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fmemopen.c
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fmemopen.c
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//
// Copyright 2011-2014 NimbusKit
// Originally ported from https://github.com/ingenuitas/python-tesseract/blob/master/fmemopen.c
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
struct fmem {
size_t pos;
size_t size;
char *buffer;
};
typedef struct fmem fmem_t;
static int readfn(void *handler, char *buf, int size) {
fmem_t *mem = handler;
size_t available = mem->size - mem->pos;
if (size > available) {
size = available;
}
memcpy(buf, mem->buffer + mem->pos, sizeof(char) * size);
mem->pos += size;
return size;
}
static int writefn(void *handler, const char *buf, int size) {
fmem_t *mem = handler;
size_t available = mem->size - mem->pos;
if (size > available) {
size = available;
}
memcpy(mem->buffer + mem->pos, buf, sizeof(char) * size);
mem->pos += size;
return size;
}
static fpos_t seekfn(void *handler, fpos_t offset, int whence) {
size_t pos;
fmem_t *mem = handler;
switch (whence) {
case SEEK_SET: {
if (offset >= 0) {
pos = (size_t)offset;
} else {
pos = 0;
}
break;
}
case SEEK_CUR: {
if (offset >= 0 || (size_t)(-offset) <= mem->pos) {
pos = mem->pos + (size_t)offset;
} else {
pos = 0;
}
break;
}
case SEEK_END: pos = mem->size + (size_t)offset; break;
default: return -1;
}
if (pos > mem->size) {
return -1;
}
mem->pos = pos;
return (fpos_t)pos;
}
static int closefn(void *handler) {
free(handler);
return 0;
}
FILE *fmemopen(void *buf, size_t size, const char *mode) {
// This data is released on fclose.
fmem_t* mem = (fmem_t *) malloc(sizeof(fmem_t));
// Zero-out the structure.
memset(mem, 0, sizeof(fmem_t));
mem->size = size;
mem->buffer = buf;
// funopen's man page: https://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man3/funopen.3.html
return funopen(mem, readfn, writefn, seekfn, closefn);
}