6 files changed, 276 insertions, 381 deletions

diff --git a/tools/ota/Android.mk b/tools/dumpkey/Android.mk
index 142c3b25..31549146 100644
--- a/tools/ota/Android.mk
+++ b/tools/dumpkey/Android.mk
@@ -15,19 +15,8 @@
 LOCAL_PATH := $(call my-dir)
 
 include $(CLEAR_VARS)
-LOCAL_FORCE_STATIC_EXECUTABLE := true
-LOCAL_MODULE := add-property-tag
-LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
-LOCAL_MODULE_TAGS := debug
-LOCAL_SRC_FILES := add-property-tag.c
-LOCAL_STATIC_LIBRARIES := libc
-include $(BUILD_EXECUTABLE)
-
-include $(CLEAR_VARS)
-LOCAL_FORCE_STATIC_EXECUTABLE := true
-LOCAL_MODULE := check-lost+found
-LOCAL_MODULE_PATH := $(TARGET_OUT_OPTIONAL_EXECUTABLES)
-LOCAL_MODULE_TAGS := debug
-LOCAL_SRC_FILES := check-lost+found.c
-LOCAL_STATIC_LIBRARIES := libcutils libc
-include $(BUILD_EXECUTABLE)
+LOCAL_MODULE := dumpkey
+LOCAL_SRC_FILES := DumpPublicKey.java
+LOCAL_JAR_MANIFEST := DumpPublicKey.mf
+LOCAL_STATIC_JAVA_LIBRARIES := bouncycastle-host
+include $(BUILD_HOST_JAVA_LIBRARY)
diff --git a/tools/dumpkey/DumpPublicKey.java b/tools/dumpkey/DumpPublicKey.java
new file mode 100644
index 00000000..3eb13984
--- /dev/null
+++ b/tools/dumpkey/DumpPublicKey.java
@@ -0,0 +1,270 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.dumpkey;
+
+import org.bouncycastle.jce.provider.BouncyCastleProvider;
+
+import java.io.FileInputStream;
+import java.math.BigInteger;
+import java.security.cert.CertificateFactory;
+import java.security.cert.X509Certificate;
+import java.security.KeyStore;
+import java.security.Key;
+import java.security.PublicKey;
+import java.security.Security;
+import java.security.interfaces.ECPublicKey;
+import java.security.interfaces.RSAPublicKey;
+import java.security.spec.ECPoint;
+
+/**
+ * Command line tool to extract RSA public keys from X.509 certificates
+ * and output source code with data initializers for the keys.
+ * @hide
+ */
+class DumpPublicKey {
+    /**
+     * @param key to perform sanity checks on
+     * @return version number of key.  Supported versions are:
+     *     1: 2048-bit RSA key with e=3 and SHA-1 hash
+     *     2: 2048-bit RSA key with e=65537 and SHA-1 hash
+     *     3: 2048-bit RSA key with e=3 and SHA-256 hash
+     *     4: 2048-bit RSA key with e=65537 and SHA-256 hash
+     * @throws Exception if the key has the wrong size or public exponent
+     */
+    static int checkRSA(RSAPublicKey key, boolean useSHA256) throws Exception {
+        BigInteger pubexp = key.getPublicExponent();
+        BigInteger modulus = key.getModulus();
+        int version;
+
+        if (pubexp.equals(BigInteger.valueOf(3))) {
+            version = useSHA256 ? 3 : 1;
+        } else if (pubexp.equals(BigInteger.valueOf(65537))) {
+            version = useSHA256 ? 4 : 2;
+        } else {
+            throw new Exception("Public exponent should be 3 or 65537 but is " +
+                                pubexp.toString(10) + ".");
+        }
+
+        if (modulus.bitLength() != 2048) {
+             throw new Exception("Modulus should be 2048 bits long but is " +
+                        modulus.bitLength() + " bits.");
+        }
+
+        return version;
+    }
+
+    /**
+     * @param key to perform sanity checks on
+     * @return version number of key.  Supported versions are:
+     *     5: 256-bit EC key with curve NIST P-256
+     * @throws Exception if the key has the wrong size or public exponent
+     */
+    static int checkEC(ECPublicKey key) throws Exception {
+        if (key.getParams().getCurve().getField().getFieldSize() != 256) {
+            throw new Exception("Curve must be NIST P-256");
+        }
+
+        return 5;
+    }
+
+    /**
+     * Perform sanity check on public key.
+     */
+    static int check(PublicKey key, boolean useSHA256) throws Exception {
+        if (key instanceof RSAPublicKey) {
+            return checkRSA((RSAPublicKey) key, useSHA256);
+        } else if (key instanceof ECPublicKey) {
+            if (!useSHA256) {
+                throw new Exception("Must use SHA-256 with EC keys!");
+            }
+            return checkEC((ECPublicKey) key);
+        } else {
+            throw new Exception("Unsupported key class: " + key.getClass().getName());
+        }
+    }
+
+    /**
+     * @param key to output
+     * @return a String representing this public key.  If the key is a
+     *    version 1 key, the string will be a C initializer; this is
+     *    not true for newer key versions.
+     */
+    static String printRSA(RSAPublicKey key, boolean useSHA256) throws Exception {
+        int version = check(key, useSHA256);
+
+        BigInteger N = key.getModulus();
+
+        StringBuilder result = new StringBuilder();
+
+        int nwords = N.bitLength() / 32;    // # of 32 bit integers in modulus
+
+        if (version > 1) {
+            result.append("v");
+            result.append(Integer.toString(version));
+            result.append(" ");
+        }
+
+        result.append("{");
+        result.append(nwords);
+
+        BigInteger B = BigInteger.valueOf(0x100000000L);  // 2^32
+        BigInteger N0inv = B.subtract(N.modInverse(B));   // -1 / N[0] mod 2^32
+
+        result.append(",0x");
+        result.append(N0inv.toString(16));
+
+        BigInteger R = BigInteger.valueOf(2).pow(N.bitLength());
+        BigInteger RR = R.multiply(R).mod(N);    // 2^4096 mod N
+
+        // Write out modulus as little endian array of integers.
+        result.append(",{");
+        for (int i = 0; i < nwords; ++i) {
+            long n = N.mod(B).longValue();
+            result.append(n);
+
+            if (i != nwords - 1) {
+                result.append(",");
+            }
+
+            N = N.divide(B);
+        }
+        result.append("}");
+
+        // Write R^2 as little endian array of integers.
+        result.append(",{");
+        for (int i = 0; i < nwords; ++i) {
+            long rr = RR.mod(B).longValue();
+            result.append(rr);
+
+            if (i != nwords - 1) {
+                result.append(",");
+            }
+
+            RR = RR.divide(B);
+        }
+        result.append("}");
+
+        result.append("}");
+        return result.toString();
+    }
+
+    /**
+     * @param key to output
+     * @return a String representing this public key.  If the key is a
+     *    version 1 key, the string will be a C initializer; this is
+     *    not true for newer key versions.
+     */
+    static String printEC(ECPublicKey key) throws Exception {
+        int version = checkEC(key);
+
+        StringBuilder result = new StringBuilder();
+
+        result.append("v");
+        result.append(Integer.toString(version));
+        result.append(" ");
+
+        BigInteger X = key.getW().getAffineX();
+        BigInteger Y = key.getW().getAffineY();
+        int nbytes = key.getParams().getCurve().getField().getFieldSize() / 8;    // # of 32 bit integers in X coordinate
+
+        result.append("{");
+        result.append(nbytes);
+
+        BigInteger B = BigInteger.valueOf(0x100L);  // 2^8
+
+        // Write out Y coordinate as array of characters.
+        result.append(",{");
+        for (int i = 0; i < nbytes; ++i) {
+            long n = X.mod(B).longValue();
+            result.append(n);
+
+            if (i != nbytes - 1) {
+                result.append(",");
+            }
+
+            X = X.divide(B);
+        }
+        result.append("}");
+
+        // Write out Y coordinate as array of characters.
+        result.append(",{");
+        for (int i = 0; i < nbytes; ++i) {
+            long n = Y.mod(B).longValue();
+            result.append(n);
+
+            if (i != nbytes - 1) {
+                result.append(",");
+            }
+
+            Y = Y.divide(B);
+        }
+        result.append("}");
+
+        result.append("}");
+        return result.toString();
+    }
+
+    static String print(PublicKey key, boolean useSHA256) throws Exception {
+        if (key instanceof RSAPublicKey) {
+            return printRSA((RSAPublicKey) key, useSHA256);
+        } else if (key instanceof ECPublicKey) {
+            return printEC((ECPublicKey) key);
+        } else {
+            throw new Exception("Unsupported key class: " + key.getClass().getName());
+        }
+    }
+
+    public static void main(String[] args) {
+        if (args.length < 1) {
+            System.err.println("Usage: DumpPublicKey certfile ... > source.c");
+            System.exit(1);
+        }
+        Security.addProvider(new BouncyCastleProvider());
+        try {
+            for (int i = 0; i < args.length; i++) {
+                FileInputStream input = new FileInputStream(args[i]);
+                CertificateFactory cf = CertificateFactory.getInstance("X.509");
+                X509Certificate cert = (X509Certificate) cf.generateCertificate(input);
+
+                boolean useSHA256 = false;
+                String sigAlg = cert.getSigAlgName();
+                if ("SHA1withRSA".equals(sigAlg) || "MD5withRSA".equals(sigAlg)) {
+                    // SignApk has historically accepted "MD5withRSA"
+                    // certificates, but treated them as "SHA1withRSA"
+                    // anyway.  Continue to do so for backwards
+                    // compatibility.
+                  useSHA256 = false;
+                } else if ("SHA256withRSA".equals(sigAlg) || "SHA256withECDSA".equals(sigAlg)) {
+                  useSHA256 = true;
+                } else {
+                  System.err.println(args[i] + ": unsupported signature algorithm \"" +
+                                     sigAlg + "\"");
+                  System.exit(1);
+                }
+
+                PublicKey key = cert.getPublicKey();
+                check(key, useSHA256);
+                System.out.print(print(key, useSHA256));
+                System.out.println(i < args.length - 1 ? "," : "");
+            }
+        } catch (Exception e) {
+            e.printStackTrace();
+            System.exit(1);
+        }
+        System.exit(0);
+    }
+}
diff --git a/tools/dumpkey/DumpPublicKey.mf b/tools/dumpkey/DumpPublicKey.mf
new file mode 100644
index 00000000..7bb3bc88
--- /dev/null
+++ b/tools/dumpkey/DumpPublicKey.mf
@@ -0,0 +1 @@
+Main-Class: com.android.dumpkey.DumpPublicKey
diff --git a/tools/ota/add-property-tag.c b/tools/ota/add-property-tag.c
deleted file mode 100644
index aab30b2d..00000000
--- a/tools/ota/add-property-tag.c
+++ /dev/null
@@ -1,141 +0,0 @@
-/*
- * Copyright (C) 2008 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include <ctype.h>
-#include <errno.h>
-#include <getopt.h>
-#include <limits.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-/*
- * Append a tag to a property value in a .prop file if it isn't already there.
- * Normally used to modify build properties to record incremental updates.
- */
-
-// Return nonzero if the tag should be added to this line.
-int should_tag(const char *line, const char *propname) {
-    const char *prop = strstr(line, propname);
-    if (prop == NULL) return 0;
-
-    // Make sure this is actually the property name (not an accidental hit)
-    const char *ptr;
-    for (ptr = line; ptr < prop && isspace(*ptr); ++ptr) ;
-    if (ptr != prop) return 0;  // Must be at the beginning of the line
-
-    for (ptr += strlen(propname); *ptr != '\0' && isspace(*ptr); ++ptr) ;
-    return (*ptr == '=');  // Must be followed by a '='
-}
-
-// Remove existing tags from the line, return the following number (if any)
-int remove_tag(char *line, const char *tag) {
-    char *pos = strstr(line, tag);
-    if (pos == NULL) return 0;
-
-    char *end;
-    int num = strtoul(pos + strlen(tag), &end, 10);
-    strcpy(pos, end);
-    return num;
-}
-
-// Write line to output with the tag added, adding a number (if >0)
-void write_tagged(FILE *out, const char *line, const char *tag, int number) {
-    const char *end = line + strlen(line);
-    while (end > line && isspace(end[-1])) --end;
-    if (number > 0) {
-        fprintf(out, "%.*s%s%d%s", (int)(end - line), line, tag, number, end);
-    } else {
-        fprintf(out, "%.*s%s%s", (int)(end - line), line, tag, end);
-    }
-}
-
-int main(int argc, char **argv) {
-    const char *filename = "/system/build.prop";
-    const char *propname = "ro.build.fingerprint";
-    const char *tag = NULL;
-    int do_remove = 0, do_number = 0;
-
-    int opt;
-    while ((opt = getopt(argc, argv, "f:p:rn")) != -1) {
-        switch (opt) {
-        case 'f': filename = optarg; break;
-        case 'p': propname = optarg; break;
-        case 'r': do_remove = 1; break;
-        case 'n': do_number = 1; break;
-        case '?': return 2;
-        }
-    }
-
-    if (argc != optind + 1) {
-        fprintf(stderr,
-            "usage: add-property-tag [flags] tag-to-add\n"
-            "flags: -f /dir/file.prop (default /system/build.prop)\n"
-            "       -p prop.name (default ro.build.fingerprint)\n"
-            "       -r (if set, remove the tag rather than adding it)\n"
-            "       -n (if set, add and increment a number after the tag)\n");
-        return 2;
-    }
-
-    tag = argv[optind];
-    FILE *input = fopen(filename, "r");
-    if (input == NULL) {
-        fprintf(stderr, "can't read %s: %s\n", filename, strerror(errno));
-        return 1;
-    }
-
-    char tmpname[PATH_MAX];
-    snprintf(tmpname, sizeof(tmpname), "%s.tmp", filename);
-    FILE *output = fopen(tmpname, "w");
-    if (output == NULL) {
-        fprintf(stderr, "can't write %s: %s\n", tmpname, strerror(errno));
-        return 1;
-    }
-
-    int found = 0;
-    char line[4096];
-    while (fgets(line, sizeof(line), input)) {
-        if (!should_tag(line, propname)) {
-            fputs(line, output);  // Pass through unmodified
-        } else {
-            found = 1;
-            int number = remove_tag(line, tag);
-            if (do_remove) {
-                fputs(line, output);  // Remove the tag but don't re-add it
-            } else {
-                write_tagged(output, line, tag, number + do_number);
-            }
-        }
-    }
-
-    fclose(input);
-    fclose(output);
-
-    if (!found) {
-        fprintf(stderr, "property %s not found in %s\n", propname, filename);
-        remove(tmpname);
-        return 1;
-    }
-
-    if (rename(tmpname, filename)) {
-        fprintf(stderr, "can't rename %s to %s: %s\n",
-            tmpname, filename, strerror(errno));
-        remove(tmpname);
-        return 1;
-    }
-
-    return 0;
-}
diff --git a/tools/ota/check-lost+found.c b/tools/ota/check-lost+found.c
deleted file mode 100644
index 8ce12d39..00000000
--- a/tools/ota/check-lost+found.c
+++ /dev/null
@@ -1,145 +0,0 @@
-/*
- * Copyright (C) 2008 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#include <dirent.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <limits.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/klog.h>
-#include <sys/reboot.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <time.h>
-#include <unistd.h>
-
-#include "private/android_filesystem_config.h"
-
-// Sentinel file used to track whether we've forced a reboot
-static const char *kMarkerFile = "/data/misc/check-lost+found-rebooted-2";
-
-// Output file in tombstones directory (first 8K will be uploaded)
-static const char *kOutputDir = "/data/tombstones";
-static const char *kOutputFile = "/data/tombstones/check-lost+found-log";
-
-// Partitions to check
-static const char *kPartitions[] = { "/system", "/data", "/cache", NULL };
-
-/*
- * 1. If /data/misc/forced-reboot is missing, touch it & force "unclean" boot.
- * 2. Write a log entry with the number of files in lost+found directories.
- */
-
-int main(int argc __attribute__((unused)), char **argv __attribute__((unused))) {
-    mkdir(kOutputDir, 0755);
-    chown(kOutputDir, AID_SYSTEM, AID_SYSTEM);
-    FILE *out = fopen(kOutputFile, "a");
-    if (out == NULL) {
-        fprintf(stderr, "Can't write %s: %s\n", kOutputFile, strerror(errno));
-        return 1;
-    }
-
-    // Note: only the first 8K of log will be uploaded, so be terse.
-    time_t start = time(NULL);
-    fprintf(out, "*** check-lost+found ***\nStarted: %s", ctime(&start));
-
-    struct stat st;
-    if (stat(kMarkerFile, &st)) {
-        // No reboot marker -- need to force an unclean reboot.
-        // But first, try to create the marker file.  If that fails,
-        // skip the reboot, so we don't get caught in an infinite loop.
-
-        int fd = open(kMarkerFile, O_WRONLY|O_CREAT, 0444);
-        if (fd >= 0 && close(fd) == 0) {
-            fprintf(out, "Wrote %s, rebooting\n", kMarkerFile);
-            fflush(out);
-            sync();  // Make sure the marker file is committed to disk
-
-            // If possible, dirty each of these partitions before rebooting,
-            // to make sure the filesystem has to do a scan on mount.
-            int i;
-            for (i = 0; kPartitions[i] != NULL; ++i) {
-                char fn[PATH_MAX];
-                snprintf(fn, sizeof(fn), "%s/%s", kPartitions[i], "dirty");
-                fd = open(fn, O_WRONLY|O_CREAT, 0444);
-                if (fd >= 0) {  // Don't sweat it if we can't write the file.
-                    TEMP_FAILURE_RETRY(write(fd, fn, sizeof(fn)));  // write, you know, some data
-                    close(fd);
-                    unlink(fn);
-                }
-            }
-
-            reboot(RB_AUTOBOOT);  // reboot immediately, with dirty filesystems
-            fprintf(out, "Reboot failed?!\n");
-            exit(1);
-        } else {
-            fprintf(out, "Can't write %s: %s\n", kMarkerFile, strerror(errno));
-        }
-    } else {
-        fprintf(out, "Found %s\n", kMarkerFile);
-    }
-
-    int i;
-    for (i = 0; kPartitions[i] != NULL; ++i) {
-        char fn[PATH_MAX];
-        snprintf(fn, sizeof(fn), "%s/%s", kPartitions[i], "lost+found");
-        DIR *dir = opendir(fn);
-        if (dir == NULL) {
-            fprintf(out, "Can't open %s: %s\n", fn, strerror(errno));
-        } else {
-            int count = 0;
-            struct dirent *ent;
-            while ((ent = readdir(dir))) {
-                if (strcmp(ent->d_name, ".") && strcmp(ent->d_name, ".."))
-                    ++count;
-            }
-            closedir(dir);
-            if (count > 0) {
-                fprintf(out, "OMGZ FOUND %d FILES IN %s\n", count, fn);
-            } else {
-                fprintf(out, "%s is clean\n", fn);
-            }
-        }
-    }
-
-    char dmesg[131073];
-    int len = klogctl(KLOG_READ_ALL, dmesg, sizeof(dmesg) - 1);
-    if (len < 0) {
-        fprintf(out, "Can't read kernel log: %s\n", strerror(errno));
-    } else {  // To conserve space, only write lines with certain keywords
-        fprintf(out, "--- Kernel log ---\n");
-        dmesg[len] = '\0';
-        char *saveptr, *line;
-        int in_yaffs = 0;
-        for (line = strtok_r(dmesg, "\n", &saveptr); line != NULL;
-             line = strtok_r(NULL, "\n", &saveptr)) {
-            if (strstr(line, "yaffs: dev is")) in_yaffs = 1;
-
-            if (in_yaffs ||
-                    strstr(line, "yaffs") ||
-                    strstr(line, "mtd") ||
-                    strstr(line, "msm_nand")) {
-                fprintf(out, "%s\n", line);
-            }
-
-            if (strstr(line, "yaffs_read_super: isCheckpointed")) in_yaffs = 0;
-        }
-    }
-
-    return 0;
-}
diff --git a/tools/ota/convert-to-bmp.py b/tools/ota/convert-to-bmp.py
deleted file mode 100644
index 446c09da..00000000
--- a/tools/ota/convert-to-bmp.py
+++ /dev/null
@@ -1,79 +0,0 @@
-#!/usr/bin/python2.4
-
-"""A simple script to convert asset images to BMP files, that supports
-RGBA image."""
-
-import struct
-import Image
-import sys
-
-infile = sys.argv[1]
-outfile = sys.argv[2]
-
-if not outfile.endswith(".bmp"):
-  print >> sys.stderr, "Warning: I'm expecting to write BMP files."
-
-im = Image.open(infile)
-if im.mode == 'RGB':
-  im.save(outfile)
-elif im.mode == 'RGBA':
-  # Python Imaging Library doesn't write RGBA BMP files, so we roll
-  # our own.
-
-  BMP_HEADER_FMT = ("<"      # little-endian
-                    "H"      # signature
-                    "L"      # file size
-                    "HH"     # reserved (set to 0)
-                    "L"      # offset to start of bitmap data)
-                    )
-
-  BITMAPINFO_HEADER_FMT= ("<"      # little-endian
-                          "L"      # size of this struct
-                          "L"      # width
-                          "L"      # height
-                          "H"      # planes (set to 1)
-                          "H"      # bit count
-                          "L"      # compression (set to 0 for minui)
-                          "L"      # size of image data (0 if uncompressed)
-                          "L"      # x pixels per meter (1)
-                          "L"      # y pixels per meter (1)
-                          "L"      # colors used (0)
-                          "L"      # important colors (0)
-                          )
-
-  fileheadersize = struct.calcsize(BMP_HEADER_FMT)
-  infoheadersize = struct.calcsize(BITMAPINFO_HEADER_FMT)
-
-  header = struct.pack(BMP_HEADER_FMT,
-                       0x4d42,   # "BM" in little-endian
-                       (fileheadersize + infoheadersize +
-                        im.size[0] * im.size[1] * 4),
-                       0, 0,
-                       fileheadersize + infoheadersize)
-
-  info = struct.pack(BITMAPINFO_HEADER_FMT,
-                     infoheadersize,
-                     im.size[0],
-                     im.size[1],
-                     1,
-                     32,
-                     0,
-                     0,
-                     1,
-                     1,
-                     0,
-                     0)
-
-  f = open(outfile, "wb")
-  f.write(header)
-  f.write(info)
-  data = im.tostring()
-  for j in range(im.size[1]-1, -1, -1):   # rows bottom-to-top
-    for i in range(j*im.size[0]*4, (j+1)*im.size[0]*4, 4):
-      f.write(data[i+2])    # B
-      f.write(data[i+1])    # G
-      f.write(data[i+0])    # R
-      f.write(data[i+3])    # A
-  f.close()
-else:
-  print >> sys.stderr, "Don't know how to handle image mode '%s'." % (im.mode,)