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authorPřemysl Eric Janouch <p@janouch.name>2021-12-10 18:57:15 +0100
committerPřemysl Eric Janouch <p@janouch.name>2021-12-10 19:08:37 +0100
commit5f4090aaee642b905c8c1a1385bb975072fca1f6 (patch)
tree7e3d35a6aff013446a1c32509562e915cbbf6fb6
parentfa15707d9b9aa3590facd6718df336d55f846815 (diff)
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pnginfo: extract some ImageMagick profiles
-rw-r--r--tools/pnginfo.c128
1 files changed, 117 insertions, 11 deletions
diff --git a/tools/pnginfo.c b/tools/pnginfo.c
index 41ebd9e..03ab1d1 100644
--- a/tools/pnginfo.c
+++ b/tools/pnginfo.c
@@ -20,6 +20,7 @@
#include <png.h>
#include <jv.h>
+#include <ctype.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
@@ -65,28 +66,120 @@ strfmt(const char *format, ...)
return result;
}
+static uint8_t *
+hexbin(const char *string, size_t *len)
+{
+ static const char *alphabet = "0123456789abcdef";
+ uint8_t *buf = calloc(1, strlen(string) / 2 + 1), *p = buf;
+ while (true) {
+ while (*string && strchr(" \t\n\r\v\f", *string))
+ string++;
+ if (!*string)
+ break;
+
+ const char *hi, *lo;
+ if (!(hi = strchr(alphabet, tolower(*string++))) || !*string ||
+ !(lo = strchr(alphabet, tolower(*string++)))) {
+ free(buf);
+ return NULL;
+ }
+
+ *p++ = (hi - alphabet) << 4 | (lo - alphabet);
+ }
+ *len = p - buf;
+ return buf;
+}
+
// --- Analysis ----------------------------------------------------------------
-static void
-redirect_libpng_error(png_structp pngp, const char* message)
+static uint8_t *
+extract_imagemagick_attribute(const char *string, size_t *len)
{
- char **storage = png_get_error_ptr(pngp);
- *storage = strfmt("%s", message);
+ if (*string++ != '\n')
+ return NULL;
+
+ // TODO(p): Try to verify this profile type, also present in the key,
+ // though beware that it may contain "generic profile" for APP1, etc.
+ const char *type = string;
+ if (!(string = strchr(type, '\n')))
+ return NULL;
+
+ // strtol() skips initial whitespace, this is mostly desired.
+ char *end = NULL;
+ long size = strtol(++string, &end, 10);
+ if (size < 0 || end == string || *end++ != '\n')
+ return NULL;
+
+ uint8_t *bin = hexbin(end, len);
+ if (!bin || (long) *len != size) {
+ free(bin);
+ return NULL;
+ }
+ return bin;
+}
+
+static jv
+extract_imagemagick_exif(jv o, const char *string)
+{
+ size_t exif_len = 0;
+ uint8_t *exif = extract_imagemagick_attribute(string, &exif_len);
+ if (!exif)
+ return add_warning(o, "invalid ImageMagick 'exif'");
+
+ o = parse_exif(o, exif, exif_len);
+ free(exif);
+ return o;
+}
+
+static jv
+extract_imagemagick_psir(jv o, const char *string)
+{
+ size_t psir_len = 0;
+ uint8_t *psir = extract_imagemagick_attribute(string, &psir_len);
+ if (!psir)
+ return add_warning(o, "invalid ImageMagick '8bim'");
+
+ o = parse_psir(o, psir, psir_len);
+ free(psir);
+ return o;
+}
+
+static bool
+process_text(jv *o, png_textp text)
+{
+ // TODO(p): Refactor info.h, so that it's the value of the text chunk,
+ // and that warnings are added to the top-level JSON.
+
+ // These seem to originate in ImageMagick,
+ // but are also used by ExifTool and GIMP, among others.
+ // https://exiftool.org/TagNames/PNG.html
+ // TODO(p): "iptc": may contain 8BIM or IPTC IIM directly.
+ // TODO(p): "APP1": may contain Exif or XMP.
+ if (!strcmp(text->key, "Raw profile type exif")) {
+ *o = extract_imagemagick_exif(*o, text->text);
+ return true;
+ }
+ if (!strcmp(text->key, "Raw profile type 8bim")) {
+ *o = extract_imagemagick_psir(*o, text->text);
+ return true;
+ }
+ return false;
}
static jv
-retrieve_texts(png_structp pngp, png_infop infop)
+retrieve_texts(jv o, png_structp pngp, png_infop infop)
{
int texts_len = 0;
png_textp texts = NULL;
png_get_text(pngp, infop, &texts, &texts_len);
- jv o = jv_object();
+ jv to = jv_object();
for (int i = 0; i < texts_len; i++) {
png_textp text = texts + i;
- o = jv_object_set(o, jv_string(text->key), jv_string(text->text));
+ to = jv_object_set(to, jv_string(text->key),
+ process_text(&o, text) ? jv_true() : jv_string(text->text));
}
- return o;
+ return jv_object_set(o, jv_string("texts"), to);
}
static jv
@@ -145,13 +238,19 @@ extract_chunks(png_structp pngp, png_infop infop)
if (png_get_iCCP(pngp, infop, &name, NULL, &profile, &profile_len))
o = jv_object_set(o, jv_string("ICC"), jv_string(name));
- // https://ftp-osl.osuosl.org/pub/libpng/documents/pngext-1.5.0.html#C.eXIf
jv set = jv_object();
png_unknown_chunkp unknowns = NULL;
int unknowns_len = png_get_unknown_chunks(pngp, infop, &unknowns);
for (int i = 0; i < unknowns_len; i++) {
set = jv_object_set(set,
jv_string((const char *) unknowns[i].name), jv_true());
+
+ // https://ftp-osl.osuosl.org/pub/libpng/documents/pngext-1.5.0.html
+ //
+ // Some software also supports the adjacent zXIf proposal,
+ // which ended up being rejected. Such files are rare, and best ignored.
+ // http://www.simplesystems.org/png-group/proposals/zXIf/history
+ // /png-proposed-zXIf-chunk-2017-03-05.html
if (!strcmp((const char *) unknowns[i].name, "eXIf"))
o = parse_exif(o, unknowns[i].data, unknowns[i].size);
}
@@ -162,8 +261,14 @@ extract_chunks(png_structp pngp, png_infop infop)
o = jv_object_set(o, jv_string("chunks"), a);
jv_free(set);
- o = jv_object_set(o, jv_string("texts"), retrieve_texts(pngp, infop));
- return o;
+ return retrieve_texts(o, pngp, infop);
+}
+
+static void
+redirect_libpng_error(png_structp pngp, const char* message)
+{
+ char **storage = png_get_error_ptr(pngp);
+ *storage = strfmt("%s", message);
}
static jv
@@ -179,6 +284,7 @@ do_file(const char *filename, volatile jv o)
goto error;
}
+ // TODO(p): Extract libpng warnings.
png_structp pngp = png_create_read_struct(PNG_LIBPNG_VER_STRING,
(png_voidp) &err, redirect_libpng_error, NULL);
if (!pngp) {