zblkpg

A Zig library to call Linux blkpg ioctls.

Note: only the BLKPG_RESIZE_PARTITION operation is implemented.

Usage

Add to your build.zig.zon:

.dependencies = .{
    .zblkpg = .{
        .url = "https://github.com/cloudboss/zblkpg/archive/<commit>.tar.gz",
        .hash = "...",
    },
},

Then in your build.zig:

const zblkpg_dep = b.dependency("zblkpg", .{
    .target = target,
    .optimize = optimize,
});
exe.root_module.addImport("zblkpg", zblkpg_dep.module("zblkpg"));

Example

const std = @import("std");
const zblkpg = @import("zblkpg");

pub fn main() !void {
    const file = try std.fs.openFileAbsolute("/dev/nvme0n1", .{ .mode = .read_write });
    defer file.close();

    // Resize partition 2: new range is sectors 456-789 with 512-byte sectors
    try zblkpg.resizePartition(file.handle, 2, 456, 789, 512);
}

API

resizePartition

pub fn resizePartition(
    fd: std.posix.fd_t,
    part_num: i32,
    start_sector: i64,
    end_sector: i64,
    sector_size: i64,
) ResizeError!void

Resizes a partition while it is mounted. This calls the blkpg ioctl with the BLKPG_RESIZE_PARTITION operation, informing the kernel about the new partition boundaries without requiring unmounting.

Parameters:

• fd: The open file descriptor of the disk device (e.g., /dev/nvme0n1).
• part_num: The number of the partition to be modified.
• start_sector: The start sector of the partition.
• end_sector: The end sector of the partition.
• sector_size: The size of the sectors in bytes.

Error Types

• AccessDenied: Access to the device was denied.
• InvalidFileDescriptor: The file descriptor is not valid or not open for writing.
• InvalidArgument: Invalid argument (e.g., partition number, start, or length).
• NotSupported: The device does not support this operation.
• Unexpected: An unexpected error occurred.

Testing

Unit tests (struct size validation):

zig build test

Integration tests (requires root, uses loop devices):

sudo zig build test-integration

License

MIT