3abd3e0bcc
* lib/linux/lseek.c (_lseek): New function. * lib/linux/lseek.c (lseek): Use it to check if we should reset read buffer. * lib/mes/__buffered_read.c (__read_buffer_max): New variable. (__buffered_read_init): Add environment override: MES_READ_BUFFER. (__buffered_read): Use it.
110 lines
3 KiB
C
110 lines
3 KiB
C
/* -*-comment-start: "//";comment-end:""-*-
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* GNU Mes --- Maxwell Equations of Software
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* Copyright © 2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
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*
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* This file is part of GNU Mes.
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*
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* GNU Mes is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or (at
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* your option) any later version.
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*
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* GNU Mes is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GNU Mes. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <mes/lib.h>
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#include <stdlib.h>
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#include <string.h>
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#if !__MESC__
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#define __READ_BUFFER_MAX 128
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int __read_buffer_max;
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#else /* FIXME: We want bin/mes-mescc's x86-linux sha256sum to stay the same. */
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#define __READ_BUFFER_MAX 100
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#define __read_buffer_max 100
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#endif
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struct __read_buffer
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{
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ssize_t size;
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char string[__READ_BUFFER_MAX];
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};
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struct __read_buffer *__read_cache = 0;
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void
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__buffered_read_init (int filedes)
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{
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if (!__read_cache)
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{
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__read_cache = (struct __read_buffer *) malloc (sizeof (struct __read_buffer) * __FILEDES_MAX);
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#if !__MESC__
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__read_buffer_max = __READ_BUFFER_MAX;
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char *p = getenv ("MES_READ_BUFFER");
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if (p)
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{
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__read_buffer_max = atoi (p);
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if (__read_buffer_max < 0)
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__read_buffer_max = 0;
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if (__read_buffer_max > __READ_BUFFER_MAX)
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__read_buffer_max = __READ_BUFFER_MAX;
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}
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#endif
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}
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}
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size_t
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__buffered_read_clear (int filedes)
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{
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__buffered_read_init (filedes);
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size_t size = __read_cache[filedes].size;
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__read_cache[filedes].size = 0;
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return size;
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}
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ssize_t
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__buffered_read (int filedes, void *buffer, size_t size)
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{
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size_t todo = size;
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__buffered_read_init (filedes);
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struct __read_buffer *cache = &__read_cache[filedes];
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char *p = buffer;
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if (!cache->size && size > __read_buffer_max)
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return _read (filedes, buffer, size);
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while (cache->size > 0 && todo)
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{
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todo--;
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*p++ = cache->string[__read_buffer_max - cache->size--];
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}
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if (todo)
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{
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#if !__MESC__
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if (todo > __read_buffer_max)
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return size - todo + _read (filedes, p, todo);
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if (__mes_debug () > 4)
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{
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eputs ("__buffered_read: ");
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eputs (itoa (__read_buffer_max));
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eputs ("\n");
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}
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#endif
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ssize_t bytes = _read (filedes, cache->string, __read_buffer_max);
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if (bytes < 0)
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return -1;
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if (bytes)
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{
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cache->size = bytes;
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if (bytes < __read_buffer_max)
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memmove (cache->string + __read_buffer_max - bytes, cache->string, bytes);
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return size - todo + __buffered_read (filedes, p, todo);
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}
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}
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return size - todo;
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}
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