Function reportErrorPosition

src/interfaces/libpq/fe-protocol3.c:1353–1571

* Add an error-location display to the error message under construction. * * The cursor location is measured in logical characters; the query string * is presumed to be in the specified encoding. */

 * is presumed to be in the specified encoding.
 */
static void
reportErrorPosition(PQExpBuffer msg, const char *query, int loc, int encoding)
{
#define DISPLAY_SIZE	60		/* screen width limit, in screen cols */
#define MIN_RIGHT_CUT	10		/* try to keep this far away from EOL */

	char	   *wquery;
	int			slen,
				cno,
				i,
			   *qidx,
			   *scridx,
				qoffset,
				scroffset,
				ibeg,
				iend,
				loc_line;
	bool		mb_encoding,
				beg_trunc,
				end_trunc;

	/* Convert loc from 1-based to 0-based; no-op if out of range */
	loc--;
	if (loc < 0)
		return;

	/* Need a writable copy of the query */
	wquery = strdup(query);
	if (wquery == NULL)
		return;					/* fail silently if out of memory */

	/*
	 * Each character might occupy multiple physical bytes in the string, and
	 * in some Far Eastern character sets it might take more than one screen
	 * column as well.  We compute the starting byte offset and starting
	 * screen column of each logical character, and store these in qidx[] and
	 * scridx[] respectively.
	 */

	/* we need a safe allocation size... */
	slen = strlen(wquery) + 1;

	qidx = (int *) malloc(slen * sizeof(int));
	if (qidx == NULL)
	{
		free(wquery);
		return;
	}
	scridx = (int *) malloc(slen * sizeof(int));
	if (scridx == NULL)
	{
		free(qidx);
		free(wquery);
		return;
	}

	/* We can optimize a bit if it's a single-byte encoding */
	mb_encoding = (pg_encoding_max_length(encoding) != 1);