diff options
Diffstat (limited to 'tools/pnginfo.c')
| -rw-r--r-- | tools/pnginfo.c | 128 |
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) { |