[PATCH] Flush buffers also where there are exactly 0 bytes left

From 36a615d278769a2678446dc4977b77147e6ee1c2 Mon Sep 17 00:00:00 2001 From: Krzysztof Piotr Oledzki <ole#ans.pl> Date: Sun, 20 Apr 2008 21:34:47 +0200
Subject: [BUG] Flush buffers also where there are exactly 0 bytes left

I noticed it was possible to get truncated http/csv stats. Sometimes. Usually the problem disappeared as fast as it appeared, but once it happend that my http-stats page was truncated for about one hour. It was quite weird as it happened independently for csv and http output and it took me some time to track & fix this bug.

Both buffer_write & buffer_write_chunk used to return 0 in two situations: is case of success or where there was exactly 0 bytes left. The first one is intentional but I believe the second one is not as it was not possible to distinguish between successful write and unsuccessful one, which means that if the buffer was 100% filled, it was never flushed and it was not possible to write more data.

This patch fixes this problem.

---
 src/buffers.c   |   12 +++++++-----
 src/dumpstats.c |   20 ++++++++++----------
 2 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/src/buffers.c b/src/buffers.c
index 8b2c4d3..fa6b8a9 100644
--- a/src/buffers.c
+++ b/src/buffers.c


@@ -29,7 +29,7 @@ int init_buffer()

 }
 
 
-/* writes <len> bytes from message <msg> to buffer <buf>. Returns 0 in case of
+/* writes <len> bytes from message <msg> to buffer <buf>. Returns -1 in case of
  * success, or the number of bytes available otherwise.
  * FIXME-20060521: handle unaligned data.
  */


@@ -48,10 +48,11 @@ int buffer_write(struct buffer *buf, const char *msg, int len)

 	buf->total += len;
 	if (buf->r == buf->data + BUFSIZE)
 		buf->r = buf->data;
-	return 0;
+
+	return -1;
 }
 
-/* writes the chunk <chunk> to buffer <buf>. Returns 0 in case of
+/* writes the chunk <chunk> to buffer <buf>. Returns -1 in case of
  * success, or the number of bytes available otherwise. If the chunk
  * has been written, its size is automatically reset to zero.
  */


@@ -60,7 +61,7 @@ int buffer_write_chunk(struct buffer *buf, struct chunk *chunk)

 	int max;
 
 	if (chunk->len == 0)
-		return 0;
+		return -1;
 
 	max = buffer_realign(buf);
 


@@ -74,7 +75,8 @@ int buffer_write_chunk(struct buffer *buf, struct chunk *chunk)

 	if (buf->r == buf->data + BUFSIZE)
 		buf->r = buf->data;
 	chunk->len = 0;
-	return 0;
+
+	return -1;
 }
 
 /*
diff --git a/src/dumpstats.c b/src/dumpstats.c
index a9fb84d..ddadddd 100644
--- a/src/dumpstats.c
+++ b/src/dumpstats.c


@@ -204,7 +204,7 @@ int stats_dump_raw(struct session *s, struct uri_auth *uri)

 	case DATA_ST_HEAD:
 		if (s->data_ctx.stats.flags & STAT_SHOW_STAT) {
 			print_csv_header(&msg, sizeof(trash));
-			if (buffer_write_chunk(rep, &msg) != 0)
+			if (buffer_write_chunk(rep, &msg) >= 0)
 				return 0;
 		}
 


@@ -240,7 +240,7 @@ int stats_dump_raw(struct session *s, struct uri_auth *uri)

 				     global.maxconn,
 				     actconn
 				     );
-			if (buffer_write_chunk(rep, &msg) != 0)
+			if (buffer_write_chunk(rep, &msg) >= 0)
 				return 0;
 		}
 


@@ -422,7 +422,7 @@ int stats_dump_http(struct session *s, struct uri_auth *uri)

 		} else {
 			print_csv_header(&msg, sizeof(trash));
 		}
-		if (buffer_write_chunk(rep, &msg) != 0)
+		if (buffer_write_chunk(rep, &msg) >= 0)
 			return 0;
 
 		s->data_state = DATA_ST_INFO;


@@ -532,7 +532,7 @@ int stats_dump_http(struct session *s, struct uri_auth *uri)

 			     ""
 			     );
 	    
-			if (buffer_write_chunk(rep, &msg) != 0)
+			if (buffer_write_chunk(rep, &msg) >= 0)
 				return 0;
 		}
 


@@ -561,7 +561,7 @@ int stats_dump_http(struct session *s, struct uri_auth *uri)

 	case DATA_ST_END:
 		if (!(s->data_ctx.stats.flags & STAT_FMT_CSV)) {
 			chunk_printf(&msg, sizeof(trash), "</body></html>\n");
-			if (buffer_write_chunk(rep, &msg) != 0)
+			if (buffer_write_chunk(rep, &msg) >= 0)
 				return 0;
 		}
 


@@ -656,7 +656,7 @@ int stats_dump_proxy(struct session *s, struct proxy *px, struct uri_auth *uri)

 				     "</tr>",
 				     px->id);
 
-			if (buffer_write_chunk(rep, &msg) != 0)
+			if (buffer_write_chunk(rep, &msg) >= 0)
 				return 0;
 		}
 


@@ -725,7 +725,7 @@ int stats_dump_proxy(struct session *s, struct proxy *px, struct uri_auth *uri)

 				     relative_pid, px->uuid, STATS_TYPE_FE);
 			}
 
-			if (buffer_write_chunk(rep, &msg) != 0)
+			if (buffer_write_chunk(rep, &msg) >= 0)
 				return 0;
 		}
 


@@ -942,7 +942,7 @@ int stats_dump_proxy(struct session *s, struct proxy *px, struct uri_auth *uri)

 				/* type, then EOL */
 				chunk_printf(&msg, sizeof(trash), "%d,\n", STATS_TYPE_SV);
 			}
-			if (buffer_write_chunk(rep, &msg) != 0)
+			if (buffer_write_chunk(rep, &msg) >= 0)
 				return 0;
 		} /* for sv */
 


@@ -1039,7 +1039,7 @@ int stats_dump_proxy(struct session *s, struct proxy *px, struct uri_auth *uri)

 				     relative_pid, px->uuid,
 				     px->cum_lbconn, STATS_TYPE_BE);
 			}
-			if (buffer_write_chunk(rep, &msg) != 0)
+			if (buffer_write_chunk(rep, &msg) >= 0)
 				return 0;
 		}
 		


@@ -1050,7 +1050,7 @@ int stats_dump_proxy(struct session *s, struct proxy *px, struct uri_auth *uri)

 		if (!(s->data_ctx.stats.flags & STAT_FMT_CSV)) {
 			chunk_printf(&msg, sizeof(trash), "</table><p>\n");
 
-			if (buffer_write_chunk(rep, &msg) != 0)
+			if (buffer_write_chunk(rep, &msg) >= 0)
 				return 0;
 		}
 
-- 
1.5.4.3