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List:       postgresql-general
Subject:    [HACKERS] PQprintf
From:       Adam Siegel <adam () sycamorehq ! com>
Date:       2002-02-28 17:23:58
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I have developed a function to help me with escaping strings more easily.  
It kind of behaves like printf and is very crude.  Before I do anymore
work, I was hoping to get some comments or notice if someone has already
done this.

I was also thinking there could be a function call PQprintfExec that would
build the sql from the printf and call PQexec in one step.

Comments Please!

Regards, 
Adam


/*
 * PQprintf
 *
 * This function acts kind of like printf.  It takes care of escaping
 * strings and bytea for you, then runs PQexec.  The format string
 * defintion is as follows:
 *
 *   %i = integer
 *   %f = float
 *   %s = normal string
 *   %e = escape the string
 *   %b = escape the bytea
 * 
 * When you use %b, you must add another argument just after the
 * variable holding the binary data with its length.
 *
 */
char *
PQprintf(const char *format, ...)
{
     va_list arg;
     char *sql = NULL;
     char *parse = (char*)strdup(format);
     char *p;
     char buff[256];
     char *str;
     char *to;
     size_t length;
     size_t size;
     size_t esize;
     char* s_arg;
     float f_arg;
     int i_arg;
     int i;

     va_start(arg, format);

     p = (char*)strtok(parse, "%");
     sql = (char*)strdup(p);
     size = strlen(sql);

     while (p)
     {
	  if ((p = (char*)strtok(NULL, "%")))
	  {
	       switch (*p) 
	       {
		    /* integer */
	       case 'i':
		    i_arg = va_arg(arg, int);
		    sprintf(buff, "%i", i_arg);
		    size += strlen(buff);
		    sql = (char*)realloc(sql, size + 1);
		    strcat(sql, buff);
		    break;

		    /* float */
	       case 'f':
		    f_arg = va_arg(arg, float);
		    sprintf(buff, "%f", f_arg);
		    size += strlen(buff);
		    sql = (char*)realloc(sql, size + 1);
		    strcat(sql, buff);
		    break;

		    /* string */
	       case 's':
		    s_arg = va_arg(arg, char*);
		    puts(s_arg);
		    size += strlen(s_arg);
		    sql = (char*)realloc(sql, size + 1);
		    strcat(sql, s_arg);
		    break;

		    /* escape string */
	       case 'e':
		    s_arg = va_arg(arg, char*);
		    to = (char*)malloc((2 * strlen(s_arg)) + 1);
		    PQescapeString(to, s_arg, strlen(s_arg));
		    size += strlen(to);
		    sql = (char*)realloc(sql, size + 1);
		    strcat(sql, to);
		    free(to);
		    break;

		    /* escape bytea */
	       case 'b':
		    s_arg = va_arg(arg, char*);
		    length = va_arg(arg, int);
		    str = PQescapeBytea(s_arg, length, &esize);
		    size += esize;
		    sql = (char*)realloc(sql, size + 1);
		    strcat(sql, str);
		    free(str);
		    break;
	       }

	       size += strlen(++p);
	       sql = (char*)realloc(sql, size + 1);
	       strcat(sql, p);
	  }
     }

     va_end(arg);

     free(parse);

     return sql;
}




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