On 11/01/2011 09:10 AM, Alon Levy wrote:
+/*
+ * read_with_eintr
+ * helper. reads until size bytes accumulated in buf, if an error other then
+ * EINTR is encountered returns -1, otherwise returns 0.
+ */
+int read_with_eintr(int fd, void *buf, size_t size)
+{
+ int read_size = 0;
+ int ret;
+
+ while (read_size< size) {
+ ret = read(fd, buf + read_size, size - read_size);
+ if (ret == -1) {
+ if (errno != EINTR) {
+ return -1;
+ }
+ continue;
+ }
+ read_size += size;
+ }
+ return 0;
+}
This fails if read returns zero. It can do so for a broken pipe on the
read side, even if fd is blocking.
A more common name I've seen for this function is fullread or read_full
(same for write). For the version that just loops if EINTR, a more
common name is saferead or read_safe.
+ /* according to the man page EINTR will mean no data written, so
+ * no need to take account of short writes. */
write can certainly do short writes if fd's buffer is too small for
"buf"! It can also return zero if fd is in non-blocking mode, but I'm
not sure that this is a problem for you.
+ while (write(fd, buf, size) != size) {
If write does a short write, you'll write the beginning of buf multiple
times, or possibly end up with an infinite loop even.
+ if (errno != EINTR) {
+ return -1;
+ }
+ }
Paolo
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