219 lines
5.8 KiB
C
219 lines
5.8 KiB
C
/*
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* Copyright (c) 2014, 2015, 2023 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* libc/stdio/fmemopen.c
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* Open a memory buffer stream.
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*/
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#include <sys/types.h>
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#include <errno.h>
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#include <FILE.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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static const int FMEMOPEN_ALLOCATED = 1 << 0;
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struct fmemopen_state
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{
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unsigned char* buffer;
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size_t buffer_true_size;
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size_t buffer_size;
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size_t buffer_offset;
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size_t buffer_used;
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int flags;
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int mode;
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};
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static ssize_t fmemopen_read(void* state_ptr, void* dst, size_t count)
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{
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struct fmemopen_state* state = (struct fmemopen_state*) state_ptr;
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if ( !(state->mode & FILE_MODE_READ) )
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return errno = EBADF, -1;
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if ( (size_t) SSIZE_MAX < count )
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count = SSIZE_MAX;
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if ( state->buffer_used < state->buffer_offset )
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return 0;
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size_t available = state->buffer_used - state->buffer_offset;
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if ( available < count )
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count = available;
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memcpy(dst, state->buffer + state->buffer_offset, count);
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state->buffer_offset += count;
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return count;
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}
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static ssize_t fmemopen_write(void* state_ptr, const void* src, size_t count)
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{
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struct fmemopen_state* state = (struct fmemopen_state*) state_ptr;
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if ( !(state->mode & FILE_MODE_WRITE) )
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return errno = EBADF, -1;
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if ( (size_t) SSIZE_MAX < count )
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count = SSIZE_MAX;
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if ( state->mode & FILE_MODE_APPEND )
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state->buffer_offset = state->buffer_used;
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if ( state->buffer_used < state->buffer_offset )
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{
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size_t distance = state->buffer_offset - state->buffer_used;
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memset(state->buffer + state->buffer_used, 0, distance);
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state->buffer_used = state->buffer_offset;
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}
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size_t available = state->buffer_size - state->buffer_offset;
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if ( available < count )
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count = available;
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memcpy(state->buffer + state->buffer_offset, src, count);
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state->buffer_offset += count;
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if ( state->buffer_used < state->buffer_offset )
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{
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state->buffer_used = state->buffer_offset;
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if ( !(state->mode & FILE_MODE_BINARY) )
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{
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if ( state->buffer_used < state->buffer_true_size )
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state->buffer[state->buffer_used] = '\0';
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}
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}
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return count;
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}
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static off_t fmemopen_seek(void* state_ptr, off_t offset, int whence)
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{
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struct fmemopen_state* state = (struct fmemopen_state*) state_ptr;
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off_t base;
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switch ( whence )
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{
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case SEEK_SET: base = 0; break;
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case SEEK_CUR: base = (off_t) state->buffer_offset; break;
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case SEEK_END: base = (off_t) state->buffer_used; break;
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default: return errno = EINVAL, -1;
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}
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if ( offset < -base || (off_t) state->buffer_size - base < offset )
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return errno = EOVERFLOW, -1;
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return (off_t) (state->buffer_offset = (size_t) (base + offset));
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}
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static int fmemopen_close(void* state_ptr)
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{
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struct fmemopen_state* state = (struct fmemopen_state*) state_ptr;
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if ( state->flags & FMEMOPEN_ALLOCATED )
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free(state->buffer);
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return 0;
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}
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FILE* fmemopen(void* restrict buffer_ptr,
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size_t buffer_size,
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const char* restrict mode_str)
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{
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int flags = 0;
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int mode = fparsemode(mode_str);
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if ( mode < 0 )
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return (FILE*) NULL;
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if ( mode & ~(FILE_MODE_READ | FILE_MODE_WRITE | FILE_MODE_CREATE |
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FILE_MODE_BINARY | FILE_MODE_TRUNCATE | FILE_MODE_APPEND) )
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return errno = EINVAL, (FILE*) NULL;
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#if OFF_MAX < SIZE_MAX
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if ( (uintmax_t) OFF_MAX < (uintmax_t) buffer_size )
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return errno = EOVERFLOW, (FILE*) NULL;
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#endif
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if ( !(mode & FILE_MODE_BINARY) &&
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(mode & FILE_MODE_WRITE) &&
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!(mode & FILE_MODE_READ) &&
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buffer_size == 0 )
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return errno = EINVAL, (FILE*) NULL;
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void* allocated_buffer = NULL;
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if ( !buffer_ptr )
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{
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if ( !(buffer_ptr = allocated_buffer = calloc(buffer_size, 1)) )
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return (FILE*) NULL;
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flags |= FMEMOPEN_ALLOCATED;
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}
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struct fmemopen_state* state =
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(struct fmemopen_state*) malloc(sizeof(struct fmemopen_state));
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if ( !state )
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return free(allocated_buffer), (FILE*) NULL;
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FILE* fp = fnewfile();
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if ( !fp )
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return free(state), free(allocated_buffer), (FILE*) NULL;
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memset(state, 0, sizeof(*state));
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state->flags = flags;
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state->mode = mode;
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state->buffer = (unsigned char*) buffer_ptr;
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state->buffer_size = buffer_size;
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state->buffer_true_size = buffer_size;
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if ( !(mode & FILE_MODE_BINARY) &&
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(mode & FILE_MODE_WRITE) &&
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!(mode & FILE_MODE_READ) )
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state->buffer_size = state->buffer_true_size - 1;
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if ( (mode & FILE_MODE_APPEND) && !(mode & FILE_MODE_BINARY) )
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{
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state->buffer_offset = strnlen((const char*) state->buffer, state->buffer_size);
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state->buffer_used = state->buffer_offset;
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}
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else if ( mode & FILE_MODE_TRUNCATE )
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{
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state->buffer_offset = 0;
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state->buffer_used = 0;
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}
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else
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{
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state->buffer_offset = 0;
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state->buffer_used = state->buffer_size;
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}
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if ( !(state->mode & FILE_MODE_BINARY) && (mode & FILE_MODE_WRITE) )
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{
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if ( state->buffer_used < state->buffer_true_size )
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state->buffer[state->buffer_used] = '\0';
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}
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if ( mode & FILE_MODE_READ )
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fp->flags |= _FILE_READABLE;
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if ( mode & FILE_MODE_WRITE )
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fp->flags |= _FILE_WRITABLE;
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fp->fd = -1;
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fp->user = state;
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fp->read_func = fmemopen_read;
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fp->write_func = fmemopen_write;
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fp->seek_func = fmemopen_seek;
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fp->close_func = fmemopen_close;
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return fp;
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}
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