From 8bdb0883b441441590589aac46f991c80e4f80f3 Mon Sep 17 00:00:00 2001 From: David Gibson Date: Wed, 28 Feb 2024 12:52:03 +1100 Subject: util: Add write_remainder() helper We have several places where we want to write(2) a buffer or buffers and we handle short write()s by retrying until everything is successfully written. Add a helper for this in util.c. This version has some differences from the typical write_all() function. First, take an IO vector rather than a single buffer, because that will be useful for some of our cases. Second, allow it to take an parameter to skip the first n bytes of the given buffers. This will be useful for some of the cases we want, and also falls out quite naturally from the implementation. Signed-off-by: David Gibson [sbrivio: Minor formatting fixes in write_remainder()] Signed-off-by: Stefano Brivio --- util.c | 35 +++++++++++++++++++++++++++++++++++ 1 file changed, 35 insertions(+) (limited to 'util.c') diff --git a/util.c b/util.c index 8acce23..81449b7 100644 --- a/util.c +++ b/util.c @@ -19,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -26,6 +27,7 @@ #include #include "util.h" +#include "iov.h" #include "passt.h" #include "packet.h" #include "log.h" @@ -574,3 +576,36 @@ int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size, int flags, return clone(fn, stack_area + stack_size / 2, flags, arg); #endif } + +/* write_remainder() - write the tail of an IO vector to an fd + * @fd: File descriptor + * @iov: IO vector + * @iovcnt: Number of entries in @iov + * @skip: Number of bytes of the vector to skip writing + * + * Return: 0 on success, -1 on error (with errno set) + * + * #syscalls write writev + */ +int write_remainder(int fd, const struct iovec *iov, int iovcnt, size_t skip) +{ + int i; + + while ((i = iov_skip_bytes(iov, iovcnt, skip, &skip)) < iovcnt) { + ssize_t rc; + + if (skip) { + rc = write(fd, (char *)iov[i].iov_base + skip, + iov[i].iov_len - skip); + } else { + rc = writev(fd, &iov[i], iovcnt - i); + } + + if (rc < 0) + return -1; + + skip += rc; + } + + return 0; +} -- cgit v1.2.3