fastboot: sanitize getvar input and make it more robust

Assuming the first part of the output always contains the
variable is wrong.

Signed-off-by: Alexander Martinz <amartinz@shiftphones.com>

Author: amartinz

src/fastboot.spec.ts

@@ -344,12 +344,49 @@ test("getvar()", async t => {
 });
 
 test("getDeviceName()", async t => {
-  const [[fastboot_true], [fastboot_error]] = fake()(
+  const [
+    [fastboot_true],
+    [fastboot_tab_at_beginning],
+    [fastboot_whitespaces_all_around],
+    [fastboot_waiting],
+    [fastboot_waiting_with_tab],
+    [fastboot_waiting_with_whitespace],
+    [fastboot_weird_output],
+    [fastboot_error]
+  ] = fake()(
     ["", "product: FP2\nFinished. Total time: 0.000s", 0],
+    ["", "\tproduct: sdm845\nFinished. Total time: 0.001s", 0],
+    ["", "     product: lahaina    \nFinished. Total time: 0.001s", 0],
+    [
+      "",
+      "< waiting for any device >\nproduct: axolotl\nFinished. Total time: 0.001s",
+      0
+    ],
+    [
+      "",
+      "< waiting for any device >\n\tproduct: otter \t \nFinished. Total time: 0.001s",
+      0
+    ],
+    [
+      "",
+      "< waiting for any device >\n    product: FP5  \nFinished. Total time: 0.001s",
+      0
+    ],
+    [
+      "",
+      "\t\n\n  \n< waiting for any device >\nThis\nis\npretty\nweird\output\n\n    product: qcm6490  \nFinished. Total time: 0.001s",
+      0
+    ],
     ["error", "", 0]
   );
   await Promise.all([
     t.is(await fastboot_true.getDeviceName(), "FP2"),
+    t.is(await fastboot_tab_at_beginning.getDeviceName(), "sdm845"),
+    t.is(await fastboot_whitespaces_all_around.getDeviceName(), "lahaina"),
+    t.is(await fastboot_waiting.getDeviceName(), "axolotl"),
+    t.is(await fastboot_waiting_with_tab.getDeviceName(), "otter"),
+    t.is(await fastboot_waiting_with_whitespace.getDeviceName(), "FP5"),
+    t.is(await fastboot_weird_output.getDeviceName(), "qcm6490"),
     t.throwsAsync(fastboot_error.getDeviceName(), {
       message: 'Unexpected getvar return: "error"'
     })

src/fastboot.ts

@@ -409,11 +409,34 @@ export class Fastboot extends Tool {
 
   /** get bootloader var */
   async getvar(variable: string): Promise<string> {
+    // This could be multiple things, such as when `variable == product`:
+    // - `product: sdm845\nFinished. Total time: 0.001s`
+    // - `< waiting for any device >\nproduct: sdm845\nFinished. Total time: 0.001s`
+    // - `< waiting for any device >\n\tproduct: sdm845\nFinished. Total time: 0.001s`
+    // - `< waiting for any device >\n    product: sdm845\nFinished. Total time: 0.001s`
     const result = await this.exec("getvar", variable);
-    const [name, value] = result
+
+    // Split result into multiple lines
+    const resultParts = result
+      // replace CR line endings with LF
       .replace(/\r\n/g, "\n")
-      .split("\n")[0]
-      .split(": ");
+      // split by new lines
+      .split("\n")
+      // remove whitespaces
+      .map(element => element.trim());
+
+    // check for lines starting with the wanted variable, e.g.: `product`
+    const resultPart = resultParts.find(element =>
+      element.startsWith(variable)
+    );
+
+    const [name, value] = resultPart
+      ? resultPart.split(": ")
+      : resultParts && resultParts.length
+        ? // for backwards compatibility return the first line as name, if it exists
+          [resultParts[0], ""]
+        : // otherwise just return empty name and value
+          ["", ""];
 
     if (name !== variable) {
       throw this.error(