Command: adds parallel and useStdErr options

Fixes #2045

src/detection/command/command.c

@@ -0,0 +1,60 @@
+#include "common/processing.h"
+#include "util/FFstrbuf.h"
+#include "detection/command/command.h"
+
+typedef struct FFCommandResultBundle
+{
+    FFProcessHandle handle;
+    const char* error;
+} FFCommandResultBundle;
+
+// FIFO, non-thread-safe list of running commands
+static FFlist commandQueue = {
+    .elementSize = sizeof(FFCommandResultBundle),
+};
+
+static const char* spawnProcess(FFCommandOptions* options, FFProcessHandle* handle)
+{
+    if (options->text.length == 0)
+        return "No command text specified";
+
+    return ffProcessSpawn(options->param.length ? (char* const[]){
+        options->shell.chars,
+        options->param.chars,
+        options->text.chars,
+        NULL
+    } : (char* const[]){
+        options->shell.chars,
+        options->text.chars,
+        NULL
+    }, options->useStdErr, handle);
+}
+
+bool ffPrepareCommand(FFCommandOptions* options)
+{
+    if (!options->parallel) return false;
+
+    FFCommandResultBundle* bundle = ffListAdd(&commandQueue);
+    bundle->error = spawnProcess(options, &bundle->handle);
+
+    return true;
+}
+
+const char* ffDetectCommand(FFCommandOptions* options, FFstrbuf* result)
+{
+    FFCommandResultBundle bundle;
+    if (!options->parallel)
+        bundle.error = spawnProcess(options, &bundle.handle);
+    else
+        ffListShift(&commandQueue, &bundle);
+
+    if (bundle.error)
+        return bundle.error;
+
+    bundle.error = ffProcessReadOutput(&bundle.handle, result);
+    if (bundle.error)
+        return bundle.error;
+
+    ffStrbufTrimRightSpace(result);
+    return NULL;
+}

src/detection/command/command.h

@@ -0,0 +1,6 @@
+#pragma once
+
+#include "fastfetch.h"
+#include "modules/command/option.h"
+
+const char* ffDetectCommand(FFCommandOptions* options, FFstrbuf* result);