4 ms·

> It's notable that in practically every other programming language on every platform the default is to truncate the file to 0 bytes when opened in write (not a

> It's notable that in practically every other programming language on every platform the default is to truncate the file to 0 bytes when opened in write (not append) mode Examples of ‘Open’ calls that require setting a bit in the ‘flags’ argument to truncate an existing file: - https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-openfile https://learn.microsoft.com/en-us/windows/win32/api/winbase/... - https://man.freebsd.org/cgi/man.cgi?query=open&sektion=2&n=1 https://man.freebsd.org/cgi/man.cgi?query=open&sektion=2&n=1

okanat 4y ago
You're comparing system call interfaces to higher level standard API defaults. Not really an apples to apples comparison. System calls are special low-level interfaces. The requirement for reading their docs carefully and general care is expected at that level. A higher level API shouldn't contain gotchas like this.
moefh 4y ago
Wow, that Win32 OpenFile function is truly cursed: - If you don't specify a directory, Windows will look for the file in a bunch of directories, but the current directory is not the first place searched. - The lpReOpenBuff is annotated as [out], but is an input when uStyle contains the OF_REOPEN flag. - The function is named OpenFile, but can be used to delete a file. Even better, the documentation is not clear what to do with the return value on success: is it a valid file handle that must be passed to CloseHandle, or just a dummy non-error file handle? - You can also use it to check the existence of the file -- the documentation says it will open and then close the file. What's the return value in that case? Is it a stale file handle, a dummy, or do you still have to close it?
- Someone 4y ago
  You’re forgetting this one: you can specify a flag that makes the call display a dialog box if a requested file does not exist. Yes, this call to open a file can run an event loop that lets the user create directories, rename files, possibly even format floppy disks, etc. If you want a prime example of a layer violation, this is it. Its replacement “CreateFile” (https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea https://learn.microsoft.com/en-us/windows/win32/api/fileapi/...) is a lot saner, but still has this: “If you rename or delete a file and then restore it shortly afterward, the system searches the cache for file information to restore. Cached information includes its short/long name pair and creation time.” That’s intended to make it easier for “Save” operations in document-based applications to keep the short name of the file, creation time and file flags around.

okanat 4y ago

You're comparing system call interfaces to higher level standard API defaults. Not really an apples to apples comparison. System calls are special low-level interfaces. The requirement for reading their docs carefully and general care is expected at that level. A higher level API shouldn't contain gotchas like this.

moefh 4y ago

Wow, that Win32 OpenFile function is truly cursed: - If you don't specify a directory, Windows will look for the file in a bunch of directories, but the current directory is not the first place searched. - The lpReOpenBuff is annotated as [out], but is an input when uStyle contains the OF_REOPEN flag. - The function is named OpenFile, but can be used to delete a file. Even better, the documentation is not clear what to do with the return value on success: is it a valid file handle that must be passed to CloseHandle, or just a dummy non-error file handle? - You can also use it to check the existence of the file -- the documentation says it will open and then close the file. What's the return value in that case? Is it a stale file handle, a dummy, or do you still have to close it?

Someone 4y ago
You’re forgetting this one: you can specify a flag that makes the call display a dialog box if a requested file does not exist. Yes, this call to open a file can run an event loop that lets the user create directories, rename files, possibly even format floppy disks, etc. If you want a prime example of a layer violation, this is it. Its replacement “CreateFile” (https://learn.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea https://learn.microsoft.com/en-us/windows/win32/api/fileapi/...) is a lot saner, but still has this: “If you rename or delete a file and then restore it shortly afterward, the system searches the cache for file information to restore. Cached information includes its short/long name pair and creation time.” That’s intended to make it easier for “Save” operations in document-based applications to keep the short name of the file, creation time and file flags around.