David Gibson <david(a)gibson.dropbear.id.au> writes: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)I'd call it write_all(), but that's strictly a matter of taste.+{ + const char *p = buf; + size_t left = len; + + while (left) { + ssize_t rc = write(fd, p, left); + + if (rc < 0) + return -1;Loop when errno == EINTR?+ 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);