setup_rust: retry the rustup install

lib/runtime.func

@@ -2538,7 +2538,16 @@ setup_rust() {
   # Scenario 1: Rustup not installed - fresh install
   if ! command -v rustup &>/dev/null; then
     msg_info "Setup Rust ($RUST_TOOLCHAIN, profile: $RUST_PROFILE)"
-    curl -fsSL https://sh.rustup.rs | $STD sh -s -- -y --profile "$RUST_PROFILE" --default-toolchain "$RUST_TOOLCHAIN" || {
+    # rustup gives up on a connection reset halfway through a component
+    local _rust_try _rust_ok=0
+    for _rust_try in 1 2 3; do
+      if curl -fsSL https://sh.rustup.rs | $STD sh -s -- -y --profile "$RUST_PROFILE" --default-toolchain "$RUST_TOOLCHAIN"; then
+        _rust_ok=1
+        break
+      fi
+      [[ "$_rust_try" -lt 3 ]] && sleep $((_rust_try * 10))
+    done
+    [[ "$_rust_ok" -eq 1 ]] || {
       msg_error "Failed to install Rust"
       msg_error "Hint: Check connectivity to sh.rustup.rs and static.rust-lang.org"
       return 7

tests/rust-install-retry.sh

@@ -0,0 +1,60 @@
+#!/usr/bin/env bash
+set -uo pipefail
+
+CORE_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")/.." && pwd)"
+eval "$(awk '/^setup_rust[(][)] [{]/,/^}/' "$CORE_DIR/lib/runtime.func")"
+
+TEST_DIR="$(mktemp -d)"
+trap 'rm -rf -- "$TEST_DIR"' EXIT
+LOG="$TEST_DIR/log"
+TRIES="$TEST_DIR/tries"
+passed=0 failed=0
+
+export STD="" HOME="$TEST_DIR"
+msg_info() { echo "info: $*" >>"$LOG"; }
+msg_ok() { echo "ok: $*" >>"$LOG"; }
+msg_warn() { echo "warn: $*" >>"$LOG"; }
+msg_error() { echo "error: $*" >>"$LOG"; }
+sleep() { :; }
+_cs_write_cargo_profile() { :; }
+cache_installed_version() { :; }
+_cs_write_cargo_net() { :; }
+rust_prune_toolchains() { :; }
+curl() { :; }
+sh() {
+  echo x >>"$TRIES"
+  [[ "$(wc -l <"$TRIES")" -ge "${MOCK_OK_AT:-99}" ]] || return 1
+  command mkdir -p "$HOME/.cargo/bin"
+  printf '#!/bin/sh\necho rustc 1.99.1\n' >"$HOME/.cargo/bin/rustc"
+  printf '#!/bin/sh\necho rustup\n' >"$HOME/.cargo/bin/rustup"
+  printf '#!/bin/sh\n' >"$HOME/.cargo/bin/cargo"
+  chmod +x "$HOME/.cargo/bin/"*
+}
+
+run() {
+  : >"$LOG"
+  : >"$TRIES"
+  rm -rf "$HOME/.cargo"
+  (PATH="/usr/bin:/bin" setup_rust)
+}
+expect() {
+  if [[ "$2" == "$3" ]]; then
+    echo "PASS $1"
+    passed=$((passed + 1))
+  else
+    echo "FAIL $1: expected <$2>, got <$3>" >&2
+    failed=$((failed + 1))
+  fi
+}
+
+MOCK_OK_AT=2 run
+expect "a reset on the first try is retried" "0" "$?"
+expect "it took two tries" "2" "$(wc -l <"$TRIES")"
+
+MOCK_OK_AT=99 run
+expect "three failures give up" "7" "$?"
+expect "after three tries" "3" "$(wc -l <"$TRIES")"
+expect "and say so" "1" "$(grep -c 'error: Failed to install Rust' "$LOG")"
+
+echo "${passed} passed, ${failed} failed"
+((failed == 0))