Fix pg_restore to do the right thing when escaping large objects.

Specifically, this makes the workflow pg_dump -Fc -> pg_restore -> file
produce correct output for BLOBs when the source database has
standard_conforming_strings turned on.  It was already okay when that was
off, or if pg_restore was told to restore directly into a database.

This is a back-port of commit b1732111f2 of
2009-08-04, with additional changes to emit old-style escaped bytea data
instead of hex-style.  At the time, we had not heard of anyone encountering
the problem in the field, so I judged it not worth the risk of changing
back branches.  Now we do have a report, from Bosco Rama, so back-patch
into 8.2 through 8.4.  9.0 and up are okay already.

src/bin/pg_dump/dumputils.c

@@ -323,6 +323,84 @@ appendStringLiteralDQ(PQExpBuffer buf, const char *str, const char *dqprefix)
 }
 
 
+/*
+ * Convert a bytea value (presented as raw bytes) to an SQL string literal
+ * and append it to the given buffer.  We assume the specified
+ * standard_conforming_strings setting.
+ *
+ * This is needed in situations where we do not have a PGconn available.
+ * Where we do, PQescapeByteaConn is a better choice.
+ */
+void
+appendByteaLiteral(PQExpBuffer buf, const unsigned char *str, size_t length,
+				   bool std_strings)
+{
+	const unsigned char *vp;
+	unsigned char *rp;
+	size_t		i;
+	size_t		len;
+	size_t		bslash_len = (std_strings ? 1 : 2);
+
+	len = 2;					/* for the quote marks */
+	vp = str;
+	for (i = length; i > 0; i--, vp++)
+	{
+		if (*vp < 0x20 || *vp > 0x7e)
+			len += bslash_len + 3;
+		else if (*vp == '\'')
+			len += 2;
+		else if (*vp == '\\')
+			len += bslash_len + bslash_len;
+		else
+			len++;
+	}
+
+	if (!enlargePQExpBuffer(buf, len))
+		return;
+
+	rp = (unsigned char *) (buf->data + buf->len);
+	*rp++ = '\'';
+
+	vp = str;
+	for (i = length; i > 0; i--, vp++)
+	{
+		if (*vp < 0x20 || *vp > 0x7e)
+		{
+			int			val = *vp;
+
+			if (!std_strings)
+				*rp++ = '\\';
+			*rp++ = '\\';
+			*rp++ = (val >> 6) + '0';
+			*rp++ = ((val >> 3) & 07) + '0';
+			*rp++ = (val & 07) + '0';
+		}
+		else if (*vp == '\'')
+		{
+			*rp++ = '\'';
+			*rp++ = '\'';
+		}
+		else if (*vp == '\\')
+		{
+			if (!std_strings)
+			{
+				*rp++ = '\\';
+				*rp++ = '\\';
+			}
+			*rp++ = '\\';
+			*rp++ = '\\';
+		}
+		else
+			*rp++ = *vp;
+	}
+
+	*rp++ = '\'';
+	*rp = '\0';
+
+	buf->len = ((char *) rp) - buf->data;
+}
+
+
 /*
  * Convert backend's version string into a number.
  */

src/bin/pg_dump/dumputils.h

@@ -27,6 +27,9 @@ extern void appendStringLiteralConn(PQExpBuffer buf, const char *str,
 						PGconn *conn);
 extern void appendStringLiteralDQ(PQExpBuffer buf, const char *str,
 					  const char *dqprefix);
+extern void appendByteaLiteral(PQExpBuffer buf,
+							   const unsigned char *str, size_t length,
+							   bool std_strings);
 extern int	parse_version(const char *versionString);
 extern bool parsePGArray(const char *atext, char ***itemarray, int *nitems);
 extern bool buildACLCommands(const char *name, const char *subname,

src/bin/pg_dump/pg_backup_archiver.c

@@ -1252,20 +1252,19 @@ dump_lo_buf(ArchiveHandle *AH)
 	}
 	else
 	{
-		unsigned char *str;
-		size_t		len;
+		PQExpBuffer buf = createPQExpBuffer();
 
-		str = PQescapeBytea((const unsigned char *) AH->lo_buf,
-							AH->lo_buf_used, &len);
-		if (!str)
-			die_horribly(AH, modulename, "out of memory\n");
+		appendByteaLiteralAHX(buf,
+							  (const unsigned char *) AH->lo_buf,
+							  AH->lo_buf_used,
+							  AH);
 
 		/* Hack: turn off writingBlob so ahwrite doesn't recurse to here */
 		AH->writingBlob = 0;
-		ahprintf(AH, "SELECT lowrite(0, '%s');\n", str);
+		ahprintf(AH, "SELECT pg_catalog.lowrite(0, %s);\n", buf->data);
 		AH->writingBlob = 1;
 
-		free(str);
+		destroyPQExpBuffer(buf);
 	}
 	AH->lo_buf_used = 0;
 }

src/bin/pg_dump/pg_backup_archiver.h

@@ -342,6 +342,9 @@ extern bool checkSeek(FILE *fp);
 #define appendStringLiteralAHX(buf,str,AH) \
 	appendStringLiteral(buf, str, (AH)->public.encoding, (AH)->public.std_strings)
 
+#define appendByteaLiteralAHX(buf,str,len,AH) \
+	appendByteaLiteral(buf, str, len, (AH)->public.std_strings)
+
 /*
  * Mandatory routines for each supported format
  */

src/bin/pg_dump/pg_backup_null.c

@@ -23,6 +23,7 @@
  */
 
 #include "pg_backup_archiver.h"
+#include "dumputils.h"
 
 #include <unistd.h>				/* for dup */
 
@@ -101,16 +102,16 @@ _WriteBlobData(ArchiveHandle *AH, const void *data, size_t dLen)
 {
 	if (dLen > 0)
 	{
-		unsigned char *str;
-		size_t		len;
+		PQExpBuffer buf = createPQExpBuffer();
 
-		str = PQescapeBytea((const unsigned char *) data, dLen, &len);
-		if (!str)
-			die_horribly(AH, NULL, "out of memory\n");
+		appendByteaLiteralAHX(buf,
+							  (const unsigned char *) data,
+							  dLen,
+							  AH);
 
-		ahprintf(AH, "SELECT lowrite(0, '%s');\n", str);
+		ahprintf(AH, "SELECT pg_catalog.lowrite(0, %s);\n", buf->data);
 
-		free(str);
+		destroyPQExpBuffer(buf);
 	}
 	return dLen;
 }