Support hex-string input and output for type BYTEA.

Both hex format and the traditional "escape" format are automatically
handled on input.  The output format is selected by the new GUC variable
bytea_output.

As committed, bytea_output defaults to HEX, which is an *incompatible
change*.  We will keep it this way for awhile for testing purposes, but
should consider whether to switch to the more backwards-compatible
default of ESCAPE before 8.5 is released.

Peter Eisentraut

1 files changed, 59 insertions, 1 deletions

diff --git a/src/interfaces/libpq/fe-exec.c b/src/interfaces/libpq/fe-exec.c
index c00f5eae6ab..f1318a4a942 100644
--- a/src/interfaces/libpq/fe-exec.c
+++ b/src/interfaces/libpq/fe-exec.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-exec.c,v 1.203 2009/06/11 14:49:13 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/interfaces/libpq/fe-exec.c,v 1.204 2009/08/04 16:08:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3167,6 +3167,29 @@ PQescapeBytea(const unsigned char *from, size_t from_length, size_t *to_length)
 }
 
 
+static const int8 hexlookup[128] = {
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
+	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
+};
+
+static inline char
+get_hex(char c)
+{
+	int			res = -1;
+
+	if (c > 0 && c < 127)
+		res = hexlookup[(unsigned char) c];
+
+	return (char) res;
+}
+
+
 #define ISFIRSTOCTDIGIT(CH) ((CH) >= '0' && (CH) <= '3')
 #define ISOCTDIGIT(CH) ((CH) >= '0' && (CH) <= '7')
 #define OCTVAL(CH) ((CH) - '0')
@@ -3198,6 +3221,40 @@ PQunescapeBytea(const unsigned char *strtext, size_t *retbuflen)
 
 	strtextlen = strlen((const char *) strtext);
 
+	if (strtext[0] == '\\' && strtext[1] == 'x')
+	{
+		const unsigned char *s;
+		unsigned char	*p;
+
+		buflen = (strtextlen - 2)/2;
+		/* Avoid unportable malloc(0) */
+		buffer = (unsigned char *) malloc(buflen > 0 ? buflen : 1);
+		if (buffer == NULL)
+			return NULL;
+
+		s = strtext + 2;
+		p = buffer;
+		while (*s)
+		{
+			char	v1,
+					v2;
+
+			/*
+			 * Bad input is silently ignored.  Note that this includes
+			 * whitespace between hex pairs, which is allowed by byteain.
+			 */
+			v1 = get_hex(*s++);
+			if (!*s || v1 == (char) -1)
+				continue;
+			v2 = get_hex(*s++);
+			if (v2 != (char) -1)
+				*p++ = (v1 << 4) | v2;
+		}
+
+		buflen = p - buffer;
+	}
+	else
+	{
 	/*
 	 * Length of input is max length of output, but add one to avoid
 	 * unportable malloc(0) if input is zero-length.
@@ -3244,6 +3301,7 @@ PQunescapeBytea(const unsigned char *strtext, size_t *retbuflen)
 		}
 	}
 	buflen = j;					/* buflen is the length of the dequoted data */
+	}
 
 	/* Shrink the buffer to be no larger than necessary */
 	/* +1 avoids unportable behavior when buflen==0 */