write(2) might not write all the data it is given. Add a write_all_buf()
helper to keep calling it until all the given data is written, or we get an
error.
Currently we use write_remainder() to do this operation in pcap_frame().
That's a little awkward since it requires constructing an iovec, and future
changes we want to make to write_remainder() will be easier in terms of
this single buffer helper.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
pcap.c | 3 +--
util.c | 25 +++++++++++++++++++++++++
util.h | 1 +
3 files changed, 27 insertions(+), 2 deletions(-)
diff --git a/pcap.c b/pcap.c
index 46cc4b0d..e6b5ced4 100644
--- a/pcap.c
+++ b/pcap.c
@@ -86,9 +86,8 @@ static void pcap_frame(const struct iovec *iov, size_t iovcnt,
.caplen = l2len,
.len = l2len
};
- struct iovec hiov = { &h, sizeof(h) };
- if (write_remainder(pcap_fd, &hiov, 1, 0) < 0 ||
+ if (write_all_buf(pcap_fd, &h, sizeof(h)) < 0 ||
write_remainder(pcap_fd, iov, iovcnt, offset) < 0)
debug_perror("Cannot log packet, length %zu", l2len);
}
diff --git a/util.c b/util.c
index eede4e58..7db7c2e7 100644
--- a/util.c
+++ b/util.c
@@ -582,6 +582,31 @@ int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size,
int flags,
#endif
}
+/* write_all_buf() - write all of a buffer to an fd
+ * @fd: File descriptor
+ * @buf: Pointer to base of buffer
+ * @len: Length of buffer
+ *
+ * Return: 0 on success, -1 on error (with errno set)
+ *
+ * #syscalls write
+ */
+int write_all_buf(int fd, const void *buf, size_t len)
+{
+ const char *p = buf;
+ size_t left = len;
+
+ while (left) {
+ ssize_t rc = write(fd, p, left);
+
+ if (rc < 0)
+ return -1;
+ p += rc;
+ left -= rc;
+ }
+ return 0;
+}
+
/* write_remainder() - write the tail of an IO vector to an fd
* @fd: File descriptor
* @iov: IO vector
diff --git a/util.h b/util.h
index c7a59d5d..5e67f1fa 100644
--- a/util.h
+++ b/util.h
@@ -200,6 +200,7 @@ void pidfile_write(int fd, pid_t pid);
int __daemon(int pidfile_fd, int devnull_fd);
int fls(unsigned long x);
int write_file(const char *path, const char *buf);
+int write_all_buf(int fd, const void *buf, size_t len);
int write_remainder(int fd, const struct iovec *iov, size_t iovcnt, size_t skip);
void close_open_files(int argc, char **argv);
--
2.46.0