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|
//
// info.h: metadata extraction utilities
//
// Copyright (c) 2021, Přemysl Eric Janouch <p@janouch.name>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//
#include <jv.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
// --- Utilities ---------------------------------------------------------------
static char *
binhex(const uint8_t *data, size_t len)
{
static const char *alphabet = "0123456789abcdef";
char *buf = calloc(1, len * 2 + 1), *p = buf;
for (size_t i = 0; i < len; i++) {
*p++ = alphabet[data[i] >> 4];
*p++ = alphabet[data[i] & 0xF];
}
return buf;
}
static uint64_t
u64be(const uint8_t *p)
{
return (uint64_t) p[0] << 56 | (uint64_t) p[1] << 48 |
(uint64_t) p[2] << 40 | (uint64_t) p[3] << 32 |
(uint64_t) p[4] << 24 | p[5] << 16 | p[6] << 8 | p[7];
}
static uint32_t
u32be(const uint8_t *p)
{
return (uint32_t) p[0] << 24 | p[1] << 16 | p[2] << 8 | p[3];
}
static uint16_t
u16be(const uint8_t *p)
{
return (uint16_t) p[0] << 8 | p[1];
}
static uint64_t
u64le(const uint8_t *p)
{
return (uint64_t) p[7] << 56 | (uint64_t) p[6] << 48 |
(uint64_t) p[5] << 40 | (uint64_t) p[4] << 32 |
(uint64_t) p[3] << 24 | p[2] << 16 | p[1] << 8 | p[0];
}
static uint32_t
u32le(const uint8_t *p)
{
return (uint32_t) p[3] << 24 | p[2] << 16 | p[1] << 8 | p[0];
}
static uint16_t
u16le(const uint8_t *p)
{
return (uint16_t) p[1] << 8 | p[0];
}
// --- TIFF --------------------------------------------------------------------
// libtiff is a mess, and the format is not particularly complicated.
// Exiv2 is senselessly copylefted, and cannot do much.
// libexif is only marginally better.
// ExifTool is too user-oriented.
static struct un {
uint64_t (*u64) (const uint8_t *);
uint32_t (*u32) (const uint8_t *);
uint16_t (*u16) (const uint8_t *);
} unbe = {u64be, u32be, u16be}, unle = {u64le, u32le, u16le};
struct tiffer {
struct un *un;
const uint8_t *begin, *p, *end;
uint16_t remaining_fields;
};
static bool
tiffer_u32(struct tiffer *self, uint32_t *u)
{
if (self->p < self->begin || self->p + 4 > self->end)
return false;
*u = self->un->u32(self->p);
self->p += 4;
return true;
}
static bool
tiffer_u16(struct tiffer *self, uint16_t *u)
{
if (self->p < self->begin || self->p + 2 > self->end)
return false;
*u = self->un->u16(self->p);
self->p += 2;
return true;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
static bool
tiffer_init(struct tiffer *self, const uint8_t *tiff, size_t len)
{
self->un = NULL;
self->begin = self->p = tiff;
self->end = tiff + len;
self->remaining_fields = 0;
const uint8_t
le[4] = {'I', 'I', 42, 0},
be[4] = {'M', 'M', 0, 42};
if (tiff + 8 > self->end)
return false;
else if (!memcmp(tiff, le, sizeof le))
self->un = &unle;
else if (!memcmp(tiff, be, sizeof be))
self->un = &unbe;
else
return false;
self->p = tiff + 4;
// The first IFD needs to be read by caller explicitly,
// even though it's required to be present by TIFF 6.0.
return true;
}
/// Read the next IFD in a sequence.
static bool
tiffer_next_ifd(struct tiffer *self)
{
// All fields from any previous IFD need to be read first.
if (self->remaining_fields)
return false;
uint32_t ifd_offset = 0;
if (!tiffer_u32(self, &ifd_offset))
return false;
// There is nothing more to read, this chain has terminated.
if (!ifd_offset)
return false;
// Note that TIFF 6.0 requires there to be at least one entry,
// but there is no need for us to check it.
self->p = self->begin + ifd_offset;
return tiffer_u16(self, &self->remaining_fields);
}
/// Initialize a derived TIFF reader for a subIFD at the given location.
static bool
tiffer_subifd(struct tiffer *self, uint32_t offset, struct tiffer *subreader)
{
*subreader = *self;
subreader->p = subreader->begin + offset;
return tiffer_u16(subreader, &subreader->remaining_fields);
}
enum tiffer_type {
BYTE = 1, ASCII, SHORT, LONG, RATIONAL,
SBYTE, UNDEFINED, SSHORT, SLONG, SRATIONAL, FLOAT, DOUBLE,
IFD // This last type from TIFF Technical Note 1 isn't really used much.
};
static size_t
tiffer_value_size(enum tiffer_type type)
{
switch (type) {
case BYTE:
case SBYTE:
case ASCII:
case UNDEFINED:
return 1;
case SHORT:
case SSHORT:
return 2;
case LONG:
case SLONG:
case FLOAT:
case IFD:
return 4;
case RATIONAL:
case SRATIONAL:
case DOUBLE:
return 8;
default:
return 0;
}
}
/// A lean iterator for values within entries.
struct tiffer_entry {
uint16_t tag;
enum tiffer_type type;
// For {S,}BYTE, ASCII, UNDEFINED, use these fields directly.
const uint8_t *p;
uint32_t remaining_count;
};
static bool
tiffer_next_value(struct tiffer_entry *entry)
{
if (!entry->remaining_count)
return false;
entry->p += tiffer_value_size(entry->type);
entry->remaining_count--;
return true;
}
static bool
tiffer_integer(
const struct tiffer *self, const struct tiffer_entry *entry, int64_t *out)
{
if (!entry->remaining_count)
return false;
// Somewhat excessively lenient, intended for display.
// TIFF 6.0 only directly suggests that a reader is should accept
// any of BYTE/SHORT/LONG for unsigned integers.
switch (entry->type) {
case BYTE:
case ASCII:
case UNDEFINED:
*out = *entry->p;
return true;
case SBYTE:
*out = (int8_t) *entry->p;
return true;
case SHORT:
*out = self->un->u16(entry->p);
return true;
case SSHORT:
*out = (int16_t) self->un->u16(entry->p);
return true;
case LONG:
case IFD:
*out = self->un->u32(entry->p);
return true;
case SLONG:
*out = (int32_t) self->un->u32(entry->p);
return true;
default:
return false;
}
}
static bool
tiffer_rational(const struct tiffer *self, const struct tiffer_entry *entry,
int64_t *numerator, int64_t *denominator)
{
if (!entry->remaining_count)
return false;
// Somewhat excessively lenient, intended for display.
switch (entry->type) {
case RATIONAL:
*numerator = self->un->u32(entry->p);
*denominator = self->un->u32(entry->p + 4);
return true;
case SRATIONAL:
*numerator = (int32_t) self->un->u32(entry->p);
*denominator = (int32_t) self->un->u32(entry->p + 4);
return true;
default:
if (tiffer_integer(self, entry, numerator)) {
*denominator = 1;
return true;
}
return false;
}
}
static bool
tiffer_real(
const struct tiffer *self, const struct tiffer_entry *entry, double *out)
{
if (!entry->remaining_count)
return false;
// Somewhat excessively lenient, intended for display.
// Assuming the host architecture uses IEEE 754.
switch (entry->type) {
int64_t numerator, denominator;
case FLOAT:
*out = *(float *) entry->p;
return true;
case DOUBLE:
*out = *(double *) entry->p;
return true;
default:
if (tiffer_rational(self, entry, &numerator, &denominator)) {
*out = (double) numerator / denominator;
return true;
}
return false;
}
}
static bool
tiffer_next_entry(struct tiffer *self, struct tiffer_entry *entry)
{
if (!self->remaining_fields)
return false;
uint16_t type = entry->type = 0xFFFF;
if (!tiffer_u16(self, &entry->tag) || !tiffer_u16(self, &type) ||
!tiffer_u32(self, &entry->remaining_count))
return false;
// Short values may and will be inlined, rather than pointed to.
size_t values_size = tiffer_value_size(type) * entry->remaining_count;
uint32_t offset = 0;
if (values_size <= sizeof offset) {
entry->p = self->p;
self->p += sizeof offset;
} else if (tiffer_u32(self, &offset)) {
entry->p = self->begin + offset;
} else {
return false;
}
// All entries are pre-checked not to overflow.
if (entry->p + values_size > self->end)
return false;
// Setting it at the end may provide an indication while debugging.
entry->type = type;
self->remaining_fields--;
return true;
}
// --- TIFF/Exif tags ----------------------------------------------------------
struct tiff_value {
const char *name;
uint16_t value;
};
struct tiff_entry {
const char *name;
uint16_t tag;
struct tiff_value *values;
};
#include "tiff-tables.h"
// TODO(p): Consider if these can't be inlined into `tiff_entries`.
static struct {
uint16_t tag;
struct tiff_entry *entries;
} tiff_subifds[] = {
{330, tiff_entries}, // SubIFDs
{34665, exif_entries}, // Exif IFD Pointer
{34853, exif_gps_entries}, // GPS Info IFD Pointer
{40965, exif_interoperability_entries}, // Interoperability IFD Pointer
{}
};
// --- Analysis ----------------------------------------------------------------
static jv
add_to_subarray(jv o, const char *key, jv value)
{
// Invalid values are not allocated, and we use up any valid one.
// Beware that jv_get() returns jv_null() rather than jv_invalid().
// Also, the header comment is lying, jv_is_valid() doesn't unreference.
jv a = jv_object_get(jv_copy(o), jv_string(key));
return jv_set(o, jv_string(key),
jv_is_valid(a) ? jv_array_append(a, value) : JV_ARRAY(value));
}
static jv
add_warning(jv o, const char *message)
{
return add_to_subarray(o, "warnings", jv_string(message));
}
static jv
add_error(jv o, const char *message)
{
return jv_object_set(o, jv_string("error"), jv_string(message));
}
// --- Exif --------------------------------------------------------------------
static jv parse_exif_ifd(struct tiffer *T, const struct tiff_entry *info);
static bool
parse_exif_subifds_entry(struct tiffer *T, const struct tiffer_entry *entry,
struct tiffer *subT)
{
int64_t offset = 0;
return tiffer_integer(T, entry, &offset) &&
offset >= 0 && offset <= UINT32_MAX && tiffer_subifd(T, offset, subT);
}
static jv
parse_exif_subifds(struct tiffer *T, struct tiffer_entry *entry,
struct tiff_entry *info)
{
struct tiffer subT = {};
if (!parse_exif_subifds_entry(T, entry, &subT))
return jv_null();
jv a = jv_array();
do a = jv_array_append(a, parse_exif_ifd(&subT, info));
while (tiffer_next_ifd(&subT));
// The chain should correspond to the values in the entry (see TIFF
// Technical Note 1: "the NextIFD value of Child #1 must point to Child #2,
// and so on"), but at least some Nikon NEFs do not follow this rule.
if (jv_array_length(jv_copy(a)) == 1) {
while (tiffer_next_value(entry) &&
parse_exif_subifds_entry(T, entry, &subT))
a = jv_array_append(a, parse_exif_ifd(&subT, info));
}
return a;
}
static jv
parse_exif_ascii(struct tiffer_entry *entry)
{
// Adobe XMP Specification Part 3: Storage in Files, 2020/1, 2.4.2
// The text may in practice contain any 8-bit encoding, but likely UTF-8.
// TODO(p): Validate UTF-8, and assume Latin 1 if unsuccessful.
jv a = jv_array();
uint8_t *nul = 0;
while ((nul = memchr(entry->p, 0, entry->remaining_count))) {
size_t len = nul - entry->p;
a = jv_array_append(a, jv_string_sized((const char *) entry->p, len));
entry->remaining_count -= len + 1;
entry->p += len + 1;
}
// Trailing NULs are required, but let's extract everything.
if (entry->remaining_count) {
a = jv_array_append(a,
jv_string_sized((const char *) entry->p, entry->remaining_count));
}
return a;
}
static jv
parse_exif_undefined(struct tiffer_entry *entry)
{
// Sometimes, it can be ASCII, but the safe bet is to hex-encode it.
char *buf = binhex(entry->p, entry->remaining_count);
jv s = jv_string(buf);
free(buf);
return s;
}
static jv
parse_exif_value(const struct tiff_value *values, double real)
{
if (values) {
for (; values->name; values++)
if (values->value == real)
return jv_string(values->name);
}
return jv_number(real);
}
static jv
parse_exif_extract_sole_array_element(jv a)
{
return jv_array_length(jv_copy(a)) == 1 ? jv_array_get(a, 0) : a;
}
static jv
parse_exif_entry(jv o, struct tiffer *T, struct tiffer_entry *entry,
const struct tiff_entry *info)
{
static struct tiff_entry empty[] = {{}};
if (!info)
info = empty;
for (; info->name; info++)
if (info->tag == entry->tag)
break;
struct tiff_entry *subentries = NULL;
for (size_t i = 0; tiff_subifds[i].tag; i++)
if (tiff_subifds[i].tag == entry->tag)
subentries = tiff_subifds[i].entries;
jv v = jv_true();
double real = 0;
if (!entry->remaining_count) {
v = jv_null();
} else if (entry->type == IFD || subentries) {
v = parse_exif_subifds(T, entry, subentries);
} else if (entry->type == ASCII) {
v = parse_exif_extract_sole_array_element(parse_exif_ascii(entry));
} else if (entry->type == UNDEFINED && !info->values) {
// Several Exif entries of UNDEFINED type contain single-byte numbers.
v = parse_exif_undefined(entry);
} else if (tiffer_real(T, entry, &real)) {
v = jv_array();
do v = jv_array_append(v, parse_exif_value(info->values, real));
while (tiffer_next_value(entry) && tiffer_real(T, entry, &real));
v = parse_exif_extract_sole_array_element(v);
}
if (info->name)
return jv_set(o, jv_string(info->name), v);
return jv_set(o, jv_string_fmt("%u", entry->tag), v);
}
static jv
parse_exif_ifd(struct tiffer *T, const struct tiff_entry *info)
{
jv ifd = jv_object();
struct tiffer_entry entry = {};
while (tiffer_next_entry(T, &entry))
ifd = parse_exif_entry(ifd, T, &entry, info);
return ifd;
}
static jv
parse_exif(jv o, const uint8_t *p, size_t len)
{
struct tiffer T = {};
if (!tiffer_init(&T, p, len))
return add_warning(o, "invalid Exif");
while (tiffer_next_ifd(&T))
o = add_to_subarray(o, "Exif", parse_exif_ifd(&T, tiff_entries));
return o;
}
// --- Photoshop Image Resources -----------------------------------------------
// Adobe XMP Specification Part 3: Storage in Files, 2020/1, 1.1.3 + 3.1.3
// https://www.adobe.com/devnet-apps/photoshop/fileformatashtml/
// Unless otherwise noted, the descriptions are derived from the above document.
static struct {
uint16_t id;
const char *description;
} psir_descriptions[] = {
{1000, "Number of channels, rows, columns, depth, mode"},
{1001, "Macintosh print manager print info record"},
{1002, "Macintosh page format information"},
{1003, "Indexed color table"},
{1005, "Resolution information"},
{1006, "Names of alpha channels (Pascal strings)"},
{1007, "Display information"},
{1008, "Caption (Pascal string)"}, // XMP Part 3 3.3.3
{1009, "Border information"},
{1010, "Background color"},
{1011, "Print flags"},
{1012, "Grayscale and multichannel halftoning information"},
{1013, "Color halftoning information"},
{1014, "Duotone halftoning information"},
{1015, "Grayscale and multichannel transfer function"},
{1016, "Color transfer functions"},
{1017, "Duotone transfer functions"},
{1018, "Duotone image information"},
{1019, "Effective B/W values for the dot range"},
{1020, "Caption"}, // XMP Part 3 3.3.3
{1021, "EPS options"},
{1022, "Quick Mask information"},
{1023, "(Obsolete)"},
{1024, "Layer state information"},
{1025, "Working path (not saved)"},
{1026, "Layers group information"},
{1027, "(Obsolete)"},
{1028, "IPTC DataSets"}, // XMP Part 3 3.3.3
{1029, "Image mode for raw format files"},
{1030, "JPEG quality"},
{1032, "Grid and guides information"},
{1033, "Thumbnail resource"},
{1034, "Copyright flag"},
{1035, "Copyright information URL"}, // XMP Part 3 3.3.3
{1036, "Thumbnail resource"},
{1037, "Global lighting angle for effects layer"},
{1038, "Color samplers information"},
{1039, "ICC profile"},
{1040, "Watermark"},
{1041, "ICC untagged profile flag"},
{1042, "Effects visible flag"},
{1043, "Spot halftone"},
{1044, "Document-specific IDs seed number"},
{1045, "Unicode alpha names"},
{1046, "Indexed color table count"},
{1047, "Transparent color index"},
{1049, "Global altitude"},
{1050, "Slices"},
{1051, "Workflow URL"},
{1052, "Jump To XPEP"},
{1053, "Alpha identifiers"},
{1054, "URL list"},
{1057, "Version info"},
{1058, "Exif metadata 1"},
{1059, "Exif metadata 3"},
{1060, "XMP metadata"},
{1061, "MD5 digest of IPTC data"}, // XMP Part 3 3.3.3
{1062, "Print scale"},
{1064, "Pixel aspect ratio"},
{1065, "Layer comps"},
{1066, "Alternate duotone colors"},
{1067, "Alternate spot colors"},
{1069, "Layer selection IDs"},
{1070, "HDR toning information"},
{1071, "Print info"},
{1072, "Layer group(s) enabled ID"},
{1073, "Color samplers"},
{1074, "Measurement scale"},
{1075, "Timeline information"},
{1076, "Sheet disclosure"},
{1077, "Display information to support floating point colors"},
{1078, "Onion skins"},
{1080, "Count information"},
{1082, "Print information"},
{1083, "Print style"},
{1084, "Macintosh NSPrintInfo"},
{1085, "Windows DEVMODE"},
{1086, "Autosave file path"},
{1087, "Autosave format"},
{1088, "Path selection state"},
// {2000-2997, "Saved paths"},
{2999, "Name of clipping path"},
{3000, "Origin path information"},
// {4000-4999, "Plug-in resource"},
{7000, "Image Ready variables"},
{7001, "Image Ready data sets"},
{7002, "Image Ready default selected state"},
{7003, "Image Ready 7 rollover expanded state"},
{7004, "Image Ready rollover expanded state"},
{7005, "Image Ready save layer settings"},
{7006, "Image Ready version"},
{8000, "Lightroom workflow"},
{10000, "Print flags"},
{}
};
static jv
process_psir_thumbnail(jv res, const uint8_t *data, size_t len)
{
uint32_t format_number = u32be(data + 0);
uint32_t compressed_size = u32be(data + 20);
// TODO(p): Recurse into the thumbnail if it's a JPEG.
jv format = jv_number(format_number);
switch (format_number) {
break; case 0: format = jv_string("kJpegRGB");
break; case 1: format = jv_string("kRawRGB");
}
res = jv_object_merge(res, JV_OBJECT(
jv_string("Format"), format,
jv_string("Width"), jv_number(u32be(data + 4)),
jv_string("Height"), jv_number(u32be(data + 8)),
jv_string("Stride"), jv_number(u32be(data + 12)),
jv_string("TotalSize"), jv_number(u32be(data + 16)),
jv_string("CompressedSize"), jv_number(compressed_size),
jv_string("BitsPerPixel"), jv_number(u16be(data + 24)),
jv_string("Planes"), jv_number(u16be(data + 26))
));
if (28 + compressed_size <= len) {
char *buf = binhex(data + 28, compressed_size);
res = jv_set(res, jv_string("Data"), jv_string(buf));
free(buf);
}
return res;
}
static const char *
process_iptc_dataset(jv *a, const uint8_t **p, size_t len)
{
const uint8_t *header = *p;
if (len < 5)
return "unexpected end of IPTC data";
if (*header != 0x1c)
return "invalid tag marker";
uint8_t record = header[1];
uint8_t dataset = header[2];
uint16_t byte_count = header[3] << 8 | header[4];
// TODO(p): Although highly unlikely to appear, we could decode it.
if (byte_count & 0x8000)
return "unsupported extended DataSet";
if (len - 5 < byte_count)
return "data overrun";
char *buf = binhex(header + 5, byte_count);
*p += 5 + byte_count;
*a = jv_array_append(*a, JV_OBJECT(
jv_string("DataSet"), jv_string_fmt("%u:%u", record, dataset),
jv_string("Data"), jv_string(buf)
));
free(buf);
return NULL;
}
static jv
process_psir_iptc(jv res, const uint8_t *data, size_t len)
{
// https://iptc.org/standards/iim/
// https://iptc.org/std/IIM/4.2/specification/IIMV4.2.pdf
jv a = jv_array();
const uint8_t *end = data + len;
while (data < end) {
const char *err = process_iptc_dataset(&a, &data, end - data);
if (err) {
a = jv_array_append(a, jv_string(err));
break;
}
}
return jv_set(res, jv_string("DataSets"), a);
}
static jv
process_psir(jv o, uint16_t resource_id, const char *name,
const uint8_t *data, size_t len)
{
const char *description = NULL;
if (resource_id >= 2000 && resource_id <= 2997)
description = "Saved paths";
if (resource_id >= 4000 && resource_id <= 4999)
description = "Plug-in resource";
for (size_t i = 0; psir_descriptions[i].id; i++)
if (psir_descriptions[i].id == resource_id)
description = psir_descriptions[i].description;
jv res = JV_OBJECT(
jv_string("name"), jv_string(name),
jv_string("id"), jv_number(resource_id),
jv_string("description"),
description ? jv_string(description) : jv_null(),
jv_string("size"), jv_number(len)
);
// Both are thumbnails, older is BGR, newer is RGB.
if ((resource_id == 1033 || resource_id == 1036) && len >= 28)
res = process_psir_thumbnail(res, data, len);
if (resource_id == 1028)
res = process_psir_iptc(res, data, len);
return add_to_subarray(o, "PSIR", res);
}
static jv
parse_psir_block(jv o, const uint8_t *p, size_t len, size_t *advance)
{
*advance = 0;
if (len < 8 || memcmp(p, "8BIM", 4))
return add_warning(o, "bad PSIR block header");
uint16_t resource_id = u16be(p + 4);
uint8_t name_len = p[6];
const uint8_t *name = &p[7];
// Add one byte for the Pascal-ish string length prefix,
// then another one for padding to make the length even.
size_t name_len_full = (name_len + 2) & ~1U;
size_t resource_len_offset = 6 + name_len_full,
header_len = resource_len_offset + 4;
if (len < header_len)
return add_warning(o, "bad PSIR block header");
uint32_t resource_len = u32be(p + resource_len_offset);
size_t resource_len_padded = (resource_len + 1) & ~1U;
if (resource_len_padded < resource_len ||
len < header_len + resource_len_padded)
return add_warning(o, "runaway PSIR block");
char *cname = calloc(1, name_len_full);
strncpy(cname, (const char *) name, name_len);
o = process_psir(o, resource_id, cname, p + header_len, resource_len);
free(cname);
*advance = header_len + resource_len_padded;
return o;
}
static jv
parse_psir(jv o, const uint8_t *p, size_t len)
{
if (len == 0)
return add_warning(o, "empty PSIR data");
size_t advance = 0;
while (len && (o = parse_psir_block(o, p, len, &advance), advance)) {
p += advance;
len -= advance;
}
return o;
}
// --- ICC profiles ------------------------------------------------------------
// v2 https://www.color.org/ICC_Minor_Revision_for_Web.pdf
// v4 https://www.color.org/specification/ICC1v43_2010-12.pdf
static jv
parse_icc_mluc(jv o, const uint8_t *tag, uint32_t tag_length)
{
// v4 10.13
if (tag_length < 16)
return add_warning(o, "invalid ICC 'mluc' structure length");
uint32_t count = u32be(tag + 8);
if (count == 0)
return add_warning(o, "unnamed ICC profile");
// There is no particularly good reason for us to iterate, take the first.
const uint8_t *record = tag + 16 /* + i * u32be(tag + 12) */;
uint32_t len = u32be(&record[4]);
uint32_t off = u32be(&record[8]);
if (off + len > tag_length)
return add_warning(o, "invalid ICC 'mluc' structure record");
// Blindly assume simple ASCII, ensure NUL-termination.
char name[len], *p = name;
for (uint32_t i = 0; i < len / 2; i++)
*p++ = tag[off + i * 2 + 1];
*p++ = 0;
return jv_set(o, jv_string("ICC"),
JV_OBJECT(jv_string("name"), jv_string(name),
jv_string("version"), jv_number(4)));
}
static jv
parse_icc_desc(jv o, const uint8_t *profile, size_t profile_len,
uint32_t tag_offset, uint32_t tag_length)
{
const uint8_t *tag = profile + tag_offset;
if (tag_offset + tag_length > profile_len)
return add_warning(o, "unexpected end of ICC profile");
if (tag_length < 4)
return add_warning(o, "invalid ICC tag structure length");
// v2 6.5.17
uint32_t sig = u32be(tag);
if (sig == 0x6D6C7563 /* mluc */)
return parse_icc_mluc(o, profile + tag_offset, tag_length);
if (sig != 0x64657363 /* desc */)
return add_warning(o, "invalid ICC 'desc' structure signature");
if (tag_length < 12)
return add_warning(o, "invalid ICC 'desc' structure length");
uint32_t count = u32be(tag + 8);
if (tag_length < 12 + count)
return add_warning(o, "invalid ICC 'desc' structure length");
// Double-ensure a trailing NUL byte.
char name[count + 1];
memcpy(name, tag + 12, count);
name[count] = 0;
return jv_set(o, jv_string("ICC"),
JV_OBJECT(jv_string("name"), jv_string(name),
jv_string("version"), jv_number(2)));
}
static jv
parse_icc(jv o, const uint8_t *profile, size_t profile_len)
{
// v2 6, v4 7
if (profile_len < 132)
return add_warning(o, "ICC profile too short");
if (u32be(profile) != profile_len)
return add_warning(o, "ICC profile size mismatch");
// TODO(p): May decode more of the header fields, and validate them.
// Need to check both v2 and v4, this is all fairly annoying.
uint32_t count = u32be(profile + 128);
if (132 + count * 12 > profile_len)
return add_warning(o, "unexpected end of ICC profile");
for (uint32_t i = 0; i < count; i++) {
const uint8_t *entry = profile + 132 + i * 12;
uint32_t sig = u32be(&entry[0]);
uint32_t off = u32be(&entry[4]);
uint32_t len = u32be(&entry[8]);
// v2 6.4.32, v4 9.2.41
if (sig == 0x64657363 /* desc */)
return parse_icc_desc(o, profile, profile_len, off, len);
}
// The description is required, so this should be unreachable.
return jv_set(o, jv_string("ICC"), jv_bool(true));
}
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