image/decoders/iccjpeg.c@ac0c01689b40 (annotated)
image/decoders/iccjpeg.c
Thu, 15 Jan 2015 15:59:08 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 15 Jan 2015 15:59:08 +0100
- branch
- TOR_BUG_9701
- changeset 10
- ac0c01689b40
- permissions
- -rw-r--r--
Implement a real Private Browsing Mode condition by changing the API/ABI;
This solves Tor bug #9701, complying with disk avoidance documented in
https://www.torproject.org/projects/torbrowser/design/#disk-avoidance.
| michael@0 | 1 | /* This Source Code Form is subject to the terms of the Mozilla Public |
| michael@0 | 2 | * License, v. 2.0. If a copy of the MPL was not distributed with this |
| michael@0 | 3 | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| michael@0 | 4 | |
| michael@0 | 5 | /* |
| michael@0 | 6 | * iccprofile.c |
| michael@0 | 7 | * |
| michael@0 | 8 | * This file provides code to read and write International Color Consortium |
| michael@0 | 9 | * (ICC) device profiles embedded in JFIF JPEG image files. The ICC has |
| michael@0 | 10 | * defined a standard format for including such data in JPEG "APP2" markers. |
| michael@0 | 11 | * The code given here does not know anything about the internal structure |
| michael@0 | 12 | * of the ICC profile data; it just knows how to put the profile data into |
| michael@0 | 13 | * a JPEG file being written, or get it back out when reading. |
| michael@0 | 14 | * |
| michael@0 | 15 | * This code depends on new features added to the IJG JPEG library as of |
| michael@0 | 16 | * IJG release 6b; it will not compile or work with older IJG versions. |
| michael@0 | 17 | * |
| michael@0 | 18 | * NOTE: this code would need surgery to work on 16-bit-int machines |
| michael@0 | 19 | * with ICC profiles exceeding 64K bytes in size. If you need to do that, |
| michael@0 | 20 | * change all the "unsigned int" variables to "INT32". You'll also need |
| michael@0 | 21 | * to find a malloc() replacement that can allocate more than 64K. |
| michael@0 | 22 | */ |
| michael@0 | 23 | |
| michael@0 | 24 | #include "iccjpeg.h" |
| michael@0 | 25 | #include <stdlib.h> /* define malloc() */ |
| michael@0 | 26 | |
| michael@0 | 27 | |
| michael@0 | 28 | /* |
| michael@0 | 29 | * Since an ICC profile can be larger than the maximum size of a JPEG marker |
| michael@0 | 30 | * (64K), we need provisions to split it into multiple markers. The format |
| michael@0 | 31 | * defined by the ICC specifies one or more APP2 markers containing the |
| michael@0 | 32 | * following data: |
| michael@0 | 33 | * Identifying string ASCII "ICC_PROFILE\0" (12 bytes) |
| michael@0 | 34 | * Marker sequence number 1 for first APP2, 2 for next, etc (1 byte) |
| michael@0 | 35 | * Number of markers Total number of APP2's used (1 byte) |
| michael@0 | 36 | * Profile data (remainder of APP2 data) |
| michael@0 | 37 | * Decoders should use the marker sequence numbers to reassemble the profile, |
| michael@0 | 38 | * rather than assuming that the APP2 markers appear in the correct sequence. |
| michael@0 | 39 | */ |
| michael@0 | 40 | |
| michael@0 | 41 | #define ICC_MARKER (JPEG_APP0 + 2) /* JPEG marker code for ICC */ |
| michael@0 | 42 | #define ICC_OVERHEAD_LEN 14 /* size of non-profile data in APP2 */ |
| michael@0 | 43 | #define MAX_BYTES_IN_MARKER 65533 /* maximum data len of a JPEG marker */ |
| michael@0 | 44 | #define MAX_DATA_BYTES_IN_MARKER (MAX_BYTES_IN_MARKER - ICC_OVERHEAD_LEN) |
| michael@0 | 45 | |
| michael@0 | 46 | /* |
| michael@0 | 47 | * Prepare for reading an ICC profile |
| michael@0 | 48 | */ |
| michael@0 | 49 | |
| michael@0 | 50 | void |
| michael@0 | 51 | setup_read_icc_profile (j_decompress_ptr cinfo) |
| michael@0 | 52 | { |
| michael@0 | 53 | /* Tell the library to keep any APP2 data it may find */ |
| michael@0 | 54 | jpeg_save_markers(cinfo, ICC_MARKER, 0xFFFF); |
| michael@0 | 55 | } |
| michael@0 | 56 | |
| michael@0 | 57 | |
| michael@0 | 58 | /* |
| michael@0 | 59 | * Handy subroutine to test whether a saved marker is an ICC profile marker. |
| michael@0 | 60 | */ |
| michael@0 | 61 | |
| michael@0 | 62 | static boolean |
| michael@0 | 63 | marker_is_icc (jpeg_saved_marker_ptr marker) |
| michael@0 | 64 | { |
| michael@0 | 65 | return |
| michael@0 | 66 | marker->marker == ICC_MARKER && |
| michael@0 | 67 | marker->data_length >= ICC_OVERHEAD_LEN && |
| michael@0 | 68 | /* verify the identifying string */ |
| michael@0 | 69 | GETJOCTET(marker->data[0]) == 0x49 && |
| michael@0 | 70 | GETJOCTET(marker->data[1]) == 0x43 && |
| michael@0 | 71 | GETJOCTET(marker->data[2]) == 0x43 && |
| michael@0 | 72 | GETJOCTET(marker->data[3]) == 0x5F && |
| michael@0 | 73 | GETJOCTET(marker->data[4]) == 0x50 && |
| michael@0 | 74 | GETJOCTET(marker->data[5]) == 0x52 && |
| michael@0 | 75 | GETJOCTET(marker->data[6]) == 0x4F && |
| michael@0 | 76 | GETJOCTET(marker->data[7]) == 0x46 && |
| michael@0 | 77 | GETJOCTET(marker->data[8]) == 0x49 && |
| michael@0 | 78 | GETJOCTET(marker->data[9]) == 0x4C && |
| michael@0 | 79 | GETJOCTET(marker->data[10]) == 0x45 && |
| michael@0 | 80 | GETJOCTET(marker->data[11]) == 0x0; |
| michael@0 | 81 | } |
| michael@0 | 82 | |
| michael@0 | 83 | |
| michael@0 | 84 | /* |
| michael@0 | 85 | * See if there was an ICC profile in the JPEG file being read; |
| michael@0 | 86 | * if so, reassemble and return the profile data. |
| michael@0 | 87 | * |
| michael@0 | 88 | * TRUE is returned if an ICC profile was found, FALSE if not. |
| michael@0 | 89 | * If TRUE is returned, *icc_data_ptr is set to point to the |
| michael@0 | 90 | * returned data, and *icc_data_len is set to its length. |
| michael@0 | 91 | * |
| michael@0 | 92 | * IMPORTANT: the data at **icc_data_ptr has been allocated with malloc() |
| michael@0 | 93 | * and must be freed by the caller with free() when the caller no longer |
| michael@0 | 94 | * needs it. (Alternatively, we could write this routine to use the |
| michael@0 | 95 | * IJG library's memory allocator, so that the data would be freed implicitly |
| michael@0 | 96 | * at jpeg_finish_decompress() time. But it seems likely that many apps |
| michael@0 | 97 | * will prefer to have the data stick around after decompression finishes.) |
| michael@0 | 98 | * |
| michael@0 | 99 | * NOTE: if the file contains invalid ICC APP2 markers, we just silently |
| michael@0 | 100 | * return FALSE. You might want to issue an error message instead. |
| michael@0 | 101 | */ |
| michael@0 | 102 | |
| michael@0 | 103 | boolean |
| michael@0 | 104 | read_icc_profile (j_decompress_ptr cinfo, |
| michael@0 | 105 | JOCTET **icc_data_ptr, |
| michael@0 | 106 | unsigned int *icc_data_len) |
| michael@0 | 107 | { |
| michael@0 | 108 | jpeg_saved_marker_ptr marker; |
| michael@0 | 109 | int num_markers = 0; |
| michael@0 | 110 | int seq_no; |
| michael@0 | 111 | JOCTET *icc_data; |
| michael@0 | 112 | unsigned int total_length; |
| michael@0 | 113 | #define MAX_SEQ_NO 255 /* sufficient since marker numbers are bytes */ |
| michael@0 | 114 | char marker_present[MAX_SEQ_NO+1]; /* 1 if marker found */ |
| michael@0 | 115 | unsigned int data_length[MAX_SEQ_NO+1]; /* size of profile data in marker */ |
| michael@0 | 116 | unsigned int data_offset[MAX_SEQ_NO+1]; /* offset for data in marker */ |
| michael@0 | 117 | |
| michael@0 | 118 | *icc_data_ptr = NULL; /* avoid confusion if FALSE return */ |
| michael@0 | 119 | *icc_data_len = 0; |
| michael@0 | 120 | |
| michael@0 | 121 | /* This first pass over the saved markers discovers whether there are |
| michael@0 | 122 | * any ICC markers and verifies the consistency of the marker numbering. |
| michael@0 | 123 | */ |
| michael@0 | 124 | |
| michael@0 | 125 | for (seq_no = 1; seq_no <= MAX_SEQ_NO; seq_no++) |
| michael@0 | 126 | marker_present[seq_no] = 0; |
| michael@0 | 127 | |
| michael@0 | 128 | for (marker = cinfo->marker_list; marker != NULL; marker = marker->next) { |
| michael@0 | 129 | if (marker_is_icc(marker)) { |
| michael@0 | 130 | if (num_markers == 0) |
| michael@0 | 131 | num_markers = GETJOCTET(marker->data[13]); |
| michael@0 | 132 | else if (num_markers != GETJOCTET(marker->data[13])) |
| michael@0 | 133 | return FALSE; /* inconsistent num_markers fields */ |
| michael@0 | 134 | seq_no = GETJOCTET(marker->data[12]); |
| michael@0 | 135 | if (seq_no <= 0 || seq_no > num_markers) |
| michael@0 | 136 | return FALSE; /* bogus sequence number */ |
| michael@0 | 137 | if (marker_present[seq_no]) |
| michael@0 | 138 | return FALSE; /* duplicate sequence numbers */ |
| michael@0 | 139 | marker_present[seq_no] = 1; |
| michael@0 | 140 | data_length[seq_no] = marker->data_length - ICC_OVERHEAD_LEN; |
| michael@0 | 141 | } |
| michael@0 | 142 | } |
| michael@0 | 143 | |
| michael@0 | 144 | if (num_markers == 0) |
| michael@0 | 145 | return FALSE; |
| michael@0 | 146 | |
| michael@0 | 147 | /* Check for missing markers, count total space needed, |
| michael@0 | 148 | * compute offset of each marker's part of the data. |
| michael@0 | 149 | */ |
| michael@0 | 150 | |
| michael@0 | 151 | total_length = 0; |
| michael@0 | 152 | for (seq_no = 1; seq_no <= num_markers; seq_no++) { |
| michael@0 | 153 | if (marker_present[seq_no] == 0) |
| michael@0 | 154 | return FALSE; /* missing sequence number */ |
| michael@0 | 155 | data_offset[seq_no] = total_length; |
| michael@0 | 156 | total_length += data_length[seq_no]; |
| michael@0 | 157 | } |
| michael@0 | 158 | |
| michael@0 | 159 | if (total_length <= 0) |
| michael@0 | 160 | return FALSE; /* found only empty markers? */ |
| michael@0 | 161 | |
| michael@0 | 162 | /* Allocate space for assembled data */ |
| michael@0 | 163 | icc_data = (JOCTET *) malloc(total_length * sizeof(JOCTET)); |
| michael@0 | 164 | if (icc_data == NULL) |
| michael@0 | 165 | return FALSE; /* oops, out of memory */ |
| michael@0 | 166 | |
| michael@0 | 167 | /* and fill it in */ |
| michael@0 | 168 | for (marker = cinfo->marker_list; marker != NULL; marker = marker->next) { |
| michael@0 | 169 | if (marker_is_icc(marker)) { |
| michael@0 | 170 | JOCTET FAR *src_ptr; |
| michael@0 | 171 | JOCTET *dst_ptr; |
| michael@0 | 172 | unsigned int length; |
| michael@0 | 173 | seq_no = GETJOCTET(marker->data[12]); |
| michael@0 | 174 | dst_ptr = icc_data + data_offset[seq_no]; |
| michael@0 | 175 | src_ptr = marker->data + ICC_OVERHEAD_LEN; |
| michael@0 | 176 | length = data_length[seq_no]; |
| michael@0 | 177 | while (length--) { |
| michael@0 | 178 | *dst_ptr++ = *src_ptr++; |
| michael@0 | 179 | } |
| michael@0 | 180 | } |
| michael@0 | 181 | } |
| michael@0 | 182 | |
| michael@0 | 183 | *icc_data_ptr = icc_data; |
| michael@0 | 184 | *icc_data_len = total_length; |
| michael@0 | 185 | |
| michael@0 | 186 | return TRUE; |
| michael@0 | 187 | } |
