io_null.c

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// SPDX-FileCopyrightText: 2017 condret <condr3t@protonmail.com>
// SPDX-FileCopyrightText: 2017 pancake <pancake@nopcode.org>
// SPDX-License-Identifier: LGPL-3.0-only
 
#include <rz_io.h>
#include <rz_lib.h>
 
typedef struct {
    ut64 size;
    ut64 offset;
} RzIONull;
 
static int __write(RzIO *io, RzIODesc *fd, const ut8 *buf, int count) {
    RzIONull *null;
    if (!fd || !fd->data || !buf) {
        return -1;
    }
    null = (RzIONull *)fd->data;
    if ((null->offset + count) > null->size) {
        int ret = null->size - null->offset;
        return ret;
    }
    null->offset += count;
    return count;
}
 
static bool __resize(RzIO *io, RzIODesc *fd, ut64 count) {
    if (fd && fd->data) {
        RzIONull *null = (RzIONull *)fd->data;
        null->size = count;
        if (null->offset >= count) {
            if (count) {
                null->offset = count - 1;
            } else {
                null->offset = 0LL;
            }
        }
        return true;
    }
    return false;
}
 
static int __read(RzIO *io, RzIODesc *fd, ut8 *buf, int count) {
    RzIONull *null;
    if (!fd || !fd->data || !buf) {
        return -1;
    }
    null = (RzIONull *)fd->data;
    if ((null->offset + count) > null->size) {
        int ret = null->size - null->offset;
        memset(buf, 0x00, ret);
        null->offset = null->size;
        return ret;
    }
    memset(buf, 0x00, count);
    null->offset += count;
    return count;
}
 
static int __close(RzIODesc *fd) {
    RZ_FREE(fd->data);
    return 0;
}
 
static ut64 __lseek(RzIO *io, RzIODesc *fd, ut64 offset, int whence) {
    RzIONull *null;
    if (!fd || !fd->data) {
        return offset;
    }
    null = (RzIONull *)fd->data;
    switch (whence) {
    case SEEK_SET:
        if (offset >= null->size) {
            return null->offset = null->size - 1;
        }
        return null->offset = offset;
    case SEEK_CUR:
        if ((null->offset + offset) >= null->size) {
            return null->offset = null->size - 1;
        }
        return null->offset += offset;
    case SEEK_END:
        return null->offset = null->size - 1;
    }
    return offset;
}
 
static bool __plugin_open(RzIO *io, const char *pathname, bool many) {
    return (!strncmp(pathname, "null://", 7));
}
 
static RzIODesc *__open(RzIO *io, const char *pathname, int rw, int mode) {
    RzIONull *null;
    if (__plugin_open(io, pathname, 0)) {
        if (!strncmp(pathname, "null://", 7) && strlen(pathname + 7)) {
            null = RZ_NEW0(RzIONull);
            null->size = rz_num_math(NULL, pathname + 7) + 1; //???
            null->offset = 0LL;
            return rz_io_desc_new(io, &rz_io_plugin_null, pathname, rw, mode, null);
        }
    }
    return NULL;
}
 
RzIOPlugin rz_io_plugin_null = {
    .name = "null",
    .desc = "Null plugin",
    .license = "LGPL3",
    .uris = "null://",
    .open = __open,
    .close = __close,
    .read = __read,
    .check = __plugin_open,
    .lseek = __lseek,
    .write = __write,
    .resize = __resize,
};
 
#ifndef RZ_PLUGIN_INCORE
RZ_API RzLibStruct rizin_plugin = {
    .type = RZ_LIB_TYPE_IO,
    .data = &rz_io_plugin_null,
    .version = RZ_VERSION
};
#endif