From f45900d7e6d1dfb2bb289b3e293c7d47efcb09a4 Mon Sep 17 00:00:00 2001
From: Filip Stevanovic <62512535+filipstev@users.noreply.github.com>
Date: Fri, 26 Sep 2025 12:54:41 +0200
Subject: [PATCH] fix(fetch): print request body for
 application/x-www-form-urlencoded in curl logs (#22849)

### What does this PR do?

fixes an issue where fetch requests with `Content-Type:
application/x-www-form-urlencoded` would not include the request body in
curl logs when `BUN_CONFIG_VERBOSE_FETCH=curl` is enabled

previously, only JSON and text-based content types were recognized as
safe-to-print in the curl formatter. This change updates the allow-list
to also handle `application/x-www-form-urlencoded`, ensuring bodies for
common form submissions are shown in logs

### How did you verify your code works?

- added `Content-Type: application/x-www-form-urlencoded` to a fetch
request and confirmed that `BUN_CONFIG_VERBOSE_FETCH=curl` now outputs a
`--data-raw` section with the encoded body
- verified the fix against the reproduction script provided in issue
#12042
 - created and ran a regression test
- checked that existing content types (JSON, text, etc.) continue to
print correctly

fixes #12042
---
 src/deps/picohttp.zig               | 11 ++++++-
 test/regression/issue/12042.test.ts | 47 +++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 test/regression/issue/12042.test.ts

diff --git a/src/deps/picohttp.zig b/src/deps/picohttp.zig
index b674897fb9..a0507c6ffa 100644
--- a/src/deps/picohttp.zig
+++ b/src/deps/picohttp.zig
@@ -97,6 +97,15 @@ pub const Request = struct {
         ignore_insecure: bool = false,
         body: []const u8 = "",
 
+        fn isPrintableBody(content_type: []const u8) bool {
+            if (content_type.len == 0) return false;
+
+            return bun.strings.hasPrefixComptime(content_type, "text/") or
+                bun.strings.hasPrefixComptime(content_type, "application/json") or
+                bun.strings.containsComptime(content_type, "json") or
+                bun.strings.hasPrefixComptime(content_type, "application/x-www-form-urlencoded");
+        }
+
         pub fn format(self: @This(), comptime _: []const u8, _: fmt.FormatOptions, writer: anytype) !void {
             const request = self.request;
             if (Output.enable_ansi_colors_stderr) {
@@ -132,7 +141,7 @@ pub const Request = struct {
                 }
             }
 
-            if (self.body.len > 0 and (content_type.len > 0 and bun.strings.hasPrefixComptime(content_type, "application/json") or bun.strings.hasPrefixComptime(content_type, "text/") or bun.strings.containsComptime(content_type, "json"))) {
+            if (self.body.len > 0 and isPrintableBody(content_type)) {
                 _ = try writer.writeAll(" --data-raw ");
                 try bun.js_printer.writeJSONString(self.body, @TypeOf(writer), writer, .utf8);
             }
diff --git a/test/regression/issue/12042.test.ts b/test/regression/issue/12042.test.ts
new file mode 100644
index 0000000000..f882aa78fe
--- /dev/null
+++ b/test/regression/issue/12042.test.ts
@@ -0,0 +1,47 @@
+import { expect, test } from "bun:test";
+import { bunEnv, bunExe, normalizeBunSnapshot, tempDir } from "harness";
+
+test("#12042 curl verbose fetch logs form-urlencoded body", async () => {
+  using dir = tempDir("issue-12042", {
+    "form.ts": `
+const server = Bun.serve({
+  port: 0,
+  fetch() {
+    return new Response(JSON.stringify({ ok: true }), {
+      headers: { "Content-Type": "application/json" },
+    });
+  },
+});
+
+const params = new URLSearchParams();
+params.set("grant_type", "client_credentials");
+params.set("client_id", "abc");
+params.set("client_secret", "xyz");
+
+await fetch(String(server.url), {
+  method: "POST",
+  headers: { "Content-Type": "application/x-www-form-urlencoded" },
+  body: params,
+});
+
+await server.stop();
+    `,
+  });
+
+  const dirPath = String(dir);
+
+  await using proc = Bun.spawn({
+    cmd: [bunExe(), "form.ts"],
+    env: { ...bunEnv, BUN_CONFIG_VERBOSE_FETCH: "curl" },
+    cwd: dirPath,
+    stdout: "pipe",
+    stderr: "pipe",
+  });
+
+  const [stdout, stderr] = await Promise.all([proc.stdout.text(), proc.stderr.text()]);
+
+  const output = stdout + stderr;
+  const normalized = normalizeBunSnapshot(output, dirPath);
+
+  expect(normalized).toContain('--data-raw "grant_type=client_credentials&client_id=abc&client_secret=xyz');
+});