/*

 * buf.c: memory buffers for libxml2

 *

 * new buffer structures and entry points to simplify the maintainance

 * of libxml2 and ensure we keep good control over memory allocations

 * and stay 64 bits clean.

 * The new entry point use the xmlBufPtr opaque structure and

 * xmlBuf...() counterparts to the old xmlBuf...() functions

 *

 * See Copyright for the status of this software.

 *

 * daniel@veillard.com

 */

#define IN_LIBXML

#include "libxml.h"

#include <string.h> /* for memset() only ! */

#include <limits.h>

#ifdef HAVE_CTYPE_H

#include <ctype.h>

#endif

#ifdef HAVE_STDLIB_H

#include <stdlib.h>

#endif

#include <libxml/tree.h>

#include <libxml/globals.h>

#include <libxml/tree.h>

#include <libxml/parserInternals.h> /* for XML_MAX_TEXT_LENGTH */

#include "buf.h"

#define WITH_BUFFER_COMPAT

/**

 * xmlBuf:

 *

 * A buffer structure. The base of the structure is somehow compatible

 * with struct _xmlBuffer to limit risks on application which accessed

 * directly the input->buf->buffer structures.

 */

struct _xmlBuf {

    xmlChar *content;		/* The buffer content UTF8 */

    unsigned int compat_use;    /* for binary compatibility */

    unsigned int compat_size;   /* for binary compatibility */

    xmlBufferAllocationScheme alloc; /* The realloc method */

    xmlChar *contentIO;		/* in IO mode we may have a different base */

    size_t use;		        /* The buffer size used */

    size_t size;		/* The buffer size */

    xmlBufferPtr buffer;        /* wrapper for an old buffer */

    int error;                  /* an error code if a failure occurred */

};

#ifdef WITH_BUFFER_COMPAT

/*

 * Macro for compatibility with xmlBuffer to be used after an xmlBuf

 * is updated. This makes sure the compat fields are updated too.

 */

#define UPDATE_COMPAT(buf)				    \

     if (buf->size < INT_MAX) buf->compat_size = buf->size; \

     else buf->compat_size = INT_MAX;			    \

     if (buf->use < INT_MAX) buf->compat_use = buf->use; \

     else buf->compat_use = INT_MAX;

/*

 * Macro for compatibility with xmlBuffer to be used in all the xmlBuf

 * entry points, it checks that the compat fields have not been modified

 * by direct call to xmlBuffer function from code compiled before 2.9.0 .

 */

#define CHECK_COMPAT(buf)				    \

     if (buf->size != (size_t) buf->compat_size)	    \

         if (buf->compat_size < INT_MAX)		    \

	     buf->size = buf->compat_size;		    \

     if (buf->use != (size_t) buf->compat_use)		    \

         if (buf->compat_use < INT_MAX)			    \

	     buf->use = buf->compat_use;

#else /* ! WITH_BUFFER_COMPAT */

#define UPDATE_COMPAT(buf)

#define CHECK_COMPAT(buf)

#endif /* WITH_BUFFER_COMPAT */

/**

 * xmlBufMemoryError:

 * @extra:  extra informations

 *

 * Handle an out of memory condition

 * To be improved...

 */

static void

xmlBufMemoryError(xmlBufPtr buf, const char *extra)

{

    __xmlSimpleError(XML_FROM_BUFFER, XML_ERR_NO_MEMORY, NULL, NULL, extra);

    if ((buf) && (buf->error == 0))

        buf->error = XML_ERR_NO_MEMORY;

}

/**

 * xmlBufOverflowError:

 * @extra:  extra informations

 *

 * Handle a buffer overflow error

 * To be improved...

 */

static void

xmlBufOverflowError(xmlBufPtr buf, const char *extra)

{

    __xmlSimpleError(XML_FROM_BUFFER, XML_BUF_OVERFLOW, NULL, NULL, extra);

    if ((buf) && (buf->error == 0))

        buf->error = XML_BUF_OVERFLOW;

}

/**

 * xmlBufCreate:

 *

 * routine to create an XML buffer.

 * returns the new structure.

 */

xmlBufPtr

xmlBufCreate(void) {

    xmlBufPtr ret;

    ret = (xmlBufPtr) xmlMalloc(sizeof(xmlBuf));

    if (ret == NULL) {

	xmlBufMemoryError(NULL, "creating buffer");

        return(NULL);

    }

    ret->compat_use = 0;

    ret->use = 0;

    ret->error = 0;

    ret->buffer = NULL;

    ret->size = xmlDefaultBufferSize;

    ret->compat_size = xmlDefaultBufferSize;

    ret->alloc = xmlBufferAllocScheme;

    ret->content = (xmlChar *) xmlMallocAtomic(ret->size * sizeof(xmlChar));

    if (ret->content == NULL) {

	xmlBufMemoryError(ret, "creating buffer");

	xmlFree(ret);

        return(NULL);

    }

    ret->content[0] = 0;

    ret->contentIO = NULL;

    return(ret);

}

/**

 * xmlBufCreateSize:

 * @size: initial size of buffer

 *

 * routine to create an XML buffer.

 * returns the new structure.

 */

xmlBufPtr

xmlBufCreateSize(size_t size) {

    xmlBufPtr ret;

    ret = (xmlBufPtr) xmlMalloc(sizeof(xmlBuf));

    if (ret == NULL) {

	xmlBufMemoryError(NULL, "creating buffer");

        return(NULL);

    }

    ret->compat_use = 0;

    ret->use = 0;

    ret->error = 0;

    ret->buffer = NULL;

    ret->alloc = xmlBufferAllocScheme;

    ret->size = (size ? size+2 : 0);         /* +1 for ending null */

    ret->compat_size = (int) ret->size;

    if (ret->size){

        ret->content = (xmlChar *) xmlMallocAtomic(ret->size * sizeof(xmlChar));

        if (ret->content == NULL) {

	    xmlBufMemoryError(ret, "creating buffer");

            xmlFree(ret);

            return(NULL);

        }

        ret->content[0] = 0;

    } else

	ret->content = NULL;

    ret->contentIO = NULL;

    return(ret);

}

/**

 * xmlBufDetach:

 * @buf:  the buffer

 *

 * Remove the string contained in a buffer and give it back to the

 * caller. The buffer is reset to an empty content.

 * This doesn't work with immutable buffers as they can't be reset.

 *

 * Returns the previous string contained by the buffer.

 */

xmlChar *

xmlBufDetach(xmlBufPtr buf) {

    xmlChar *ret;

    if (buf == NULL)

        return(NULL);

    if (buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE)

        return(NULL);

    if (buf->buffer != NULL)

        return(NULL);

    if (buf->error)

        return(NULL);

    ret = buf->content;

    buf->content = NULL;

    buf->size = 0;

    buf->use = 0;

    buf->compat_use = 0;

    buf->compat_size = 0;

    return ret;

}

/**

 * xmlBufCreateStatic:

 * @mem: the memory area

 * @size:  the size in byte

 *

 * routine to create an XML buffer from an immutable memory area.

 * The area won't be modified nor copied, and is expected to be

 * present until the end of the buffer lifetime.

 *

 * returns the new structure.

 */

xmlBufPtr

xmlBufCreateStatic(void *mem, size_t size) {

    xmlBufPtr ret;

    if (mem == NULL)

        return(NULL);

    ret = (xmlBufPtr) xmlMalloc(sizeof(xmlBuf));

    if (ret == NULL) {

	xmlBufMemoryError(NULL, "creating buffer");

        return(NULL);

    }

    if (size < INT_MAX) {

        ret->compat_use = size;

        ret->compat_size = size;

    } else {

        ret->compat_use = INT_MAX;

        ret->compat_size = INT_MAX;

    }

    ret->use = size;

    ret->size = size;

    ret->alloc = XML_BUFFER_ALLOC_IMMUTABLE;

    ret->content = (xmlChar *) mem;

    ret->error = 0;

    ret->buffer = NULL;

    return(ret);

}

/**

 * xmlBufGetAllocationScheme:

 * @buf:  the buffer

 *

 * Get the buffer allocation scheme

 *

 * Returns the scheme or -1 in case of error

 */

int

xmlBufGetAllocationScheme(xmlBufPtr buf) {

    if (buf == NULL) {

#ifdef DEBUG_BUFFER

        xmlGenericError(xmlGenericErrorContext,

		"xmlBufGetAllocationScheme: buf == NULL\n");

#endif

        return(-1);

    }

    return(buf->alloc);

}

/**

 * xmlBufSetAllocationScheme:

 * @buf:  the buffer to tune

 * @scheme:  allocation scheme to use

 *

 * Sets the allocation scheme for this buffer

 *

 * returns 0 in case of success and -1 in case of failure

 */

int

xmlBufSetAllocationScheme(xmlBufPtr buf,

                          xmlBufferAllocationScheme scheme) {

    if ((buf == NULL) || (buf->error != 0)) {

#ifdef DEBUG_BUFFER

        xmlGenericError(xmlGenericErrorContext,

		"xmlBufSetAllocationScheme: buf == NULL or in error\n");

#endif

        return(-1);

    }

    if ((buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE) ||

        (buf->alloc == XML_BUFFER_ALLOC_IO))

        return(-1);

    if ((scheme == XML_BUFFER_ALLOC_DOUBLEIT) ||

        (scheme == XML_BUFFER_ALLOC_EXACT) ||

        (scheme == XML_BUFFER_ALLOC_HYBRID) ||

        (scheme == XML_BUFFER_ALLOC_IMMUTABLE) ||

	(scheme == XML_BUFFER_ALLOC_BOUNDED)) {

	buf->alloc = scheme;

        if (buf->buffer)

            buf->buffer->alloc = scheme;

        return(0);

    }

    /*

     * Switching a buffer ALLOC_IO has the side effect of initializing

     * the contentIO field with the current content

     */

    if (scheme == XML_BUFFER_ALLOC_IO) {

        buf->alloc = XML_BUFFER_ALLOC_IO;

        buf->contentIO = buf->content;

    }

    return(-1);

}

/**

 * xmlBufFree:

 * @buf:  the buffer to free

 *

 * Frees an XML buffer. It frees both the content and the structure which

 * encapsulate it.

 */

void

xmlBufFree(xmlBufPtr buf) {

    if (buf == NULL) {

#ifdef DEBUG_BUFFER

        xmlGenericError(xmlGenericErrorContext,

		"xmlBufFree: buf == NULL\n");

#endif

	return;

    }

    if ((buf->alloc == XML_BUFFER_ALLOC_IO) &&

        (buf->contentIO != NULL)) {

        xmlFree(buf->contentIO);

    } else if ((buf->content != NULL) &&

        (buf->alloc != XML_BUFFER_ALLOC_IMMUTABLE)) {

        xmlFree(buf->content);

    }

    xmlFree(buf);

}

/**

 * xmlBufEmpty:

 * @buf:  the buffer

 *

 * empty a buffer.

 */

void

xmlBufEmpty(xmlBufPtr buf) {

    if ((buf == NULL) || (buf->error != 0)) return;

    if (buf->content == NULL) return;

    CHECK_COMPAT(buf)

    buf->use = 0;

    if (buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE) {

        buf->content = BAD_CAST "";

    } else if ((buf->alloc == XML_BUFFER_ALLOC_IO) &&

               (buf->contentIO != NULL)) {

        size_t start_buf = buf->content - buf->contentIO;

	buf->size += start_buf;

        buf->content = buf->contentIO;

        buf->content[0] = 0;

    } else {

        buf->content[0] = 0;

    }

    UPDATE_COMPAT(buf)

}

/**

 * xmlBufShrink:

 * @buf:  the buffer to dump

 * @len:  the number of xmlChar to remove

 *

 * Remove the beginning of an XML buffer.

 * NOTE that this routine behaviour differs from xmlBufferShrink()

 * as it will return 0 on error instead of -1 due to size_t being

 * used as the return type.

 *

 * Returns the number of byte removed or 0 in case of failure

 */

size_t

xmlBufShrink(xmlBufPtr buf, size_t len) {

    if ((buf == NULL) || (buf->error != 0)) return(0);

    CHECK_COMPAT(buf)

    if (len == 0) return(0);

    if (len > buf->use) return(0);

    buf->use -= len;

    if ((buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE) ||

        ((buf->alloc == XML_BUFFER_ALLOC_IO) && (buf->contentIO != NULL))) {

	/*

	 * we just move the content pointer, but also make sure

	 * the perceived buffer size has shrinked accordingly

	 */

        buf->content += len;

	buf->size -= len;

        /*

	 * sometimes though it maybe be better to really shrink

	 * on IO buffers

	 */

	if ((buf->alloc == XML_BUFFER_ALLOC_IO) && (buf->contentIO != NULL)) {

	    size_t start_buf = buf->content - buf->contentIO;

	    if (start_buf >= buf->size) {

		memmove(buf->contentIO, &buf->content[0], buf->use);

		buf->content = buf->contentIO;

		buf->content[buf->use] = 0;

		buf->size += start_buf;

	    }

	}

    } else {

	memmove(buf->content, &buf->content[len], buf->use);

	buf->content[buf->use] = 0;

    }

    UPDATE_COMPAT(buf)

    return(len);

}

/**

 * xmlBufGrowInternal:

 * @buf:  the buffer

 * @len:  the minimum free size to allocate

 *

 * Grow the available space of an XML buffer, @len is the target value

 * Error checking should be done on buf->error since using the return

 * value doesn't work that well

 *

 * Returns 0 in case of error or the length made available otherwise

 */

static size_t

xmlBufGrowInternal(xmlBufPtr buf, size_t len) {

    size_t size;

    xmlChar *newbuf;

    if ((buf == NULL) || (buf->error != 0)) return(0);

    CHECK_COMPAT(buf)

    if (buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE) return(0);

    if (buf->use + len < buf->size)

        return(buf->size - buf->use);

    /*

     * Windows has a BIG problem on realloc timing, so we try to double

     * the buffer size (if that's enough) (bug 146697)

     * Apparently BSD too, and it's probably best for linux too

     * On an embedded system this may be something to change

     */

#if 1

    if (buf->size > (size_t) len)

        size = buf->size * 2;

    else

        size = buf->use + len + 100;

#else

    size = buf->use + len + 100;

#endif

    if (buf->alloc == XML_BUFFER_ALLOC_BOUNDED) {

        /*

	 * Used to provide parsing limits

	 */

        if ((buf->use + len >= XML_MAX_TEXT_LENGTH) ||

	    (buf->size >= XML_MAX_TEXT_LENGTH)) {

	    xmlBufMemoryError(buf, "buffer error: text too long\n");

	    return(0);

	}

	if (size >= XML_MAX_TEXT_LENGTH)

	    size = XML_MAX_TEXT_LENGTH;

    }

    if ((buf->alloc == XML_BUFFER_ALLOC_IO) && (buf->contentIO != NULL)) {

        size_t start_buf = buf->content - buf->contentIO;

	newbuf = (xmlChar *) xmlRealloc(buf->contentIO, start_buf + size);

	if (newbuf == NULL) {

	    xmlBufMemoryError(buf, "growing buffer");

	    return(0);

	}

	buf->contentIO = newbuf;

	buf->content = newbuf + start_buf;

    } else {

	newbuf = (xmlChar *) xmlRealloc(buf->content, size);

	if (newbuf == NULL) {

	    xmlBufMemoryError(buf, "growing buffer");

	    return(0);

	}

	buf->content = newbuf;

    }

    buf->size = size;

    UPDATE_COMPAT(buf)

    return(buf->size - buf->use);

}

/**

 * xmlBufGrow:

 * @buf:  the buffer

 * @len:  the minimum free size to allocate

 *

 * Grow the available space of an XML buffer, @len is the target value

 * This is been kept compatible with xmlBufferGrow() as much as possible

 *

 * Returns -1 in case of error or the length made available otherwise

 */

int

xmlBufGrow(xmlBufPtr buf, int len) {

    size_t ret;

    if ((buf == NULL) || (len < 0)) return(-1);

    if (len == 0)

        return(0);

    ret = xmlBufGrowInternal(buf, len);

    if (buf->error != 0)

        return(-1);

    return((int) ret);

}

/**

 * xmlBufInflate:

 * @buf:  the buffer

 * @len:  the minimum extra free size to allocate

 *

 * Grow the available space of an XML buffer, adding at least @len bytes

 *

 * Returns 0 if successful or -1 in case of error

 */

int

xmlBufInflate(xmlBufPtr buf, size_t len) {

    if (buf == NULL) return(-1);

    xmlBufGrowInternal(buf, len + buf->size);

    if (buf->error)

        return(-1);

    return(0);

}

/**

 * xmlBufDump:

 * @file:  the file output

 * @buf:  the buffer to dump

 *

 * Dumps an XML buffer to  a FILE *.

 * Returns the number of #xmlChar written

 */

size_t

xmlBufDump(FILE *file, xmlBufPtr buf) {

    size_t ret;

    if ((buf == NULL) || (buf->error != 0)) {

#ifdef DEBUG_BUFFER

        xmlGenericError(xmlGenericErrorContext,

		"xmlBufDump: buf == NULL or in error\n");

#endif

	return(0);

    }

    if (buf->content == NULL) {

#ifdef DEBUG_BUFFER

        xmlGenericError(xmlGenericErrorContext,

		"xmlBufDump: buf->content == NULL\n");

#endif

	return(0);

    }

    CHECK_COMPAT(buf)

    if (file == NULL)

	file = stdout;

    ret = fwrite(buf->content, sizeof(xmlChar), buf->use, file);

    return(ret);

}

/**

 * xmlBufContent:

 * @buf:  the buffer

 *

 * Function to extract the content of a buffer

 *

 * Returns the internal content

 */

xmlChar *

xmlBufContent(const xmlBuf *buf)

{

    if ((!buf) || (buf->error))

        return NULL;

    return(buf->content);

}

/**

 * xmlBufEnd:

 * @buf:  the buffer

 *

 * Function to extract the end of the content of a buffer

 *

 * Returns the end of the internal content or NULL in case of error

 */

xmlChar *

xmlBufEnd(xmlBufPtr buf)

{

    if ((!buf) || (buf->error))

        return NULL;

    CHECK_COMPAT(buf)

    return(&buf->content[buf->use]);

}

/**

 * xmlBufAddLen:

 * @buf:  the buffer

 * @len:  the size which were added at the end

 *

 * Sometime data may be added at the end of the buffer without

 * using the xmlBuf APIs that is used to expand the used space

 * and set the zero terminating at the end of the buffer

 *

 * Returns -1 in case of error and 0 otherwise

 */

int

xmlBufAddLen(xmlBufPtr buf, size_t len) {

    if ((buf == NULL) || (buf->error))

        return(-1);

    CHECK_COMPAT(buf)

    if (len > (buf->size - buf->use))

        return(-1);

    buf->use += len;

    UPDATE_COMPAT(buf)

    if (buf->size > buf->use)

        buf->content[buf->use] = 0;

    else

        return(-1);

    return(0);

}

/**

 * xmlBufErase:

 * @buf:  the buffer

 * @len:  the size to erase at the end

 *

 * Sometime data need to be erased at the end of the buffer

 *

 * Returns -1 in case of error and 0 otherwise

 */

int

xmlBufErase(xmlBufPtr buf, size_t len) {

    if ((buf == NULL) || (buf->error))

        return(-1);

    CHECK_COMPAT(buf)

    if (len > buf->use)

        return(-1);

    buf->use -= len;

    buf->content[buf->use] = 0;

    UPDATE_COMPAT(buf)

    return(0);

}

/**

 * xmlBufLength:

 * @buf:  the buffer

 *

 * Function to get the length of a buffer

 *

 * Returns the length of data in the internal content

 */

size_t

xmlBufLength(const xmlBufPtr buf)

{

    if ((!buf) || (buf->error))

        return 0;

    CHECK_COMPAT(buf)

    return(buf->use);

}

/**

 * xmlBufUse:

 * @buf:  the buffer

 *

 * Function to get the length of a buffer

 *

 * Returns the length of data in the internal content

 */

size_t

xmlBufUse(const xmlBufPtr buf)

{

    if ((!buf) || (buf->error))

        return 0;

    CHECK_COMPAT(buf)

    return(buf->use);

}

/**

 * xmlBufAvail:

 * @buf:  the buffer

 *

 * Function to find how much free space is allocated but not

 * used in the buffer. It does not account for the terminating zero

 * usually needed

 *

 * Returns the amount or 0 if none or an error occurred

 */

size_t

xmlBufAvail(const xmlBufPtr buf)

{

    if ((!buf) || (buf->error))

        return 0;

    CHECK_COMPAT(buf)

    return(buf->size - buf->use);

}

/**

 * xmlBufIsEmpty:

 * @buf:  the buffer

 *

 * Tell if a buffer is empty

 *

 * Returns 0 if no, 1 if yes and -1 in case of error

 */

int

xmlBufIsEmpty(const xmlBufPtr buf)

{

    if ((!buf) || (buf->error))

        return(-1);

    CHECK_COMPAT(buf)

    return(buf->use == 0);

}

/**

 * xmlBufResize:

 * @buf:  the buffer to resize

 * @size:  the desired size

 *

 * Resize a buffer to accommodate minimum size of @size.

 *

 * Returns  0 in case of problems, 1 otherwise

 */

int

xmlBufResize(xmlBufPtr buf, size_t size)

{

    unsigned int newSize;

    xmlChar* rebuf = NULL;

    size_t start_buf;

    if ((buf == NULL) || (buf->error))

        return(0);

    CHECK_COMPAT(buf)

    if (buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE) return(0);

    if (buf->alloc == XML_BUFFER_ALLOC_BOUNDED) {

        /*

	 * Used to provide parsing limits

	 */

        if (size >= XML_MAX_TEXT_LENGTH) {

	    xmlBufMemoryError(buf, "buffer error: text too long\n");

	    return(0);

	}

    }

    /* Don't resize if we don't have to */

    if (size < buf->size)

        return 1;

    /* figure out new size */

    switch (buf->alloc){

	case XML_BUFFER_ALLOC_IO:

	case XML_BUFFER_ALLOC_DOUBLEIT:

	    /*take care of empty case*/

	    newSize = (buf->size ? buf->size*2 : size + 10);

	    while (size > newSize) {

	        if (newSize > UINT_MAX / 2) {

	            xmlBufMemoryError(buf, "growing buffer");

	            return 0;

	        }

	        newSize *= 2;

	    }

	    break;

	case XML_BUFFER_ALLOC_EXACT:

	    newSize = size+10;

	    break;

        case XML_BUFFER_ALLOC_HYBRID:

            if (buf->use < BASE_BUFFER_SIZE)

                newSize = size;

            else {

                newSize = buf->size * 2;

                while (size > newSize) {

                    if (newSize > UINT_MAX / 2) {

                        xmlBufMemoryError(buf, "growing buffer");

                        return 0;

                    }

                    newSize *= 2;

                }

            }

            break;

	default:

	    newSize = size+10;

	    break;

    }

    if ((buf->alloc == XML_BUFFER_ALLOC_IO) && (buf->contentIO != NULL)) {

        start_buf = buf->content - buf->contentIO;

        if (start_buf > newSize) {

	    /* move data back to start */

	    memmove(buf->contentIO, buf->content, buf->use);

	    buf->content = buf->contentIO;

	    buf->content[buf->use] = 0;

	    buf->size += start_buf;

	} else {

	    rebuf = (xmlChar *) xmlRealloc(buf->contentIO, start_buf + newSize);

	    if (rebuf == NULL) {

		xmlBufMemoryError(buf, "growing buffer");

		return 0;

	    }

	    buf->contentIO = rebuf;

	    buf->content = rebuf + start_buf;

	}

    } else {

	if (buf->content == NULL) {

	    rebuf = (xmlChar *) xmlMallocAtomic(newSize);

	} else if (buf->size - buf->use < 100) {

	    rebuf = (xmlChar *) xmlRealloc(buf->content, newSize);

        } else {

	    /*

	     * if we are reallocating a buffer far from being full, it's

	     * better to make a new allocation and copy only the used range

	     * and free the old one.

	     */

	    rebuf = (xmlChar *) xmlMallocAtomic(newSize);

	    if (rebuf != NULL) {

		memcpy(rebuf, buf->content, buf->use);

		xmlFree(buf->content);

		rebuf[buf->use] = 0;

	    }

	}

	if (rebuf == NULL) {

	    xmlBufMemoryError(buf, "growing buffer");

	    return 0;

	}

	buf->content = rebuf;

    }

    buf->size = newSize;

    UPDATE_COMPAT(buf)

    return 1;

}

/**

 * xmlBufAdd:

 * @buf:  the buffer to dump

 * @str:  the #xmlChar string

 * @len:  the number of #xmlChar to add

 *

 * Add a string range to an XML buffer. if len == -1, the length of

 * str is recomputed.

 *

 * Returns 0 successful, a positive error code number otherwise

 *         and -1 in case of internal or API error.

 */

int

xmlBufAdd(xmlBufPtr buf, const xmlChar *str, int len) {

    unsigned int needSize;

    if ((str == NULL) || (buf == NULL) || (buf->error))

	return -1;

    CHECK_COMPAT(buf)

    if (buf->alloc == XML_BUFFER_ALLOC_IMMUTABLE) return -1;

    if (len < -1) {

#ifdef DEBUG_BUFFER

        xmlGenericError(xmlGenericErrorContext,

		"xmlBufAdd: len < 0\n");

#endif