Adding switch_mprintf (broken out from sqlite)

Adding new %w to mprintf to auto escape both single quote and backslashes
Improve the tab completion a tad and fix some sqlite/odbc compat with new mprintf opts
Change the default stream writer to use switch_vmprintf so %q/%w can be used there too



git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@15875 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/include/switch_mprintf.h

@@ -0,0 +1,63 @@
+/*
+** 2001 September 22
+**
+** The author disclaims copyright to this source code.  In place of
+** a legal notice, here is a blessing:
+**
+**    May you do good and not evil.
+**    May you find forgiveness for yourself and forgive others.
+**    May you share freely, never taking more than you give.
+**
+*************************************************************************
+*/
+#ifndef SWITCH_MPRINTF_H
+#define SWITCH_MPRINTF_H
+
+SWITCH_BEGIN_EXTERN_C
+
+/**
+ * This routine is a variant of the "sprintf()" from the
+ * standard C library.  The resulting string is written into memory
+ * obtained from malloc() so that there is never a possiblity of buffer
+ * overflow.  This routine also implement some additional formatting
+ * options that are useful for constructing SQL statements.
+ *
+ * The strings returned by this routine should be freed by calling
+ * switch_core_db_free().
+ *
+ * All of the usual printf formatting options apply.  In addition, there
+ * is a "%q" option.  %q works like %s in that it substitutes a null-terminated
+ * string from the argument list.  But %q also doubles every '\'' character.
+ * %q is designed for use inside a string literal.  By doubling each '\''
+ * character it escapes that character and allows it to be inserted into
+ * the string.
+ *
+ * For example, so some string variable contains text as follows:
+ *
+ *      char *zText = "It's a happy day!";
+ *
+ * We can use this text in an SQL statement as follows:
+ *
+ *      char *z = switch_core_db_mprintf("INSERT INTO TABLES('%q')", zText);
+ *      switch_core_db_exec(db, z, callback1, 0, 0);
+ *      switch_core_db_free(z);
+ *
+ * Because the %q format string is used, the '\'' character in zText
+ * is escaped and the SQL generated is as follows:
+ *
+ *      INSERT INTO table1 VALUES('It''s a happy day!')
+ *
+ * This is correct.  Had we used %s instead of %q, the generated SQL
+ * would have looked like this:
+ *
+ *      INSERT INTO table1 VALUES('It's a happy day!');
+ *
+ * This second example is an SQL syntax error.  As a general rule you
+ * should always use %q instead of %s when inserting text into a string
+ * literal.
+ */
+SWITCH_DECLARE(char *) switch_mprintf(const char *zFormat, ...);
+SWITCH_DECLARE(char *) switch_vmprintf(const char *zFormat, va_list ap);
+
+SWITCH_END_EXTERN_C
+#endif /* SWITCH_MPRINTF_H */