From: Stephan Bosch <stephan.bosch@open-xchange.com>
Date: Thu, 23 Feb 2023 00:31:31 +0000 (+0100)
Subject: lib: ostream-file - Improve write errors: mention the failing syscall.
X-Git-Tag: 2.4.0~2883
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=01d2a3ad7857785ad1d5a032caff1b0bfcfbd6b1;p=thirdparty%2Fdovecot%2Fcore.git

lib: ostream-file - Improve write errors: mention the failing syscall.
---

diff --git a/src/lib/ostream-file-private.h b/src/lib/ostream-file-private.h
index 2d58933559..fd2ac632f4 100644
--- a/src/lib/ostream-file-private.h
+++ b/src/lib/ostream-file-private.h
@@ -8,7 +8,7 @@ struct file_ostream {
 
 	ssize_t (*writev)(struct file_ostream *fstream,
 		 const struct const_iovec *iov,
-		 unsigned int iov_count);
+		 unsigned int iov_count, const char **error_r);
 
 	int fd;
 	struct io *io;
@@ -34,8 +34,8 @@ struct ostream *
 o_stream_create_file_common(struct file_ostream *fstream,
 	int fd, size_t max_buffer_size, bool autoclose_fd);
 ssize_t o_stream_file_writev(struct file_ostream *fstream,
-				   const struct const_iovec *iov,
-				   unsigned int iov_size);
+			     const struct const_iovec *iov,
+			     unsigned int iov_size, const char **error_r);
 ssize_t o_stream_file_sendv(struct ostream_private *stream,
 				   const struct const_iovec *iov,
 				   unsigned int iov_count);
diff --git a/src/lib/ostream-file.c b/src/lib/ostream-file.c
index 7ad9c0b7fd..241ea6bea5 100644
--- a/src/lib/ostream-file.c
+++ b/src/lib/ostream-file.c
@@ -153,9 +153,11 @@ static int o_stream_lseek(struct file_ostream *fstream)
 }
 
 ssize_t o_stream_file_writev(struct file_ostream *fstream,
-				   const struct const_iovec *iov,
-				   unsigned int iov_count)
+			     const struct const_iovec *iov,
+			     unsigned int iov_count,
+			     const char **error_r)
 {
+	const char *syscall = NULL;
 	ssize_t ret;
 	size_t size, sent;
 	unsigned int i;
@@ -165,17 +167,22 @@ ssize_t o_stream_file_writev(struct file_ostream *fstream,
 
 		if (!fstream->file ||
 		    fstream->real_offset == fstream->buffer_offset) {
+			syscall = "write";
 			ret = write(fstream->fd, iov->iov_base, iov->iov_len);
 			if (ret > 0)
 				fstream->real_offset += ret;
 		} else {
+			syscall = "pwrite";
 			ret = pwrite(fstream->fd, iov->iov_base, iov->iov_len,
 				     fstream->buffer_offset);
 		}
 	} else {
-		if (o_stream_lseek(fstream) < 0)
+		if (o_stream_lseek(fstream) < 0) {
+			*error_r = t_strdup(o_stream_get_error(&fstream->ostream.ostream));
 			return -1;
+		}
 
+		syscall = "writev";
 		sent = 0;
 		while (iov_count > IOV_MAX) {
 			size = 0;
@@ -211,6 +218,10 @@ ssize_t o_stream_file_writev(struct file_ostream *fstream,
 			ret = sent;
 		}
 	}
+	if (ret < 0) {
+		i_assert(syscall != NULL);
+		*error_r = t_strdup_printf("%s() failed: %m", syscall);
+	}
 	return ret;
 }
 
@@ -219,6 +230,7 @@ o_stream_file_writev_full(struct file_ostream *fstream,
 				   const struct const_iovec *iov,
 				   unsigned int iov_count)
 {
+	const char *error = NULL;
 	ssize_t ret, ret2;
 	size_t size, total_size;
 	bool partial;
@@ -228,10 +240,11 @@ o_stream_file_writev_full(struct file_ostream *fstream,
 		total_size += iov[i].iov_len;
 
 	o_stream_socket_cork(fstream);
-	ret = fstream->writev(fstream, iov, iov_count);
+	ret = fstream->writev(fstream, iov, iov_count, &error);
 	partial = ret != (ssize_t)total_size;
 
 	if (ret < 0) {
+		i_assert(error != NULL);
 		if (fstream->file) {
 			if (errno == EINTR) {
 				/* automatically retry */
@@ -241,6 +254,7 @@ o_stream_file_writev_full(struct file_ostream *fstream,
 			/* try again later */
 			return 0;
 		}
+		io_stream_set_error(&fstream->ostream.iostream, "%s", error);
 		fstream->ostream.ostream.stream_errno = errno;
 		stream_closed(fstream);
 		return -1;
diff --git a/src/lib/ostream-unix.c b/src/lib/ostream-unix.c
index 279913549a..1d12baacb2 100644
--- a/src/lib/ostream-unix.c
+++ b/src/lib/ostream-unix.c
@@ -17,8 +17,9 @@ o_stream_unix_close(struct iostream_private *stream, bool close_parent)
 }
 
 static ssize_t o_stream_unix_writev(struct file_ostream *fstream,
-				   const struct const_iovec *iov,
-				   unsigned int iov_count)
+				    const struct const_iovec *iov,
+				    unsigned int iov_count,
+				    const char **error_r)
 {
 	struct unix_ostream *ustream =
 		container_of(fstream, struct unix_ostream, fstream);
@@ -27,7 +28,7 @@ static ssize_t o_stream_unix_writev(struct file_ostream *fstream,
 
 	if (ustream->write_fd == -1) {
 		/* no fd */
-		return o_stream_file_writev(fstream, iov, iov_count);
+		return o_stream_file_writev(fstream, iov, iov_count, error_r);
 	}
 
 	/* send first iovec along with fd */
@@ -36,8 +37,10 @@ static ssize_t o_stream_unix_writev(struct file_ostream *fstream,
 	i_assert(iov[0].iov_len > 0);
 	ret = fd_send(fstream->fd, ustream->write_fd,
 		iov[0].iov_base, iov[0].iov_len);
-	if (ret < 0)
+	if (ret < 0) {
+		*error_r = t_strdup_printf("fd_send() failed: %m");
 		return ret;
+	}
 
 	/* update stream */
 	sent = ret;
@@ -51,7 +54,7 @@ static ssize_t o_stream_unix_writev(struct file_ostream *fstream,
 	}
 
 	/* send remaining iovecs */
-	ret = o_stream_file_writev(fstream, &iov[1], iov_count-1);
+	ret = o_stream_file_writev(fstream, &iov[1], iov_count-1, error_r);
 	if (ret < 0)
 		return  (errno == EAGAIN || errno == EINTR ? (ssize_t)sent : ret);
 	sent += ret;