Add exfat_open() function.

It opens the special file and ensures that this is either a block device
or a regular file.

1 files changed, 29 insertions, 0 deletions

diff --git a/libexfat/io.c b/libexfat/io.c
index 65d8d74..3d63fa9 100644
--- a/libexfat/io.c
+++ b/libexfat/io.c
@@ -22,6 +22,8 @@
 #include <inttypes.h>
 #include <sys/types.h>
 #include <sys/uio.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 #define __USE_UNIX98 /* for pread() in Linux */
 #include <unistd.h>
 
@@ -29,6 +31,33 @@
 	#error You should define _FILE_OFFSET_BITS=64
 #endif
 
+int exfat_open(const char* spec, int ro)
+{
+	int fd;
+	struct stat stbuf;
+
+	fd = open(spec, ro ? O_RDONLY : O_RDWR);
+	if (fd < 0)
+	{
+		exfat_error("failed to open `%s'", spec);
+		return -1;
+	}
+	if (fstat(fd, &stbuf) != 0)
+	{
+		close(fd);
+		exfat_error("failed to fstat `%s'", spec);
+		return -1;
+	}
+	if (!S_ISBLK(stbuf.st_mode) && !S_ISREG(stbuf.st_mode))
+	{
+		close(fd);
+		exfat_error("`%s' is neither a block device, nor a regular file",
+				spec);
+		return -1;
+	}
+	return fd;
+}
+
 void exfat_read_raw(void* buffer, size_t size, off_t offset, int fd)
 {
 	if (pread(fd, buffer, size, offset) != size)