glibc/argp/argp-fmtstream.c

/* Word-wrapping and line-truncating streams
   Copyright (C) 1997 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Written by Miles Bader <miles@gnu.ai.mit.edu>.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library 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
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library; see the file COPYING.LIB.  If not,
   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

/* This package emulates glibc `line_wrap_stream' semantics for systems that
   don't have that.  */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stdarg.h>
#include <ctype.h>

#include "argp-fmtstream.h"
#include "argp-namefrob.h"

#ifndef ARGP_FMTSTREAM_USE_LINEWRAP

#ifndef isblank
#define isblank(ch) ((ch)==' ' || (ch)=='\t')
#endif

#define INIT_BUF_SIZE 200
#define PRINTF_SIZE_GUESS 150

/* Return an argp_fmtstream that outputs to STREAM, and which prefixes lines
   written on it with LMARGIN spaces and limits them to RMARGIN columns
   total.  If WMARGIN >= 0, words that extend past RMARGIN are wrapped by
   replacing the whitespace before them with a newline and WMARGIN spaces.
   Otherwise, chars beyond RMARGIN are simply dropped until a newline.
   Returns NULL if there was an error.  */
argp_fmtstream_t
__argp_make_fmtstream (FILE *stream,
		       size_t lmargin, size_t rmargin, ssize_t wmargin)
{
  argp_fmtstream_t fs = malloc (sizeof (struct argp_fmtstream));
  if (fs)
    {
      fs->stream = stream;

      fs->lmargin = lmargin;
      fs->rmargin = rmargin;
      fs->wmargin = wmargin;
      fs->point_col = 0;
      fs->point_offs = 0;

      fs->buf = malloc (INIT_BUF_SIZE);
      if (! fs->buf)
	{
	  free (fs);
	  fs = 0;
	}
      else
	{
	  fs->p = fs->buf;
	  fs->end = fs->buf + INIT_BUF_SIZE;
	}
    }

  return fs;
}
#ifdef weak_alias
weak_alias (__argp_make_fmtstream, argp_make_fmtstream)
#endif

/* Flush FS to its stream, and free it (but don't close the stream).  */
void
__argp_fmtstream_free (argp_fmtstream_t fs)
{
  __argp_fmtstream_update (fs);
  if (fs->p > fs->buf)
    fwrite (fs->buf, 1, fs->p - fs->buf, fs->stream);
  free (fs->buf);
  free (fs);
}
#ifdef weak_alias
weak_alias (__argp_fmtstream_free, argp_fmtstream_free)
#endif

/* Process FS's buffer so that line wrapping is done from POINT_OFFS to the
   end of its buffer.  This code is mostly from glibc stdio/linewrap.c.  */
void
__argp_fmtstream_update (argp_fmtstream_t fs)
{
  char *buf, *nl;
  size_t len;

  /* Scan the buffer for newlines.  */
  buf = fs->buf + fs->point_offs;
  while (buf < fs->p)
    {
      size_t r;

      if (fs->point_col == 0 && fs->lmargin != 0)
	{
	  /* We are starting a new line.  Print spaces to the left margin.  */
	  const size_t pad = fs->lmargin;
	  if (fs->p + pad < fs->end)
	    {
	      /* We can fit in them in the buffer by moving the
		 buffer text up and filling in the beginning.  */
	      memmove (buf + pad, buf, fs->p - buf);
	      fs->p += pad; /* Compensate for bigger buffer. */
	      memset (buf, ' ', pad); /* Fill in the spaces.  */
	      buf += pad; /* Don't bother searching them.  */
	    }
	  else
	    {
	      /* No buffer space for spaces.  Must flush.  */
	      size_t i;
	      for (i = 0; i < pad; i++)
		putc (' ', fs->stream);
	    }
	  fs->point_col = pad;
	}

      len = fs->p - buf;
      nl = memchr (buf, '\n', len);

      if (fs->point_col < 0)
	fs->point_col = 0;

      if (!nl)
	{
	  /* The buffer ends in a partial line.  */

	  if (fs->point_col + len < fs->rmargin)
	    {
	      /* The remaining buffer text is a partial line and fits
		 within the maximum line width.  Advance point for the
		 characters to be written and stop scanning.  */
	      fs->point_col += len;
	      break;
	    }
	  else
	    /* Set the end-of-line pointer for the code below to
	       the end of the buffer.  */
	    nl = fs->p;
	}
      else if (fs->point_col + (nl - buf) < fs->rmargin)
	{
	  /* The buffer contains a full line that fits within the maximum
	     line width.  Reset point and scan the next line.  */
	  fs->point_col = 0;
	  buf = nl + 1;
	  continue;
	}

      /* This line is too long.  */
      r = fs->rmargin - 1;

      if (fs->wmargin < 0)
	{
	  /* Truncate the line by overwriting the excess with the
	     newline and anything after it in the buffer.  */
	  if (nl < fs->p)
	    {
	      memmove (buf + (r - fs->point_col), nl, fs->p - nl);
	      fs->p -= buf + (r - fs->point_col) - nl;
	      /* Reset point for the next line and start scanning it.  */
	      fs->point_col = 0;
	      buf += r + 1; /* Skip full line plus \n. */
	    }
	  else
	    {
	      /* The buffer ends with a partial line that is beyond the
		 maximum line width.  Advance point for the characters
		 written, and discard those past the max from the buffer.  */
	      fs->point_col += len;
	      fs->p -= fs->point_col - r;
	      break;
	    }
	}
      else
	{
	  /* Do word wrap.  Go to the column just past the maximum line
	     width and scan back for the beginning of the word there.
	     Then insert a line break.  */

	  char *p, *nextline;
	  int i;

	  p = buf + (r + 1 - fs->point_col);
	  while (p >= buf && !isblank (*p))
	    --p;
	  nextline = p + 1;	/* This will begin the next line.  */

	  if (nextline > buf)
	    {
	      /* Swallow separating blanks.  */
	      if (p > buf)
		do
		  --p;
		while (p > buf && isblank (*p));
	      nl = p + 1;	/* The newline will replace the first blank. */
	    }
	  else
	    {
	      /* A single word that is greater than the maximum line width.
		 Oh well.  Put it on an overlong line by itself.  */
	      p = buf + (r + 1 - fs->point_col);
	      /* Find the end of the long word.  */
	      do
		++p;
	      while (p < nl && !isblank (*p));
	      if (p == nl)
		{
		  /* It already ends a line.  No fussing required.  */
		  fs->point_col = 0;
		  buf = nl + 1;
		  continue;
		}
	      /* We will move the newline to replace the first blank.  */
	      nl = p;
	      /* Swallow separating blanks.  */
	      do
		++p;
	      while (isblank (*p));
	      /* The next line will start here.  */
	      nextline = p;
	    }

	  if (nextline - (nl + 1) < fs->wmargin)
	    /* The margin needs more blanks than we removed.  */
	    if (fs->end - fs->p > fs->wmargin + 1)
	      /* Make some space for them.  */
	      {
		size_t mv = fs->p - nextline;
		memmove (nl + 1 + fs->wmargin, nextline, mv);
		nextline = nl + 1 + fs->wmargin;
		len = nextline + mv - buf;
		*nl++ = '\n';
	      }
	    else
	      /* Output the first line so we can use the space.  */
	      {
		if (nl > fs->buf)
		  fwrite (fs->buf, 1, nl - fs->buf, fs->stream);
		putc ('\n', fs->stream);
		len += buf - fs->buf;
		nl = buf = fs->buf;
	      }
	  else
	    /* We can fit the newline and blanks in before
	       the next word.  */
	    *nl++ = '\n';

	  if (nextline - nl >= fs->wmargin)
	    /* Add blanks up to the wrap margin column.  */
	    for (i = 0; i < fs->wmargin; ++i)
	      *nl++ = ' ';
	  else
	    for (i = 0; i < fs->wmargin; ++i)
	      putc (' ', fs->stream);

	  /* Copy the tail of the original buffer into the current buffer
	     position.  */
	  if (nl != nextline)
	    memmove (nl, nextline, buf + len - nextline);
	  len -= nextline - buf;

	  /* Continue the scan on the remaining lines in the buffer.  */
	  buf = nl;

	  /* Restore bufp to include all the remaining text.  */
	  fs->p = nl + len;

	  /* Reset the counter of what has been output this line.  If wmargin
	     is 0, we want to avoid the lmargin getting added, so we set
	     point_col to a magic value of -1 in that case.  */
	  fs->point_col = fs->wmargin ? fs->wmargin : -1;
	}
    }

  /* Remember that we've scanned as far as the end of the buffer.  */
  fs->point_offs = fs->p - fs->buf;
}

/* Ensure that FS has space for AMOUNT more bytes in its buffer, either by
   growing the buffer, or by flushing it.  True is returned iff we succeed. */
int
__argp_fmtstream_ensure (struct argp_fmtstream *fs, size_t amount)
{
  if (fs->end - fs->p < amount)
    {
      ssize_t wrote;

      /* Flush FS's buffer.  */
      __argp_fmtstream_update (fs);

      wrote = fwrite (fs->buf, 1, fs->p - fs->buf, fs->stream);
      if (wrote == fs->p - fs->buf)
	{
	  fs->p = fs->buf;
	  fs->point_offs = 0;
	}
      else
	{
	  fs->p -= wrote;
	  fs->point_offs -= wrote;
	  memmove (fs->buf, fs->buf + wrote, fs->p - fs->buf);
	  return 0;
	}

      if (fs->end - fs->buf < amount)
	/* Gotta grow the buffer.  */
	{
	  size_t new_size = fs->end - fs->buf + amount;
	  char *new_buf = realloc (fs->buf, new_size);

	  if (! new_buf)
	    {
	      __set_errno (ENOMEM);
	      return 0;
	    }

	  fs->buf = new_buf;
	  fs->end = new_buf + new_size;
	  fs->p = fs->buf;
	}
    }

  return 1;
}

ssize_t
__argp_fmtstream_printf (struct argp_fmtstream *fs, const char *fmt, ...)
{
  size_t out;
  size_t size_guess = PRINTF_SIZE_GUESS; /* How much space to reserve. */

  do
    {
      va_list args;

      if (! __argp_fmtstream_ensure (fs, size_guess))
	return -1;
      size_guess += size_guess;

      va_start (args, fmt);
      out = __vsnprintf (fs->p, fs->end - fs->p, fmt, args);
      va_end (args);
    }
  while (out == -1);

  fs->p += out;

  return out;
}
#ifdef weak_alias
weak_alias (__argp_fmtstream_printf, argp_fmtstream_printf)
#endif

#endif /* !ARGP_FMTSTREAM_USE_LINEWRAP */