
+		if (buf1[i] == '\n') line_cnt++;
+		char_cnt++;
+	}
+	if (n1 != n2) {		/* EOF on one of the input files. */
+		printf("cmp: EOF on %s\n", (n1 < n2) ? file_1 : file_2);
+		return(1);
+	}
+  } while (n > 0);		/* While not EOF on any file */
+  return(exit_status);
+}
+
+fastcmp(fd1, fd2)
+int fd1, fd2;
+{
+  int n1, n2;
+
+  while (1) {
+	n1 = read(fd1, buf1, BLOCK_SIZE);
+	n2 = read(fd2, buf2, BLOCK_SIZE);
+	if (n1 != n2) return(1);	/* Bug! - depends on buffering */
+	if (n1 == 0) return(0);
+	if (n1 < 0) return(1);
+	if (memcmp((void *) buf1, (void *) buf2, (size_t) n1) != 0)
+		return(1);
+  }
+}
+
+usage()
+{
+  fprintf(stderr, "Usage: cmp [-l | -s] file1 file2\n");
+  exit(2);
+}
+
+cantopen(s)
+char *s;
+{
+  fprintf(stderr, "cmp: cannot open %s\n", s);
+  exit(1);
+}