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 <sjg@chromium.org>
Reviewed-by: Marek Behún <marek.behun@nic.cz>

diff --git a/arch/sandbox/cpu/os.c b/arch/sandbox/cpu/os.c
index 151f42a..a426288 100644 (file)
--- 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 7b20d60..7661078 100644 (file)
--- 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