Update handling of embedded palette data in image files.

The pal (formerly wtf2) value indicates the presence of a palette: 0x1000 if
present; 0 otherwise.  Then, immediately following the offsets comes the
palette header: 2 bytes always zero, 2 bytes for the number of entries.
Entries are sequential starting from zero.

This makes the logo images work.

diff --git a/src/image.c b/src/image.c
index c1ad351983f8300e213946e1b8f941713cd83f0a..4f1a2bd0c805e718f234c9ca92794058afcddb62 100644 (file)
--- a/src/image.c
+++ b/src/image.c
@@ -14,8 +14,9 @@
 
 struct lbx_image {
        uint16_t width, height;
-       uint16_t wtf1, wtf2;
+       uint16_t wtf1;
        uint16_t offs, frames;
+       uint16_t pal;
 
        FILE *f;
        long foff;
@@ -36,19 +37,20 @@ struct lbx_image *lbximg_fopen(FILE *f)
        if (fread(&tmp.wtf1,   sizeof tmp.wtf1,    1, f) != 1) goto readerr;
        if (fread(&tmp.offs,   sizeof tmp.offs,    1, f) != 1) goto readerr;
        if (fread(&tmp.frames, sizeof tmp.frames,  1, f) != 1) goto readerr;
-       if (fread(&tmp.wtf2,   sizeof tmp.wtf2,    1, f) != 1) goto readerr;
+       if (fread(&tmp.pal,    sizeof tmp.pal,     1, f) != 1) goto readerr;
 
        tmp.width  = letohs(tmp.width);  tmp.foff += sizeof tmp.width;
        tmp.height = letohs(tmp.height); tmp.foff += sizeof tmp.height;
        tmp.wtf1   = letohs(tmp.wtf1);   tmp.foff += sizeof tmp.wtf1;
        tmp.offs   = letohs(tmp.offs);   tmp.foff += sizeof tmp.offs;
        tmp.frames = letohs(tmp.frames); tmp.foff += sizeof tmp.frames;
-       tmp.wtf2   = letohs(tmp.wtf2);   tmp.foff += sizeof tmp.wtf2;
+       tmp.pal    = letohs(tmp.pal);    tmp.foff += sizeof tmp.pal;
 
        /* For some reason, the format seems to need this. */
        tmp.offs++;
        tmp.frames++;
 
+       /* Format constraints. */
        if (tmp.offs <= tmp.frames) {
                lbx_errno = LBX_EFORMAT;
                return NULL;
@@ -62,6 +64,7 @@ struct lbx_image *lbximg_fopen(FILE *f)
         */
        _lbx_assert(tmp.wtf1 == 0);
        _lbx_assert(tmp.offs == tmp.frames + 1);
+       _lbx_assert(tmp.pal  == 0 || tmp.pal == 0x1000);
 
        new = malloc(sizeof *new + tmp.offs * sizeof *new->offsets);
        if (!new) {
@@ -260,18 +263,38 @@ int lbximg_loadpalette(FILE *f, struct lbx_colour palette[static 256])
 int
 lbximg_getpalette(struct lbx_image *img, struct lbx_colour palette[static 256])
 {
-       int index = 0;
+       size_t hdrlen = 6*(sizeof img->pal)+(img->offs)*(sizeof *img->offsets);
+       unsigned int i;
        size_t rc;
-       size_t hdrlen = 6*(sizeof img->width)
-                       + (img->offs)*(sizeof *img->offsets);
-       
-       uint8_t entry[4];
+
+       uint16_t zero, count;
+       uint8_t  entry[4];
+
+       /* Do nothing if the image doesn't have embedded palette data. */
+       if (img->pal == 0)
+               return 0;
 
        /* Palette data is located right after the header. */
        if (_lbx_fseek(img->f, &img->foff, hdrlen) == -1)
                return -1;
        
-       while (img->foff + sizeof entry <= img->offsets[0]) {
+       /* Palette header */
+       if (fread(&zero,  sizeof zero,  1, img->f) != 1) goto readerr;
+       if (fread(&count, sizeof count, 1, img->f) != 1) goto readerr;
+       zero  = letohs(zero);  img->foff += sizeof zero;
+       count = letohs(count); img->foff += sizeof count;
+
+       if (zero != 0 || count > 256) {
+               lbx_errno = LBX_EFORMAT;
+               return -1;
+       }
+
+       if (hdrlen + 2*(sizeof zero) + count*(sizeof entry) > img->offsets[0]) {
+               lbx_errno = LBX_EFORMAT;
+               return -1;
+       }
+
+       for (i = 0; i < count; i++) {
                rc = fread(entry, 1, sizeof entry, img->f);
                img->foff += rc;
 
@@ -279,17 +302,12 @@ lbximg_getpalette(struct lbx_image *img, struct lbx_colour palette[static 256])
                        goto readerr;
                }
 
-               if (entry[0] == 0) {
-                       index++;
-                       if (index >= 256) {
-                               lbx_errno = LBX_EFORMAT;
-                               return -1;
-                       }
-               } else {
-                       index = entry[0];
+               if (entry[0] != 0) {
+                       lbx_errno = LBX_EFORMAT;
+                       return -1;
                }
 
-               palette[index] = (struct lbx_colour){
+               palette[i] = (struct lbx_colour){
                        .red   = entry[1] << 2,
                        .green = entry[2] << 2,
                        .blue  = entry[3] << 2,
@@ -298,10 +316,7 @@ lbximg_getpalette(struct lbx_image *img, struct lbx_colour palette[static 256])
 
        return 0;
 readerr:
-       if (feof(img->f))
-               lbx_errno = LBX_EEOF;
-       else
-               lbx_errno = -errno;
+       lbx_errno = feof(img->f) ? LBX_EEOF : -errno;
        return -1;
 }