As of version 4.3, sendfile(2) can return more error codes than are
documented in sendfile.2. This patch adds some details:
- EINVAL can be returned if count is negative, from function rw_verify_area
in fs/read_write.c, called from do_sendfile, called from sys_sendfile.
- EOVERFLOW can be returned if count is too large, from rw_verify_area,
called from do_sendfile, called from sys_sendfile, or directly from
do_sendfile in one case (pos + count > max size of either in_fd or
out_fd).
- ESPIPE can be returned if offset is not a NULL pointer but the input file
does not support FMODE_PREAD, from do_sendfile, called from sys_sendfile.
Signed-off-by: Laurent Georget <laurent.georget@xxxxxxxxxx>
---
I removed EPERM from the patch because actually, it cannot be returned in a
vanilla kernel. I had it in my case because of SELinux. There is a call to the
LSM hook security_file_permission inside the function rw_verify_area.
Cheers,
Laurent
man2/sendfile.2 | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/man2/sendfile.2 b/man2/sendfile.2
index 93cf7e1..b56365e 100644
--- a/man2/sendfile.2
+++ b/man2/sendfile.2
@@ -136,7 +136,10 @@ Bad address.
Descriptor is not valid or locked, or an
.BR mmap (2)-like
operation is not available for
-.IR in_fd .
+.IR in_fd ,
+or
+.I count
+is negative.
.TP
.B EINVAL
.I out_fd
@@ -153,6 +156,16 @@ Unspecified error while reading from
.B ENOMEM
Insufficient memory to read from
.IR in_fd .
+.TP
+.B EOVERFLOW
+.I count
+is too large, the operation would result in exceeding the maximum size of either
+the input file or the output file.
+.TP
+.B ESPIPE
+.I offset
+is not NULL but the input file is not
+.BR seek (2)-able.
.SH VERSIONS
.BR sendfile ()
first appeared in Linux 2.2.
--
2.4.10
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