- Move most of the I/O in both libpq and the backend to a set

of common routines in pqcomprim.c (pq communication primitives).
    Not all adapted to it yet, but it's a start.

  - Rewritten some of those routines, to write/read bigger chunks of
    data, precomputing stuff in buffers instead of sending out byte
    by byte.

  - As a consequence, I need to know the endianness of the machine.
    Currently I rely on getting it from machine/endian.h, but this
    may not be available everywhere? (Who the hell thought it was
    a good idea to pass integers to the backend the other way around
    than the normal network byte order? *argl*)

  - Libpq looks in the environment for magic variables, and upon
    establishing a connection to the backend, sends it queries
    of the form "SET var_name TO 'var_value'". This needs a change
    in the backend parser (Mr. Parser, are you there? :)

  - Currently it looks for two Env-Vars, namely PG_DATEFORMAT
    and PG_FLOATFORMAT. What else makes sense? PG_TIMEFORMAT?
    PG_TIMEZONE?

From: "Martin J. Laubach" <mjl@wwx.vip.at>

src/backend/libpq/pqcomprim.c

@@ -27,6 +27,164 @@
 #error Please write byte order macros
 #endif
 
+/* --------------------------------------------------------------------- */
+int pqPutShort(const int integer, FILE *f)
+    {
+    int retval = 0;
+    u_short n;
+		
+    n = hton_s(integer);
+    if(fwrite(&n, sizeof(u_short), 1, f) != 1)
+    	retval = EOF;
+    
+    return retval;
+    }
+
+/* --------------------------------------------------------------------- */
+int pqPutLong(const int integer, FILE *f)
+    {
+    int retval = 0;
+    u_long n;
+		
+    n = hton_l(integer);
+    if(fwrite(&n, sizeof(u_long), 1, f) != 1)
+    	retval = EOF;
+    
+    return retval;
+    }
+    
+/* --------------------------------------------------------------------- */
+int pqGetShort(int *result, FILE *f)
+    {
+    int retval = 0;
+    u_short n;
+
+    if(fread(&n, sizeof(u_short), 1, f) != 1)
+    	retval = EOF;
+			
+    *result = ntoh_s(n);
+    return retval;
+    }
+
+/* --------------------------------------------------------------------- */
+int pqGetLong(int *result, FILE *f)
+    {
+    int retval = 0;
+    u_long n;
+		
+    if(fread(&n, sizeof(u_long), 1, f) != 1)
+    	retval = EOF;
+			
+    *result = ntoh_l(n);
+    return retval;
+    }
+
+/* --------------------------------------------------------------------- */
+/* pqGetNBytes: Read a chunk of exactly len bytes in buffer s.
+	Return 0 if ok.
+*/
+int pqGetNBytes(char* s, const int len, FILE *f)
+	{
+	int cnt;
+
+	if (f == NULL)
+		return EOF;
+  
+	cnt = fread(s, 1, len, f);
+	s[cnt] = '\0';
+   /* mjl: actually needs up to len+1 bytes, is this okay? XXX */
+
+	return (cnt == len) ? 0 : EOF;
+	}
+
+/* --------------------------------------------------------------------- */
+int pqPutNBytes(const char *s, const int len, FILE *f)
+	{    
+	if (f == NULL)
+		return 0;
+
+   if(fwrite(s, 1, len, f) != len)
+	    return EOF;
+
+	return 0;
+	}
+	
+/* --------------------------------------------------------------------- */
+int pqGetString(char *s, int len, FILE *f)
+	{
+	int c;
+
+	if (f == NULL)
+	return EOF;
+  
+	while (len-- && (c = getc(f)) != EOF && c)
+		*s++ = c;
+	*s = '\0';
+   /* mjl: actually needs up to len+1 bytes, is this okay? XXX */
+
+	return 0;
+	}
+
+/* --------------------------------------------------------------------- */
+int pqPutString(const char *s, FILE *f)
+	{
+	if (f == NULL)
+		return 0;
+  
+	if (fputs(s, f) == EOF)
+		return EOF;
+
+	fputc('\0', f); /* important to send an ending \0 since backend expects it */
+	fflush(f);
+
+	return 0;
+	}
+
+/* --------------------------------------------------------------------- */
+int pqGetByte(FILE *f)
+	{
+	return getc(f);
+	}
+	
+/* --------------------------------------------------------------------- */
+int pqPutByte(const int c, FILE *f)
+	{
+	if(!f)	return 0;
+	
+	return (putc(c, f) == c) ? 0 : EOF;
+	}
+	
+/* --------------------------------------------------------------------- */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "postgres.h"
+#include "libpq/pqcomm.h"
+
+/* --------------------------------------------------------------------- */
+/* Is the other way around than system ntoh/hton, so we roll our own
+	here */
+	
+#if BYTE_ORDER == LITTLE_ENDIAN
+#define ntoh_s(n) n
+#define ntoh_l(n) n
+#define hton_s(n) n
+#define hton_l(n) n
+#endif
+#if BYTE_ORDER == BIG_ENDIAN
+#define ntoh_s(n) (u_short)(((u_char *) &n)[0] << 8 | ((u_char *) &n)[1]);
+#define ntoh_l(n) (u_long)(((u_char *)&n)[0] << 24 | ((u_char *)&n)[1] << 16 |\
+      	             	   ((u_char *)&n)[2] << 8 | ((u_char *)&n)[3]);
+#define hton_s(n) (ntoh_s(n))
+#define hton_l(n) (ntoh_l(n))
+#endif
+#if BYTE_ORDER == PDP_ENDIAN
+#endif
+#ifndef ntoh_s
+#error Please write byte order macros
+#endif
+
 /* --------------------------------------------------------------------- */
 int pqPutShort(const int integer, FILE *f)
     {