Analogous to what we have with write()/write_full(), introduce a
lightweight wrapper around pwrite() that guarantees the either all
data is going to be written or a negative error code would be
returned.
Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
---
include/libfile.h | 1 +
lib/libfile.c | 24 ++++++++++++++++++++++++
2 files changed, 25 insertions(+)
diff --git a/include/libfile.h b/include/libfile.h
index 2c5eef71f..f1d695187 100644
--- a/include/libfile.h
+++ b/include/libfile.h
@@ -1,6 +1,7 @@
#ifndef __LIBFILE_H
#define __LIBFILE_H
+int pwrite_full(int fd, const void *buf, size_t size, loff_t offset);
int write_full(int fd, const void *buf, size_t size);
int read_full(int fd, void *buf, size_t size);
diff --git a/lib/libfile.c b/lib/libfile.c
index 0052e789f..39c85b2fc 100644
--- a/lib/libfile.c
+++ b/lib/libfile.c
@@ -23,6 +23,30 @@
#include <stdlib.h>
#include <linux/stat.h>
+/*
+ * pwrite_full - write to filedescriptor at offset
+ *
+ * Like pwrite, but guarantees to write the full buffer out, else it
+ * returns with an error.
+ */
+int pwrite_full(int fd, const void *buf, size_t size, loff_t offset)
+{
+ size_t insize = size;
+ int now;
+
+ while (size) {
+ now = pwrite(fd, buf, size, offset);
+ if (now <= 0)
+ return now;
+ size -= now;
+ buf += now;
+ offset += now;
+ }
+
+ return insize;
+}
+EXPORT_SYMBOL(pwrite_full);
+
/*
* write_full - write to filedescriptor
*
--
2.17.1
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