stdio.c

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/* Copyright (C) 1996 Robert de Bath <[e-mail]>
 * This file is part of the Linux-8086 C library and is distributed
 * under the GNU Library General Public License.
 */

/* This is an implementation of the C standard IO package.
 *
 * Updates:
 * 29-Sep-2000 W. Greathouse    1. fgetc copying beyond end of buffer
 *                              2. stdout needs flushed when input requested on
 *                                 stdin.
 *                              3. bufend was set incorrectly to 4 bytes beyond
 *                                 bufin (sizeof a pointer) instead of BUFSIZ.
 *                                 This resulted in 4 byte buffers for full
 *                                 buffered stdin and stdout and an 8 byte
 *                                 buffer for the unbuffered stderr!
 */

/*
 * Feb 27, 2001            Manuel Novoa III
 *
 * Most of the core functionality has been completely rewritten.
 * A number of functions have been added as well, as mandated by C89.
 *
 * An extension function "fsfopen" has been added:
 *   Open a file using an automatically (stack) or statically allocated FILE.
 *   The FILE * returned behaves just as any other FILE * with respect to the
 *   stdio functions, but be aware of the following:
 *   NOTE: The buffer used for the file is FILE's builtin 2-byte buffer, so
 *         setting a new buffer is probably advisable.
 *   NOTE: This function is primarily intended to be used for stack-allocated
 *         FILEs when uClibc stdio has no dynamic memory support.
 *         For the statically allocated case, it is probably better to increase
 *         the value of FIXED_STREAMS in stdio.c.
 *   WARNING: If allocated on the stack, make sure you call fclose before the
 *            stack memory is reclaimed!
 */


#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <malloc.h>
#include <errno.h>
#include <string.h>
#include <assert.h>
#include <limits.h>

extern off_t _uClibc_fwrite(const unsigned char *buf, off_t bytes, FILE *fp);
extern off_t _uClibc_fread(unsigned char *buf, off_t bytes, FILE *fp);

/* Used internally to actually open files */
extern FILE *__fopen __P((__const char *__restrict __filename, int __fd,
	                FILE *__restrict __stream, __const char *__restrict __mode));

/* Note: This def of READING is ok since 1st ungetc puts in buf. */
#define READING(fp) (fp->bufstart < fp->bufread)
#define WRITING(fp) (fp->bufwrite > fp->bufstart)

#define READABLE(fp) (fp->bufread != 0)
#define WRITEABLE(fp) (fp->bufwrite != 0)
#define EOF_OR_ERROR(fp) (fp->mode & (__MODE_EOF | __MODE_ERR))

/***********************************************************************/
/* BUILD TIME OPTIONS                                                  */
/***********************************************************************/
/*
 * FIXED_STREAMS must be >= 3 and FIXED_BUFFERS must be >= 2.
 * As a feature, these can be increased, although this is probably
 * only useful if DISABLE_DYNAMIC is set to 1 below.
 */

#define FIXED_STREAMS 3
#define FIXED_BUFFERS 2

/*
 * As a feature, you can build uClibc with no dynamic allocation done
 * by the stdio package.  Just set DISABLE_DYNAMIC to nonzero.  Note that
 * use of asprintf, getdelim, or getline will pull malloc into the link.
 *
 * Note: You can't trust FOPEN_MAX if DISABLE_DYNAMIC != 0.
 */
#define DISABLE_DYNAMIC 0

/*
 * As a feature, you can try to allow setvbuf calls after file operations.
 * Setting FLEXIBLE_SETVBUF to nonzero will cause setvbuf to try to fflush
 * any buffered writes or sync the file position for buffered reads.  If it
 * is successful, the buffer change can then take place.
 */
#define FLEXIBLE_SETVBUF 0
/***********************************************************************/

#if DISABLE_DYNAMIC != 0
#undef malloc
#undef free
#define malloc(x) 0
#define free(x)
#endif

extern FILE *__IO_list;			/* For fflush. */
extern FILE *_free_file_list;
extern char _free_buffer_index;
extern FILE _stdio_streams[FIXED_STREAMS];
extern unsigned char _fixed_buffers[FIXED_BUFFERS * BUFSIZ];

extern unsigned char *_alloc_stdio_buffer(size_t size);
extern void _free_stdio_buffer_of_file(FILE *fp);
extern void _free_stdio_stream(FILE *fp);

#ifdef L__alloc_stdio_buffer
unsigned char *_alloc_stdio_buffer(size_t size)
{
	unsigned char *buf;

	if ((size == BUFSIZ) && (_free_buffer_index < FIXED_BUFFERS)) {
		buf = _fixed_buffers + ((unsigned int)_free_buffer_index) * BUFSIZ;
		_free_buffer_index = *buf;
		return buf;
	}
	return malloc(size);
}
#endif

#ifdef L__free_stdio_buffer_of_file
void _free_stdio_buffer_of_file(FILE *fp)
{
	unsigned char *buf;

	if (!(fp->mode & __MODE_FREEBUF)) {
		return;
	}
	fp->mode &= ~(__MODE_FREEBUF);
	buf = fp->bufstart;

	if ((buf >= _fixed_buffers) 
	 && (buf < _fixed_buffers + (FIXED_BUFFERS * BUFSIZ))) {
		*buf = _free_buffer_index;
		_free_buffer_index = (buf - _fixed_buffers)/BUFSIZ;
		return;
	}
	free(buf);
}
#endif

#ifdef L__stdio_init

#if FIXED_BUFFERS < 2
#error FIXED_BUFFERS must be >= 2
#endif

#if FIXED_BUFFERS >= UCHAR_MAX
#error FIXED_BUFFERS must be < UCHAR_MAX
#endif

#define bufin (_fixed_buffers)
#define bufout (_fixed_buffers + BUFSIZ)
#define buferr (_stdio_streams[2].unbuf) /* Stderr is unbuffered */

unsigned char _fixed_buffers[FIXED_BUFFERS * BUFSIZ];

#if FIXED_STREAMS < 3
#error FIXED_STREAMS must be >= 3
#endif

FILE _stdio_streams[FIXED_STREAMS] = {
	{bufin, bufin,      0, bufin, bufin + BUFSIZ,
	 _stdio_streams + 1,
	 0, _IOFBF | __MODE_FREEFIL | __MODE_FREEBUF | __MODE_TIED },
	{bufout,    0, bufout, bufout, bufout + BUFSIZ,
	 _stdio_streams + 2,
	 1, _IOFBF | __MODE_FREEFIL | __MODE_FREEBUF | __MODE_TIED },
	{buferr,    0, buferr, buferr, buferr + 1,
	 NULL,
	 2, _IONBF | __MODE_FREEFIL }
};

FILE *stdin = _stdio_streams + 0;
FILE *stdout = _stdio_streams + 1;
FILE *stderr = _stdio_streams + 2;

/*
 * Note: the following forces linking of the __init_stdio function if
 * any of the stdio functions are used since they all call fflush directly
 * or indirectly.
 */
FILE *__IO_list = _stdio_streams;			/* For fflush. */

FILE *_free_file_list = 0;
char _free_buffer_index = FIXED_BUFFERS;

/*
 * __stdio_close_all is automatically when exiting if stdio is used.
 * See misc/internals/__uClibc_main.c and and stdlib/atexit.c.
 */
void __stdio_close_all(void)
{
	fflush(NULL);				/* Files will be closed on _exit call. */
}

/*
 * __init_stdio is automatically by __uClibc_main if stdio is used.
 */
void __init_stdio(void)
{
#if (FIXED_BUFFERS > 2) || (FIXED_STREAMS > 3)
	int i;
#endif
#if FIXED_BUFFERS > 2
	_free_buffer_index = 2;
	for ( i = 2 ; i < FIXED_BUFFERS ; i++ ) {
		_fixed_buffers[i*BUFSIZ] = i;
	}
#endif
#if FIXED_STREAMS > 3
	_free_file_list = _stdio_streams + 3;
	for ( i = 3 ; i < FIXED_STREAMS-1 ; i++ ) {
		_stdio_streams[i].next = _stdio_streams + i + 1;
	}
	_stdio_streams[i].next = 0;
#endif

#if _IOFBF != 0 || _IOLBF != 1
#error Assumption violated -- values of _IOFBF and/or _IOLBF
/* This asssumption is also made in _fopen. */
#endif

	/* stdout uses line buffering when connected to a tty. */
	_stdio_streams[1].mode |= isatty(1);
}
#endif

#ifdef L_fputc
int fputc(int c, FILE *fp)
{
	unsigned char buf[1];

	*buf = (unsigned char) c;

	if (_uClibc_fwrite(buf, 1, fp)) {
		return (unsigned char) c;
	}
	return EOF;
}
#endif

#ifdef L_fgetc
int fgetc(FILE *fp)
{
	unsigned char buf[1];

	if (_uClibc_fread(buf, 1, fp)) {
		return *buf;
	}
	return EOF;
}
#endif

#ifdef L_fflush
int fflush(FILE *fp)
{
	int rv;

	rv = 0;

	if (fp == NULL) {			/* On NULL flush the lot. */
		for (fp = __IO_list; fp; fp = fp->next) {
			if (WRITEABLE(fp) && fflush(fp)) {
				rv = EOF;
			}
		}
	} else if (WRITING(fp)) {	/* Output buffer contents. */
		_uClibc_fwrite(NULL, 0, fp);
		if (fp->mode & __MODE_ERR) {
			rv = -1;
		}
	} else if (!WRITEABLE(fp)) { /* File opened read-only!!! */
		/*
		 * According to info, glibc returns an error when the file is opened
		 * in read-only mode.
		 * ANSI says behavior in this case is undefined but also says you
		 * shouldn't flush a stream you were reading from.
		 */
		__set_errno(EBADF);			/* Should we set stream error indicator? */
		rv = -1;
	}

	return rv;
}
#endif

#ifdef L_fgets
/* Nothing special here ... */
char *fgets(char *s, int count, FILE *fp)
{
	int ch;
	char *p;
	
	p = s;
	while (count-- > 1) {		/* Guard against count arg == INT_MIN. */
		ch = getc(fp);
		if (ch == EOF) {
			break;
		}
		*p++ = ch;
		if (ch == '\n') {
			break;
		}
	}
	if (ferror(fp) || (s == p)) {
		return 0;
	}
	*p = 0;
	return s;
}
#endif

#ifdef L_gets
link_warning (gets, "the `gets' function is dangerous and should not be used.")
char *gets(char *str) /* This is an UNSAFE function! */
{
	/* 
	 * Strictly speaking, this implementation is incorrect as the number
	 * of chars gets can read should be unlimited.  However, I can't
	 * imagine anyone wanting to gets() into a buffer bigger than INT_MAX.
	 *
	 * Besides, this function is inherently unsafe and shouldn't be used.
	 */
	return fgets(str, INT_MAX, stdin);
}
#endif

#ifdef L_fputs
int fputs(const char *str, FILE *fp)
{
	int n;

	n = strlen(str);

	_uClibc_fwrite((const unsigned char *)str, n, fp);
	if (fp->mode & __MODE_ERR) {
		n = EOF;
	}
	return n;
}
#endif

#ifdef L_puts
int puts(const char *str)
{
	int n;

	n = fputs(str, stdout);	/* Let next fputc handle EOF or error. */
	if (fputc('\n', stdout) == EOF) { /* Don't use putc since we want to */
		return EOF;				/* fflush stdout if it is line buffered. */
	}
	return n + 1;
}
#endif

#ifdef L_fread
/*
 * fread will often be used to read in large chunks of data calling read()
 * directly can be a big win in this case. Beware also fgetc calls this
 * function to fill the buffer.
 */
size_t fread(buf, size, nelm, fp)
void *buf;
size_t size;
size_t nelm;
FILE *fp;
{
	unsigned char *p;
	unsigned char *q;

#warning TODO: handle possible overflow of size * nelm
	p = (unsigned char *) buf;
	q = p + (size * nelm);

	while ((p < q) && !EOF_OR_ERROR(fp)) {
		p += _uClibc_fread(p, q - p, fp);
	}
	return (p - (unsigned char *) buf)/size;
}
#endif

#ifdef L__uClibc_fread
off_t _uClibc_fread(unsigned char *buf, off_t bytes, FILE *fp)
{
	unsigned char *p;
	off_t len;

	if (!READABLE(fp)) {
		fp->mode |= __MODE_ERR;
	} else if (WRITING(fp)) {
		fflush(fp);
	} else if (fp->mode & stdout->mode & __MODE_TIED) {
		fflush(stdout);
	}
	if (EOF_OR_ERROR(fp) || (bytes <= 0)) {
		return 0;
	}

	p = (unsigned char *) buf;

	if (fp->mode & __MODE_UNGOT) { /* If we had an ungetc'd char, */
		fp->mode ^= __MODE_UNGOT; /* reset the flag and return it. */
		*p++ = fp->ungot;
		--bytes;
	}

 FROM_BUF:
	len = fp->bufread - fp->bufpos;
	if (len > bytes) {			/* Enough buffered */
		len = bytes;
	}
	
	bytes -= len;
	while (len--) {
		*p++ = *fp->bufpos++;
	}

	if (bytes && !EOF_OR_ERROR(fp)) { /* More requested but buffer empty. */
		if (bytes < fp->bufend - fp->bufstart) {
			fp->bufpos = fp->bufread = fp->bufstart; /* Reset pointers. */
			fp->bufread += _uClibc_fread(fp->bufstart,
										 fp->bufend - fp->bufstart, fp);
			goto FROM_BUF;
		}

	TRY_READ:
		len = read(fp->fd, p, (unsigned) bytes);
		if (len < 0) {
			if (errno == EINTR) { /* We were interrupted, so try again. */
				goto TRY_READ;
			}
			fp->mode |= __MODE_ERR;
		} else {
			p += len;
			if (len == 0) {
				fp->mode |= __MODE_EOF;
			}
		}
	}

	return (p - (unsigned char *)buf);

}
#endif

#ifdef L_fwrite
/*
 * Like fread, fwrite will often be used to write out large chunks of
 * data; calling write() directly can be a big win in this case.
 * 
 * But first we check to see if there's space in the buffer.
 */
size_t fwrite(buf, size, nelm, fp)
const void *buf;
size_t size;
size_t nelm;
FILE *fp;
{
	off_t bytes;

#warning TODO: handle possible overflow for bytes
	bytes = size * nelm;		/* How many bytes do we want? */

	bytes = _uClibc_fwrite((const unsigned char *)buf, bytes, fp);

	return bytes/size;
}
#endif

#ifdef L__uClibc_fwrite
/*
 * If buf == NULL, fflush.
 * If buf != NULL, (fflush and) write
 * Returns number of chars written from fp buffer _OR_ from buf.
 */

off_t _uClibc_fwrite(const unsigned char *buf, off_t bytes, FILE *fp)
{
	unsigned char *p;
	int rv, had_newline;

	/*
	 * Fail if stream isn't writable, if we were reading and get an error
	 * changing over to write mode (ie. can't update stream position),
	 * or if the stream was already in an error state.
	 */
	if (!WRITEABLE(fp)) {		/* Fail if stream isn't writable. */
		fp->mode |= __MODE_ERR;
	} else if (READING(fp)) {	/* If read buffer isn't empty, */
		fseek(fp, 0, SEEK_CUR); /* stop reading and update position. */
	} else if (READABLE(fp)) {
		fp->bufread = fp->bufstart;	/* Reset start of read buffer. */
	}
	if (EOF_OR_ERROR(fp)) {
		return 0;
	}

	p = (unsigned char *)buf;
	if (p && (fp->bufpos + bytes <= fp->bufend)) { /* Enough buffer space? */
		had_newline = 0;
		while (bytes--) {
			if (*p == '\n') {
				had_newline = 1;
			}
			*fp->bufpos++ = *p++;
		}
		if (fp->bufpos < fp->bufend) { /* Buffer is not full. */
			fp->bufwrite = fp->bufend;
			if ((fp->mode & __MODE_BUF) == _IOLBF) {
				fp->bufwrite = fp->bufpos;
				if (had_newline) {
					goto FFLUSH;
				}
			}
			goto DONE;
		}
	FFLUSH:
		/* If we get here, either buffer is full or we need to flush anyway. */
		buf = fp->bufpos - (p - (unsigned char *)buf);
		p = NULL;
	}
	if (!p) {					/* buf == NULL means fflush */
		p = fp->bufstart;
		bytes = fp->bufpos - p;
		fp->bufpos = fp->bufwrite = p;
	} else if (fp->bufpos > fp->bufstart) {	/* If there are buffered chars, */
		_uClibc_fwrite(NULL, 0, fp); /* write them. */
		if (ferror(fp)) {
			return 0;
		}
	}