lib: istream-file/unix - don't ignore EINTR for blocking istream reads

Just fail the istream read entirely. Although there's a small possibility
that this interrupt was unwanted and should be retried, it's more likely
that a blocking istream is hanging and admin wants to stop the process.
If the EINTR is ignored all the time, it's not possible to abort a
blocking read with ^C or anything else than SIGKILL.

src/lib/istream-file.c

@@ -58,20 +58,18 @@ ssize_t i_stream_file_read(struct istream_private *stream)
 	}
 
 	offset = stream->istream.v_offset + (stream->pos - stream->skip);
-	do {
-		if (fstream->file) {
-			ret = pread(stream->fd, stream->w_buffer + stream->pos,
-				    size, offset);
-		} else if (fstream->seen_eof) {
-			/* don't try to read() again. EOF from keyboard (^D)
-			   requires this to work right. */
-			ret = 0;
-		} else {
-			ret = read(stream->fd, stream->w_buffer + stream->pos,
-				   size);
-		}
-	} while (unlikely(ret < 0 && errno == EINTR &&
-			  stream->istream.blocking));
+
+	if (fstream->file) {
+		ret = pread(stream->fd, stream->w_buffer + stream->pos,
+			    size, offset);
+	} else if (fstream->seen_eof) {
+		/* don't try to read() again. EOF from keyboard (^D)
+		   requires this to work right. */
+		ret = 0;
+	} else {
+		ret = read(stream->fd, stream->w_buffer + stream->pos,
+			   size);
+	}
 
 	if (ret == 0) {
 		/* EOF */
@@ -81,8 +79,8 @@ ssize_t i_stream_file_read(struct istream_private *stream)
 	}
 
 	if (unlikely(ret < 0)) {
-		if (errno == EINTR || errno == EAGAIN) {
-			i_assert(!stream->istream.blocking);
+		if ((errno == EINTR || errno == EAGAIN) &&
+		    !stream->istream.blocking) {
 			ret = 0;
 		} else {
 			i_assert(errno != 0);

src/lib/istream-unix.c

@@ -34,12 +34,8 @@ static ssize_t i_stream_unix_read(struct istream_private *stream)
 	if (!i_stream_try_alloc(stream, 1, &size))
 		return -2;
 
-	do {
-		ret = fd_read(stream->fd,
-			      stream->w_buffer + stream->pos, size,
-			      &ustream->read_fd);
-	} while (unlikely(ret < 0 && errno == EINTR &&
-			  stream->istream.blocking));
+	ret = fd_read(stream->fd, stream->w_buffer + stream->pos, size,
+		      &ustream->read_fd);
 	if (ustream->read_fd != -1)
 		ustream->next_read_fd = FALSE;
 
@@ -51,8 +47,8 @@ static ssize_t i_stream_unix_read(struct istream_private *stream)
 	}
 
 	if (unlikely(ret < 0)) {
-		if (errno == EINTR || errno == EAGAIN) {
-			i_assert(!stream->istream.blocking);
+		if ((errno == EINTR || errno == EAGAIN) &&
+		    !stream->istream.blocking) {
 			return 0;
 		} else {
 			i_assert(errno != 0);