Fix pg_ctl's readfile() to not go into infinite loop on an empty file

(could happen if either postgresql.conf or postmaster.opts is empty).
It's been broken since the C version was written for 8.0, so patch
all the way back.

initdb's copy of the function is broken in the same way, but it's
less important there since the input files should never be empty.
Patch that in HEAD only, and also fix some cosmetic differences that
crept into that copy of the function.

Per report from Corry Haines and Jeff Davis.

src/bin/initdb/initdb.c

@@ -42,7 +42,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  * Portions taken from FreeBSD.
  *
- * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.173 2009/09/01 02:54:52 alvherre Exp $
+ * $PostgreSQL: pgsql/src/bin/initdb/initdb.c,v 1.174 2009/09/02 02:40:52 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -149,7 +149,7 @@ static char **replace_token(char **lines,
 #ifndef HAVE_UNIX_SOCKETS
 static char **filter_lines_with_token(char **lines, const char *token);
 #endif
-static char **readfile(char *path);
+static char **readfile(const char *path);
 static void writefile(char *path, char **lines);
 static FILE *popen_check(const char *command, const char *mode);
 static int	mkdir_p(char *path, mode_t omode);
@@ -362,10 +362,10 @@ filter_lines_with_token(char **lines, const char *token)
  * get the lines from a text file
  */
 static char **
-readfile(char *path)
+readfile(const char *path)
 {
 	FILE	   *infile;
-	int			maxlength = 0,
+	int			maxlength = 1,
 				linelen = 0;
 	int			nlines = 0;
 	char	  **result;
@@ -394,26 +394,20 @@ readfile(char *path)
 	}
 
 	/* handle last line without a terminating newline (yuck) */
-
 	if (linelen)
 		nlines++;
 	if (linelen > maxlength)
 		maxlength = linelen;
 
 	/* set up the result and the line buffer */
-
-	result = (char **) pg_malloc((nlines + 2) * sizeof(char *));
-	buffer = (char *) pg_malloc(maxlength + 2);
+	result = (char **) pg_malloc((nlines + 1) * sizeof(char *));
+	buffer = (char *) pg_malloc(maxlength + 1);
 
 	/* now reprocess the file and store the lines */
-
 	rewind(infile);
 	nlines = 0;
 	while (fgets(buffer, maxlength + 1, infile) != NULL)
-	{
-		result[nlines] = xstrdup(buffer);
-		nlines++;
-	}
+		result[nlines++] = xstrdup(buffer);
 
 	fclose(infile);
 	free(buffer);

src/bin/pg_ctl/pg_ctl.c

@@ -4,7 +4,7 @@
  *
  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/bin/pg_ctl/pg_ctl.c,v 1.112 2009/08/27 16:59:38 tgl Exp $
+ * $PostgreSQL: pgsql/src/bin/pg_ctl/pg_ctl.c,v 1.113 2009/09/02 02:40:52 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -292,7 +292,7 @@ static char **
 readfile(const char *path)
 {
 	FILE	   *infile;
-	int			maxlength = 0,
+	int			maxlength = 1,
 				linelen = 0;
 	int			nlines = 0;
 	char	  **result;