Enhanced reading and skipping methods

include/libg1m/internals/format.h

@@ -186,7 +186,7 @@ struct g3a_subheader {
 	uint8_t icon[0x300];
 
 	/* unused */
-	uint8_t unused[0x92C];
+	uint8_t unused[0x92c];
 
 	/* G3A filename (seriously?!) */
 	uint8_t g3a_filename[0x144];

src/parse.c

@@ -16,8 +16,13 @@
 /* ************************************************************************** */
 #define min(A, B) ((A) < (B) ? (A) : (B))
 /* read with EOF check */
-#define READ(TO, SZ) \
-	if (!fread(TO, SZ, 1, stream)) return (g1m_error_eof);
+#define READ(TO, SZ) { \
+	size_t READ_size = fread(TO, 1, SZ, stream); \
+	if (READ_size < (SZ)) { \
+		log_info("READING failed: read %zu/%zu bytes, %zu missing.", \
+			READ_size, SZ, (SZ) - READ_size); \
+		return (g1m_error_eof); \
+	}}
 /* read with EOF check, declare var before */
 #define DREAD(NAM, STRUCT) \
 	struct STRUCT NAM; \
@@ -33,6 +38,9 @@
  *	skip:
  *	Skip some bytes.
  *
+ *	I've made two loops to avoid conditions in each loop iteration
+ *	when checksum is not calculated.
+ *
  *	@arg	stream		the stream where to skip bytes.
  *	@arg	size		the size to skip.
  *	@arg	checksum	pointer to the checksum variable if there is one.
@@ -41,6 +49,7 @@
 static int skip(FILE *stream, size_t size, uint_fast32_t *checksum)
 {
 	uint8_t buf[1024];
+	size_t size_ini = size;
 
 	if (checksum) {
 		uint_fast32_t add = 0;
@@ -49,13 +58,20 @@ static int skip(FILE *stream, size_t size, uint_fast32_t *checksum)
 			if (!size) break;
 
 			/* read that much */
-			size_t curlen = min(size, 1024);
-			READ(buf, curlen)
-			size -= curlen;
+			{
+				size_t curlen = min(size, 1024);
+				size_t read_len = fread(buf, 1, curlen, stream);
+				size -= read_len;
+				if (read_len < curlen) {
+					log_info("SKIPPING failed, skipped %zu/%zu bytes, "
+						"%zu missing", size_ini - size, size_ini, size);
+					return (g1m_error_eof);
+				}
 
-			/* feed the checksum */
-			for (size_t i = 0; i < curlen; i++)
-				add += buf[i];
+				/* feed the checksum */
+				for (size_t i = 0; i < curlen; i++)
+					add += buf[i];
+			}
 		}
 		*checksum += add;
 	} else {
@@ -63,9 +79,17 @@ static int skip(FILE *stream, size_t size, uint_fast32_t *checksum)
 			/* if no size left, exit */
 			if (!size) break;
 
-			size_t curlen = min(size, 1024);
-			READ(buf, curlen);
-			size -= curlen;
+			/* read that much */
+			{
+				size_t curlen = min(size, 1024);
+				size_t read_len = fread(buf, 1, curlen, stream);
+				size -= read_len;
+				if (read_len < curlen) {
+					log_info("SKIPPING failed, skipped %zu/%zu bytes, "
+						"%zu missing", size_ini - size, size_ini, size);
+					return (g1m_error_eof);
+				}
+			}
 		}
 	}
 
@@ -156,6 +180,10 @@ static int g1m_parse_addin(g1m_t *handle, FILE *stream)
 	log_info("version is %.10s", hd.version);
 	log_info("creation date is %.14s", hd.creation_date);
 
+	/* skip size */
+	SKIP(hd.filesize - sizeof(struct standard_header)
+		- sizeof(struct g1a_subheader))
+
 	/* no errors */
 	return (0);
 }
@@ -223,7 +251,7 @@ static int g1m_parse_mcs_spreadsheet(g1m_t *handle, FILE *stream)
 
 		/* get the row directory */
 		uint8_t row_directory[0x80];
-		READ(&row_directory, 0x80)
+		READ(&row_directory, (size_t)0x80)
 
 		/* initialize loop values */
 		uint8_t *rd = row_directory;
@@ -501,6 +529,7 @@ static int g1m_parse_eact_eact(g1m_t *handle, uint8_t *buf, size_t bufsize,
 	int err;
 
 	/* get e-act subheader */
+	if (bufsize < sizeof(struct eact_eactheader)) return (g1m_error_eof);
 	struct eact_eactheader ehd;
 	memcpy(&ehd, buf, sizeof(struct eact_eactheader));
 
@@ -510,6 +539,9 @@ static int g1m_parse_eact_eact(g1m_t *handle, uint8_t *buf, size_t bufsize,
 	/* get the line descriptors
 	 *	there is actually a "bonus" line descriptor at the end, but the
 	 *	fact that we're using offsets lets us unaware of it. */
+	if (bufsize < sizeof(struct eact_eactheader)
+		+ (ehd.line_count + 1) * sizeof(struct line_descriptor))
+		return (g1m_error_eof);
 	struct line_descriptor *lds = (void*)&buf[sizeof(struct eact_eactheader)];
 
 	/* browse the lines */
@@ -535,6 +567,10 @@ static int g1m_parse_eact_eact(g1m_t *handle, uint8_t *buf, size_t bufsize,
 		uint_fast8_t entry_type = lds[i].entry_type;
 		uint_fast32_t entry_offset = lds[i].entry_offset;
 
+		/* check if buffer is big enough */
+		if (entry_offset + linesize > bufsize)
+			return (g1m_error_eof);
+
 		/* log data */
 		log_info("[>%d][%ld] Is '%s' (0x%02x)", depth, i + 1,
 			g1m_get_eact_ltype_string(entry_type), entry_type);
@@ -574,6 +610,7 @@ static int g1m_parse_eact_cont(g1m_t *handle, uint8_t *buf, size_t bufsize,
 
 	/* read content header */
 	size_t could_read = min(bufsize, sizeof(struct eact_contentheader));
+	if (could_read < 9) return (g1m_error_eof);
 	struct eact_contentheader hd = {};
 	memcpy(&hd, buf, could_read);
 
@@ -630,7 +667,6 @@ static int g1m_parse_eact(g1m_t * handle, FILE *stream)
 	/* get content buffer */
 	size_t bufsize = hd.filesize - sizeof(struct standard_header)
 		- sizeof(struct eact_header) - hd.setup_area_size;
-	log_info("bufsize is %zuo", bufsize);
 	uint8_t buf[bufsize];
 	READ(&buf, bufsize)