Zig 0.17.0-dev (Split by item)

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readFile

Read all of file contents using a preallocated buffer.

The returned slice has the same pointer as buffer. If the length matches buffer.len the situation is ambiguous. It could either mean that the entire file was read, and it exactly fits the buffer, or it could mean the buffer was not big enough for the entire file.

On Windows, file_path should be encoded as WTF-8.
On WASI, file_path should be encoded as valid UTF-8.
On other platforms, file_path is an opaque sequence of bytes with no particular encoding.

Dir.readFile

pub fn readFile(dir: Dir, io: Io, file_path: []const u8, buffer: []u8) ReadFileError![]u8

File

lib/std/Io/Dir.zig:756

Code

pub fn readFile(dir: Dir, io: Io, file_path: []const u8, buffer: []u8) ReadFileError![]u8 {
    var file = try dir.openFile(io, file_path, .{
        // We can take advantage of this on Windows since it doesn't involve any extra syscalls,
        // so we can get error.IsDir during open rather than during the read.
        .allow_directory = if (native_os == .windows) false else true,
    });
    defer file.close(io);

    var reader = file.reader(io, &.{});
    const n = reader.interface.readSliceShort(buffer) catch |err| switch (err) {
        error.ReadFailed => return reader.err.?,
    };

    return buffer[0..n];
}