Error with std::filesystem::copy copying a file to another pre-existing directory - c++

See below for the following code, and below that, the error that follows.
std::string source = "C:\\Users\\cambarchian\\Documents\\tested";
std::string destination = "C:\\Users\\cambarchian\\Documents\\tester";
std::filesystem::path sourcepath = source;
std::filesystem::path destpath = destination;
std::filesystem::copy_options::update_existing;
std::filesystem::copy(sourcepath, destpath);
terminate called after throwing an instance of 'std::filesystem::__cxx11::filesystem_error'
what(): filesystem error: cannot copy: File exists [C:\Users\cambarchian\Documents\tested] [C:\Users\cambarchian\Documents\tester]
Tried to use filesystem::copy, along with trying different paths. No luck with anything. Not too much I can write here as the problem is listed above, could be a simple formatting issue. That being said, it worked on my home computer using visual studio 2022, however using VS Code with gcc 11.2 gives me this issue.

Using:
filesystem::copy_file(oldPath, newPath, filesystem::copy_options::overwrite_existing);

The overloads of std::filesystem::copy are documented. You're using the first overload, but want the second:
void copy(from, to) which is equivalent to [overload 2, below] using copy_options::none
void copy(from, to, options)
Writing the statement std::filesystem::copy_options::update_existing; before calling copy doesn't achieve anything at all, whereas passing the option to the correct overload like
std::filesystem::copy(sourcepath, destpath,
std::filesystem::copy_options::update_existing);
should do what you want.
... it worked on my home computer using visual studio 2022 ...
you don't say whether the destination file existed in that case, which is the first thing you should check.
I put the copy_options within the copy function but it didn't work so I started moving it around, I probably should have mentioned that.
Randomly permuting your code isn't a good way of generating clean examples for others to help with.
In the rare event that hacking away at something does fix it, I strongly recommend pausing to figure out why. When you've hacked away at something and it still doesn't work, by all means leave comments to remind yourself what you tried, but the code itself should still be in a good state.
Still doesn't work when I write std::filesystem::copy(sourcepath, destpath, std::filesystem::copy_options::recursive)
Well, that's a different option, isn't it? Were you randomly permuting which copy_options you selected as well?
Trying recursive and update_existing yields the same issue.
The documentation says
The behavior is undefined if there is more than one option in any of the copy_options option group present in options (even in the copy_file group).
so you shouldn't be setting both anyway. There's no benefit to recursively copying a single file, but there may be a benefit to updating or overwriting one. If the destination already exists. Which, according to your error, it does.
Since you do have an error explicitly saying "File exists", you should certainly look at the "options controlling copy_file() when the file already exists" section of the table here.

Visual Studio 2022 fixed the problem

Related

reading (not writing) last_write_time gives a file creation error

I'm stumped... it took me a while to track this down.. because I don't have visual C++ IDE installed on the problematic system (it is windows server 2019)... my code works fine with VS 2022 on my laptop (W11 22H2)... anyhow.. I get this exception
Cannot create a file when that file already exists
I tracked it down to this code:
const auto fileTime = fs::last_write_time(p);
apparently this function can also write to the file to modify the time.
but I'm just trying to read it... (I didn't add the arguments necessary to write)
does anyone have any idea why this error might be happening?
https://en.cppreference.com/w/cpp/filesystem/last_write_time
please note it is highly likely that sometimes the file is actually being written to when I call this code (this code is called in a loop, and so is the file that is being written by another program)

CMAKE file(COPY <src> <dest>) not alaways working

So I am having a problem when calling the command:
file( COPY ${src_dir} DESTINATION ${dest_dir} )
Half the time it works, and then half the time I get an error:
file COPY cannot set permissions on "${dest_dir}/subdir"
My issue is I have changed no permissions or touched these files in between execution. I would prefer to use this method to copy our files, as the other methods with add_custom_command/target does not seem to work on our side. I need to copy these files before our executable target is ultimately declared.
I would even be open to use a bash shell to do this copy command, but it has to be done at this specific point of cmake execution.
I have been wondering if file (COPY...) throws a return value, and if there is a way to possibly rerun the copy command if I get a return. Does anybody know if that is possible?
Can anybody give any help if they have run into this problem?
Thank you!
Edit:
I have already tried using different FILE_PERMISSIONS to see if it would function.
You might set permissions explicitly, with PERMISSIONS <permissions>, FILE_PERMISSIONS <permissions> and DIRECTORY_PERMISSIONS <permissions>, or skip setting-of-permissions through NO_SOURCE_PERMISSIONS.
You could hack in a ls -laR ${dest_dir} command to see if there's anything special going on in the filesystem at the time file(COPY ...) is invoked.
So, what I ended up doing is simply using this copy step in a while loop, because it usually works the 2'nd time, if not the first. Not an elegant way, and may only apply to my case, but please leave other answers if somebody can think of other methods.

Filesystem cant copy files because they open in another program c++

As you can see by the title I have issues when copying files from a directory to another. The code works perfectly fine but when the files are in use, obviously I get an error. Is there any way I can skip these files? (that are in use) and simply move on to the next?
I have tried looking for a solution to my issue but it seems there isn't a function from what I've seen on the internet for filesystem, any information given helps. I provided the code below for copying files.
std::filesystem::copy("C:\\Users\\"+ user+"\\AppData\\Local\\tee\\test\\User Data", "C:\\Users\\"+user+"\\AppData\\Local\\tee\\test\\Application", std::filesystem::copy_options::overwrite_existing | std::filesystem::copy_options::recursive);
If you can't copy you will get an exception, if you don't catch that the program chrashes. You can skip the files if you catch the exception with a simple try-catch statement. eg.:
try{
std::filesystem::copy(/*Params*/);
}catch(...){
std::cout<<"cant-copy '"<<filename<<"'";
/*Handle it if you don't want to just ignore (sleep and try later or ask the user what to to...)*/
}

Diagnosing QDir::rmdir failure

I’m using the following code to delete an empty folder on Linux:
bool removeFolder (const QString& path)
{
QDir dir(path);
assert(dir.exists());
return dir.rmdir(".");
}
For some reason it sometimes returns false (for specific folders, but those folders don’t seem to be wrong in any way). If I subsequently use ::rmdir from <unistd.h> to remove the same folder, it succeeds.
How can I tell why QDir::rmdir is failing?
This never happened on Windows so far, QDir::rmdir just works.
Confirming: works on windown, fails on linux.
Reading the "rmdir" doc in <unistd>, here https://pubs.opengroup.org/onlinepubs/007904875/functions/rmdir.html, it says there that "If the path argument refers to a path whose final component is either dot or dot-dot, rmdir() shall fail." So what's probably happening is that QDir::rmdir() is calling the unistd rmdir() function in linux, and this one fails with ".".
I tried to just use the full absolute path ( QDir::rmdir(absolutePath) ) and it worked; however, i see basically no point in using QDir::rmdir() over unistd's rmdir(), so i''ll stick w/ the unistd rmdir() from now on.
note: QDir::removeRecursively() is a different story: it seems to work okay, and it's way more convenient than going through opendir() and then successive readdir()'s (or the nftw(...FTW_DEPTH...) thingie).
I had the same problem but on Windows, I could not delete an empty directory with QDir().rmdir(path);. This happened on some older hard drive so may be the ancient file system was to blame. But I found a hack:
QFile(path).setPermissions(QFile::WriteOther); // this works even for dirs
bool success = QDir().rmdir(path);
Of course, you should revert the permissions back to original values if the deletion was unsuccessful anyway, but that's a different story.
Try to use this one:
dir.rmdir(dir.absolutePath())

Strange semantic error

I have reinstalled emacs 24.2.50 on a new linux host and started a new dotEmacs config based on magnars emacs configuration. Since I have used CEDET to some success in my previous workflow I started configuring it. However, there is some strange behaviour whenever I load a C++ source file.
[This Part Is Solved]
As expected, semantic parses all included files (and during the initial setup parses all files specified by the semantic-add-system-include variables), but it prints this an error message that goes like this:
WARNING: semantic-find-file-noselect called for /usr/include/c++/4.7/vector while in set-auto-mode for /usr/include/c++/4.7/vector. You should call the responsible function into 'mode-local-init-hook'.
In the above example the error is printed for the STL vector but a corresponding error message is printed for every file included by the one I'm visiting and any subsequent includes. As a result it takes quite a long time to finish and unfortunately the process is repeated any type I open a new buffer.
[This Problem Is Solved Too]
Furthermore it looks like the parsing doesn't really work as when I place the point above a non-c primitive type (i.e. not int,double,float, etc) instead of printing the type's definition in the modeline an error message like
Idle Service Error semantic-idle-local-symbol-highlight-idle-function: "#<buffer DEPFETResolutionAnalysis.cc> - Wrong type argument: stringp, (((0) \"IndexMap\"))"
Idle Service Error semantic-idle-summary-idle-function: "#<buffer DEPFETResolutionAnalysis.cc> - Wrong type argument: stringp, ((\"fXBetween\" 0 nil nil))"
where DEPFETResolutionAnalysis.cc is the file & buffer I'm currently editing and IndexMap and fXBetween are types defined in files included by the file I'm editing/some file included by the file I'm editing.
I have not tested any further features of CEDET/semantic as the problem is pretty annoying. My cedet config can be found here.
EDIT: With the help of Alex Ott I kinda solved the first problem. It was due to my horrible cedet initialisation. See his first answer for the proper way to configure CEDET!
There still remains the problem with the Idle Service Error (which, when enabling global-semantic-idle-local-symbol-highlight-mode, occurs permanently, not only when checking the definition of the type at point).
And there is the new problem of how to disable the site-wise init file(s).
EDIT2: I have executed semantic-debug-idle-function in a buffer where the problem occurs and it produces a ~700kb [sic!] output. It looks like it is performing some operations on a data container which, by the looks of it, contains information on all the symbols defined in the files parsed. As I have parsed a rather large package (~20Mb source files) this table is rather large. Can semantic handle a database that large or is this impossible and the reason of my problem?
EDIT3: Deleting the content of ~/.semanticdb and reparsing all includes did the trick. I still need to disable the site-wise init files but as this is not related to CEDET I will close this question (the question related to the site-wise init files can be found here).
You need to change your init file so it will perform loading of CEDET only once, not in the hook that will be called for each .h/.hpp/.c/.cpp files. You can change this config as the base, and read more in following article.
The problem that you have is caused because Semantic is trying to analyze header files, and when it tries to open them, then its initialization routines are called again, and again...
The first problem was solved by correctly configuring CEDET which is discribed on Alex Ott's homepage. His answer solves this first problem. The config file specified in his answer is a great start for a nice config; I have used the very same to config CEDET for my needs.
The second problem vanished once I updated CEDET from 1.1 to the bazaar (repository) version, which is explained here and in Alex' article. Additionaly one must delete the content of the directory ~/.semanticdb (which contains the semantic database and was corrupted I guess).
I'd like to thank Alex Ott for his help and sticking with me throughout my journey to the solution :)