+/* Read from FD into the buffer BUF with COUNT bytes. Attempt to fill
+ BUF. Wait until input is available; this matters because files are
+ opened O_NONBLOCK for security reasons, and on some file systems
+ this can cause read to fail with errno == EAGAIN. Return the
+ actual number of bytes read, zero for EOF, or
+ SAFE_READ_ERROR upon error. */
+size_t
+blocking_read (int fd, void *buf, size_t count)
+{
+ size_t bytes = safe_read (fd, buf, count);
+
+#if defined F_SETFL && O_NONBLOCK
+ if (bytes == SAFE_READ_ERROR && errno == EAGAIN)
+ {
+ int flags = fcntl (fd, F_GETFL);
+ if (0 <= flags && flags & O_NONBLOCK
+ && fcntl (fd, F_SETFL, flags & ~O_NONBLOCK) != -1)
+ bytes = safe_read (fd, buf, count);
+ }
+#endif
+
+ return bytes;
+}
+
+/* Write to FD from the buffer BUF with COUNT bytes. Do a full write.
+ Wait until an output buffer is available; this matters because
+ files are opened O_NONBLOCK for security reasons, and on some file
+ systems this can cause write to fail with errno == EAGAIN. Return
+ the actual number of bytes written, setting errno if that is less
+ than COUNT. */
+size_t
+blocking_write (int fd, void const *buf, size_t count)
+{
+ size_t bytes = full_write (fd, buf, count);
+
+#if defined F_SETFL && O_NONBLOCK
+ if (bytes < count && errno == EAGAIN)
+ {
+ int flags = fcntl (fd, F_GETFL);
+ if (0 <= flags && flags & O_NONBLOCK
+ && fcntl (fd, F_SETFL, flags & ~O_NONBLOCK) != -1)
+ {
+ char const *buffer = buf;
+ bytes += full_write (fd, buffer + bytes, count - bytes);
+ }
+ }
+#endif
+
+ return bytes;
+}
+