bootstrap: improve error recovery flags to curl

src/bootstrap/bootstrap.py

@@ -79,6 +79,11 @@ def get(base, url, path, checksums, verbose=False):
                 eprint("removing", temp_path)
             os.unlink(temp_path)
 
+def curl_version():
+    m = re.match(bytes("^curl ([0-9]+)\\.([0-9]+)", "utf8"), require(["curl", "-V"]))
+    if m is None:
+        return (0, 0)
+    return (int(m[1]), int(m[2]))
 
 def download(path, url, probably_big, verbose):
     for _ in range(4):
@@ -107,11 +112,15 @@ def _download(path, url, probably_big, verbose, exception):
         # If curl is not present on Win32, we should not sys.exit
         #   but raise `CalledProcessError` or `OSError` instead
         require(["curl", "--version"], exception=platform_is_win32())
-        run(["curl", option,
+        extra_flags = []
+        if curl_version() > (7, 70):
+            extra_flags = [ "--retry-all-errors" ]
+        run(["curl", option] + extra_flags + [
             "-L", # Follow redirect.
             "-y", "30", "-Y", "10",    # timeout if speed is < 10 bytes/sec for > 30 seconds
             "--connect-timeout", "30",  # timeout if cannot connect within 30 seconds
             "-o", path,
+            "--continue-at", "-",
             "--retry", "3", "-SRf", url],
             verbose=verbose,
             exception=True, # Will raise RuntimeError on failure

src/bootstrap/src/core/download.rs

@@ -21,6 +21,27 @@ fn try_run(config: &Config, cmd: &mut Command) -> Result<(), ()> {
     config.try_run(cmd)
 }
 
+fn extract_curl_version(out: &[u8]) -> (u16, u16) {
+    let out = &out[5..];
+    let Some(i) = out.iter().position(|&x| x == b' ') else { return (0, 0) };
+    let out = &out[..i];
+    let Some(k) = out.iter().rev().position(|&x| x == b'.') else { return (0, 0) };
+    let out = &out[..out.len() - k - 1];
+    let Ok(s) = std::str::from_utf8(out) else { return (0, 0) };
+    let parts = s.split('.').collect::<Vec<_>>();
+    let [s_major, s_minor] = &parts[..] else { return (0, 0) };
+    let (Ok(major), Ok(minor)) = (s_major.parse(), s_minor.parse()) else { return (0, 0) };
+    (major, minor)
+}
+
+fn curl_version() -> (u16, u16) {
+    let mut curl = Command::new("curl");
+    curl.arg("-V");
+    let Ok(out) = curl.output() else { return (0, 0) };
+    let out = out.stdout;
+    extract_curl_version(&out)
+}
+
 /// Generic helpers that are useful anywhere in bootstrap.
 impl Config {
     pub fn is_verbose(&self) -> bool {
@@ -219,6 +240,8 @@ impl Config {
             "30", // timeout if cannot connect within 30 seconds
             "-o",
             tempfile.to_str().unwrap(),
+            "--continue-at",
+            "-",
             "--retry",
             "3",
             "-SRf",
@@ -229,6 +252,10 @@ impl Config {
         } else {
             curl.arg("--progress-bar");
         }
+        // --retry-all-errors was added in 7.71.0, don't use it if curl is old.
+        if curl_version() > (7, 70) {
+            curl.arg("--retry-all-errors");
+        }
         curl.arg(url);
         if !self.check_run(&mut curl) {
             if self.build.contains("windows-msvc") {