sandbox: Add a way to find the size of a file

Add a function to return the size of a file. This is useful in situations
where we need to allocate memory for it before reading it.

Signed-off-by: Simon Glass <[email protected]>
Reviewed-by: Marek Behún <[email protected]>

2 files changed, 24 insertions, 6 deletions

diff --git a/arch/sandbox/cpu/os.c b/arch/sandbox/cpu/os.c
index 151f42a5d6c..a4262881c54 100644
--- a/arch/sandbox/cpu/os.c
+++ b/arch/sandbox/cpu/os.c
@@ -133,6 +133,19 @@ int os_write_file(const char *fname, const void *buf, int size)
 	return 0;
 }
 
+int os_filesize(int fd)
+{
+	off_t size;
+
+	size = os_lseek(fd, 0, OS_SEEK_END);
+	if (size < 0)
+		return -errno;
+	if (os_lseek(fd, 0, OS_SEEK_SET) < 0)
+		return -errno;
+
+	return size;
+}
+
 int os_read_file(const char *fname, void **bufp, int *sizep)
 {
 	off_t size;
@@ -144,15 +157,12 @@ int os_read_file(const char *fname, void **bufp, int *sizep)
 		printf("Cannot open file '%s'\n", fname);
 		goto err;
 	}
-	size = os_lseek(fd, 0, OS_SEEK_END);
+	size = os_filesize(fd);
 	if (size < 0) {
-		printf("Cannot seek to end of file '%s'\n", fname);
-		goto err;
-	}
-	if (os_lseek(fd, 0, OS_SEEK_SET) < 0) {
-		printf("Cannot seek to start of file '%s'\n", fname);
+		printf("Cannot get file size of '%s'\n", fname);
 		goto err;
 	}
+
 	*bufp = os_malloc(size);
 	if (!*bufp) {
 		printf("Not enough memory to read file '%s'\n", fname);
diff --git a/include/os.h b/include/os.h
index 7b20d606dd0..7661078d336 100644
--- a/include/os.h
+++ b/include/os.h
@@ -52,6 +52,14 @@ off_t os_lseek(int fd, off_t offset, int whence);
 #define OS_SEEK_END	2
 
 /**
+ * os_filesize() - Calculate the size of a file
+ *
+ * @fd:		File descriptor as returned by os_open()
+ * Return:	file size or negative error code
+ */
+int os_filesize(int fd);
+
+/**
  * Access to the OS open() system call
  *
  * @pathname:	Pathname of file to open