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#include "xmp_parser.h"
#include "subsurface-string.h"
#include <libxml/parser.h>
#include <libxml/tree.h>
#include <cctype>
extern "C" timestamp_t utc_mktime(struct tm *tm); // declared in core/dive.h
static timestamp_t parse_xmp_date(const char *date)
{
// Format: "yyyy-mm-dd[Thh:mm[:ss[.ms]][-05:00]]"
int year, month, day;
if (sscanf(date, "%d-%d-%d", &year, &month, &day) != 3)
return 0;
int hours = 0, minutes = 0, seconds = 0, milliseconds = 0;
int timezone = 0;
// Check for time part
if ((date = strchr(date, 'T')) != nullptr) {
++date; // Skip 'T'
if (sscanf(date, "%d:%d:%d.%d", &hours, &minutes, &seconds, &milliseconds) < 2)
return 0;
// Check for timezone part. Note that we simply ignore 'Z' as that
// means no time zone
while (*date && *date != '+' && *date != '-')
++date;
if (*date) {
int sign = *date == '+' ? 1 : -1;
int timezone_hours, timezone_minutes;
++date;
if (sscanf(date, "%d:%d", &timezone_hours, &timezone_minutes) != 2)
return 0;
timezone = sign * (timezone_hours * 60 + timezone_minutes) * 60;
}
}
// Round to seconds, since our timestamps are in seconds
if (milliseconds >= 500)
seconds += 1;
struct tm tm = { 0 };
tm.tm_year = year - 1900;
tm.tm_mon = month - 1;
tm.tm_mday = day;
tm.tm_hour = hours;
tm.tm_min = minutes;
tm.tm_sec = seconds;
timestamp_t res = utc_mktime(&tm);
res += timezone;
return res;
}
static timestamp_t extract_timestamp_from_attributes(const xmlNode *node)
{
for (const xmlAttr *p = node->properties; p; p = p->next) {
const xmlChar *ns = p->ns ? p->ns->prefix : nullptr;
// Check for xmp::CreateDate property
if (!strcmp((const char *)ns, "xmp") && !strcmp((const char *)p->name, "CreateDate")) {
// We only support a single property value
if (!p->children || !p->children->content)
return 0;
const char *date = (const char *)p->children->content;
return parse_xmp_date(date);
}
}
return 0;
}
static timestamp_t extract_timestamp(const xmlNode *node)
{
// We use a private stack, so that we can return in one go without
// having to unwind the call-stack. We only recurse to a fixed depth,
// since the data we are interested in are at a shallow depth.
// This can be increased on demand.
static const int max_recursion_depth = 16;
const xmlNode *stack[max_recursion_depth];
stack[0] = node;
int stack_depth = 1;
while (stack_depth > 0) {
const xmlNode *node = stack[stack_depth - 1];
// Parse attributes
timestamp_t timestamp = extract_timestamp_from_attributes(node);
if (timestamp)
return timestamp;
// Parse content, if not blank node. Content can only be at the second level,
// since it is always contained in a tag.
// TODO: We have to cast node to pointer to non-const, since we're supporting
// old libxml2 versions, where xmlIsBlankNode takes such a pointer. Remove
// in due course.
if (!xmlIsBlankNode((xmlNode *)node) && stack_depth >= 2) {
const xmlNode *parent = stack[stack_depth - 2];
// If this is a text node and the parent node is exif:DateTimeOriginal, try to parse as date
if (!node->ns && parent->ns &&
same_string((const char *)parent->ns->prefix, "exif") &&
same_string((const char *)parent->name, "DateTimeOriginal")) {
const char *date = (const char *)node->content;
timestamp_t res = parse_xmp_date(date);
if(res)
return res;
}
}
// If there are sub-items and we haven't reached recursion depth, recurse
if (node->children && stack_depth < max_recursion_depth) {
stack[stack_depth++] = node->children;
continue;
}
// Advance stack to next node in this level
while (stack_depth > 0) {
if ((stack[stack_depth - 1] = stack[stack_depth - 1]->next) != nullptr)
break;
// No more nodes at this level -> go up a level.
--stack_depth;
}
}
return 0;
}
timestamp_t parse_xmp(const char *data, size_t size)
{
const char *encoding = xmlGetCharEncodingName(XML_CHAR_ENCODING_UTF8);
// TODO: What do we pass as URL-parameter?
xmlDoc *doc = xmlReadMemory(data, size, "url", encoding, 0);
if (!doc)
return 0;
timestamp_t res = extract_timestamp(xmlDocGetRootElement(doc));
xmlFreeDoc(doc);
return res;
}
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