119 lines
3.2 KiB
C
119 lines
3.2 KiB
C
/*
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* Copyright (c) 2015 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/open_memstream.c
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* Open a memory 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 <limits.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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struct memstream
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{
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char** string_out;
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size_t* used_out;
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char* string;
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size_t offset;
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size_t used;
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size_t size;
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};
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static ssize_t memstream_write(void* ms_ptr, const void* src, size_t count)
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{
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struct memstream* ms = (struct memstream*) ms_ptr;
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if ( (size_t) SSIZE_MAX < count )
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count = SSIZE_MAX;
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if ( ms->offset == SIZE_MAX && 1 <= count )
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return errno = EOVERFLOW, -1;
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if ( (size_t) SSIZE_MAX - ms->offset < count )
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count = SIZE_MAX - ms->offset;
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size_t required_size = ms->offset + count;
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if ( ms->size < required_size )
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{
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// TODO: Multiplication overflow.
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size_t new_size = 2 * ms->size;
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if ( new_size < 16 )
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new_size = 16;
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if ( new_size < required_size )
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new_size = required_size;
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if ( SIZE_MAX - new_size < 1 )
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return errno = EOVERFLOW, -1;
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char* new_string = (char*) realloc(ms->string, new_size + 1);
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if ( !new_string )
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return -1;
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ms->string = new_string;
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ms->size = new_size;
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}
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memcpy(ms->string + ms->offset, src, count);
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ms->offset += count;
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if ( ms->used < required_size )
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{
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ms->used = required_size;
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ms->string[ms->used] = '\0';
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}
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*ms->string_out = ms->string;
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*ms->used_out = ms->used;
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return count;
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}
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static off_t memstream_seek(void* ms_ptr, off_t offset, int whence)
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{
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struct memstream* ms = (struct memstream*) ms_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) ms->offset; break;
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case SEEK_END: base = (off_t) ms->used; break;
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default: return errno = EINVAL, -1;
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}
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if ( offset < -base || base - SSIZE_MAX < offset )
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return errno = EOVERFLOW, -1;
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return (off_t) (ms->offset = (size_t) (base + offset));
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}
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FILE* open_memstream(char** string_out, size_t* used_out)
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{
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char* string = (char*) malloc(1);
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if ( !string )
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return NULL;
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string[0] = '\0';
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struct memstream* ms = (struct memstream*) malloc(sizeof(struct memstream));
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if ( !ms )
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return free(string), (FILE*) NULL;
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FILE* fp = fnewfile();
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if ( !fp )
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return free(ms), free(string), (FILE*) NULL;
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ms->string_out = string_out;
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ms->used_out = used_out;
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ms->string= string;
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ms->offset = 0;
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ms->used = 0;
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ms->size = 0;
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fp->flags |= _FILE_WRITABLE;
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fp->fd = -1;
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fp->user = ms;
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fp->write_func = memstream_write;
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fp->seek_func = memstream_seek;
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*string_out = ms->string;
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*used_out = ms->used;
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return fp;
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}
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