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fabric: properly retry download when fabric installer is invalid #620

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Merged
merged 1 commit into from
Aug 13, 2025
Merged

fabric: properly retry download when fabric installer is invalid #620

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73 changes: 41 additions & 32 deletions src/main/java/me/itzg/helpers/fabric/FabricMetaClient.java
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Original file line number Diff line number Diff line change
@@ -1,7 +1,8 @@
package me.itzg.helpers.fabric;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.file.Files;
import java.nio.file.Path;
import java.time.Duration;
Expand All @@ -16,6 +17,7 @@
import me.itzg.helpers.http.FileDownloadStatusHandler;
import me.itzg.helpers.http.SharedFetch;
import me.itzg.helpers.http.UriBuilder;
import org.apache.commons.codec.binary.Hex;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;
import reactor.core.publisher.Mono;
Expand Down Expand Up @@ -155,52 +157,59 @@ public Mono<Path> downloadLauncher(
.handleStatus(statusHandler)
.assemble()
.retryWhen(Retry.backoff(downloadRetryMaxAttempts, downloadRetryMinBackoff).filter(IOException.class::isInstance))
.flatMap(path -> skipValidation ? Mono.just(path) : validateLauncherJar(path))
.doOnError(InvalidContentException.class, e -> log.warn("Invalid launcher jar, will try again", e))
.flatMap(path -> skipValidation ?
Mono.just(path)
: validateLauncherJar(path).subscribeOn(Schedulers.boundedElastic())
)
.doOnError(InvalidContentException.class, e ->
log.warn("Invalid launcher jar, will try again: {}", e.getMessage())
)
.retryWhen(Retry.backoff(downloadRetryMaxAttempts, downloadRetryMinBackoff).filter(InvalidContentException.class::isInstance))
.checkpoint("downloadLauncher");
}

private Mono<Path> validateLauncherJar(Path path) {
return Mono.fromCallable(() -> {
log.debug("Validating Fabric launcher file {}", path);
return Mono.create(sink -> {
log.debug("Validating Fabric launcher file {}", path);

if (!path.toFile().isFile()) {
throw new InvalidContentException("Downloaded launcher jar is not a file");
}
try {
final Properties installProperties = IoStreams.readFileFromZip(path, "install.properties", in -> {
Properties p = new Properties();
p.load(in);
return p;
}
);
if (installProperties == null) {
debugDownloadedContent(path);
throw new InvalidContentException("Downloaded launcher jar does not contain an install.properties");
}
if (!installProperties.containsKey("game-version")) {
debugDownloadedContent(path);
throw new InvalidContentException("Downloaded launcher jar does not contain a valid install.properties");
if (!path.toFile().isFile()) {
sink.error(new InvalidContentException("Downloaded launcher jar is not a file"));
}
try {
final Properties installProperties = IoStreams.readFileFromZip(path, "install.properties", in -> {
Properties p = new Properties();
p.load(in);
return p;
}
} catch (IOException e) {
);
if (installProperties == null) {
debugDownloadedContent(path);
throw new InvalidContentException("Downloaded launcher jar could not be read as a jar/zip", e);
sink.error(new InvalidContentException("Does not contain an install.properties"));
}
else if (!installProperties.containsKey("game-version")) {
debugDownloadedContent(path);
sink.error(new InvalidContentException("Does not contain a valid install.properties"));
}
} catch (IOException e) {
debugDownloadedContent(path);
sink.error(new InvalidContentException("Could not be read as a jar/zip", e));
}

return path;
})
.subscribeOn(Schedulers.boundedElastic());
sink.success(path);
});
}

private static void debugDownloadedContent(Path path) {
if (log.isDebugEnabled()) {
try (BufferedReader reader = Files.newBufferedReader(path)) {
final char[] buf = new char[100];
final int amount = reader.read(buf);
log.debug("Downloaded launcher jar content starts with: {}", new String(buf, 0, amount));
try (InputStream in = Files.newInputStream(path)) {
final byte[] buf = new byte[100];
final int amount = in.read(buf);

log.debug("Downloaded launcher jar content starts with: {}",
Hex.encodeHexString(ByteBuffer.wrap(buf, 0, amount))
);
} catch (IOException e) {
throw new GenericException("Failed to read downloaded launcher jar for debugging", e);
log.warn("Failed to debug content of launcher jar", e);
}
}
}
Expand Down