diff --git a/libsparse/output_file.c b/libsparse/output_file.c
index 6578d99..2115998 100644
--- a/libsparse/output_file.c
+++ b/libsparse/output_file.c
@@ -63,7 +63,7 @@
 	int (*open)(struct output_file *, int fd);
 	int (*skip)(struct output_file *, int64_t);
 	int (*pad)(struct output_file *, int64_t);
-	int (*write)(struct output_file *, void *, int);
+	int (*write)(struct output_file *, void *, size_t);
 	void (*close)(struct output_file *);
 };
 
@@ -149,18 +149,23 @@
 	return 0;
 }
 
-static int file_write(struct output_file *out, void *data, int len)
+static int file_write(struct output_file *out, void *data, size_t len)
 {
-	int ret;
+	ssize_t ret;
 	struct output_file_normal *outn = to_output_file_normal(out);
 
-	ret = write(outn->fd, data, len);
-	if (ret < 0) {
-		error_errno("write");
-		return -1;
-	} else if (ret < len) {
-		error("incomplete write");
-		return -1;
+	while (len > 0) {
+		ret = write(outn->fd, data, len);
+		if (ret < 0) {
+			if (errno == EINTR) {
+				continue;
+			}
+			error_errno("write");
+			return -1;
+		}
+
+		data = (char *)data + ret;
+		len -= ret;
 	}
 
 	return 0;
@@ -232,18 +237,20 @@
 	return 0;
 }
 
-static int gz_file_write(struct output_file *out, void *data, int len)
+static int gz_file_write(struct output_file *out, void *data, size_t len)
 {
 	int ret;
 	struct output_file_gz *outgz = to_output_file_gz(out);
 
-	ret = gzwrite(outgz->gz_fd, data, len);
-	if (ret < 0) {
-		error_errno("gzwrite");
-		return -1;
-	} else if (ret < len) {
-		error("incomplete gzwrite");
-		return -1;
+	while (len > 0) {
+		ret = gzwrite(outgz->gz_fd, data,
+			      min(len, (unsigned int)INT_MAX));
+		if (ret == 0) {
+			error("gzwrite %s", gzerror(outgz->gz_fd, NULL));
+			return -1;
+		}
+		len -= ret;
+		data = (char *)data + ret;
 	}
 
 	return 0;
@@ -293,7 +300,7 @@
 	return -1;
 }
 
-static int callback_file_write(struct output_file *out, void *data, int len)
+static int callback_file_write(struct output_file *out, void *data, size_t len)
 {
 	struct output_file_callback *outc = to_output_file_callback(out);
 
@@ -698,14 +705,16 @@
 	int ret;
 	int64_t aligned_offset;
 	int aligned_diff;
-	int buffer_size;
+	uint64_t buffer_size;
 	char *ptr;
 
 	aligned_offset = offset & ~(4096 - 1);
 	aligned_diff = offset - aligned_offset;
-	buffer_size = len + aligned_diff;
+	buffer_size = (uint64_t)len + (uint64_t)aligned_diff;
 
 #ifndef _WIN32
+	if (buffer_size > SIZE_MAX)
+		return -E2BIG;
 	char *data = mmap64(NULL, buffer_size, PROT_READ, MAP_SHARED, fd,
 			aligned_offset);
 	if (data == MAP_FAILED) {