ProcessRunner.cs

using System.Diagnostics;
using System.Text;

namespace DbBackupTool
{
    // Shared "shell out to a native CLI tool and check the result" helper - every
    // provider (exp, sqlcmd, mysqldump) goes through this exact same path, which is
    // what keeps the three providers this uniform. Uses ArgumentList (not a
    // hand-built command string) so arguments containing spaces/quotes - file paths,
    // passwords - can never break quoting.
    public static class ProcessRunner
    {
        public static async Task<string> RunAsync(
            string fileName, IEnumerable<string> args, TimeSpan timeout, CancellationToken ct,
            IDictionary<string, string>? environmentVariables = null)
        {
            var psi = new ProcessStartInfo
            {
                FileName = fileName,
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                UseShellExecute = false,
                CreateNoWindow = true,
            };
            foreach (var a in args) psi.ArgumentList.Add(a);
            if (environmentVariables != null)
                foreach (var (key, value) in environmentVariables)
                    psi.Environment[key] = value;

            using var process = new Process { StartInfo = psi };
            var stdout = new StringBuilder();
            var stderr = new StringBuilder();
            process.OutputDataReceived += (_, e) => { if (e.Data != null) stdout.AppendLine(e.Data); };
            process.ErrorDataReceived += (_, e) => { if (e.Data != null) stderr.AppendLine(e.Data); };

            try
            {
                process.Start();
            }
            catch (Exception ex)
            {
                throw new InvalidOperationException(
                    $"Could not start '{fileName}'. Is it installed and on PATH (or is the configured *Path setting a full path)? {ex.Message}", ex);
            }

            process.BeginOutputReadLine();
            process.BeginErrorReadLine();

            using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(ct);
            timeoutCts.CancelAfter(timeout);
            try
            {
                await process.WaitForExitAsync(timeoutCts.Token);
            }
            catch (OperationCanceledException) when (!ct.IsCancellationRequested)
            {
                TryKill(process);
                throw new TimeoutException($"{fileName} timed out after {timeout}.\nSTDOUT:\n{stdout}\nSTDERR:\n{stderr}");
            }
            catch (OperationCanceledException)
            {
                TryKill(process);
                throw;
            }

            if (process.ExitCode != 0)
                throw new InvalidOperationException(
                    $"{fileName} exited with code {process.ExitCode}.\nSTDOUT:\n{stdout}\nSTDERR:\n{stderr}");

            return stdout.ToString().Trim();
        }

        private static void TryKill(Process process)
        {
            try { process.Kill(entireProcessTree: true); } catch { /* best effort */ }
        }
    }
}