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lib/membuff.c
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/* * 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 == ' ' || *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); } |