path: root/src/csplit.c

/* csplit - split a file into sections determined by context lines
   Copyright (C) 1991-2023 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 3 of the License, 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, see <https://www.gnu.org/licenses/>.  */

/* Written by Stuart Kemp, cpsrk@groper.jcu.edu.au.
   Modified by David MacKenzie, djm@gnu.ai.mit.edu. */

#include <config.h>

#include <getopt.h>
#include <sys/types.h>
#include <signal.h>
#include <stdckdint.h>

#include "system.h"

#include <regex.h>

#include "fd-reopen.h"
#include "quote.h"
#include "safe-read.h"
#include "stdio--.h"
#include "xdectoint.h"
#include "xstrtol.h"

/* The official name of this program (e.g., no 'g' prefix).  */
#define PROGRAM_NAME "csplit"

#define AUTHORS \
  proper_name ("Stuart Kemp"), \
  proper_name ("David MacKenzie")

/* The default prefix for output file names. */
#define DEFAULT_PREFIX	"xx"

/* A compiled pattern arg. */
struct control
{
  intmax_t offset;		/* Offset from regexp to split at. */
  intmax_t lines_required;	/* Number of lines required. */
  intmax_t repeat;		/* Repeat count. */
  int argnum;			/* ARGV index. */
  bool repeat_forever;		/* True if '*' used as a repeat count. */
  bool ignore;			/* If true, produce no output (for regexp). */
  bool regexpr;			/* True if regular expression was used. */
  struct re_pattern_buffer re_compiled;	/* Compiled regular expression. */
};

/* Initial size of data area in buffers. */
#define START_SIZE	8191

/* Number of lines kept in each node in line list. */
#define CTRL_SIZE	80

#ifdef DEBUG
/* Some small values to test the algorithms. */
# define START_SIZE	200
# define CTRL_SIZE	1
#endif

/* A string with a length count. */
struct cstring
{
  idx_t len;
  char *str;
};

/* Pointers to the beginnings of lines in the buffer area.
   These structures are linked together if needed. */
struct line
{
  idx_t used;			/* Number of offsets used in this struct. */
  idx_t insert_index;		/* Next offset to use when inserting line. */
  idx_t retrieve_index;	/* Next index to use when retrieving line. */
  struct cstring starts[CTRL_SIZE]; /* Lines in the data area. */
  struct line *next;		/* Next in linked list. */
};

/* The structure to hold the input lines.
   Contains a pointer to the data area and a list containing
   pointers to the individual lines. */
struct buffer_record
{
  idx_t bytes_alloc;		/* Size of the buffer area. */
  idx_t bytes_used;		/* Bytes used in the buffer area. */
  intmax_t start_line;		/* First line number in this buffer. */
  intmax_t first_available;	/* First line that can be retrieved. */
  idx_t num_lines;		/* Number of complete lines in this buffer. */
  char *buffer;			/* Data area. */
  struct line *line_start;	/* Head of list of pointers to lines. */
  struct line *curr_line;	/* The line start record currently in use. */
  struct buffer_record *next;
};

static void close_output_file (void);
static void create_output_file (void);
static void delete_all_files (bool);
static void save_line_to_file (const struct cstring *line);

/* Start of buffer list. */
static struct buffer_record *head = nullptr;

/* Partially read line. */
static char *hold_area = nullptr;

/* Number of bytes in 'hold_area'. */
static idx_t hold_count = 0;

/* Number of the last line in the buffers. */
static intmax_t last_line_number = 0;

/* Number of the line currently being examined. */
static intmax_t current_line = 0;

/* If true, we have read EOF. */
static bool have_read_eof = false;

/* Name of output files. */
static char *volatile filename_space = nullptr;

/* Prefix part of output file names. */
static char const *volatile prefix = nullptr;

/* Suffix part of output file names. */
static char *volatile suffix = nullptr;

/* Number of digits to use in output file names. */
static int volatile digits = 2;

/* Number of files created so far. */
static int volatile files_created = 0;

/* Number of bytes written to current file. */
static intmax_t bytes_written;

/* Output file pointer. */
static FILE *output_stream = nullptr;

/* Output file name. */
static char *output_filename = nullptr;

/* Perhaps it would be cleaner to pass arg values instead of indexes. */
static char **global_argv;

/* If true, do not print the count of bytes in each output file. */
static bool suppress_count;

/* If true, remove output files on error. */
static bool volatile remove_files;

/* If true, remove all output files which have a zero length. */
static bool elide_empty_files;

/* If true, suppress the lines that match the PATTERN */
static bool suppress_matched;

/* The compiled pattern arguments, which determine how to split
   the input file. */
static struct control *controls;

/* Number of elements in 'controls'. */
static idx_t control_used;

/* The set of signals that are caught.  */
static sigset_t caught_signals;

/* For long options that have no equivalent short option, use a
   non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
enum
{
  SUPPRESS_MATCHED_OPTION = CHAR_MAX + 1
};

static struct option const longopts[] =
{
  {"digits", required_argument, nullptr, 'n'},
  {"quiet", no_argument, nullptr, 'q'},
  {"silent", no_argument, nullptr, 's'},
  {"keep-files", no_argument, nullptr, 'k'},
  {"elide-empty-files", no_argument, nullptr, 'z'},
  {"prefix", required_argument, nullptr, 'f'},
  {"suffix-format", required_argument, nullptr, 'b'},
  {"suppress-matched", no_argument, nullptr, SUPPRESS_MATCHED_OPTION},
  {GETOPT_HELP_OPTION_DECL},
  {GETOPT_VERSION_OPTION_DECL},
  {nullptr, 0, nullptr, 0}
};

/* Optionally remove files created so far; then exit.
   Called when an error detected. */

static void
cleanup (void)
{
  sigset_t oldset;

  close_output_file ();

  sigprocmask (SIG_BLOCK, &caught_signals, &oldset);
  delete_all_files (false);
  sigprocmask (SIG_SETMASK, &oldset, nullptr);
}

static _Noreturn void
cleanup_fatal (void)
{
  cleanup ();
  exit (EXIT_FAILURE);
}

extern void
xalloc_die (void)
{
  error (0, 0, "%s", _("memory exhausted"));
  cleanup_fatal ();
}

static void
interrupt_handler (int sig)
{
  delete_all_files (true);
  signal (sig, SIG_DFL);
  /* The signal has been reset to SIG_DFL, but blocked during this
     handler.  Force the default action of this signal once the
     handler returns and the block is removed.  */
  raise (sig);
}

/* Keep track of NUM bytes of a partial line in buffer START.
   These bytes will be retrieved later when another large buffer is read.  */

static void
save_to_hold_area (char *start, idx_t num)
{
  free (hold_area);
  hold_area = start;
  hold_count = num;
}

/* Read up to MAX_N_BYTES bytes from the input stream into DEST.
   Return the number of bytes read. */

static idx_t
read_input (char *dest, idx_t max_n_bytes)
{
  idx_t bytes_read;

  if (max_n_bytes == 0)
    return 0;

  bytes_read = safe_read (STDIN_FILENO, dest, max_n_bytes);

  if (bytes_read == 0)
    have_read_eof = true;

  if (bytes_read == SAFE_READ_ERROR)
    {
      error (0, errno, _("read error"));
      cleanup_fatal ();
    }

  return bytes_read;
}

/* Initialize existing line record P. */

static void
clear_line_control (struct line *p)
{
  p->used = 0;
  p->insert_index = 0;
  p->retrieve_index = 0;
}

/* Return a new, initialized line record. */

static struct line *
new_line_control (void)
{
  struct line *p = xmalloc (sizeof *p);

  p->next = nullptr;
  clear_line_control (p);

  return p;
}

/* Record LINE_START, which is the address of the start of a line
   of length LINE_LEN in the large buffer, in the lines buffer of B. */

static void
keep_new_line (struct buffer_record *b, char *line_start, idx_t line_len)
{
  struct line *l;

  /* If there is no existing area to keep line info, get some. */
  if (b->line_start == nullptr)
    b->line_start = b->curr_line = new_line_control ();

  /* If existing area for lines is full, get more. */
  if (b->curr_line->used == CTRL_SIZE)
    {
      b->curr_line->next = new_line_control ();
      b->curr_line = b->curr_line->next;
    }

  l = b->curr_line;

  /* Record the start of the line, and update counters. */
  l->starts[l->insert_index].str = line_start;
  l->starts[l->insert_index].len = line_len;
  l->used++;
  l->insert_index++;
}

/* Scan the buffer in B for newline characters
   and record the line start locations and lengths in B.
   Return the number of lines found in this buffer.

   There may be an incomplete line at the end of the buffer;
   a pointer is kept to this area, which will be used when
   the next buffer is filled. */

static idx_t
record_line_starts (struct buffer_record *b)
{
  char *line_start;		/* Start of current line. */
  idx_t lines;			/* Number of lines found. */
  idx_t line_length;		/* Length of each line found. */

  if (b->bytes_used == 0)
    return 0;

  lines = 0;
  line_start = b->buffer;
  char *buffer_end = line_start + b->bytes_used;
  *buffer_end = '\n';

  while (true)
    {
      char *line_end = rawmemchr (line_start, '\n');
      if (line_end == buffer_end)
        break;
      line_length = line_end - line_start + 1;
      keep_new_line (b, line_start, line_length);
      line_start = line_end + 1;
      lines++;
    }

  /* Check for an incomplete last line. */
  idx_t bytes_left = buffer_end - line_start;
  if (bytes_left)
    {
      if (have_read_eof)
        {
          keep_new_line (b, line_start, bytes_left);
          lines++;
        }
      else
        save_to_hold_area (ximemdup (line_start, bytes_left), bytes_left);
    }

  b->num_lines = lines;
  b->first_available = b->start_line = last_line_number + 1;
  last_line_number += lines;

  return lines;
}

/* Work around <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109614>.  */
#if 13 <= __GNUC__
# pragma GCC diagnostic ignored "-Wanalyzer-mismatching-deallocation"
# pragma GCC diagnostic ignored "-Wanalyzer-use-after-free"
# pragma GCC diagnostic ignored "-Wanalyzer-use-of-uninitialized-value"
#endif

static void
free_buffer (struct buffer_record *buf)
{
  for (struct line *l = buf->line_start; l;)
    {
      struct line *n = l->next;
      free (l);
      l = n;
    }
  free (buf->buffer);
  free (buf);
}

/* Return a new buffer of at least MINSIZE bytes.  */

static ATTRIBUTE_DEALLOC (free_buffer, 1)
struct buffer_record *
get_new_buffer (idx_t min_size)
{
  struct buffer_record *new_buffer = xmalloc (sizeof *new_buffer);
  new_buffer->bytes_alloc = 0;
  new_buffer->buffer = xpalloc (nullptr, &new_buffer->bytes_alloc, min_size,
                                -1, 1);
  new_buffer->bytes_used = 0;
  new_buffer->start_line = new_buffer->first_available = last_line_number + 1;
  new_buffer->num_lines = 0;
  new_buffer->line_start = new_buffer->curr_line = nullptr;
  new_buffer->next = nullptr;

  return new_buffer;
}

/* Append buffer BUF to the linked list of buffers that contain
   some data yet to be processed. */

static void
save_buffer (struct buffer_record *buf)
{
  struct buffer_record *p;

  buf->next = nullptr;
  buf->curr_line = buf->line_start;

  if (head == nullptr)
    head = buf;
  else
    {
      for (p = head; p->next; p = p->next)
        /* Do nothing. */ ;
      p->next = buf;
    }
}

/* Fill a buffer of input.

   Set the initial size of the buffer to a default.
   Fill the buffer (from the hold area and input stream)
   and find the individual lines.
   If no lines are found (the buffer is too small to hold the next line),
   release the current buffer (whose contents would have been put in the
   hold area) and repeat the process with another large buffer until at least
   one entire line has been read.

   Return true if a new buffer was obtained, otherwise false
   (in which case end-of-file must have been encountered). */

static bool
load_buffer (void)
{
  if (have_read_eof)
    return false;

  /* We must make the buffer at least as large as the amount of data
     in the partial line left over from the last call,
     plus room for a sentinel '\n'. */
  idx_t bytes_wanted = MAX (START_SIZE, hold_count + 1);

  while (true)
    {
      struct buffer_record *b = get_new_buffer (bytes_wanted);
      idx_t bytes_alloc = b->bytes_alloc;
      idx_t bytes_avail = bytes_alloc;
      char *p = b->buffer;

      /* First check the 'holding' area for a partial line. */
      if (hold_count)
        {
          p = mempcpy (p, hold_area, hold_count);
          b->bytes_used += hold_count;
          bytes_avail -= hold_count;
          hold_count = 0;
        }

      b->bytes_used += read_input (p, bytes_avail - 1);

      if (record_line_starts (b) != 0)
        {
          save_buffer (b);
          return true;
        }

      free_buffer (b);
      if (have_read_eof)
        return false;
      if (ckd_add (&bytes_wanted, bytes_alloc, bytes_alloc >> 1))
        xalloc_die ();
    }
}

/* Return the line number of the first line that has not yet been retrieved. */

static intmax_t
get_first_line_in_buffer (void)
{
  if (head == nullptr && !load_buffer ())
    error (EXIT_FAILURE, errno, _("input disappeared"));

  return head->first_available;
}

/* Return a pointer to the logical first line in the buffer and make the
   next line the logical first line.
   Return nullptr if there is no more input. */

static struct cstring *
remove_line (void)
{
  /* If non-null, this is the buffer for which the previous call
     returned the final line.  So now, presuming that line has been
     processed, we can free the buffer and reset this pointer.  */
  static struct buffer_record *prev_buf = nullptr;

  struct cstring *line;		/* Return value. */
  struct line *l;		/* For convenience. */

  if (prev_buf)
    {
      free_buffer (prev_buf);
      prev_buf = nullptr;
    }

  if (head == nullptr && !load_buffer ())
    return nullptr;

  if (current_line < head->first_available)
    current_line = head->first_available;

  ++(head->first_available);

  l = head->curr_line;

  line = &l->starts[l->retrieve_index];

  /* Advance index to next line. */
  if (++l->retrieve_index == l->used)
    {
      /* Go on to the next line record. */
      head->curr_line = l->next;
      if (head->curr_line == nullptr || head->curr_line->used == 0)
        {
          /* Go on to the next data block.
             but first record the current one so we can free it
             once the line we're returning has been processed.  */
          prev_buf = head;
          head = head->next;
        }
    }

  return line;
}

/* Search the buffers for line LINENUM, reading more input if necessary.
   Return a pointer to the line, or nullptr if it is not found in the file. */

static struct cstring *
find_line (intmax_t linenum)
{
  struct buffer_record *b;

  if (head == nullptr && !load_buffer ())
    return nullptr;

  if (linenum < head->start_line)
    return nullptr;

  for (b = head;;)
    {
      if (linenum < b->start_line + b->num_lines)
        {
          /* The line is in this buffer. */
          struct line *l;
          idx_t offset;	/* How far into the buffer the line is. */

          l = b->line_start;
          offset = linenum - b->start_line;
          /* Find the control record. */
          while (offset >= CTRL_SIZE)
            {
              l = l->next;
              offset -= CTRL_SIZE;
            }
          return &l->starts[offset];
        }
      if (b->next == nullptr && !load_buffer ())
        return nullptr;
      b = b->next;		/* Try the next data block. */
    }
}

/* Return true if at least one more line is available for input. */

static bool
no_more_lines (void)
{
  return find_line (current_line + 1) == nullptr;
}

/* Open NAME as standard input.  */

static void
set_input_file (char const *name)
{
  if (! STREQ (name, "-") && fd_reopen (STDIN_FILENO, name, O_RDONLY, 0) < 0)
    error (EXIT_FAILURE, errno, _("cannot open %s for reading"),
           quoteaf (name));
}

/* Write all lines from the beginning of the buffer up to, but
   not including, line LAST_LINE, to the current output file.
   If IGNORE is true, do not output lines selected here.
   ARGNUM is the index in ARGV of the current pattern. */

static void
write_to_file (intmax_t last_line, bool ignore, int argnum)
{
  struct cstring *line;
  intmax_t first_line;		/* First available input line. */
  intmax_t lines;		/* Number of lines to output. */
  intmax_t i;

  first_line = get_first_line_in_buffer ();

  if (first_line > last_line)
    {
      error (0, 0, _("%s: line number out of range"),
             quote (global_argv[argnum]));
      cleanup_fatal ();
    }

  lines = last_line - first_line;

  for (i = 0; i < lines; i++)
    {
      line = remove_line ();
      if (line == nullptr)
        {
          error (0, 0, _("%s: line number out of range"),
                 quote (global_argv[argnum]));
          cleanup_fatal ();
        }
      if (!ignore)
        save_line_to_file (line);
    }
}

/* Output any lines left after all regexps have been processed. */

static void
dump_rest_of_file (void)
{
  struct cstring *line;

  while ((line = remove_line ()) != nullptr)
    save_line_to_file (line);
}

/* Handle an attempt to read beyond EOF under the control of record P,
   on iteration REPETITION if nonzero. */

static void
handle_line_error (const struct control *p, intmax_t repetition)
{
  char buf[INT_BUFSIZE_BOUND (intmax_t)];

  fprintf (stderr, _("%s: %s: line number out of range"),
           program_name, quote (imaxtostr (p->lines_required, buf)));
  if (repetition)
    fprintf (stderr, _(" on repetition %s\n"), imaxtostr (repetition, buf));
  else
    fprintf (stderr, "\n");

  cleanup_fatal ();
}

/* Determine the line number that marks the end of this file,
   then get those lines and save them to the output file.
   P is the control record.
   REPETITION is the repetition number. */

static void
process_line_count (const struct control *p, intmax_t repetition)
{
  intmax_t linenum;
  intmax_t last_line_to_save = p->lines_required * (repetition + 1);

  create_output_file ();

  /* Ensure that the line number specified is not 1 greater than
     the number of lines in the file.
     When suppressing matched lines, check before the loop. */
  if (no_more_lines () && suppress_matched)
    handle_line_error (p, repetition);

  linenum = get_first_line_in_buffer ();
  while (linenum++ < last_line_to_save)
    {
      struct cstring *line = remove_line ();
      if (line == nullptr)
        handle_line_error (p, repetition);
      save_line_to_file (line);
    }

  close_output_file ();

  if (suppress_matched)
    remove_line ();

  /* Ensure that the line number specified is not 1 greater than
     the number of lines in the file. */
  if (no_more_lines () && !suppress_matched)
    handle_line_error (p, repetition);
}

static void
regexp_error (struct control *p, intmax_t repetition, bool ignore)
{
  fprintf (stderr, _("%s: %s: match not found"),
           program_name, quote (global_argv[p->argnum]));

  if (repetition)
    {
      char buf[INT_BUFSIZE_BOUND (intmax_t)];
      fprintf (stderr, _(" on repetition %s\n"), imaxtostr (repetition, buf));
    }
  else
    fprintf (stderr, "\n");

  if (!ignore)
    {
      dump_rest_of_file ();
      close_output_file ();
    }
  cleanup_fatal ();
}

/* Read the input until a line matches the regexp in P, outputting
   it unless P->IGNORE is true.
   REPETITION is this repeat-count; 0 means the first time. */

static void
process_regexp (struct control *p, intmax_t repetition)
{
  struct cstring *line;		/* From input file. */
  idx_t line_len;		/* To make "$" in regexps work. */
  intmax_t break_line;		/* First line number of next file. */
  bool ignore = p->ignore;	/* If true, skip this section. */
  regoff_t ret;

  if (!ignore)
    create_output_file ();

  /* If there is no offset for the regular expression, or
     it is positive, then it is not necessary to buffer the lines. */

  if (p->offset >= 0)
    {
      while (true)
        {
          line = find_line (++current_line);
          if (line == nullptr)
            {
              if (p->repeat_forever)
                {
                  if (!ignore)
                    {
                      dump_rest_of_file ();
                      close_output_file ();
                    }
                  exit (EXIT_SUCCESS);
                }
              else
                regexp_error (p, repetition, ignore);
            }
          line_len = line->len;
          if (line->str[line_len - 1] == '\n')
            line_len--;
          ret = re_search (&p->re_compiled, line->str, line_len,
                           0, line_len, nullptr);
          if (ret == -2)
            {
              error (0, 0, _("error in regular expression search"));
              cleanup_fatal ();
            }
          if (ret == -1)
            {
              line = remove_line ();
              if (!ignore)
                save_line_to_file (line);
            }
          else
            break;
        }
    }
  else
    {
      /* Buffer the lines. */
      while (true)
        {
          line = find_line (++current_line);
          if (line == nullptr)
            {
              if (p->repeat_forever)
                {
                  if (!ignore)
                    {
                      dump_rest_of_file ();
                      close_output_file ();
                    }
                  exit (EXIT_SUCCESS);
                }
              else
                regexp_error (p, repetition, ignore);
            }
          line_len = line->len;
          if (line->str[line_len - 1] == '\n')
            line_len--;
          ret = re_search (&p->re_compiled, line->str, line_len,
                           0, line_len, nullptr);
          if (ret == -2)
            {
              error (0, 0, _("error in regular expression search"));
              cleanup_fatal ();
            }
          if (ret != -1)
            break;
        }
    }

  /* Account for any offset from this regexp. */
  break_line = current_line + p->offset;

  write_to_file (break_line, ignore, p->argnum);

  if (!ignore)
    close_output_file ();

  if (p->offset > 0)
    current_line = break_line;

  if (suppress_matched)
    remove_line ();
}

/* Split the input file according to the control records we have built. */

static void
split_file (void)
{
  for (idx_t i = 0; i < control_used; i++)
    {
      intmax_t j;
      if (controls[i].regexpr)
        {
          for (j = 0; (controls[i].repeat_forever
                       || j <= controls[i].repeat); j++)
            process_regexp (&controls[i], j);
        }
      else
        {
          for (j = 0; (controls[i].repeat_forever
                       || j <= controls[i].repeat); j++)
            process_line_count (&controls[i], j);
        }
    }

  create_output_file ();
  dump_rest_of_file ();
  close_output_file ();
}

/* Return the name of output file number NUM.

   This function is called from a signal handler, so it should invoke
   only reentrant functions that are async-signal-safe.  POSIX does
   not guarantee this for the functions called below, but we don't
   know of any hosts where this implementation isn't safe.  */

static char *
make_filename (int num)
{
  strcpy (filename_space, prefix);
  if (suffix)
    sprintf (filename_space + strlen (prefix), suffix, num);
  else
    sprintf (filename_space + strlen (prefix), "%0*d", digits, num);
  return filename_space;
}

/* Create the next output file. */

static void
create_output_file (void)
{
  int nfiles = files_created;
  bool fopen_ok;
  int fopen_errno;

  output_filename = make_filename (nfiles);

  if (nfiles == INT_MAX)
    {
      fopen_ok = false;
      fopen_errno = EOVERFLOW;
    }
  else
    {
      /* Create the output file in a critical section, to avoid races.  */
      sigset_t oldset;
      sigprocmask (SIG_BLOCK, &caught_signals, &oldset);
      output_stream = fopen (output_filename, "w");
      fopen_ok = (output_stream != nullptr);
      fopen_errno = errno;
      files_created = nfiles + fopen_ok;
      sigprocmask (SIG_SETMASK, &oldset, nullptr);
    }

  if (! fopen_ok)
    {
      error (0, fopen_errno, "%s", quotef (output_filename));
      cleanup_fatal ();
    }
  bytes_written = 0;
}

/* If requested, delete all the files we have created.  This function
   must be called only from critical sections.  */

static void
delete_all_files (bool in_signal_handler)
{
  if (! remove_files)
    return;

  for (int i = files_created; 0 <= --i; )
    {
      char const *name = make_filename (i);
      if (unlink (name) != 0 && errno != ENOENT && !in_signal_handler)
        error (0, errno, "%s", quotef (name));
    }

  files_created = 0;
}

/* Close the current output file and print the count
   of characters in this file. */

static void
close_output_file (void)
{
  if (output_stream)
    {
      if (ferror (output_stream))
        {
          error (0, 0, _("write error for %s"), quoteaf (output_filename));
          output_stream = nullptr;
          cleanup_fatal ();
        }
      if (fclose (output_stream) != 0)
        {
          error (0, errno, "%s", quotef (output_filename));
          output_stream = nullptr;
          cleanup_fatal ();
        }
      if (bytes_written == 0 && elide_empty_files)
        {
          sigset_t oldset;
          bool unlink_ok;
          int unlink_errno;

          /* Remove the output file in a critical section, to avoid races.  */
          sigprocmask (SIG_BLOCK, &caught_signals, &oldset);
          unlink_ok = (unlink (output_filename) == 0);
          unlink_errno = errno;
          files_created--;
          sigprocmask (SIG_SETMASK, &oldset, nullptr);

          if (! unlink_ok && unlink_errno != ENOENT)
            error (0, unlink_errno, "%s", quotef (output_filename));
        }
      else
        {
          if (!suppress_count)
            {
              char buf[INT_BUFSIZE_BOUND (intmax_t)];
              fprintf (stdout, "%s\n", imaxtostr (bytes_written, buf));
            }
        }
      output_stream = nullptr;
    }
}

/* Save line LINE to the output file and
   increment the character count for the current file. */

static void
save_line_to_file (const struct cstring *line)
{
  idx_t l = fwrite (line->str, sizeof (char), line->len, output_stream);
  if (l != line->len)
    {
      error (0, errno, _("write error for %s"), quoteaf (output_filename));
      output_stream = nullptr;
      cleanup_fatal ();
    }
  bytes_written += line->len;
}

/* Return a new, initialized control record. */

static struct control *
new_control_record (void)
{
  static idx_t control_allocated = 0; /* Total space allocated. */
  struct control *p;

  if (control_used == control_allocated)
    controls = xpalloc (controls, &control_allocated, 1, -1, sizeof *controls);
  p = &controls[control_used++];
  p->regexpr = false;
  p->repeat = 0;
  p->repeat_forever = false;
  p->lines_required = 0;
  p->offset = 0;
  return p;
}

/* Check if there is a numeric offset after a regular expression.
   STR is the entire command line argument.
   P is the control record for this regular expression.
   NUM is the numeric part of STR. */

static void
check_for_offset (struct control *p, char const *str, char const *num)
{
  if (xstrtoimax (num, nullptr, 10, &p->offset, "") != LONGINT_OK)
    error (EXIT_FAILURE, 0, _("%s: integer expected after delimiter"),
           quote (str));
}

/* Given that the first character of command line arg STR is '{',
   make sure that the rest of the string is a valid repeat count
   and store its value in P.
   ARGNUM is the ARGV index of STR. */

static void
parse_repeat_count (int argnum, struct control *p, char *str)
{
  char *end;

  end = str + strlen (str) - 1;
  if (*end != '}')
    error (EXIT_FAILURE, 0, _("%s: '}' is required in repeat count"),
           quote (str));
  *end = '\0';

  if (str + 1 == end - 1 && *(str + 1) == '*')
    p->repeat_forever = true;
  else
    {
      uintmax_t val;
      if (xstrtoumax (str + 1, nullptr, 10, &val, "") != LONGINT_OK
          || INTMAX_MAX < val)
        {
          error (EXIT_FAILURE, 0,
                 _("%s}: integer required between '{' and '}'"),
                 quote (global_argv[argnum]));
        }
      p->repeat = val;
    }

  *end = '}';
}

/* Extract the regular expression from STR and check for a numeric offset.
   STR should start with the regexp delimiter character.
   Return a new control record for the regular expression.
   ARGNUM is the ARGV index of STR.
   Unless IGNORE is true, mark these lines for output. */

static struct control *
extract_regexp (int argnum, bool ignore, char const *str)
{
  idx_t len;			/* Number of bytes in this regexp. */
  char delim = *str;
  char const *closing_delim;
  struct control *p;
  char const *err;

  closing_delim = strrchr (str + 1, delim);
  if (closing_delim == nullptr)
    error (EXIT_FAILURE, 0,
           _("%s: closing delimiter '%c' missing"), str, delim);

  len = closing_delim - str - 1;
  p = new_control_record ();
  p->argnum = argnum;
  p->ignore = ignore;

  p->regexpr = true;
  p->re_compiled.buffer = nullptr;
  p->re_compiled.allocated = 0;
  p->re_compiled.fastmap = xmalloc (UCHAR_MAX + 1);
  p->re_compiled.translate = nullptr;
  re_syntax_options =
    RE_SYNTAX_POSIX_BASIC & ~RE_CONTEXT_INVALID_DUP & ~RE_NO_EMPTY_RANGES;
  err = re_compile_pattern (str + 1, len, &p->re_compiled);
  if (err)
    {
      error (0, 0, _("%s: invalid regular expression: %s"), quote (str), err);
      cleanup_fatal ();
    }

  if (closing_delim[1])
    check_for_offset (p, str, closing_delim + 1);

  return p;
}

/* Extract the break patterns from args START through ARGC - 1 of ARGV.
   After each pattern, check if the next argument is a repeat count. */

static void
parse_patterns (int argc, int start, char **argv)
{
  struct control *p;		/* New control record created. */
  static intmax_t last_val = 0;

  for (int i = start; i < argc; i++)
    {
      if (*argv[i] == '/' || *argv[i] == '%')
        {
          p = extract_regexp (i, *argv[i] == '%', argv[i]);
        }
      else
        {
          p = new_control_record ();
          p->argnum = i;

          uintmax_t val;
          if (xstrtoumax (argv[i], nullptr, 10, &val, "") != LONGINT_OK
              || INTMAX_MAX < val)
            error (EXIT_FAILURE, 0, _("%s: invalid pattern"), quote (argv[i]));
          if (val == 0)
            error (EXIT_FAILURE, 0,
                   _("%s: line number must be greater than zero"), argv[i]);
          if (val < last_val)
            {
              char buf[INT_BUFSIZE_BOUND (intmax_t)];
              error (EXIT_FAILURE, 0,
                     _("line number %s is smaller than preceding line number,"
                       " %s"),
                     quote (argv[i]), imaxtostr (last_val, buf));
            }

          if (val == last_val)
            error (0, 0,
           _("warning: line number %s is the same as preceding line number"),
                   quote (argv[i]));

          last_val = val;

          p->lines_required = val;
        }

      if (i + 1 < argc && *argv[i + 1] == '{')
        {
          /* We have a repeat count. */
          i++;
          parse_repeat_count (i, p, argv[i]);
        }
    }
}



/* Names for the printf format flags ' and #.  These can be ORed together.  */
enum { FLAG_THOUSANDS = 1, FLAG_ALTERNATIVE = 2 };

/* Scan the printf format flags in FORMAT, storing info about the
   flags into *FLAGS_PTR.  Return the number of flags found.  */
static idx_t
get_format_flags (char const *format, int *flags_ptr)
{
  int flags = 0;

  for (idx_t count = 0; ; count++)
    {
      switch (format[count])
        {
        case '-':
        case '0':
          break;

        case '\'':
          flags |= FLAG_THOUSANDS;
          break;

        case '#':
          flags |= FLAG_ALTERNATIVE;
          break;

        default:
          *flags_ptr = flags;
          return count;
        }
    }
}

/* Check that the printf format conversion specifier *FORMAT is valid
   and compatible with FLAGS.  Change it to 'd' if it is 'u',
   since the format will be used with a signed value.  */
static void
check_format_conv_type (char *format, int flags)
{
  unsigned char ch = *format;
  int compatible_flags = FLAG_THOUSANDS;

  switch (ch)
    {
    case 'd':
    case 'i':
      break;

    case 'u':
      *format = 'd';
      break;

    case 'o':
    case 'x':
    case 'X':
      compatible_flags = FLAG_ALTERNATIVE;
      break;

    case 0:
      error (EXIT_FAILURE, 0, _("missing conversion specifier in suffix"));

    default:
      if (isprint (ch))
        error (EXIT_FAILURE, 0,
               _("invalid conversion specifier in suffix: %c"), ch);
      else
        error (EXIT_FAILURE, 0,
               _("invalid conversion specifier in suffix: \\%.3o"), ch);
    }

  if (flags & ~ compatible_flags)
    error (EXIT_FAILURE, 0,
           _("invalid flags in conversion specification: %%%c%c"),
           (flags & ~ compatible_flags & FLAG_ALTERNATIVE ? '#' : '\''), ch);
}

/* Return the maximum number of bytes that can be generated by
   applying FORMAT to an int value.  If the format is
   invalid, diagnose the problem and exit.  */
static idx_t
max_out (char *format)
{
  bool percent = false;

  for (char *f = format; *f; f++)
    if (*f == '%' && *++f != '%')
      {
        if (percent)
          error (EXIT_FAILURE, 0,
                 _("too many %% conversion specifications in suffix"));
        percent = true;
        int flags;
        f += get_format_flags (f, &flags);
        while (ISDIGIT (*f))
          f++;
        if (*f == '.')
          while (ISDIGIT (*++f))
            continue;
        check_format_conv_type (f, flags);
      }

  if (! percent)
    error (EXIT_FAILURE, 0,
           _("missing %% conversion specification in suffix"));

  int maxlen = snprintf (nullptr, 0, format, INT_MAX);
  if (maxlen < 0)
    xalloc_die ();
  return maxlen;
}

int
main (int argc, char **argv)
{
  int optc;

  initialize_main (&argc, &argv);
  set_program_name (argv[0]);
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);

  atexit (close_stdout);

  global_argv = argv;
  controls = nullptr;
  control_used = 0;
  suppress_count = false;
  remove_files = true;
  suppress_matched = false;
  prefix = DEFAULT_PREFIX;

  while ((optc = getopt_long (argc, argv, "f:b:kn:sqz", longopts, nullptr))
         != -1)
    switch (optc)
      {
      case 'f':
        prefix = optarg;
        break;

      case 'b':
        suffix = optarg;
        break;

      case 'k':
        remove_files = false;
        break;

      case 'n':
        digits = xdectoimax (optarg, 0, MIN (INT_MAX, IDX_MAX), "",
                             _("invalid number"), 0);
        break;

      case 's':
      case 'q':
        suppress_count = true;
        break;

      case 'z':
        elide_empty_files = true;
        break;

      case SUPPRESS_MATCHED_OPTION:
        suppress_matched = true;
        break;

      case_GETOPT_HELP_CHAR;

      case_GETOPT_VERSION_CHAR (PROGRAM_NAME, AUTHORS);

      default:
        usage (EXIT_FAILURE);
      }

  if (argc - optind < 2)
    {
      if (argc <= optind)
        error (0, 0, _("missing operand"));
      else
        error (0, 0, _("missing operand after %s"), quote (argv[argc - 1]));
      usage (EXIT_FAILURE);
    }

  idx_t prefix_len = strlen (prefix);
  idx_t max_digit_string_len
    = (suffix
       ? max_out (suffix)
       : MAX (INT_STRLEN_BOUND (int), digits));
  idx_t filename_size;
  if (ckd_add (&filename_size, prefix_len, max_digit_string_len + 1))
    xalloc_die ();
  filename_space = ximalloc (filename_size);

  set_input_file (argv[optind++]);

  parse_patterns (argc, optind, argv);

  {
    int i;
    static int const sig[] =
      {
        /* The usual suspects.  */
        SIGALRM, SIGHUP, SIGINT, SIGPIPE, SIGQUIT, SIGTERM,
#ifdef SIGPOLL
        SIGPOLL,
#endif
#ifdef SIGPROF
        SIGPROF,
#endif
#ifdef SIGVTALRM
        SIGVTALRM,
#endif
#ifdef SIGXCPU
        SIGXCPU,
#endif
#ifdef SIGXFSZ
        SIGXFSZ,
#endif
      };
    enum { nsigs = ARRAY_CARDINALITY (sig) };

    struct sigaction act;

    sigemptyset (&caught_signals);
    for (i = 0; i < nsigs; i++)
      {
        sigaction (sig[i], nullptr, &act);
        if (act.sa_handler != SIG_IGN)
          sigaddset (&caught_signals, sig[i]);
      }

    act.sa_handler = interrupt_handler;
    act.sa_mask = caught_signals;
    act.sa_flags = 0;

    for (i = 0; i < nsigs; i++)
      if (sigismember (&caught_signals, sig[i]))
        sigaction (sig[i], &act, nullptr);
  }

  split_file ();

  if (close (STDIN_FILENO) != 0)
    {
      error (0, errno, _("read error"));
      cleanup_fatal ();
    }

  return EXIT_SUCCESS;
}

void
usage (int status)
{
  if (status != EXIT_SUCCESS)
    emit_try_help ();
  else
    {
      printf (_("\
Usage: %s [OPTION]... FILE PATTERN...\n\
"),
              program_name);
      fputs (_("\
Output pieces of FILE separated by PATTERN(s) to files 'xx00', 'xx01', ...,\n\
and output byte counts of each piece to standard output.\n\
"), stdout);
       fputs (_("\
\n\
Read standard input if FILE is -\n\
"), stdout);

      emit_mandatory_arg_note ();

      fputs (_("\
  -b, --suffix-format=FORMAT  use sprintf FORMAT instead of %02d\n\
  -f, --prefix=PREFIX        use PREFIX instead of 'xx'\n\
  -k, --keep-files           do not remove output files on errors\n\
"), stdout);
      fputs (_("\
      --suppress-matched     suppress the lines matching PATTERN\n\
"), stdout);
      fputs (_("\
  -n, --digits=DIGITS        use specified number of digits instead of 2\n\
  -s, --quiet, --silent      do not print counts of output file sizes\n\
  -z, --elide-empty-files    suppress empty output files\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      fputs (_("\
\n\
Each PATTERN may be:\n\
  INTEGER            copy up to but not including specified line number\n\
  /REGEXP/[OFFSET]   copy up to but not including a matching line\n\
  %REGEXP%[OFFSET]   skip to, but not including a matching line\n\
  {INTEGER}          repeat the previous pattern specified number of times\n\
  {*}                repeat the previous pattern as many times as possible\n\
\n\
A line OFFSET is an integer optionally preceded by '+' or '-'\n\
"), stdout);
      emit_ancillary_info (PROGRAM_NAME);
    }
  exit (status);
}