/* 
 * Copyright (c) 2005, 2006 by KoanLogic s.r.l. - All rights reserved.  
 */

static const char rcsid[] =
    "$Id: buf.c,v 1.1 2006/05/28 15:39:43 tat Exp $";

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

#include <sys/types.h>
#include <sys/stat.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <u/libu.h>
#include <u/buf.h>


struct u_buf_s
{
    char *data;
    size_t size, len;
};

/**
 *  \defgroup string String
 *  \{
 */

/**
 * \brief  Enlarge the underlaying memory block of the given buffer
 *
 * Enlarge the buffer data block to (at least) \a size bytes.
 *
 * \param ubuf  buffer object
 * \param size  requested size
 *
 * \return \c 0 on success, not zero on failure
 */
int u_buf_reserve(u_buf_t *ubuf, size_t size)
{
    char *nbuf;

    dbg_err_if(ubuf == NULL);

    if(size <= ubuf->size)
        return 0; /* nothing to do */
   
    /* size plus 1 char to store a '\0' */
    nbuf = u_realloc(ubuf->data, size+1);
    dbg_err_if(nbuf == NULL);

    /* buffer data will always be zero-terminated (but the len field will not
     * count the last '\0') */
    nbuf[size] = 0;

    ubuf->data = (void*)nbuf;
    ubuf->size = size;

    return 0;
err:
    return ~0;
}

/**
 * \brief  Append some data to the buffer
 *
 * Append \a data of size \a size to the given buffer. If needed the buffer
 * will be enlarged.
 *
 * \param ubuf  buffer object
 * \param data  the data block to append
 * \param size  size of \a data
 *
 * \return \c 0 on success, not zero on failure
 */
int u_buf_append(u_buf_t *ubuf, void *data, size_t size)
{
    dbg_err_if(ubuf == NULL);
//    dbg_err_if(data == NULL);
    dbg_err_if(size == 0);

    if(ubuf->size - ubuf->len < size)
    {   /* buffer too small, need to resize */
        dbg_err_if(u_buf_reserve(ubuf, ubuf->size + ubuf->len + 2*size));
    }
   
    if (data) {
        memcpy(ubuf->data + ubuf->len, data, size);
        ubuf->len += size;

        /* zero term the buffer so it can be used (when applicable) as a string */
        ubuf->data[ubuf->len] = 0;
    }

    return 0;
err:
    return ~0;
}

void u_buf_set_len(u_buf_t *buf, size_t len)
{
    buf->len = len;
}

/**
 * \brief  Fill a buffer object with the content of a file
 *
 * Open \a filename and copy its whole content into the given buffer.
 *
 * \param ubuf     buffer object
 * \param filename the source filename
 *
 * \return \c 0 on success, not zero on failure
 */
int u_buf_load(u_buf_t *ubuf, char *filename)
{
    enum { BUFSZ = 4096 };
    struct stat st;
    FILE *fp = NULL;

    dbg_err_if(ubuf == NULL);
    dbg_err_if(filename == NULL);

    dbg_err_if(stat(filename, &st));

    /* clear the current data */
    dbg_err_if(u_buf_clear(ubuf));

    /* be sure to have a big enough buffer */
    dbg_err_if(u_buf_reserve(ubuf, st.st_size));

    warn_err_sif((fp = fopen(filename, "r")) == NULL);

    /* fill the buffer with the whole file content */
    dbg_err_if(fread(ubuf->data, st.st_size, 1, fp) == 0);
    ubuf->len = st.st_size;

    fclose(fp);

    return 0;
err:
    if(fp)
        fclose(fp);
    return ~0;
}

/**
 * \brief  Release buffer's underlaying memory block without freeing it
 *
 * Release the underlaying memory block of the given buffer without 
 * calling free() on it. The caller must free the buffer later on (probably
 * after using it somwhow). 
 *
 * Use u_buf_ptr() to get the pointer of the memory block, u_buf_size() to
 * get its size and u_buf_len() to get its length.
 *
 * \param ubuf     buffer object
 *
 * \return \c 0 on success, not zero on failure
 */
int u_buf_detach(u_buf_t *ubuf)
{
    dbg_err_if(ubuf == NULL);

    ubuf->data = NULL;
    ubuf->size = 0;
    ubuf->len = 0;

    return 0;
err:
    return ~0;
}

/**
 * \brief  Return the size of memory block allocated by the buffer
 *
 * Return the size of memory block allocated by the buffer. 
 *
 * \param ubuf     buffer object
 *
 * \return the data buffer length
 */
size_t u_buf_size(u_buf_t *ubuf)
{
    dbg_err_if(ubuf == NULL);

    return ubuf->size;
err:
    return 0;
}

/**
 * \brief  Return the length of the buffer
 *
 * Return the length of data store in the given buffer.
 *
 * \param ubuf     buffer object
 *
 * \return the data buffer length
 */
size_t u_buf_len(u_buf_t *ubuf)
{
    dbg_err_if(ubuf == NULL);

    return ubuf->len;
err:
    return 0;
}

/**
 * \brief  Clear a buffer
 *
 * Totally erase the content of the given buffer. The memory allocated by
 * the buffer will not be released until u_buf_free() is called.
 *
 * \param ubuf     buffer object
 *
 * \return \c 0 on success, not zero on failure
 */
int u_buf_clear(u_buf_t *ubuf)
{
    dbg_err_if(ubuf == NULL);
    
    ubuf->len = 0;

    return 0;
err:
    return ~0;
}

/**
 * \brief  Set the value of a buffer
 *
 * Set the value of \a ubuf to \a data. If needed the buffer object will alloc
 * more memory to store the \a data value.
 *
 * \param ubuf  buffer object
 * \param data  the value that will be copied into the buffer
 * \param size  size of \a data
 *
 * \return \c 0 on success, not zero on failure
 */
int u_buf_set(u_buf_t *ubuf, void *data, size_t size)
{
    dbg_err_if(ubuf == NULL);
    dbg_err_if(data == NULL);
    dbg_err_if(size == 0);

    dbg_err_if(u_buf_clear(ubuf));

    dbg_err_if(u_buf_append(ubuf, data, size));

    return 0;
err:
    return ~0;
}

char *u_buf_steal(u_buf_t *ubuf)
{
    char *buf = ubuf->data;
    ubuf->data = NULL;
    ubuf->size = 0;
    ubuf->len = 0;
    return buf;
}


/**
 * \brief  Return a pointer to the buffer internal momory block
 *
 * Return a void* pointer to the memory block allocated by the buffer object.
 *
 * \param ubuf     buffer object
 *
 * \return \c 0 on success, not zero on failure
 */
void* u_buf_ptr(u_buf_t *ubuf)
{
    dbg_err_if(ubuf == NULL);
    
    return ubuf->data;
err:
    return NULL;
}

/**
 * \brief  Free a buffer
 *
 * Release all resources and free the given buffer object.
 *
 * \param ubuf     buffer object
 *
 * \return \c 0 on success, not zero on failure
 */
int u_buf_free(u_buf_t *ubuf)
{
    dbg_err_if(ubuf == NULL);

    if(ubuf->data)
        u_free(ubuf->data);

    u_free(ubuf);
    return 0;
err:
    return ~0;
}

/**
 * \brief  Create a new buffer
 *
 * Create a new buffer object and save its pointer to \a *ps.
 *
 * \param pubuf    on success will get the new buffer object
 *
 * \return \c 0 on success, not zero on failure
 */
int u_buf_create(u_buf_t **pubuf)
{
    u_buf_t *ubuf = NULL;

    dbg_err_if(pubuf == NULL);

    ubuf = (u_buf_t*)u_zalloc(sizeof(u_buf_t));
    dbg_err_if(ubuf == NULL);

    *pubuf = ubuf;

    return 0;
err:
    return ~0;
}


int u_buf_construct(u_buf_t *ubuf, void *ptr, size_t size, size_t len)
{
    if (ubuf->data) {
        free(ubuf->data);
    }
    ubuf->data = ptr;
    ubuf->size = size;
    ubuf->len  = len;
    return 0;
}


/**
 *      \}
 */