/* ply-buffer.c - facilities for buffering data
 *
 * Copyright (C) 2008 Red Hat, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 *
 * Written by: Ray Strode <rstrode@redhat.com>
 */
#include "ply-buffer.h"

#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include "ply-utils.h"

#ifndef PLY_BUFFER_MAX_APPEND_SIZE
#define PLY_BUFFER_MAX_APPEND_SIZE 1024
#endif

#ifndef PLY_BUFFER_MAX_BUFFER_CAPACITY
#define PLY_BUFFER_MAX_BUFFER_CAPACITY (255 * 4096)
#endif

struct _ply_buffer
{
        char  *data;
        size_t size;
        size_t capacity;
};

static bool
ply_buffer_increase_capacity (ply_buffer_t *buffer)
{
        assert (buffer != NULL);

        if ((buffer->capacity * 2) > PLY_BUFFER_MAX_BUFFER_CAPACITY)
                return false;

        buffer->capacity *= 2;

        buffer->data = realloc (buffer->data, buffer->capacity);
        return true;
}

void
ply_buffer_remove_bytes (ply_buffer_t *buffer,
                         size_t        bytes_to_remove)
{
        assert (buffer != NULL);

        bytes_to_remove = MIN (buffer->size, bytes_to_remove);

        if (bytes_to_remove == buffer->size) {
                buffer->size = 0;
        } else {
                memmove (buffer->data, buffer->data + bytes_to_remove,
                         buffer->size - bytes_to_remove);
                buffer->size -= bytes_to_remove;
        }
        buffer->data[buffer->size] = '\0';
}

void
ply_buffer_remove_bytes_at_end (ply_buffer_t *buffer,
                                size_t        bytes_to_remove)
{
        assert (buffer != NULL);

        bytes_to_remove = MIN (buffer->size, bytes_to_remove);

        buffer->size -= bytes_to_remove;
        buffer->data[buffer->size] = '\0';
}

ply_buffer_t *
ply_buffer_new (void)
{
        ply_buffer_t *buffer;

        buffer = calloc (1, sizeof(ply_buffer_t));

        buffer->capacity = 4096;
        buffer->data = calloc (1, buffer->capacity);
        buffer->size = 0;

        return buffer;
}

void
ply_buffer_free (ply_buffer_t *buffer)
{
        if (buffer == NULL)
                return;

        free (buffer->data);
        free (buffer);
}

static bool
ply_buffer_validate_format_string (ply_buffer_t *buffer,
                                   const char   *format)
{
        char *n, *p;

        p = (char *) format;

        /* lame checks to limit the damage
         * of some potential exploits.
         */
        while ((n = strstr (p, "%n")) != NULL) {
                if (n == format)
                        return false;

                if (n[-1] != '%')
                        return false;

                p = n + 1;
        }

        return true;
}

void
ply_buffer_append_with_non_literal_format_string (ply_buffer_t *buffer,
                                                  const char   *format,
                                                  ...)
{
        va_list args;
        size_t string_size;
        char write_buffer[PLY_BUFFER_MAX_APPEND_SIZE] = "";

        assert (buffer != NULL);

        if (!ply_buffer_validate_format_string (buffer, format))
                return;

        va_start (args, format);
        string_size = vsnprintf (write_buffer, 0, format, args) + 1;
        va_end (args);

        if (string_size > PLY_BUFFER_MAX_APPEND_SIZE)
                return;

        va_start (args, format);
        vsnprintf (write_buffer, PLY_BUFFER_MAX_APPEND_SIZE,
                   format, args);
        va_end (args);

        ply_buffer_append_bytes (buffer, write_buffer, string_size - 1);
}

void
ply_buffer_append_bytes (ply_buffer_t *buffer,
                         const void   *bytes_in,
                         size_t        length)
{
        assert (buffer != NULL);
        assert (bytes_in != NULL);

        const uint8_t *bytes = bytes_in;

        if (length == 0)
                return;

        if (length > PLY_BUFFER_MAX_BUFFER_CAPACITY) {
                bytes += length - (PLY_BUFFER_MAX_BUFFER_CAPACITY - 1);
                length = (PLY_BUFFER_MAX_BUFFER_CAPACITY - 1);
        }

        while ((buffer->size + length) >= buffer->capacity) {
                if (!ply_buffer_increase_capacity (buffer))
                        ply_buffer_remove_bytes (buffer, length);
        }

        assert (buffer->size + length < buffer->capacity);

        memcpy (buffer->data + buffer->size,
                bytes, length);

        buffer->size += length;
        buffer->data[buffer->size] = '\0';
}

void
ply_buffer_append_from_fd (ply_buffer_t *buffer,
                           int           fd)
{
        char bytes[PLY_BUFFER_MAX_APPEND_SIZE] = "";
        ssize_t bytes_read;

        assert (buffer != NULL);
        assert (fd >= 0);

        if (!ply_fd_has_data (fd))
                return;

        bytes_read = read (fd, bytes, sizeof(bytes));

        if (bytes_read > 0)
                ply_buffer_append_bytes (buffer, bytes, bytes_read);
}

void
ply_buffer_set_bytes (ply_buffer_t *buffer,
                      void         *bytes,
                      size_t        number_of_bytes,
                      size_t        capacity)
{
        if (buffer->data != bytes)
                free (buffer->data);

        buffer->data = bytes;
        buffer->size = number_of_bytes;
        buffer->capacity = capacity;
}

const char *
ply_buffer_get_bytes (ply_buffer_t *buffer)
{
        assert (buffer != NULL);
        return buffer->data;
}

char *
ply_buffer_steal_bytes (ply_buffer_t *buffer)
{
        char *bytes;

        assert (buffer != NULL);

        bytes = buffer->data;

        buffer->data = calloc (1, buffer->capacity);
        buffer->size = 0;

        return bytes;
}

size_t
ply_buffer_get_capacity (ply_buffer_t *buffer)
{
        return buffer->capacity;
}

size_t
ply_buffer_get_size (ply_buffer_t *buffer)
{
        return buffer->size;
}

void
ply_buffer_clear (ply_buffer_t *buffer)
{
        if (buffer->size == 0)
                return;

        memset (buffer->data, '\0', buffer->size);
        buffer->size = 0;
}