decode: fix invalid error return for 0-length EXIF (#248)

randy408 · web-flow · commit e68ba5df5717 · 2023-04-28T07:05:41.000+03:00
diff --git a/spng/spng.c b/spng/spng.c
@@ -2691,6 +2691,7 @@ static int read_non_idat_chunks(spng_ctx *ctx)
             if(!memcmp(chunk.type, type_exif, 4))
             {
                 if(ctx->file.exif) return SPNG_EDUP_EXIF;
+                if(!chunk.length) return SPNG_EEXIF;
 
                 ctx->file.exif = 1;
 

Original file line number	Diff line number	Diff line change
`@@ -2691,6 +2691,7 @@ static int read_non_idat_chunks(spng_ctx *ctx)`
`2691`	`2691`	`if(!memcmp(chunk.type, type_exif, 4))`
`2692`	`2692`	`{`
`2693`	`2693`	`if(ctx->file.exif) return SPNG_EDUP_EXIF;`
	`2694`	`+ if(!chunk.length) return SPNG_EEXIF;`
`2694`	`2695`
`2695`	`2696`	`ctx->file.exif = 1;`
`2696`	`2697`