From 003590672f8f6bd768611f866866c30767bd0449 Mon Sep 17 00:00:00 2001
From: Bron Gondwana <brong@fastmail.fm>
Date: Thu, 21 May 2009 13:59:54 +1000
Subject: [PATCH] Rewrite zlib inflate handling

Use a single fixed-size buffer, and return to "inflate"
again for further data rather than resizing the output
buffer.
---
 lib/prot.c |  119 +++++++++++++++++++++++++++++-------------------------------
 lib/prot.h |    1 -
 2 files changed, 57 insertions(+), 63 deletions(-)

diff --git a/lib/prot.c b/lib/prot.c
index 5261f75..331b767 100644
--- a/lib/prot.c
+++ b/lib/prot.c
@@ -94,7 +94,6 @@ int write;
     newstream = (struct protstream *) xzmalloc(sizeof(struct protstream));
     newstream->buf = (unsigned char *) 
 	xmalloc(sizeof(char) * (PROT_BUFSIZE));
-    newstream->buf_size = PROT_BUFSIZE;
     newstream->ptr = newstream->buf;
     newstream->maxplain = PROT_BUFSIZE;
     newstream->fd = fd;
@@ -106,6 +105,10 @@ int write;
 
     newstream->bytes_in = 0;
     newstream->bytes_out = 0;
+#ifdef HAVE_ZLIB
+    newstream->zbuf = 0;
+    newstream->zbuf_size = 0;
+#endif
 
     return newstream;
 }
@@ -275,7 +278,7 @@ static void zfree(voidpf opaque __attribute__((unused)),
 
 /*
  * Turn on (de)compression for this connection
- * If its an output stream, initialize a compressor,
+ * If its an output stream, iOnitialize a compressor,
  * otherwise initialize a decompressor.
  */
 
@@ -520,6 +523,32 @@ int prot_fill(struct protstream *s)
     if (s->eof || s->error) return EOF;
 
     do {
+#ifdef HAVE_ZLIB
+	/* check if there's anything in the zlib buffer already */
+	if (s->zstrm && s->zstrm->avail_in) {
+	    int zr;
+	    if (!s->zbuf)
+		s->zbuf = (unsigned char *)xmalloc(sizeof(char) * (PROT_BUFSIZE));
+	    s->zstrm->next_out = s->zbuf;
+	    s->zstrm->avail_out = PROT_BUFSIZE;
+	    zr = inflate(s->zstrm, Z_SYNC_FLUSH);
+	    if (zr != Z_OK) {
+		/* Error decompressing */
+		syslog(LOG_ERR, "zlib error: %d %s", zr, s->zstrm->msg);
+		s->error = xstrdup("Error decompressing data");
+		return EOF;
+	    }
+
+	    if (s->zstrm->avail_out < PROT_BUFSIZE) {
+		/* inflated some data */
+		s->ptr = s->zbuf;
+		s->cnt = PROT_BUFSIZE - s->zstrm->avail_out;
+		syslog(LOG_DEBUG, "   => decompressed to %d bytes", s->cnt);
+		break;
+	    }
+	}
+#endif
+
 	/* wait until get input */
 	haveinput = 0;
 
@@ -640,75 +669,41 @@ int prot_fill(struct protstream *s)
 	}
 
 #ifdef HAVE_ZLIB
-	if (s->zstrm && s->cnt > 0) {
-	    /* Decompress the data */
-	    int zr = Z_OK;
+	if (s->zstrm) {
+	    /* transfer the stream to the input of the z_stream and loop */
 
 	    s->zstrm->next_in = s->ptr;
 	    s->zstrm->avail_in = s->cnt;
-	    s->zstrm->next_out = s->zbuf;
-	    s->zstrm->avail_out = s->zbuf_size;
-
-	    syslog(LOG_DEBUG, "inflate(%d bytes)", s->cnt);
+	    s->cnt = 0;
+	}
+#endif /* HAVE_ZLIB */
+    } while (!s->cnt);
 
-	    do {
-		if (!s->zstrm->avail_out) {
-		    /* Need more space to decompress */
-		    syslog(LOG_DEBUG,
-			   "growing decompress buffer from %d to %d bytes",
-			   s->zbuf_size, s->zbuf_size + PROT_BUFSIZE);
-
-		    s->zbuf = (unsigned char *)
-			xrealloc(s->zbuf, s->zbuf_size + PROT_BUFSIZE);
-		    s->zstrm->next_out = s->zbuf + s->zbuf_size;
-		    s->zstrm->avail_out = PROT_BUFSIZE;
-		    s->zbuf_size += PROT_BUFSIZE;
-		}
+    if (s->logfd != -1) {
+	time_t newtime;
+	char timebuf[20];
 
-		zr = inflate(s->zstrm, Z_SYNC_FLUSH);
-	    } while (zr == Z_OK && !s->zstrm->avail_out);
+	time(&newtime);
+	snprintf(timebuf, sizeof(timebuf), "<%ld<", newtime);
+	write(s->logfd, timebuf, strlen(timebuf));
 
-	    if (zr != Z_OK || s->zstrm->avail_in) {
-		/* Error decompressing */
-		s->error = xstrdup("Error decompressing data");
-		return EOF;
+	left = s->cnt;
+	ptr = s->ptr;
+	do {
+	    n = write(s->logfd, ptr, left);
+	    if (n == -1 && (errno != EINTR || signals_poll())) {
+		break;
 	    }
-
-	    s->ptr = s->zbuf;
-	    s->cnt = s->zbuf_size - s->zstrm->avail_out;
-
-	    syslog(LOG_DEBUG, "   => decompressed to %d bytes", s->cnt);
-	}
-#endif /* HAVE_ZLIB */
-	
-	if (s->cnt > 0) {
-	    if (s->logfd != -1) {
-		time_t newtime;
-		char timebuf[20];
-
-		time(&newtime);
-		snprintf(timebuf, sizeof(timebuf), "<%ld<", newtime);
-		write(s->logfd, timebuf, strlen(timebuf));
-
-		left = s->cnt;
-		ptr = s->ptr;
-		do {
-		    n = write(s->logfd, ptr, left);
-		    if (n == -1 && (errno != EINTR || signals_poll())) {
-			break;
-		    }
-		    if (n > 0) {
-			ptr += n;
-			left -= n;
-		    }
-		} while (left);
+	    if (n > 0) {
+		ptr += n;
+		left -= n;
 	    }
+	} while (left);
+    }
 
-	    s->cnt--;		/* we return the first char */
-	    s->bytes_in++;
-	    return *s->ptr++;
-	}
-    } while (1);
+    s->cnt--;		/* we return the first char */
+    s->bytes_in++;
+    return *s->ptr++;
 }
 
 /*
diff --git a/lib/prot.h b/lib/prot.h
index 17109f3..2d9688f 100644
--- a/lib/prot.h
+++ b/lib/prot.h
@@ -73,7 +73,6 @@ typedef void prot_readcallback_t(struct protstream *s, void *rock);
 struct protstream {
     /* The Buffer */
     unsigned char *buf;
-    unsigned buf_size;
     unsigned char *ptr; /* The end of data in the buffer */
     unsigned cnt; /* Space Remaining in buffer */
 
-- 
1.5.6.5