buf.c

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/*
 * buf.c: memory buffers for libxml2
 *
 * new buffer structures and entry points to simplify the maintenance
 * 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>
#include <ctype.h>
#include <stdlib.h>
 
#include <libxml/tree.h>
#include <libxml/parserInternals.h> /* for XML_MAX_TEXT_LENGTH */
 
#include "private/buf.h"
#include "private/error.h"
 
#ifndef SIZE_MAX
#define SIZE_MAX ((size_t) -1)
#endif
 
#define WITH_BUFFER_COMPAT
 
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 */
 
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;
}
 
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;
}
 
 
xmlBufPtr
xmlBufCreate(void) {
    xmlBufPtr ret;
 
    ret = (xmlBufPtr) xmlMalloc(sizeof(xmlBuf));
    if (ret == NULL) {
    xmlBufMemoryError(NULL, "creating buffer");
        return(NULL);
    }
    ret->use = 0;
    ret->error = 0;
    ret->buffer = NULL;
    ret->size = xmlDefaultBufferSize;
    UPDATE_COMPAT(ret);
    ret->alloc = xmlBufferAllocScheme;
    ret->content = (xmlChar *) xmlMallocAtomic(ret->size);
    if (ret->content == NULL) {
    xmlBufMemoryError(ret, "creating buffer");
    xmlFree(ret);
        return(NULL);
    }
    ret->content[0] = 0;
    ret->contentIO = NULL;
    return(ret);
}
 
xmlBufPtr
xmlBufCreateSize(size_t size) {
    xmlBufPtr ret;
 
    if (size == SIZE_MAX)
        return(NULL);
    ret = (xmlBufPtr) xmlMalloc(sizeof(xmlBuf));
    if (ret == NULL) {
    xmlBufMemoryError(NULL, "creating buffer");
        return(NULL);
    }
    ret->use = 0;
    ret->error = 0;
    ret->buffer = NULL;
    ret->alloc = xmlBufferAllocScheme;
    ret->size = (size ? size + 1 : 0);         /* +1 for ending null */
    UPDATE_COMPAT(ret);
    if (ret->size){
        ret->content = (xmlChar *) xmlMallocAtomic(ret->size);
        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);
}
 
xmlChar *
xmlBufDetach(xmlBufPtr buf) {
    xmlChar *ret;
 
    if (buf == NULL)
        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;
    UPDATE_COMPAT(buf);
 
    return ret;
}
 
int
xmlBufGetAllocationScheme(xmlBufPtr buf) {
    if (buf == NULL) {
        return(-1);
    }
    return(buf->alloc);
}
 
int
xmlBufSetAllocationScheme(xmlBufPtr buf,
                          xmlBufferAllocationScheme scheme) {
    if ((buf == NULL) || (buf->error != 0)) {
        return(-1);
    }
    if (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_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);
}
 
void
xmlBufFree(xmlBufPtr buf) {
    if (buf == NULL) {
    return;
    }
 
    if ((buf->alloc == XML_BUFFER_ALLOC_IO) &&
        (buf->contentIO != NULL)) {
        xmlFree(buf->contentIO);
    } else if (buf->content != NULL) {
        xmlFree(buf->content);
    }
    xmlFree(buf);
}
 
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_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)
}
 
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_IO) && (buf->contentIO != NULL)) {
    /*
     * we just move the content pointer, but also make sure
     * the perceived buffer size has shrunk 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);
}
 
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 (len < buf->size - buf->use)
        return(buf->size - buf->use - 1);
    if (len >= SIZE_MAX - buf->use) {
        xmlBufMemoryError(buf, "growing buffer past SIZE_MAX");
        return(0);
    }
 
    if (buf->size > (size_t) len) {
        size = buf->size > SIZE_MAX / 2 ? SIZE_MAX : buf->size * 2;
    } else {
        size = buf->use + len;
        size = size > SIZE_MAX - 100 ? SIZE_MAX : size + 100;
    }
 
    if (buf->alloc == XML_BUFFER_ALLOC_BOUNDED) {
        /*
     * Used to provide parsing limits
     */
        if ((buf->use + len + 1 >= 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 - 1);
}
 
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(ret > INT_MAX ? INT_MAX : ret);
}
 
size_t
xmlBufDump(FILE *file, xmlBufPtr buf) {
    size_t ret;
 
    if ((buf == NULL) || (buf->error != 0)) {
    return(0);
    }
    if (buf->content == NULL) {
    return(0);
    }
    CHECK_COMPAT(buf)
    if (file == NULL)
    file = stdout;
    ret = fwrite(buf->content, 1, buf->use, file);
    return(ret);
}
 
xmlChar *
xmlBufContent(const xmlBuf *buf)
{
    if ((!buf) || (buf->error))
        return NULL;
 
    return(buf->content);
}
 
xmlChar *
xmlBufEnd(xmlBufPtr buf)
{
    if ((!buf) || (buf->error))
        return NULL;
    CHECK_COMPAT(buf)
 
    return(&buf->content[buf->use]);
}
 
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;
    buf->content[buf->use] = 0;
    UPDATE_COMPAT(buf)
    return(0);
}
 
size_t
xmlBufLength(const xmlBufPtr buf)
{
    if ((!buf) || (buf->error))
        return 0;
    CHECK_COMPAT(buf)
 
    return(buf->use);
}
 
size_t
xmlBufUse(const xmlBufPtr buf)
{
    if ((!buf) || (buf->error))
        return 0;
    CHECK_COMPAT(buf)
 
    return(buf->use);
}
 
size_t
xmlBufAvail(const xmlBufPtr buf)
{
    if ((!buf) || (buf->error))
        return 0;
    CHECK_COMPAT(buf)
 
    return((buf->size > buf->use) ? (buf->size - buf->use - 1) : 0);
}
 
int
xmlBufIsEmpty(const xmlBufPtr buf)
{
    if ((!buf) || (buf->error))
        return(-1);
    CHECK_COMPAT(buf)
 
    return(buf->use == 0);
}
 
int
xmlBufResize(xmlBufPtr buf, size_t size)
{
    size_t newSize;
    xmlChar* rebuf = NULL;
    size_t start_buf;
 
    if ((buf == NULL) || (buf->error))
        return(0);
    CHECK_COMPAT(buf)
 
    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*/
            if (buf->size == 0) {
                newSize = (size > SIZE_MAX - 10 ? SIZE_MAX : size + 10);
            } else {
                newSize = buf->size;
            }
        while (size > newSize) {
            if (newSize > SIZE_MAX / 2) {
                xmlBufMemoryError(buf, "growing buffer");
                return 0;
            }
            newSize *= 2;
        }
        break;
    case XML_BUFFER_ALLOC_EXACT:
            newSize = (size > SIZE_MAX - 10 ? SIZE_MAX : size + 10);
        break;
        case XML_BUFFER_ALLOC_HYBRID:
            if (buf->use < BASE_BUFFER_SIZE)
                newSize = size;
            else {
                newSize = buf->size;
                while (size > newSize) {
                    if (newSize > SIZE_MAX / 2) {
                        xmlBufMemoryError(buf, "growing buffer");
                        return 0;
                    }
                    newSize *= 2;
                }
            }
            break;
 
    default:
            newSize = (size > SIZE_MAX - 10 ? SIZE_MAX : 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);
        buf->use = 0;
            if (rebuf != NULL)
            rebuf[buf->use] = 0;
    } 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;
}
 
int
xmlBufAdd(xmlBufPtr buf, const xmlChar *str, int len) {
    size_t needSize;
 
    if ((str == NULL) || (buf == NULL) || (buf->error))
    return -1;
    CHECK_COMPAT(buf)
 
    if (len < -1) {
    return -1;
    }
    if (len == 0) return 0;
 
    if (len < 0)
        len = xmlStrlen(str);
 
    if (len < 0) return -1;
    if (len == 0) return 0;
 
    /* Note that both buf->size and buf->use can be zero here. */
    if ((size_t) len >= buf->size - buf->use) {
        if ((size_t) len >= SIZE_MAX - buf->use) {
            xmlBufMemoryError(buf, "growing buffer past SIZE_MAX");
            return(-1);
        }
        needSize = buf->use + len + 1;
    if (buf->alloc == XML_BUFFER_ALLOC_BOUNDED) {
        /*
         * Used to provide parsing limits
         */
        if (needSize >= XML_MAX_TEXT_LENGTH) {
        xmlBufMemoryError(buf, "buffer error: text too long\n");
        return(-1);
        }
    }
        if (!xmlBufResize(buf, needSize)){
        xmlBufMemoryError(buf, "growing buffer");
            return XML_ERR_NO_MEMORY;
        }
    }
 
    memmove(&buf->content[buf->use], str, len);
    buf->use += len;
    buf->content[buf->use] = 0;
    UPDATE_COMPAT(buf)
    return 0;
}
 
int
xmlBufCat(xmlBufPtr buf, const xmlChar *str) {
    if ((buf == NULL) || (buf->error))
        return(-1);
    CHECK_COMPAT(buf)
    if (str == NULL) return -1;
    return xmlBufAdd(buf, str, -1);
}
 
int
xmlBufCCat(xmlBufPtr buf, const char *str) {
    return xmlBufCat(buf, (const xmlChar *) str);
}
 
int
xmlBufWriteQuotedString(xmlBufPtr buf, const xmlChar *string) {
    const xmlChar *cur, *base;
    if ((buf == NULL) || (buf->error))
        return(-1);
    CHECK_COMPAT(buf)
    if (xmlStrchr(string, '\"')) {
        if (xmlStrchr(string, '\'')) {
        xmlBufCCat(buf, "\"");
            base = cur = string;
            while(*cur != 0){
                if(*cur == '"'){
                    if (base != cur)
                        xmlBufAdd(buf, base, cur - base);
                    xmlBufAdd(buf, BAD_CAST "&quot;", 6);
                    cur++;
                    base = cur;
                }
                else {
                    cur++;
                }
            }
            if (base != cur)
                xmlBufAdd(buf, base, cur - base);
        xmlBufCCat(buf, "\"");
    }
        else{
        xmlBufCCat(buf, "\'");
            xmlBufCat(buf, string);
        xmlBufCCat(buf, "\'");
        }
    } else {
        xmlBufCCat(buf, "\"");
        xmlBufCat(buf, string);
        xmlBufCCat(buf, "\"");
    }
    return(0);
}
 
xmlBufPtr
xmlBufFromBuffer(xmlBufferPtr buffer) {
    xmlBufPtr ret;
 
    if (buffer == NULL)
        return(NULL);
 
    ret = (xmlBufPtr) xmlMalloc(sizeof(xmlBuf));
    if (ret == NULL) {
    xmlBufMemoryError(NULL, "creating buffer");
        return(NULL);
    }
    ret->use = buffer->use;
    ret->size = buffer->size;
    UPDATE_COMPAT(ret);
    ret->error = 0;
    ret->buffer = buffer;
    ret->alloc = buffer->alloc;
    ret->content = buffer->content;
    ret->contentIO = buffer->contentIO;
 
    return(ret);
}
 
xmlBufferPtr
xmlBufBackToBuffer(xmlBufPtr buf) {
    xmlBufferPtr ret;
 
    if (buf == NULL)
        return(NULL);
    CHECK_COMPAT(buf)
    if ((buf->error) || (buf->buffer == NULL)) {
        xmlBufFree(buf);
        return(NULL);
    }
 
    ret = buf->buffer;
    /*
     * What to do in case of error in the buffer ???
     */
    if (buf->use > INT_MAX) {
        /*
         * Worse case, we really allocated and used more than the
         * maximum allowed memory for an xmlBuffer on this architecture.
         * Keep the buffer but provide a truncated size value.
         */
        xmlBufOverflowError(buf, "Used size too big for xmlBuffer");
        ret->use = INT_MAX;
        ret->size = INT_MAX;
    } else if (buf->size > INT_MAX) {
        /*
         * milder case, we allocated more than the maximum allowed memory
         * for an xmlBuffer on this architecture, but used less than the
         * limit.
         * Keep the buffer but provide a truncated size value.
         */
        xmlBufOverflowError(buf, "Allocated size too big for xmlBuffer");
        ret->use = buf->use;
        ret->size = INT_MAX;
    } else {
        ret->use = buf->use;
        ret->size = buf->size;
    }
    ret->alloc = buf->alloc;
    ret->content = buf->content;
    ret->contentIO = buf->contentIO;
    xmlFree(buf);
    return(ret);
}
 
int
xmlBufMergeBuffer(xmlBufPtr buf, xmlBufferPtr buffer) {
    int ret = 0;
 
    if ((buf == NULL) || (buf->error)) {
    xmlBufferFree(buffer);
        return(-1);
    }
    CHECK_COMPAT(buf)
    if ((buffer != NULL) && (buffer->content != NULL) &&
             (buffer->use > 0)) {
        ret = xmlBufAdd(buf, buffer->content, buffer->use);
    }
    xmlBufferFree(buffer);
    return(ret);
}
 
int
xmlBufResetInput(xmlBufPtr buf, xmlParserInputPtr input) {
    if (input == NULL)
        return(-1);
    if ((buf == NULL) || (buf->error)) {
        input->base = input->cur = input->end = BAD_CAST "";
        return(-1);
    }
    CHECK_COMPAT(buf)
    input->base = input->cur = buf->content;
    input->end = &buf->content[buf->use];
    return(0);
}
 
int
xmlBufUpdateInput(xmlBufPtr buf, xmlParserInputPtr input, size_t pos) {
    if (input == NULL)
        return(-1);
    /*
     * TODO: It might be safer to keep using the buffer content if there
     * was an error.
     */
    if ((buf == NULL) || (buf->error)) {
        input->base = input->cur = input->end = BAD_CAST "";
        return(-1);
    }
    CHECK_COMPAT(buf)
    input->base = buf->content;
    input->cur = input->base + pos;
    input->end = &buf->content[buf->use];
    return(0);
}