--- /dev/null
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * Copyright (c) 1992 Simon Glass
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#ifndef _MEMBUFF_H
+#define _MEMBUFF_H
+
+/**
+ * @struct membuff: holds the state of a membuff - it is used for input and
+ * output buffers. The buffer extends from @start to (@start + @size - 1).
+ * Data in the buffer extends from @tail to @head: it is written in at
+ * @head and read out from @tail. The membuff is empty when @head == @tail
+ * and full when adding another character would make @head == @tail. We
+ * therefore waste one character in the membuff to avoid having an extra flag
+ * to determine whether (when @head == @tail) the membuff is empty or full.
+ *
+ * xxxxxx data
+ * ...... empty
+ *
+ * .............xxxxxxxxxxxxxxxx.........................
+ * ^ ^
+ * tail head
+ *
+ * xxxxxxxxxxxxx................xxxxxxxxxxxxxxxxxxxxxxxxx
+ * ^ ^
+ * head tail
+ */
+struct membuff {
+ char *start; /** the start of the buffer */
+ char *end; /** the end of the buffer (start + length) */
+ char *head; /** current buffer head */
+ char *tail; /** current buffer tail */
+};
+
+/**
+ * membuff_purge() - reset a membuff to the empty state
+ *
+ * Initialise head and tail pointers so that the membuff becomes empty.
+ *
+ * @mb: membuff to purge
+ */
+void membuff_purge(struct membuff *mb);
+
+/**
+ * membuff_putraw() - find out where bytes can be written
+ *
+ * Work out where in the membuff some data could be written. Return a pointer
+ * to the address and the number of bytes which can be written there. If
+ * @update is true, the caller must then write the data immediately, since
+ * the membuff is updated as if the write has been done,
+ *
+ * Note that because the spare space in a membuff may not be contiguous, this
+ * function may not return @maxlen even if there is enough space in the
+ * membuff. However, by calling this function twice (with @update == true),
+ * you will get access to all the spare space.
+ *
+ * @mb: membuff to adjust
+ * @maxlen: the number of bytes we want to write
+ * @update: true to update the membuff as if the write happened, false to not
+ * @data: the address data can be written to
+ * @return number of bytes which can be written
+ */
+int membuff_putraw(struct membuff *mb, int maxlen, bool update, char **data);
+
+/**
+ * membuff_getraw() - find and return a pointer to available bytes
+ *
+ * Returns a pointer to any valid input data in the given membuff and
+ * optionally marks it as read. Note that not all input data may not be
+ * returned, since data is not necessarily contiguous in the membuff. However,
+ * if you call this function twice (with @update == true) you are guaranteed
+ * to get all available data, in at most two installments.
+ *
+ * @mb: membuff to adjust
+ * @maxlen: maximum number of bytes to get
+ * @update: true to update the membuff as if the bytes have been read (use
+ * false to check bytes without reading them)
+ * @data: returns address of data in input membuff
+ * @return the number of bytes available at *@data
+ */
+int membuff_getraw(struct membuff *mb, int maxlen, bool update, char **data);
+
+/**
+ * membuff_putbyte() - Writes a byte to a membuff
+ *
+ * @mb: membuff to adjust
+ * @ch: byte to write
+ * @return true on success, false if membuff is full
+ */
+bool membuff_putbyte(struct membuff *mb, int ch);
+
+/**
+ * @mb: membuff to adjust
+ * membuff_getbyte() - Read a byte from the membuff
+ * @return the byte read, or -1 if the membuff is empty
+ */
+int membuff_getbyte(struct membuff *mb);
+
+/**
+ * membuff_peekbyte() - check the next available byte
+ *
+ * Return the next byte which membuff_getbyte() would return, without
+ * removing it from the membuff.
+ *
+ * @mb: membuff to adjust
+ * @return the byte peeked, or -1 if the membuff is empty
+ */
+int membuff_peekbyte(struct membuff *mb);
+
+/**
+ * membuff_get() - get data from a membuff
+ *
+ * Copies any available data (up to @maxlen bytes) to @buff and removes it
+ * from the membuff.
+ *
+ * @mb: membuff to adjust
+ * @Buff: address of membuff to transfer bytes to
+ * @maxlen: maximum number of bytes to read
+ * @return the number of bytes read
+ */
+int membuff_get(struct membuff *mb, char *buff, int maxlen);
+
+/**
+ * membuff_put() - write data to a membuff
+ *
+ * Writes some data to a membuff. Returns the number of bytes added. If this
+ * is less than @lnehgt, then the membuff got full
+ *
+ * @mb: membuff to adjust
+ * @data: the data to write
+ * @length: number of bytes to write from 'data'
+ * @return the number of bytes added
+ */
+int membuff_put(struct membuff *mb, const char *buff, int length);
+
+/**
+ * membuff_isempty() - check if a membuff is empty
+ *
+ * @mb: membuff to check
+ * @return true if empty, else false
+ */
+bool membuff_isempty(struct membuff *mb);
+
+/**
+ * membuff_avail() - check available data in a membuff
+ *
+ * @mb: membuff to check
+ * @return number of bytes of data available
+ */
+int membuff_avail(struct membuff *mb);
+
+/**
+ * membuff_size() - get the size of a membuff
+ *
+ * Note that a membuff can only old data up to one byte less than its size.
+ *
+ * @mb: membuff to check
+ * @return total size
+ */
+int membuff_size(struct membuff *mb);
+
+/**
+ * membuff_makecontig() - adjust all membuff data to be contiguous
+ *
+ * This places all data in a membuff into a single contiguous lump, if
+ * possible
+ *
+ * @mb: membuff to adjust
+ * @return true on success
+ */
+bool membuff_makecontig(struct membuff *mb);
+
+/**
+ * membuff_free() - find the number of bytes that can be written to a membuff
+ *
+ * @mb: membuff to check
+ * @return returns the number of bytes free in a membuff
+ */
+int membuff_free(struct membuff *mb);
+
+/**
+ * membuff_readline() - read a line of text from a membuff
+ *
+ * Reads a line of text of up to 'maxlen' characters from a membuff and puts
+ * it in @str. Any character less than @minch is assumed to be the end of
+ * line character
+ *
+ * @mb: membuff to adjust
+ * @str: Place to put the line
+ * @maxlen: Maximum line length (excluding terminator)
+ * @return number of bytes read (including terminator) if a line has been
+ * read, 0 if nothing was there
+ */
+int membuff_readline(struct membuff *mb, char *str, int maxlen, int minch);
+
+/**
+ * membuff_extend_by() - expand a membuff
+ *
+ * Extends a membuff by the given number of bytes
+ *
+ * @mb: membuff to adjust
+ * @by: Number of bytes to increase the size by
+ * @max: Maximum size to allow
+ * @return 0 if the expand succeeded, -ENOMEM if not enough memory, -E2BIG
+ * if the the size would exceed @max
+ */
+int membuff_extend_by(struct membuff *mb, int by, int max);
+
+/**
+ * membuff_init() - set up a new membuff using an existing membuff
+ *
+ * @mb: membuff to set up
+ * @buff: Address of buffer
+ * @size: Size of buffer
+ */
+void membuff_init(struct membuff *mb, char *buff, int size);
+
+/**
+ * membuff_uninit() - clear a membuff so it can no longer be used
+ *
+ * @mb: membuff to uninit
+ */
+void membuff_uninit(struct membuff *mb);
+
+/**
+ * membuff_new() - create a new membuff
+ *
+ * @mb: membuff to init
+ * @size: size of membuff to create
+ * @return 0 if OK, -ENOMEM if out of memory
+ */
+int membuff_new(struct membuff *mb, int size);
+
+/**
+ * membuff_dispose() - free memory allocated to a membuff and uninit it
+ *
+ * @mb: membuff to dispose
+ */
+void membuff_dispose(struct membuff *mb);
+
+#endif
--- /dev/null
+/*
+ * Copyright (c) 2015 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * Copyright (c) 1992 Simon Glass
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <errno.h>
+#include <malloc.h>
+#include "membuff.h"
+
+void membuff_purge(struct membuff *mb)
+{
+ /* set mb->head and mb->tail so the buffers look empty */
+ mb->head = mb->start;
+ mb->tail = mb->start;
+}
+
+static int membuff_putrawflex(struct membuff *mb, int maxlen, bool update,
+ char ***data, int *offsetp)
+{
+ int len;
+
+ /* always write to 'mb->head' */
+ assert(data && offsetp);
+ *data = &mb->start;
+ *offsetp = mb->head - mb->start;
+
+ /* if there is no buffer, we can do nothing */
+ if (!mb->start)
+ return 0;
+
+ /*
+ * if head is ahead of tail, we can write from head until the end of
+ * the buffer
+ */
+ if (mb->head >= mb->tail) {
+ /* work out how many bytes can fit here */
+ len = mb->end - mb->head - 1;
+ if (maxlen >= 0 && len > maxlen)
+ len = maxlen;
+
+ /* update the head pointer to mark these bytes as written */
+ if (update)
+ mb->head += len;
+
+ /*
+ * if the tail isn't at start of the buffer, then we can
+ * write one more byte right at the end
+ */
+ if ((maxlen < 0 || len < maxlen) && mb->tail != mb->start) {
+ len++;
+ if (update)
+ mb->head = mb->start;
+ }
+
+ /* otherwise now we can write until head almost reaches tail */
+ } else {
+ /* work out how many bytes can fit here */
+ len = mb->tail - mb->head - 1;
+ if (maxlen >= 0 && len > maxlen)
+ len = maxlen;
+
+ /* update the head pointer to mark these bytes as written */
+ if (update)
+ mb->head += len;
+ }
+
+ /* return the number of bytes which can be/must be written */
+ return len;
+}
+
+int membuff_putraw(struct membuff *mb, int maxlen, bool update, char **data)
+{
+ char **datap;
+ int offset;
+ int size;
+
+ size = membuff_putrawflex(mb, maxlen, update, &datap, &offset);
+ *data = *datap + offset;
+
+ return size;
+}
+
+bool membuff_putbyte(struct membuff *mb, int ch)
+{
+ char *data;
+
+ if (membuff_putraw(mb, 1, true, &data) != 1)
+ return false;
+ *data = ch;
+
+ return true;
+}
+
+int membuff_getraw(struct membuff *mb, int maxlen, bool update, char **data)
+{
+ int len;
+
+ /* assume for now there is no data to get */
+ len = 0;
+
+ /*
+ * in this case head is ahead of tail, so we must return data between
+ *'tail' and 'head'
+ */
+ if (mb->head > mb->tail) {
+ /* work out the amount of data */
+ *data = mb->tail;
+ len = mb->head - mb->tail;
+
+ /* check it isn't too much */
+ if (maxlen >= 0 && len > maxlen)
+ len = maxlen;
+
+ /* & mark it as read from the buffer */
+ if (update)
+ mb->tail += len;
+ }
+
+ /*
+ * if head is before tail, then we have data between 'tail' and 'end'
+ * and some more data between 'start' and 'head'(which we can't
+ * return this time
+ */
+ else if (mb->head < mb->tail) {
+ /* work out the amount of data */
+ *data = mb->tail;
+ len = mb->end - mb->tail;
+ if (maxlen >= 0 && len > maxlen)
+ len = maxlen;
+ if (update) {
+ mb->tail += len;
+ if (mb->tail == mb->end)
+ mb->tail = mb->start;
+ }
+ }
+
+ debug("getraw: maxlen=%d, update=%d, head=%d, tail=%d, data=%d, len=%d",
+ maxlen, update, (int)(mb->head - mb->start),
+ (int)(mb->tail - mb->start), (int)(*data - mb->start), len);
+
+ /* return the number of bytes we found */
+ return len;
+}
+
+int membuff_getbyte(struct membuff *mb)
+{
+ char *data = 0;
+
+ return membuff_getraw(mb, 1, true, &data) != 1 ? -1 : *(uint8_t *)data;
+}
+
+int membuff_peekbyte(struct membuff *mb)
+{
+ char *data = 0;
+
+ return membuff_getraw(mb, 1, false, &data) != 1 ? -1 : *(uint8_t *)data;
+}
+
+int membuff_get(struct membuff *mb, char *buff, int maxlen)
+{
+ char *data = 0, *buffptr = buff;
+ int len = 1, i;
+
+ /*
+ * do this in up to two lots(see GetRaw for why) stopping when there
+ * is no more data
+ */
+ for (i = 0; len && i < 2; i++) {
+ /* get a pointer to the data available */
+ len = membuff_getraw(mb, maxlen, true, &data);
+
+ /* copy it into the buffer */
+ memcpy(buffptr, data, len);
+ buffptr += len;
+ maxlen -= len;
+ }
+
+ /* return the number of bytes read */
+ return buffptr - buff;
+}
+
+int membuff_put(struct membuff *mb, const char *buff, int length)
+{
+ char *data;
+ int towrite, i, written;
+
+ for (i = written = 0; i < 2; i++) {
+ /* ask where some data can be written */
+ towrite = membuff_putraw(mb, length, true, &data);
+
+ /* and write it, updating the bytes length */
+ memcpy(data, buff, towrite);
+ written += towrite;
+ buff += towrite;
+ length -= towrite;
+ }
+
+ /* return the number of bytes written */
+ return written;
+}
+
+bool membuff_isempty(struct membuff *mb)
+{
+ return mb->head == mb->tail;
+}
+
+int membuff_avail(struct membuff *mb)
+{
+ struct membuff copy;
+ int i, avail;
+ char *data = 0;
+
+ /* make a copy of this buffer's control data */
+ copy = *mb;
+
+ /* now read everything out of the copied buffer */
+ for (i = avail = 0; i < 2; i++)
+ avail += membuff_getraw(©, -1, true, &data);
+
+ /* and return how much we read */
+ return avail;
+}
+
+int membuff_size(struct membuff *mb)
+{
+ return mb->end - mb->start;
+}
+
+bool membuff_makecontig(struct membuff *mb)
+{
+ int topsize, botsize;
+
+ debug("makecontig: head=%d, tail=%d, size=%d",
+ (int)(mb->head - mb->start), (int)(mb->tail - mb->start),
+ (int)(mb->end - mb->start));
+
+ /*
+ * first we move anything at the start of the buffer into the correct
+ * place some way along
+ */
+ if (mb->tail > mb->head) {
+ /*
+ * the data is split into two parts, from 0 to ->head and
+ * from ->tail to ->end. We move the stuff from 0 to ->head
+ * up to make space for the other data before it
+ */
+ topsize = mb->end - mb->tail;
+ botsize = mb->head - mb->start;
+
+ /*
+ * must move data at bottom up by 'topsize' bytes - check if
+ * there's room
+ */
+ if (mb->head + topsize >= mb->tail)
+ return false;
+ memmove(mb->start + topsize, mb->start, botsize);
+ debug(" - memmove(%d, %d, %d)", topsize, 0, botsize);
+
+ /* nothing at the start, so skip that step */
+ } else {
+ topsize = mb->head - mb->tail;
+ botsize = 0;
+ }
+
+ /* now move data at top down to the bottom */
+ memcpy(mb->start, mb->tail, topsize);
+ debug(" - memcpy(%d, %d, %d)", 0, (int)(mb->tail - mb->start), topsize);
+
+ /* adjust pointers */
+ mb->tail = mb->start;
+ mb->head = mb->start + topsize + botsize;
+
+ debug(" - head=%d, tail=%d", (int)(mb->head - mb->start),
+ (int)(mb->tail - mb->start));
+
+ /* all ok */
+ return true;
+}
+
+int membuff_free(struct membuff *mb)
+{
+ return mb->end == mb->start ? 0 :
+ (mb->end - mb->start) - 1 - membuff_avail(mb);
+}
+
+int membuff_readline(struct membuff *mb, char *str, int maxlen, int minch)
+{
+ int len; /* number of bytes read (!= string length) */
+ char *s, *end;
+ bool ok = false;
+ char *orig = str;
+
+ end = mb->head >= mb->tail ? mb->head : mb->end;
+ for (len = 0, s = mb->tail; s < end && len < maxlen - 1; str++) {
+ *str = *s++;
+ len++;
+ if (*str == '\n' || *str < minch) {
+ ok = true;
+ break;
+ }
+ if (s == end && mb->tail > mb->head) {
+ s = mb->start;
+ end = mb->head;
+ }
+ }
+
+ /* couldn't get the whole string */
+ if (!ok) {
+ if (maxlen)
+ *orig = '\0';
+ return 0;
+ }
+
+ /* terminate the string, update the membuff and return success */
+ *str = '\0';
+ mb->tail = s == mb->end ? mb->start : s;
+
+ return len;
+}
+
+int membuff_extend_by(struct membuff *mb, int by, int max)
+{
+ int oldhead, oldtail;
+ int size, orig;
+ char *ptr;
+
+ /* double the buffer size until it is big enough */
+ assert(by >= 0);
+ for (orig = mb->end - mb->start, size = orig; size < orig + by;)
+ size *= 2;
+ if (max != -1)
+ size = min(size, max);
+ by = size - orig;
+
+ /* if we're already at maximum, give up */
+ if (by <= 0)
+ return -E2BIG;
+
+ oldhead = mb->head - mb->start;
+ oldtail = mb->tail - mb->start;
+ ptr = realloc(mb->start, size);
+ if (!ptr)
+ return -ENOMEM;
+ mb->start = ptr;
+ mb->head = mb->start + oldhead;
+ mb->tail = mb->start + oldtail;
+
+ if (mb->head < mb->tail) {
+ memmove(mb->tail + by, mb->tail, orig - oldtail);
+ mb->tail += by;
+ }
+ mb->end = mb->start + size;
+
+ return 0;
+}
+
+void membuff_init(struct membuff *mb, char *buff, int size)
+{
+ mb->start = buff;
+ mb->end = mb->start + size;
+ membuff_purge(mb);
+}
+
+int membuff_new(struct membuff *mb, int size)
+{
+ mb->start = malloc(size);
+ if (!mb->start)
+ return -ENOMEM;
+
+ membuff_init(mb, mb->start, size);
+ return 0;
+}
+
+void membuff_uninit(struct membuff *mb)
+{
+ mb->end = NULL;
+ mb->start = NULL;
+ membuff_purge(mb);
+}
+
+void membuff_dispose(struct membuff *mb)
+{
+ free(&mb->start);
+ membuff_uninit(mb);
+}
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