diff options
| -rw-r--r-- | library/std/src/sys/pal/windows/mod.rs | 17 | ||||
| -rw-r--r-- | library/std/src/sys/pal/windows/os.rs | 2 |
2 files changed, 14 insertions, 5 deletions
diff --git a/library/std/src/sys/pal/windows/mod.rs b/library/std/src/sys/pal/windows/mod.rs index b49585599cb..ff41f6e77be 100644 --- a/library/std/src/sys/pal/windows/mod.rs +++ b/library/std/src/sys/pal/windows/mod.rs @@ -201,14 +201,21 @@ pub fn to_u16s<S: AsRef<OsStr>>(s: S) -> crate::io::Result<Vec<u16>> { // currently reside in the buffer. This function is an abstraction over these // functions by making them easier to call. // -// The first callback, `f1`, is yielded a (pointer, len) pair which can be +// The first callback, `f1`, is passed a (pointer, len) pair which can be // passed to a syscall. The `ptr` is valid for `len` items (u16 in this case). -// The closure is expected to return what the syscall returns which will be -// interpreted by this function to determine if the syscall needs to be invoked -// again (with more buffer space). +// The closure is expected to: +// - On success, return the actual length of the written data *without* the null terminator. +// This can be 0. In this case the last_error must be left unchanged. +// - On insufficient buffer space, +// - either return the required length *with* the null terminator, +// - or set the last-error to ERROR_INSUFFICIENT_BUFFER and return `len`. +// - On other failure, return 0 and set last_error. +// +// This is how most but not all syscalls indicate the required buffer space. +// Other syscalls may need translation to match this protocol. // // Once the syscall has completed (errors bail out early) the second closure is -// yielded the data which has been read from the syscall. The return value +// passed the data which has been read from the syscall. The return value // from this closure is then the return value of the function. pub fn fill_utf16_buf<F1, F2, T>(mut f1: F1, f2: F2) -> crate::io::Result<T> where diff --git a/library/std/src/sys/pal/windows/os.rs b/library/std/src/sys/pal/windows/os.rs index 374c9845ea4..64d8b72aed2 100644 --- a/library/std/src/sys/pal/windows/os.rs +++ b/library/std/src/sys/pal/windows/os.rs @@ -326,6 +326,8 @@ fn home_dir_crt() -> Option<PathBuf> { super::fill_utf16_buf( |buf, mut sz| { + // GetUserProfileDirectoryW does not quite use the usual protocol for + // negotiating the buffer size, so we have to translate. match c::GetUserProfileDirectoryW( ptr::without_provenance_mut(CURRENT_PROCESS_TOKEN), buf, |