Initial revision

1 files changed, 380 insertions, 0 deletions

diff --git a/src/head.c b/src/head.c
new file mode 100644
index 000000000..0302b60ac
--- /dev/null
+++ b/src/head.c
@@ -0,0 +1,380 @@
+/* head -- output first part of file(s)
+   Copyright (C) 1989, 1990, 1991 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+/* Options:
+   -b			Print first N 512-byte blocks.
+   -c, --bytes=N[bkm]	Print first N bytes
+			[or 512-byte blocks, kilobytes, or megabytes].
+   -k			Print first N kilobytes.
+   -N, -l, -n, --lines=N	Print first N lines.
+   -m			Print first N megabytes.
+   -q, --quiet, --silent	Never print filename headers.
+   -v, --verbose		Always print filename headers.
+
+   Reads from standard input if no files are given or when a filename of
+   ``-'' is encountered.
+   By default, filename headers are printed only if more than one file
+   is given.
+   By default, prints the first 10 lines (head -n 10).
+
+   David MacKenzie <djm@ai.mit.edu> */
+
+#include <stdio.h>
+#include <getopt.h>
+#include <ctype.h>
+#include <sys/types.h>
+#include "system.h"
+
+#ifdef isascii
+#define ISDIGIT(c) (isascii ((c)) && isdigit ((c)))
+#else
+#define ISDIGIT(c) (isdigit ((c)))
+#endif
+
+/* Number of lines/chars/blocks to head. */
+#define DEFAULT_NUMBER 10
+
+/* Size of atomic reads. */
+#define BUFSIZE (512 * 8)
+
+/* Number of bytes per item we are printing.
+   If 0, head in lines. */
+int unit_size;
+
+/* If nonzero, print filename headers. */
+int print_headers;
+
+/* When to print the filename banners. */
+enum header_mode
+{
+  multiple_files, always, never
+};
+
+int head ();
+int head_bytes ();
+int head_file ();
+int head_lines ();
+long atou ();
+void error ();
+void parse_unit ();
+void usage ();
+void write_header ();
+void xwrite ();
+
+/* The name this program was run with. */
+char *program_name;
+
+/* Have we ever read standard input?  */
+int have_read_stdin;
+
+struct option long_options[] =
+{
+  {"bytes", 1, NULL, 'c'},
+  {"lines", 1, NULL, 'n'},
+  {"quiet", 0, NULL, 'q'},
+  {"silent", 0, NULL, 'q'},
+  {"verbose", 0, NULL, 'v'},
+  {NULL, 0, NULL, 0}
+};
+
+void
+main (argc, argv)
+     int argc;
+     char **argv;
+{
+  enum header_mode header_mode = multiple_files;
+  int exit_status = 0;
+  long number = -1;		/* Number of items to print (-1 if undef.). */
+  int c;			/* Option character. */
+
+  program_name = argv[0];
+  have_read_stdin = 0;
+  unit_size = 0;
+  print_headers = 0;
+
+  if (argc > 1 && argv[1][0] == '-' && ISDIGIT (argv[1][1]))
+    {
+      /* Old option syntax; a dash, one or more digits, and one or
+	 more option letters.  Move past the number. */
+      for (number = 0, ++argv[1]; ISDIGIT (*argv[1]); ++argv[1])
+	number = number * 10 + *argv[1] - '0';
+      /* Parse any appended option letters. */
+      while (*argv[1])
+	{
+	  switch (*argv[1])
+	    {
+	    case 'b':
+	      unit_size = 512;
+	      break;
+
+	    case 'c':
+	      unit_size = 1;
+	      break;
+
+	    case 'k':
+	      unit_size = 1024;
+	      break;
+
+	    case 'l':
+	      unit_size = 0;
+	      break;
+
+	    case 'm':
+	      unit_size = 1048576;
+	      break;
+
+	    case 'q':
+	      header_mode = never;
+	      break;
+
+	    case 'v':
+	      header_mode = always;
+	      break;
+
+	    default:
+	      error (0, 0, "unrecognized option `-%c'", *argv[1]);
+	      usage ();
+	    }
+	  ++argv[1];
+	}
+      /* Make the options we just parsed invisible to getopt. */
+      argv[1] = argv[0];
+      argv++;
+      argc--;
+    }
+
+  while ((c = getopt_long (argc, argv, "c:n:qv", long_options, (int *) 0))
+	 != EOF)
+    {
+      switch (c)
+	{
+	case 'c':
+	  unit_size = 1;
+	  parse_unit (optarg);
+	  goto getnum;
+	case 'n':
+	  unit_size = 0;
+	getnum:
+	  number = atou (optarg);
+	  if (number == -1)
+	    error (1, 0, "invalid number `%s'", optarg);
+	  break;
+
+	case 'q':
+	  header_mode = never;
+	  break;
+
+	case 'v':
+	  header_mode = always;
+	  break;
+
+	default:
+	  usage ();
+	}
+    }
+
+  if (number == -1)
+    number = DEFAULT_NUMBER;
+
+  if (unit_size > 1)
+    number *= unit_size;
+
+  if (header_mode == always
+      || (header_mode == multiple_files && optind < argc - 1))
+    print_headers = 1;
+
+  if (optind == argc)
+    exit_status |= head_file ("-", number);
+
+  for (; optind < argc; ++optind)
+    exit_status |= head_file (argv[optind], number);
+
+  if (have_read_stdin && close (0) < 0)
+    error (1, errno, "-");
+  if (close (1) < 0)
+    error (1, errno, "write error");
+
+  exit (exit_status);
+}
+
+int
+head_file (filename, number)
+     char *filename;
+     long number;
+{
+  int fd;
+
+  if (!strcmp (filename, "-"))
+    {
+      have_read_stdin = 1;
+      filename = "standard input";
+      if (print_headers)
+	write_header (filename);
+      return head (filename, 0, number);
+    }
+  else
+    {
+      fd = open (filename, O_RDONLY);
+      if (fd >= 0)
+	{
+	  int errors;
+
+	  if (print_headers)
+	    write_header (filename);
+	  errors = head (filename, fd, number);
+	  if (close (fd) == 0)
+	    return errors;
+	}
+      error (0, errno, "%s", filename);
+      return 1;
+    }
+}
+
+void
+write_header (filename)
+     char *filename;
+{
+  static int first_file = 1;
+
+  if (first_file)
+    {
+      xwrite (1, "==> ", 4);
+      first_file = 0;
+    }
+  else
+    xwrite (1, "\n==> ", 5);
+  xwrite (1, filename, strlen (filename));
+  xwrite (1, " <==\n", 5);
+}
+
+int
+head (filename, fd, number)
+     char *filename;
+     int fd;
+     long number;
+{
+  if (unit_size)
+    return head_bytes (filename, fd, number);
+  else
+    return head_lines (filename, fd, number);
+}
+
+int
+head_bytes (filename, fd, bytes_to_write)
+     char *filename;
+     int fd;
+     long bytes_to_write;
+{
+  char buffer[BUFSIZE];
+  int bytes_read;
+
+  while (bytes_to_write)
+    {
+      bytes_read = read (fd, buffer, BUFSIZE);
+      if (bytes_read == -1)
+	{
+	  error (0, errno, "%s", filename);
+	  return 1;
+	}
+      if (bytes_read == 0)
+	break;
+      if (bytes_read > bytes_to_write)
+	bytes_read = bytes_to_write;
+      xwrite (1, buffer, bytes_read);
+      bytes_to_write -= bytes_read;
+    }
+  return 0;
+}
+
+int
+head_lines (filename, fd, lines_to_write)
+     char *filename;
+     int fd;
+     long lines_to_write;
+{
+  char buffer[BUFSIZE];
+  int bytes_read;
+  int bytes_to_write;
+
+  while (lines_to_write)
+    {
+      bytes_read = read (fd, buffer, BUFSIZE);
+      if (bytes_read == -1)
+	{
+	  error (0, errno, "%s", filename);
+	  return 1;
+	}
+      if (bytes_read == 0)
+	break;
+      bytes_to_write = 0;
+      while (bytes_to_write < bytes_read)
+	if (buffer[bytes_to_write++] == '\n' && --lines_to_write == 0)
+	  break;
+      xwrite (1, buffer, bytes_to_write);
+    }
+  return 0;
+}
+
+void
+parse_unit (str)
+     char *str;
+{
+  int arglen = strlen (str);
+
+  if (arglen == 0)
+    return;
+
+  switch (str[arglen - 1])
+    {
+    case 'b':
+      unit_size = 512;
+      str[arglen - 1] = '\0';
+      break;
+    case 'k':
+      unit_size = 1024;
+      str[arglen - 1] = '\0';
+      break;
+    case 'm':
+      unit_size = 1048576;
+      str[arglen - 1] = '\0';
+      break;
+    }
+}
+
+/* Convert STR, a string of ASCII digits, into an unsigned integer.
+   Return -1 if STR does not represent a valid unsigned integer. */
+
+long
+atou (str)
+     char *str;
+{
+  int value;
+
+  for (value = 0; ISDIGIT (*str); ++str)
+    value = value * 10 + *str - '0';
+  return *str ? -1 : value;
+}
+
+void
+usage ()
+{
+  fprintf (stderr, "\
+Usage: %s [-c N[bkm]] [-n N] [-qv] [--bytes=N[bkm]] [--lines=N]\n\
+       [--quiet] [--silent] [--verbose] [file...]\n\
+       %s [-Nbcklmqv] [file...]\n", program_name, program_name);
+  exit (1);
+}