Move ethash_io_prepare to io.c

- Platform specific io.c files now contain only the minimum amount of
  code they can.

internal.c

@@ -371,12 +371,13 @@ ethash_full_t ethash_full_new(char const *dirname,
 	ret->file_size = (size_t)params->full_size;
 	switch (ethash_io_prepare(dirname, *seed_hash, &f, (size_t)params->full_size)) {
 	case ETHASH_IO_FAIL:
+	case ETHASH_IO_MEMO_SIZE_MISMATCH:
 		goto fail_free_full;
 	case ETHASH_IO_MEMO_MATCH:
 		match = true;
 	case ETHASH_IO_MEMO_MISMATCH:
 		ret->file = f;
-		if ((fd = fileno(ret->file)) == -1) {
+		if ((fd = ethash_fileno(ret->file)) == -1) {
 			goto fail_free_full;
 		}
 		ret->data = mmap(

io.c

@@ -48,3 +48,61 @@ free_name:
 	free(fullname);
 	return ret;
 }
+
+enum ethash_io_rc ethash_io_prepare(char const *dirname,
+	ethash_h256_t const seedhash,
+	FILE **output_file,
+	size_t file_size)
+{
+	char mutable_name[DAG_MUTABLE_NAME_MAX_SIZE];
+	enum ethash_io_rc ret = ETHASH_IO_FAIL;
+
+	// assert directory exists
+	if (!ethash_mkdir(dirname)) {
+		goto end;
+	}
+
+	ethash_io_mutable_name(REVISION, &seedhash, mutable_name);
+	char *tmpfile = ethash_io_create_filename(dirname, mutable_name, strlen(mutable_name));
+	if (!tmpfile) {
+		goto end;
+	}
+
+	// try to open the file
+	FILE *f = ethash_fopen(tmpfile, "rb+");
+	if (f) {
+		size_t found_size;
+		if (!ethash_file_size(f, &found_size)) {
+			fclose(f);
+			goto free_memo;
+		}
+		if (file_size != found_size) {
+			fclose(f);
+			ret = ETHASH_IO_MEMO_SIZE_MISMATCH;
+			goto free_memo;
+		}
+	} else {
+		// file does not exist, will need to be created
+		f = ethash_fopen(tmpfile, "wb+");
+		if (!f) {
+			goto free_memo;
+		}
+		// make sure it's of the proper size
+		if (fseek(f, file_size - 1, SEEK_SET) != 0) {
+			fclose(f);
+			goto free_memo;
+		}
+		fputc('\n', f);
+		fflush(f);
+		ret = ETHASH_IO_MEMO_MISMATCH;
+		goto set_file;
+	}
+
+	ret = ETHASH_IO_MEMO_MATCH;
+set_file:
+	*output_file = f;
+free_memo:
+	free(tmpfile);
+end:
+	return ret;
+}

io.h

@@ -37,9 +37,10 @@ extern "C" {
 #define DAG_MUTABLE_NAME_MAX_SIZE (10 + 1 + 16 + 1)
 /// Possible return values of @see ethash_io_prepare
 enum ethash_io_rc {
-	ETHASH_IO_FAIL = 0,      ///< There has been an IO failure
+	ETHASH_IO_FAIL = 0,           ///< There has been an IO failure
-	ETHASH_IO_MEMO_MISMATCH, ///< The DAG file did not exist or there was revision/hash mismatch
+	ETHASH_IO_MEMO_SIZE_MISMATCH, ///< DAG with revision/hash match, but file size was wrong.
-	ETHASH_IO_MEMO_MATCH,    ///< DAG file existed and revision/hash matched. No need to do anything
+	ETHASH_IO_MEMO_MISMATCH,      ///< The DAG file did not exist or there was revision/hash mismatch
+	ETHASH_IO_MEMO_MATCH,         ///< DAG file existed and revision/hash matched. No need to do anything
 };
 
 /**
@@ -78,6 +79,7 @@ enum ethash_io_rc ethash_io_prepare(char const *dirname,
  * @return                 The FILE* or NULL in failure
  */
 FILE *ethash_fopen(const char *file_name, const char *mode);
+
 /**
  * An strncat wrapper for no-warnings crossplatform strncat.
  *
@@ -96,6 +98,32 @@ FILE *ethash_fopen(const char *file_name, const char *mode);
  */
 char *ethash_strncat(char *dest, size_t dest_size, const char *src, size_t count);
 
+/**
+ * A cross-platform mkdir wrapper to create a directory or assert it's there
+ * 
+ * @param dirname        The full path of the directory to create
+ * @return               true if the directory was created or if it already
+ *                       existed
+ */
+bool ethash_mkdir(char const *dirname);
+
+/**
+ * Get a file's size
+ *
+ * @param[in] f        The open file stream whose size to get
+ * @param[out] size    Pass a size_t by reference to contain the file size
+ * @return             true in success and false if there was a failure
+ */
+bool ethash_file_size(FILE *f, size_t *ret_size);
+
+/**
+ * Get a file descriptor number from a FILE stream
+ * 
+ * @param f            The file stream whose fd to get
+ * @return             Platform specific fd handler
+ */
+int ethash_fileno(FILE *f);
+
 static inline bool ethash_io_mutable_name(uint32_t revision,
 	ethash_h256_t const* seed_hash,
 	char* output)

io_posix.c

@@ -37,52 +37,24 @@ char *ethash_strncat(char *dest, size_t dest_size, const char *src, size_t count
 	return strlen(dest) + count + 1 <= dest_size ? strncat(dest, src, count) : NULL;
 }
 
-enum ethash_io_rc ethash_io_prepare(char const *dirname,
+bool ethash_mkdir(char const *dirname)
-	ethash_h256_t const seedhash,
-	FILE **output_file,
-	size_t file_size)
 {
-	char mutable_name[DAG_MUTABLE_NAME_MAX_SIZE];
-	enum ethash_io_rc ret = ETHASH_IO_FAIL;
-
-	// assert directory exists, full owner permissions and read/search for others
 	int rc = mkdir(dirname, S_IRWXU | S_IRWXG | S_IROTH | S_IXOTH);
-	if (rc == -1 && errno != EEXIST) {
+	return rc != -1 || errno == EEXIST;
-		goto end;
+}
-	}
 
-	ethash_io_mutable_name(REVISION, &seedhash, mutable_name);
+int ethash_fileno(FILE *f)
-	char *tmpfile = ethash_io_create_filename(dirname, mutable_name, strlen(mutable_name));
+{
-	if (!tmpfile) {
+	return fileno(f);
-		goto end;
+}
-	}
 
-	// try to open the file
+bool ethash_file_size(FILE *f, size_t *ret_size)
-	FILE *f = ethash_fopen(tmpfile, "rb+");
+{
-	if (f) {
+	struct stat st;
-		// TODO: check for file size
+	int fd;
-	} else {
+	if ((fd = fileno(f)) == -1 || fstat(fd, &st) != 0) {
-		// file does not exist, will need to be created
+		return false;
-		f = ethash_fopen(tmpfile, "wb+");
-		if (!f) {
-			goto free_memo;
-		}
-		// make sure it's of the proper size
-		if (fseek(f, file_size - 1, SEEK_SET) != 0) {
-			fclose(f);
-			goto free_memo;
-		}
-		fputc('\n', f);
-		fflush(f);
-		ret = ETHASH_IO_MEMO_MISMATCH;
-		goto set_file;
 	}
-
+	*ret_size = st.st_size;
-	ret = ETHASH_IO_MEMO_MATCH;
+	return true;
-set_file:
-	*output_file = f;
-free_memo:
-	free(tmpfile);
-end:
-	return ret;
 }

io_win32.c

@@ -35,50 +35,24 @@ char *ethash_strncat(char *dest, size_t dest_size, const char *src, size_t count
 	return strncat_s(dest, dest_size, src, count) == 0 ? dest : NULL;
 }
 
-enum ethash_io_rc ethash_io_prepare(char const *dirname,
+bool ethash_mkdir(char const *dirname)
-	ethash_h256_t const seedhash,
-	FILE **output_file,
-	size_t file_size)
 {
-	char mutable_name[DAG_MUTABLE_NAME_MAX_SIZE];
-	enum ethash_io_rc ret = ETHASH_IO_FAIL;
-
-	// assert directory exists
 	int rc = _mkdir(dirname);
-	if (rc == -1 && errno != EEXIST) {
+	return rc != -1 || errno == EEXIST;
-		goto end;
+}
-	}
 
-	ethash_io_mutable_name(REVISION, &seedhash, mutable_name);
+int ethash_fileno(FILE *f)
-	char *tmpfile = ethash_io_create_filename(dirname, mutable_name, strlen(mutable_name));
+{
-	if (!tmpfile) {
+	return _fileno(f);
-		goto end;
+}
-	}
 
-	// try to open the file
+bool ethash_file_size(FILE *f, size_t *ret_size)
-	FILE *f = ethash_fopen(tmpfile, "rb+");
+{
-	if (!f) {
+	struct _stat st;
-		// file does not exist, will need to be created
+	int fd;
-		f = ethash_fopen(tmpfile, "wb+");
+	if ((fd = _fileno(f)) == -1 || _fstat(fd, &st) != 0) {
-		if (!f) {
+		return false;
-			goto free_memo;
-		}
-		// make sure it's of the proper size
-		if (fseek(f, file_size - 1, SEEK_SET) != 0) {
-			fclose(f);
-			goto free_memo;
-		}
-		fputc('\n', f);
-		fflush(f);
-		ret = ETHASH_IO_MEMO_MISMATCH;
-		goto set_file;
 	}
-
+	*ret_size = st.st_size;
-	ret = ETHASH_IO_MEMO_MATCH;
+	return true;
-set_file:
-	*output_file = f;
-free_memo:
-	free(tmpfile);
-end:
-	return ret;
 }