[PATCH v2 13/15] arch: sandbox: Add function to create temporary files

Sean Anderson
2023-11-04T20:41:59Z

When working with sparse data buffers that may be larger than the address
space, it is convenient to work with files instead. Add a function to create
temporary files of a certain size.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
---

(no changes since v1)

arch/sandbox/cpu/os.c | 17 +++++++++++++++++
include/os.h | 13 +++++++++++++
2 files changed, 30 insertions(+)

diff --git a/arch/sandbox/cpu/os.c b/arch/sandbox/cpu/os.c
index 85d0d6a1703..8847c4cd0a8 100644
--- a/arch/sandbox/cpu/os.c
+++ b/arch/sandbox/cpu/os.c
@@ -282,6 +282,23 @@ int os_persistent_file(char *buf, int maxsize, const char *fname)
return 0;
}

+int os_mktemp(char *fname, off_t size)
+{
+ int fd;
+
+ fd = mkostemp(fname, O_CLOEXEC);
+ if (fd < 0)
+ return -errno;
+
+ if (unlink(fname) < 0)
+ return -errno;
+
+ if (ftruncate(fd, size))
+ return -errno;
+
+ return fd;
+}
+
/* Restore tty state when we exit */
static struct termios orig_term;
static bool term_setup;
diff --git a/include/os.h b/include/os.h
index fc8a1b15cbf..877404a6c13 100644
--- a/include/os.h
+++ b/include/os.h
@@ -108,6 +108,19 @@ int os_unlink(const char *pathname);
*/
int os_persistent_file(char *buf, int maxsize, const char *fname);

+/**
+ * os_mktemp() - Create a temporary file
+ * @fname: The template to use for the file name. This must end with 6 Xs. It
+ * will be modified to the opened filename on success.
+ * @size: The size of the file
+ *
+ * Create a temporary file using @fname as a template, unlink it, and truncate
+ * it to @size.
+ *
+ * Return: A file descriptor, or negative errno on error
+ */
+int os_mktemp(char *fname, off_t size);
+
/**
* os_exit() - access to the OS exit() system call
*
--
2.37.1