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199 lines
4.1 KiB
C

// SPDX-License-Identifier: LGPL-3.0-or-later
/**
* \file mem_file.c
*
* Implements operations over `MemFile` and its `StmOps` interface.
*
* \copyright The DoubleFourteen Code Forge (C) All Rights Reserved
* \author Lorenzo Cogotti
*/
#include "sys/sys.h"
#include "mem_file.h"
#include <stdlib.h>
#include <string.h>
static Judgement Stm_MemFileGrow(MemFile *stm, size_t size)
{
char *buf;
size = ALIGN(size, stm->gran);
if ((stm->flags & MEM_FILE_OWNBIT) == 0) {
// Original buffer not owned by `file`, allocate anew
buf = (char *) malloc(size);
if (!buf) {
Sys_OutOfMemory();
return NG;
}
memcpy(buf, stm->buf, stm->nbytes);
} else {
// May just reallocate the old one
buf = (char *) realloc(stm->buf, size);
if (!buf) {
Sys_OutOfMemory();
return NG;
}
}
stm->buf = buf;
stm->cap = size;
// Buffer is now owned, regardless of the previous state
stm->flags |= MEM_FILE_OWNBIT;
return OK;
}
static Sint64 Stm_OpMemFileRead(void *streamp, void *buf, size_t nbytes)
{
return Stm_MemFileRead((MemFile *) streamp, buf, nbytes);
}
static Sint64 Stm_OpMemFileWrite(void *streamp, const void *buf, size_t nbytes)
{
return Stm_MemFileWrite((MemFile *) streamp, buf, nbytes);
}
static Sint64 Stm_OpMemFileSeek(void *streamp, Sint64 off, SeekMode whence)
{
return Stm_MemFileSeek((MemFile *) streamp, off, whence);
}
static Sint64 Stm_OpMemFileTell(void *streamp)
{
return ((MemFile *) streamp)->pos;
}
static Judgement Stm_OpMemFileFinish(void *streamp)
{
USED(streamp);
return OK; // NOP
}
static void Stm_OpMemFileClose(void *streamp)
{
Stm_MemFileClose((MemFile *) streamp);
}
static const StmOps mem_stmOps = {
Stm_OpMemFileRead,
Stm_OpMemFileWrite,
Stm_OpMemFileSeek,
Stm_OpMemFileTell,
Stm_OpMemFileFinish,
Stm_OpMemFileClose
};
static const StmOps mem_ncStmOps = {
Stm_OpMemFileRead,
Stm_OpMemFileWrite,
Stm_OpMemFileSeek,
Stm_OpMemFileTell,
Stm_OpMemFileFinish,
NULL
};
const StmOps *const Stm_MemFileOps = &mem_stmOps;
const StmOps *const Stm_NcMemFileOps = &mem_ncStmOps;
void Stm_InitMemFile(MemFile *stm, size_t gran, unsigned flags)
{
memset(stm, 0, sizeof(*stm));
stm->gran = gran;
flags &= ~MEM_FILE_NOGROWBIT;
stm->flags = flags | MEM_FILE_WRBIT;
}
void Stm_MemFileFromBuf(MemFile *stm,
void *buf,
size_t nbytes,
size_t gran,
unsigned flags)
{
memset(stm, 0, sizeof(*stm));
stm->buf = (char *) buf;
stm->cap = nbytes;
stm->gran = gran;
stm->flags = flags | MEM_FILE_WRBIT;
}
void Stm_RoMemFileFromBuf(MemFile *stm, const void *buf, size_t nbytes)
{
memset(stm, 0, sizeof(*stm));
stm->buf = (char *) buf; // safe, MEM_FILE_RDBIT
stm->nbytes = nbytes;
stm->flags = MEM_FILE_RDBIT | MEM_FILE_NOGROWBIT;
}
Sint64 Stm_MemFileRead(MemFile *stm, void *buf, size_t nbytes)
{
if ((stm->flags & MEM_FILE_RDBIT) == 0)
return -1;
size_t nleft = stm->nbytes - stm->pos;
if (nbytes > nleft)
nbytes = nleft;
memcpy(buf, &stm->buf[stm->pos], nbytes);
stm->pos += nbytes;
return nbytes;
}
Sint64 Stm_MemFileWrite(MemFile *stm, const void *buf, size_t nbytes)
{
if ((stm->flags & MEM_FILE_WRBIT) == 0)
return -1;
size_t navail = stm->cap - stm->pos;
size_t nreq = nbytes + 1; // for trailing '\0'
if (navail < nreq) {
if ((stm->flags & MEM_FILE_NOGROWBIT) == 0) {
// grow buffer
if (Stm_MemFileGrow(stm, stm->pos + nreq) != OK)
return -1;
} else
nbytes = navail; // short write
}
memcpy(&stm->buf[stm->pos], buf, nbytes);
stm->pos += nbytes;
stm->nbytes += nbytes;
if (stm->pos == stm->nbytes)
stm->buf[stm->pos] = '\0'; // always NUL-terminate
return nbytes;
}
Sint64 Stm_MemFileSeek(MemFile *stm, Sint64 off, SeekMode whence)
{
switch (whence) {
case SK_SET:
break;
case SK_CUR:
off += stm->pos;
break;
case SK_END:
off += stm->nbytes;
break;
default: return -1;
}
// Make sure cursor isn't set out of bounds
stm->pos = CLAMP(off, 0, (Sint64) stm->nbytes);
return stm->pos;
}
void Stm_MemFileClose(MemFile *stm)
{
if (stm->flags & MEM_FILE_OWNBIT)
free(stm->buf);
}