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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * iccjpeg.c
+ *
+ * This file provides code to read and write International Color Consortium
+ * (ICC) device profiles embedded in JFIF JPEG image files. The ICC has
+ * defined a standard format for including such data in JPEG "APP2" markers.
+ * The code given here does not know anything about the internal structure
+ * of the ICC profile data; it just knows how to put the profile data into
+ * a JPEG file being written, or get it back out when reading.
+ *
+ * This code depends on new features added to the IJG JPEG library as of
+ * IJG release 6b; it will not compile or work with older IJG versions.
+ *
+ * NOTE: this code would need surgery to work on 16-bit-int machines
+ * with ICC profiles exceeding 64K bytes in size. If you need to do that,
+ * change all the "unsigned int" variables to "INT32". You'll also need
+ * to find a malloc() replacement that can allocate more than 64K.
+ */
+
+#include "iccjpeg.h"
+#include <stdlib.h> /* define malloc() */
+
+
+/*
+ * Since an ICC profile can be larger than the maximum size of a JPEG marker
+ * (64K), we need provisions to split it into multiple markers. The format
+ * defined by the ICC specifies one or more APP2 markers containing the
+ * following data:
+ * Identifying string ASCII "ICC_PROFILE\0" (12 bytes)
+ * Marker sequence number 1 for first APP2, 2 for next, etc (1 byte)
+ * Number of markers Total number of APP2's used (1 byte)
+ * Profile data (remainder of APP2 data)
+ * Decoders should use the marker sequence numbers to reassemble the profile,
+ * rather than assuming that the APP2 markers appear in the correct sequence.
+ */
+
+#define ICC_MARKER (JPEG_APP0 + 2) /* JPEG marker code for ICC */
+#define ICC_OVERHEAD_LEN 14 /* size of non-profile data in APP2 */
+#define MAX_BYTES_IN_MARKER 65533 /* maximum data len of a JPEG marker */
+#define MAX_DATA_BYTES_IN_MARKER (MAX_BYTES_IN_MARKER - ICC_OVERHEAD_LEN)
+
+/*
+ * Prepare for reading an ICC profile
+ */
+
+void
+setup_read_icc_profile (j_decompress_ptr cinfo)
+{
+ /* Tell the library to keep any APP2 data it may find */
+ jpeg_save_markers(cinfo, ICC_MARKER, 0xFFFF);
+}
+
+
+/*
+ * Handy subroutine to test whether a saved marker is an ICC profile marker.
+ */
+
+static boolean
+marker_is_icc (jpeg_saved_marker_ptr marker)
+{
+ return
+ marker->marker == ICC_MARKER &&
+ marker->data_length >= ICC_OVERHEAD_LEN &&
+ /* verify the identifying string */
+ GETJOCTET(marker->data[0]) == 0x49 &&
+ GETJOCTET(marker->data[1]) == 0x43 &&
+ GETJOCTET(marker->data[2]) == 0x43 &&
+ GETJOCTET(marker->data[3]) == 0x5F &&
+ GETJOCTET(marker->data[4]) == 0x50 &&
+ GETJOCTET(marker->data[5]) == 0x52 &&
+ GETJOCTET(marker->data[6]) == 0x4F &&
+ GETJOCTET(marker->data[7]) == 0x46 &&
+ GETJOCTET(marker->data[8]) == 0x49 &&
+ GETJOCTET(marker->data[9]) == 0x4C &&
+ GETJOCTET(marker->data[10]) == 0x45 &&
+ GETJOCTET(marker->data[11]) == 0x0;
+}
+
+
+/*
+ * See if there was an ICC profile in the JPEG file being read;
+ * if so, reassemble and return the profile data.
+ *
+ * TRUE is returned if an ICC profile was found, FALSE if not.
+ * If TRUE is returned, *icc_data_ptr is set to point to the
+ * returned data, and *icc_data_len is set to its length.
+ *
+ * IMPORTANT: the data at **icc_data_ptr has been allocated with malloc()
+ * and must be freed by the caller with free() when the caller no longer
+ * needs it. (Alternatively, we could write this routine to use the
+ * IJG library's memory allocator, so that the data would be freed implicitly
+ * at jpeg_finish_decompress() time. But it seems likely that many apps
+ * will prefer to have the data stick around after decompression finishes.)
+ *
+ * NOTE: if the file contains invalid ICC APP2 markers, we just silently
+ * return FALSE. You might want to issue an error message instead.
+ */
+
+boolean
+read_icc_profile (j_decompress_ptr cinfo,
+ JOCTET** icc_data_ptr,
+ unsigned int* icc_data_len)
+{
+ jpeg_saved_marker_ptr marker;
+ int num_markers = 0;
+ int seq_no;
+ JOCTET* icc_data;
+ unsigned int total_length;
+#define MAX_SEQ_NO 255 /* sufficient since marker numbers are bytes */
+ char marker_present[MAX_SEQ_NO+1]; /* 1 if marker found */
+ unsigned int data_length[MAX_SEQ_NO+1]; /* size of profile data in marker */
+ unsigned int data_offset[MAX_SEQ_NO+1]; /* offset for data in marker */
+
+ *icc_data_ptr = NULL; /* avoid confusion if FALSE return */
+ *icc_data_len = 0;
+
+ /* This first pass over the saved markers discovers whether there are
+ * any ICC markers and verifies the consistency of the marker numbering.
+ */
+
+ for (seq_no = 1; seq_no <= MAX_SEQ_NO; seq_no++) {
+ marker_present[seq_no] = 0;
+ }
+
+ for (marker = cinfo->marker_list; marker != NULL; marker = marker->next) {
+ if (marker_is_icc(marker)) {
+ if (num_markers == 0) {
+ num_markers = GETJOCTET(marker->data[13]);
+ } else if (num_markers != GETJOCTET(marker->data[13])) {
+ return FALSE; /* inconsistent num_markers fields */
+ }
+ seq_no = GETJOCTET(marker->data[12]);
+ if (seq_no <= 0 || seq_no > num_markers) {
+ return FALSE; /* bogus sequence number */
+ }
+ if (marker_present[seq_no]) {
+ return FALSE; /* duplicate sequence numbers */
+ }
+ marker_present[seq_no] = 1;
+ data_length[seq_no] = marker->data_length - ICC_OVERHEAD_LEN;
+ }
+ }
+
+ if (num_markers == 0) {
+ return FALSE;
+ }
+
+ /* Check for missing markers, count total space needed,
+ * compute offset of each marker's part of the data.
+ */
+
+ total_length = 0;
+ for (seq_no = 1; seq_no <= num_markers; seq_no++) {
+ if (marker_present[seq_no] == 0) {
+ return FALSE; /* missing sequence number */
+ }
+ data_offset[seq_no] = total_length;
+ total_length += data_length[seq_no];
+ }
+
+ if (total_length <= 0) {
+ return FALSE; /* found only empty markers? */
+ }
+
+ /* Allocate space for assembled data */
+ icc_data = (JOCTET*) malloc(total_length * sizeof(JOCTET));
+ if (icc_data == NULL) {
+ return FALSE; /* oops, out of memory */
+ }
+
+ /* and fill it in */
+ for (marker = cinfo->marker_list; marker != NULL; marker = marker->next) {
+ if (marker_is_icc(marker)) {
+ JOCTET FAR* src_ptr;
+ JOCTET* dst_ptr;
+ unsigned int length;
+ seq_no = GETJOCTET(marker->data[12]);
+ dst_ptr = icc_data + data_offset[seq_no];
+ src_ptr = marker->data + ICC_OVERHEAD_LEN;
+ length = data_length[seq_no];
+ while (length--) {
+ *dst_ptr++ = *src_ptr++;
+ }
+ }
+ }
+
+ *icc_data_ptr = icc_data;
+ *icc_data_len = total_length;
+
+ return TRUE;
+}