add directory study

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

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+/* comm - select lines from two sorted files	Author: Martin C. Atkins */
+
+/*
+ *	This program was written by:
+ *		Martin C. Atkins,
+ *		University of York,
+ *		Heslington,
+ *		York. Y01 5DD
+ *		England
+ *	and is released into the public domain, on the condition
+ *	that this comment is always included without alteration.
+ */
+
+#include <sys/types.h>
+#include <fcntl.h>
+
+#define BUFSIZ (512)
+#define LINMAX (600)
+
+struct file {
+  char *name;			/* the file's name */
+  int fd;			/* the file descripter */
+  char buf[BUFSIZ];		/* buffer storage */
+  char *next;			/* the next character to read */
+  char *endp;			/* the first invalid character */
+  int seeneof;			/* an end of file has been seen */
+} files[2];
+
+char lines[2][LINMAX];
+
+int colflgs[3] = {1, 2, 3};	/* number of tabs + 1: 0 => no column */
+
+static char *umsg = "Usage: comm [-[123]] file1 file2\n";
+
+main(argc, argv)
+int argc;
+char *argv[];
+{
+  int cnt;
+  if (argc > 1 && argv[1][0] == '-' && argv[1][1] != '\0') {
+	char *ap;
+	for (ap = &argv[1][1]; *ap; ap++) switch (*ap) {
+		    case '1':
+		    case '2':
+		    case '3':
+			cnt = *ap - '1';
+			if (colflgs[cnt] == 0) break;
+			colflgs[cnt] = 0;
+			for (cnt++; cnt < 3; cnt++) colflgs[cnt]--;
+			break;
+		    default:	usage();
+		}
+	argc--;
+	argv++;
+  }
+  if (argc != 3) usage();
+  eopen(argv[1], &files[0]);
+  eopen(argv[2], &files[1]);
+  comm();
+  exit(0);
+}
+
+usage()
+{
+
+  std_err(umsg);
+  exit(1);
+}
+
+error(s, f)
+char *s, *f;
+{
+  std_err("comm: ");
+  std_err(s);
+  if (f) std_err(f);
+  std_err("\n");
+  exit(1);
+}
+
+int eopen(fn, file)
+char *fn;
+struct file *file;
+{
+  file->name = fn;
+  file->next = file->endp = &file->buf[0];
+  file->seeneof = 0;
+  if (fn[0] == '-' && fn[1] == '\0')
+	file->fd = 0;
+  else if ((file->fd = open(fn, O_RDONLY)) < 0)
+	error("can't open ", fn);
+}
+
+
+int getbuf(file)
+struct file *file;
+{
+/* Get a buffer-full from the file.  Return true if no characters
+ * were obtained because we are at end of file.
+ */
+  int n;
+
+  if (file->seeneof) return(1);
+  if ((n = read(file->fd, &file->buf[0], BUFSIZ)) < 0)
+	error("read error on ", file->name);
+  if (n == 0) {
+	file->seeneof++;
+	return 1;
+  }
+  file->next = &file->buf[0];
+  file->endp = &file->buf[n];
+  return(0);
+}
+
+
+int readline(fno)
+int fno;
+{
+/* Read up to the next '\n' character to buf.
+ * Return a complete line, even if end of file occurs within a line.
+ * Return false at end of file/
+ */
+  register struct file *file = &files[fno];
+  char *buf = lines[fno];
+
+  if (file->next == file->endp && getbuf(file)) return(0);
+  while ((*buf++ = *file->next++) != '\n')
+	if (file->next == file->endp && getbuf(file)) {
+		*buf++ = '\n';
+		*buf = '\0';
+		return(1);
+	}
+  *buf = '\0';
+  return(1);
+}
+
+comm()
+{
+  register int res;
+
+  if (!readline(0)) {
+	cpycol(1);
+	return;
+  }
+  if (!readline(1)) {
+	putcol(0, lines[0]);
+	cpycol(0);
+	return;
+  }
+  for (;;) {
+	if ((res = strcmp(lines[0], lines[1])) != 0) {
+		res = res > 0;
+		putcol(res, lines[res]);
+		if (!readline(res)) {
+			putcol(!res, lines[!res]);
+			cpycol(!res);
+			return;
+		}
+	} else {
+		putcol(2, lines[0]);	/* files[1]lin == f2lin */
+		if (!readline(0)) {
+			cpycol(1);
+			return;
+		}
+		if (!readline(1)) {
+			putcol(0, lines[0]);
+			cpycol(0);
+			return;
+		}
+	}
+  }
+
+  /* NOTREACHED */
+}
+
+putcol(col, buf)
+int col;
+char *buf;
+{
+  int cnt;
+
+  if (colflgs[col] == 0) return;
+  for (cnt = 0; cnt < colflgs[col] - 1; cnt++) prints("\t");
+  prints("%s", buf);
+}
+
+cpycol(col)
+int col;
+{
+  if (colflgs[col]) while (readline(col))
+		putcol(col, lines[col]);
+}