Fix(cf curl): Prevent errors when handling binary API responses (#3605)

Author: prkalle

command/v7/curl_command.go

@@ -1,8 +1,11 @@
 package v7
 
 import (
+	"bytes"
+	"net/http"
 	"net/http/httputil"
 	"os"
+	"strings"
 
 	"code.cloudfoundry.org/cli/command/flag"
 	"code.cloudfoundry.org/cli/command/translatableerror"
@@ -39,9 +42,9 @@ func (cmd CurlCommand) Execute(args []string) error {
 	}
 
 	var bytesToWrite []byte
-
-	if cmd.IncludeResponseHeaders {
-		headerBytes, _ := httputil.DumpResponse(httpResponse, false)
+	var headerBytes []byte
+	if cmd.IncludeResponseHeaders && httpResponse != nil {
+		headerBytes, _ = httputil.DumpResponse(httpResponse, false)
 		bytesToWrite = append(bytesToWrite, headerBytes...)
 	}
 
@@ -54,9 +57,38 @@ func (cmd CurlCommand) Execute(args []string) error {
 		}
 
 		cmd.UI.DisplayOK()
+		return nil
+	}
+
+	// Check if the response contains binary data
+	if isBinary(httpResponse, responseBodyBytes) {
+		// For binary data, write response headers with string conversion
+		// and the response body without string conversion
+		if cmd.IncludeResponseHeaders {
+			cmd.UI.DisplayTextLiteral(string(headerBytes))
+		}
+		cmd.UI.GetOut().Write(responseBodyBytes)
 	} else {
 		cmd.UI.DisplayText(string(bytesToWrite))
 	}
 
 	return nil
 }
+
+// isBinary determines if the provided `data` is likely binary content.
+// It first checks if the given `contentType` (e.g., from an HTTP header) is a known binary MIME type.
+// If not, it then scans the `data` byte slice for the presence of null bytes (0x00),
+// which are a strong heuristic for binary data.
+// Returns `true` if identified as binary, `false` otherwise.
+func isBinary(response *http.Response, data []byte) bool {
+	responseContextType := ""
+	if response != nil && response.Header != nil {
+		responseContextType = response.Header.Get("Content-Type")
+	}
+	if strings.Contains(responseContextType, "image/") ||
+		strings.Contains(responseContextType, "application/octet-stream") ||
+		strings.Contains(responseContextType, "application/pdf") {
+		return true
+	}
+	return bytes.ContainsRune(data, 0x00) // Check for null byte
+}

command/v7/curl_command_test.go

@@ -149,4 +149,88 @@ var _ = Describe("curl Command", func() {
 		})
 	})
 
+	When("the response contains binary data", func() {
+		var binaryData []byte
+
+		BeforeEach(func() {
+			// Create binary data with null bytes (like a droplet file)
+			binaryData = []byte{0x50, 0x4B, 0x03, 0x04, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00}
+			fakeActor.MakeCurlRequestReturns(binaryData, &http.Response{
+				Header: http.Header{
+					"Content-Type": []string{"application/octet-stream"},
+				},
+			}, nil)
+		})
+
+		It("writes binary data directly to stdout without string conversion", func() {
+			Expect(executeErr).NotTo(HaveOccurred())
+			Expect(testUI.Out).To(Say(string(binaryData)))
+		})
+
+		When("Content-Type is not a known binary MIME type", func() {
+			BeforeEach(func() {
+				// Create binary data with null bytes (like a droplet file)
+				binaryData = []byte{0x50, 0x4B, 0x03, 0x04, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00}
+				fakeActor.MakeCurlRequestReturns(binaryData, &http.Response{
+					Header: http.Header{
+						"Content-Type": []string{"text/plain"},
+					},
+				}, nil)
+			})
+			It("inspects the response data and writes binary data directly to stdout without string conversion", func() {
+				Expect(executeErr).NotTo(HaveOccurred())
+				Expect(testUI.Out).To(Say(string(binaryData)))
+			})
+		})
+
+		When("include-response-headers flag is set", func() {
+			BeforeEach(func() {
+				cmd.IncludeResponseHeaders = true
+			})
+
+			It("writes headers as text and binary data separately", func() {
+				Expect(executeErr).NotTo(HaveOccurred())
+
+				// Check that headers are written as text (using DisplayTextLiteral)
+				Expect(testUI.Out).To(Say("Content-Type: application/octet-stream"))
+
+				// Check that binary data is preserved
+				Expect(testUI.Out).To(Say(string(binaryData)))
+			})
+		})
+
+		When("output file is specified", func() {
+			BeforeEach(func() {
+				outputFile, err := os.CreateTemp("", "binary-output")
+				Expect(err).NotTo(HaveOccurred())
+				cmd.OutputFile = flag.Path(outputFile.Name())
+			})
+
+			AfterEach(func() {
+				os.RemoveAll(string(cmd.OutputFile))
+			})
+
+			It("writes binary data to the file correctly", func() {
+				Expect(executeErr).NotTo(HaveOccurred())
+
+				fileContents, err := os.ReadFile(string(cmd.OutputFile))
+				Expect(err).ToNot(HaveOccurred())
+				Expect(fileContents).To(Equal(binaryData))
+			})
+		})
+	})
+
+	When("the response is empty", func() {
+		BeforeEach(func() {
+			fakeActor.MakeCurlRequestReturns([]byte{}, &http.Response{
+				Header: http.Header{},
+			}, nil)
+		})
+
+		It("handles empty response correctly", func() {
+			Expect(executeErr).NotTo(HaveOccurred())
+			Expect(testUI.Out).To(Say(""))
+		})
+	})
+
 })