syncfiles/macos/tempfile.c

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// Copyright 2022 Dietrich Epp.
// This file is part of SyncFiles. SyncFiles is licensed under the terms of the
// Mozilla Public License, version 2.0. See LICENSE.txt for details.
#include "macos/tempfile.h"
#include <string.h>
// Filename prefix for temporary files.
static const char kTempPrefix[] = "SyncFiles.";
// Hexadecimal digits.
static const char kHexDigits[16] = {'0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
static void U32ToHex(unsigned char *ptr, UInt32 x)
{
int i;
for (i = 0; i < 8; i++) {
ptr[7 - i] = kHexDigits[x & 15];
x >>= 4;
}
}
OSErr MakeTempFile(short vRefNum, FSSpec *spec)
{
short tempVRefNum;
long tempParID;
unsigned long time;
OSErr err;
int pos;
unsigned char name[32];
// This is inspired by IM: Files listing 1-10, page 1-25.
// Generate hopefully unique name.
GetDateTime(&time);
memcpy(name + 1, kTempPrefix, sizeof(kTempPrefix) - 1);
pos = sizeof(kTempPrefix);
U32ToHex(name + pos, time);
pos += 8;
name[0] = pos - 1;
err = FindFolder(vRefNum, kTemporaryFolderType, TRUE, &tempVRefNum,
&tempParID);
if (err != noErr) {
return err;
}
err = FSMakeFSSpec(tempVRefNum, tempParID, name, spec);
if (err != noErr && err != fnfErr) {
return err;
}
return noErr;
}