server/src/util/parser.c

#include <platform.h>
#include "parser.h"
#include "unicode.h"
#include "base36.h"
#include "log.h"

#include <assert.h>
#include <stdlib.h>
#include <wctype.h>
#include <memory.h>

#define SPACE_REPLACEMENT '~'
#define ESCAPE_CHAR       '\\'
#define MAXTOKENSIZE      8192

typedef struct parser_state {
  const char *current_token;
  struct parser_state *next;
} parser_state;

static parser_state *states;

static int eatwhitespace_c(const char **str_p)
{
  int ret = 0;
  ucs4_t ucs;
  size_t len;
  const char *str = *str_p;

  /* skip over potential whitespace */
  for (;;) {
    unsigned char utf8_character = (unsigned char)*str;
    if (~utf8_character & 0x80) {
      if (!iswxspace(utf8_character))
        break;
      ++str;
    } else {
      ret = unicode_utf8_to_ucs4(&ucs, str, &len);
      if (ret != 0) {
        log_warning("illegal character sequence in UTF8 string: %s\n", str);
        break;
      }
      if (!iswxspace((wint_t) ucs))
        break;
      str += len;
    }
  }
  *str_p = str;
  return ret;
}

void init_tokens_str(const char *initstr)
{
  if (states == NULL) {
    states = malloc(sizeof(parser_state));
  }
  states->current_token = initstr;
}

void parser_pushstate(void)
{
  parser_state *new_state = malloc(sizeof(parser_state));
  new_state->current_token = NULL;
  new_state->next = states;
  states = new_state;
}

void parser_popstate(void)
{
  parser_state *new_state = states->next;
  free(states);
  states = new_state;
}

bool parser_end(void)
{
    if (states->current_token) {
        eatwhitespace_c(&states->current_token);
        return *states->current_token == 0;
    }
    return true;
}

void skip_token(void)
{
  char quotechar = 0;
  eatwhitespace_c(&states->current_token);

  while (*states->current_token) {
    ucs4_t ucs;
    size_t len;

    unsigned char utf8_character = (unsigned char)states->current_token[0];
    if (~utf8_character & 0x80) {
      ucs = utf8_character;
      ++states->current_token;
    } else {
      int ret = unicode_utf8_to_ucs4(&ucs, states->current_token, &len);
      if (ret == 0) {
        states->current_token += len;
      } else {
        log_warning("illegal character sequence in UTF8 string: %s\n", states->current_token);
      }
    }
    if (iswxspace((wint_t) ucs) && quotechar == 0) {
      return;
    } else {
      switch (utf8_character) {
        case '"':
        case '\'':
          if (utf8_character == quotechar)
            return;
          quotechar = utf8_character;
          break;
        case ESCAPE_CHAR:
          ++states->current_token;
          break;
      }
    }
  }
}

char *parse_token(const char **str, char *lbuf, size_t len)
{
    char *cursor = lbuf;
    char quotechar = 0;
    bool escape = false;
    const char *ctoken = *str;

    if (!ctoken) {
        return 0;
    }
    eatwhitespace_c(&ctoken);
    if (!*ctoken) {
        if (len > 0) {
            *cursor = 0;
        }
        return 0;
    }
    while (*ctoken && cursor-len < lbuf-1) {
        ucs4_t ucs;
        size_t len;
        bool copy = false;

        unsigned char utf8_character = *(unsigned char *)ctoken;
        if (~utf8_character & 0x80) {
            ucs = utf8_character;
            len = 1;
        }
        else {
            int ret = unicode_utf8_to_ucs4(&ucs, ctoken, &len);
            if (ret != 0) {
                log_warning("illegal character sequence in UTF8 string: %s\n", ctoken);
                break;
            }
        }
        if (escape) {
            copy = true;
            escape = false;
        }
        else if (iswxspace((wint_t)ucs)) {
            if (quotechar == 0)
                break;
            copy = true;
        }
        else if (utf8_character == '"' || utf8_character == '\'') {
            if (utf8_character == quotechar) {
                ++ctoken;
                break;
            }
            else if (quotechar == 0) {
                quotechar = utf8_character;
                ++ctoken;
            }
            else {
                *cursor++ = *ctoken++;
            }
        }
        else if (utf8_character == SPACE_REPLACEMENT) {
            *cursor++ = ' ';
            ++ctoken;
        }
        else if (utf8_character == ESCAPE_CHAR) {
            escape = true;
            ++ctoken;
        }
        else {
            copy = true;
        }
        if (copy) {
            memcpy(cursor, ctoken, len);
            cursor += len;
            ctoken += len;
        }
    }

    assert(cursor - len < lbuf - 1); // TODO: handle too-small buffers
    *cursor = '\0';
    *str = ctoken;
    return lbuf;
}

const char *parse_token_depr(const char **str)
{
  static char lbuf[MAXTOKENSIZE];       /* STATIC_RESULT: used for return, not across calls */
  return parse_token(str, lbuf, MAXTOKENSIZE);
}

const char *getstrtoken(void)
{
    char lbuf[MAXTOKENSIZE];
    return parse_token((const char **)&states->current_token, lbuf, MAXTOKENSIZE);
}

const char *gettoken(char *lbuf, size_t bufsize)
{
    return parse_token((const char **)&states->current_token, lbuf, bufsize);
}

int getid(void)
{
    char token[16];
    const char *str = gettoken(token, sizeof(token));
    int i = str ? atoi36(str) : 0;
    if (i < 0) {
        return -1;
    }
    return i;
}