postgres/src/bin/psql/stringutils.c

#include <config.h>
#include <c.h>
#include "stringutils.h"

//#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
//#include <stdio.h>

#include <postgres.h>
#ifndef HAVE_STRDUP
#include <strdup.h>
#endif
#include <libpq-fe.h>



static void
unescape_quotes(char *source, char quote, char escape);


/*
 * Replacement for strtok() (a.k.a. poor man's flex)
 *
 * The calling convention is similar to that of strtok.
 * s -          string to parse, if NULL continue parsing the last string
 * delim -      set of characters that delimit tokens (usually whitespace)
 * quote -      set of characters that quote stuff, they're not part of the token
 * escape -     character than can quote quotes
 * was_quoted - if not NULL, stores the quoting character if any was encountered
 * token_pos -  if not NULL, receives a count to the start of the token in the
 *              parsed string
 *
 * Note that the string s is _not_ overwritten in this implementation.
 */
char * strtokx(const char *s,
	       const char *delim,
	       const char *quote,
	       char escape,
	       char * was_quoted,
	       unsigned int * token_pos)
{
    static char * storage = NULL; /* store the local copy of the users string here */
    static char * string  = NULL; /* pointer into storage where to continue on next call */
    /* variously abused variables: */
    unsigned int offset;
    char * start;
    char *cp = NULL;

    if (s) {
	free(storage);
	storage = strdup(s);
	string = storage;
    }

    if (!storage)
	return NULL;

    /* skip leading "whitespace" */
    offset = strspn(string, delim);

    /* end of string reached */
    if (string[offset] == '\0') {
	/* technically we don't need to free here, but we're nice */
	free(storage);
	storage = NULL;
	string = NULL;
	return NULL;
    }

    /* test if quoting character */
    if (quote)
	cp = strchr(quote, string[offset]);

    if (cp) {
	/* okay, we have a quoting character, now scan for the closer */
	char *p;
	start = &string[offset+1];

	if (token_pos)
	    *token_pos = start - storage;

	for(p = start;
	    *p && (*p != *cp || *(p-1) == escape) ;
#ifdef MULTIBYTE
	    p += PQmblen(p)
#else
	    p++
#endif
	    );

	/* not yet end of string? */
	if (*p != '\0') {
	    *p = '\0';
	    string = p + 1;
	    if (was_quoted)
		*was_quoted = *cp;
	    unescape_quotes (start, *cp, escape);
	    return start;
	}
	else {
	    if (was_quoted)
		*was_quoted = *cp;
	    string = p;

	    unescape_quotes (start, *cp, escape);
	    return start;
	}
    }

    /* otherwise no quoting character. scan till next delimiter */
    start = &string[offset];

    if (token_pos)
	*token_pos = start - storage;

    offset = strcspn(start, delim);
    if (was_quoted)
	*was_quoted = 0;

    if (start[offset] != '\0') {
	start[offset] = '\0';
	string = &start[offset]+1;

	return start;
    }
    else {
	string = &start[offset];
	return start;
    }
}




/*
 * unescape_quotes
 *
 * Resolves escaped quotes. Used by strtokx above.
 */
static void
unescape_quotes(char *source, char quote, char escape)
{
    char *p;
    char *destination, *tmp;

#ifdef USE_ASSERT_CHECKING
    assert(source);
#endif

    destination = (char *) calloc(1, strlen(source)+1);
    if (!destination) {
	perror("calloc");
	exit(EXIT_FAILURE);
    }

    tmp = destination;

    for (p = source; *p; p++)
    {
	char c;

	if (*p == escape && *(p+1) && quote == *(p+1)) {
	    c = *(p+1);
	    p++;
	}
	else
	    c = *p;

	*tmp = c;
	tmp ++;
    }

    /* Terminating null character */
    *tmp = '\0';

    strcpy(source, destination);
}