util.c

Apache HTTP Server 是一个功能强大的灵活的与HTTP/1.1相兼容的web服务器.这里给出的是Apache HTTP服务器的源码。

/*
 * copy at most n leading directories of s into d
 * d should be at least as large as s plus 1 extra byte
 * assumes n > 0
 * the return value is the ever useful pointer to the trailing \0 of d
 *
 * MODIFIED FOR HAVE_DRIVE_LETTERS and NETWARE environments, 
 * so that if n == 0, "/" is returned in d with n == 1 
 * and s == "e:/test.html", "e:/" is returned in d
 * *** See also directory_walk in modules/http/http_request.c

 * examples:
 *    /a/b, 0  ==> /  (true for all platforms)
 *    /a/b, 1  ==> /
 *    /a/b, 2  ==> /a/
 *    /a/b, 3  ==> /a/b/
 *    /a/b, 4  ==> /a/b/
 *
 *    c:/a/b 0 ==> /
 *    c:/a/b 1 ==> c:/
 *    c:/a/b 2 ==> c:/a/
 *    c:/a/b 3 ==> c:/a/b
 *    c:/a/b 4 ==> c:/a/b
 */
AP_DECLARE(char *) ap_make_dirstr_prefix(char *d, const char *s, int n)
{
    if (n < 1) {
        *d = '/';
        *++d = '\0';
        return (d);
    }

    for (;;) {
        if (*s == '\0' || (*s == '/' && (--n) == 0)) {
            *d = '/';
            break;
        }
        *d++ = *s++;
    }
    *++d = 0;
    return (d);
}


/*
 * return the parent directory name including trailing / of the file s
 */
AP_DECLARE(char *) ap_make_dirstr_parent(apr_pool_t *p, const char *s)
{
    const char *last_slash = ap_strrchr_c(s, '/');
    char *d;
    int l;

    if (last_slash == NULL) {
        return apr_pstrdup(p, "");
    }
    l = (last_slash - s) + 1;
    d = apr_palloc(p, l + 1);
    memcpy(d, s, l);
    d[l] = 0;
    return (d);
}


AP_DECLARE(int) ap_count_dirs(const char *path)
{
    register int x, n;

    for (x = 0, n = 0; path[x]; x++)
        if (path[x] == '/')
            n++;
    return n;
}

AP_DECLARE(char *) ap_getword_nc(apr_pool_t *atrans, char **line, char stop)
{
    return ap_getword(atrans, (const char **) line, stop);
}

AP_DECLARE(char *) ap_getword(apr_pool_t *atrans, const char **line, char stop)
{
    const char *pos = *line;
    int len;
    char *res;

    while ((*pos != stop) && *pos) {
        ++pos;
    }

    len = pos - *line;
    res = (char *)apr_palloc(atrans, len + 1);
    memcpy(res, *line, len);
    res[len] = 0;

    if (stop) {
        while (*pos == stop) {
            ++pos;
        }
    }
    *line = pos;

    return res;
}

AP_DECLARE(char *) ap_getword_white_nc(apr_pool_t *atrans, char **line)
{
    return ap_getword_white(atrans, (const char **) line);
}

AP_DECLARE(char *) ap_getword_white(apr_pool_t *atrans, const char **line)
{
    const char *pos = *line;
    int len;
    char *res;

    while (!apr_isspace(*pos) && *pos) {
        ++pos;
    }

    len = pos - *line;
    res = (char *)apr_palloc(atrans, len + 1);
    memcpy(res, *line, len);
    res[len] = 0;

    while (apr_isspace(*pos)) {
        ++pos;
    }

    *line = pos;

    return res;
}

AP_DECLARE(char *) ap_getword_nulls_nc(apr_pool_t *atrans, char **line,
                                       char stop)
{
    return ap_getword_nulls(atrans, (const char **) line, stop);
}

AP_DECLARE(char *) ap_getword_nulls(apr_pool_t *atrans, const char **line,
                                    char stop)
{
    const char *pos = ap_strchr_c(*line, stop);
    char *res;

    if (!pos) {
        res = apr_pstrdup(atrans, *line);
        *line += strlen(*line);
        return res;
    }

    res = apr_pstrndup(atrans, *line, pos - *line);

    ++pos;

    *line = pos;

    return res;
}

/* Get a word, (new) config-file style --- quoted strings and backslashes
 * all honored
 */

static char *substring_conf(apr_pool_t *p, const char *start, int len,
                            char quote)
{
    char *result = apr_palloc(p, len + 2);
    char *resp = result;
    int i;

    for (i = 0; i < len; ++i) {
        if (start[i] == '\\' && (start[i + 1] == '\\'
                                 || (quote && start[i + 1] == quote)))
            *resp++ = start[++i];
        else
            *resp++ = start[i];
    }

    *resp++ = '\0';
#if RESOLVE_ENV_PER_TOKEN
    return (char *)ap_resolve_env(p,result);
#else
    return result;
#endif
}

AP_DECLARE(char *) ap_getword_conf_nc(apr_pool_t *p, char **line)
{
    return ap_getword_conf(p, (const char **) line);
}

AP_DECLARE(char *) ap_getword_conf(apr_pool_t *p, const char **line)
{
    const char *str = *line, *strend;
    char *res;
    char quote;

    while (*str && apr_isspace(*str))
        ++str;

    if (!*str) {
        *line = str;
        return "";
    }

    if ((quote = *str) == '"' || quote == '\'') {
        strend = str + 1;
        while (*strend && *strend != quote) {
            if (*strend == '\\' && strend[1] && strend[1] == quote)
                strend += 2;
            else
                ++strend;
        }
        res = substring_conf(p, str + 1, strend - str - 1, quote);

        if (*strend == quote)
            ++strend;
    }
    else {
        strend = str;
        while (*strend && !apr_isspace(*strend))
            ++strend;

        res = substring_conf(p, str, strend - str, 0);
    }

    while (*strend && apr_isspace(*strend))
        ++strend;
    *line = strend;
    return res;
}

/* Check a string for any ${ENV} environment variable
 * construct and replace each them by the value of
 * that environment variable, if it exists. If the
 * environment value does not exist, leave the ${ENV}
 * construct alone; it means something else.
 */
AP_DECLARE(const char *) ap_resolve_env(apr_pool_t *p, const char * word)
{
# define SMALL_EXPANSION 5
    struct sll {
        struct sll *next;
        const char *string;
        apr_size_t len;
    } *result, *current, sresult[SMALL_EXPANSION];
    char *res_buf, *cp;
    const char *s, *e, *ep;
    unsigned spc;
    apr_size_t outlen;

    s = ap_strchr_c(word, '$');
    if (!s) {
        return word;
    }

    /* well, actually something to do */
    ep = word + strlen(word);
    spc = 0;
    result = current = &(sresult[spc++]);
    current->next = NULL;
    current->string = word;
    current->len = s - word;
    outlen = current->len;

    do {
        /* prepare next entry */
        if (current->len) {
            current->next = (spc < SMALL_EXPANSION)
                            ? &(sresult[spc++])
                            : (struct sll *)apr_palloc(p,
                                                       sizeof(*current->next));
            current = current->next;
            current->next = NULL;
            current->len = 0;
        }

        if (*s == '$') {
            if (s[1] == '{' && (e = ap_strchr_c(s, '}'))) {
                word = getenv(apr_pstrndup(p, s+2, e-s-2));
                if (word) {
                    current->string = word;
                    current->len = strlen(word);
                    outlen += current->len;
                }
                else {
                    current->string = s;
                    current->len = e - s + 1;
                    outlen += current->len;
                }
                s = e + 1;
            }
            else {
                current->string = s++;
                current->len = 1;
                ++outlen;
            }
        }
        else {
            word = s;
            s = ap_strchr_c(s, '$');
            current->string = word;
            current->len = s ? s - word : ep - word;
            outlen += current->len;
        }
    } while (s && *s);

    /* assemble result */
    res_buf = cp = apr_palloc(p, outlen + 1);
    do {
        if (result->len) {
            memcpy(cp, result->string, result->len);
            cp += result->len;
        }
        result = result->next;
    } while (result);
    res_buf[outlen] = '\0';

    return res_buf;
}

AP_DECLARE(int) ap_cfg_closefile(ap_configfile_t *cfp)
{
#ifdef DEBUG
    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, NULL, 
        "Done with config file %s", cfp->name);
#endif
    return (cfp->close == NULL) ? 0 : cfp->close(cfp->param);
}

static apr_status_t cfg_close(void *param)
{
    apr_file_t *cfp = (apr_file_t *) param;
    return (apr_file_close(cfp));
}

static int cfg_getch(void *param)
{
    char ch;
    apr_file_t *cfp = (apr_file_t *) param;
    if (apr_file_getc(&ch, cfp) == APR_SUCCESS)
        return ch;
    return (int)EOF;
}

static void *cfg_getstr(void *buf, size_t bufsiz, void *param)
{
    apr_file_t *cfp = (apr_file_t *) param;
    apr_status_t rv;
    rv = apr_file_gets(buf, bufsiz, cfp);
    if (rv == APR_SUCCESS || (APR_STATUS_IS_EOF(rv) && strcmp(buf, "")))
        return buf;
    return NULL;
}

/* Open a ap_configfile_t as FILE, return open ap_configfile_t struct pointer */
AP_DECLARE(apr_status_t) ap_pcfg_openfile(ap_configfile_t **ret_cfg,
                                          apr_pool_t *p, const char *name)
{
    ap_configfile_t *new_cfg;
    apr_file_t *file = NULL;
    apr_finfo_t finfo;
    apr_status_t status;
#ifdef DEBUG
    char buf[120];
#endif

    if (name == NULL) {
        ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL,
               "Internal error: pcfg_openfile() called with NULL filename");
        return APR_EBADF;
    }

    status = apr_file_open(&file, name, APR_READ | APR_BUFFERED,
                           APR_OS_DEFAULT, p);
#ifdef DEBUG
    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, NULL,
                "Opening config file %s (%s)",
                name, (status != APR_SUCCESS) ? 
                apr_strerror(status, buf, sizeof(buf)) : "successful");
#endif
    if (status != APR_SUCCESS)
        return status;

    status = apr_file_info_get(&finfo, APR_FINFO_TYPE, file);
    if (status != APR_SUCCESS)
        return status;

    if (finfo.filetype != APR_REG &&
#if defined(WIN32) || defined(OS2) || defined(NETWARE)
        strcasecmp(apr_filename_of_pathname(name), "nul") != 0) {
#else
        strcmp(name, "/dev/null") != 0) {
#endif /* WIN32 || OS2 */
        ap_log_error(APLOG_MARK, APLOG_ERR, 0, NULL,
                     "Access to file %s denied by server: not a regular file",
                     name);
        apr_file_close(file);
        return APR_EBADF;
    }

#ifdef WIN32
    /* Some twisted character [no pun intended] at MS decided that a
     * zero width joiner as the lead wide character would be ideal for
     * describing Unicode text files.  This was further convoluted to
     * another MSism that the same character mapped into utf-8, EF BB BF
     * would signify utf-8 text files.
     *
     * Since MS configuration files are all protecting utf-8 encoded
     * Unicode path, file and resource names, we already have the correct 
     * WinNT encoding.  But at least eat the stupid three bytes up front.
     */
    {
        unsigned char buf[4];
        apr_size_t len = 3;
        status = apr_file_read(file, buf, &len);
        if ((status != APR_SUCCESS) || (len < 3) 
              || memcmp(buf, "\xEF\xBB\xBF", 3) != 0) {
            apr_off_t zero = 0;
            apr_file_seek(file, APR_SET, &zero);
        }
    }
#endif

    new_cfg = apr_palloc(p, sizeof(*new_cfg));
    new_cfg->param = file;
    new_cfg->name = apr_pstrdup(p, name);
    new_cfg->getch = (int (*)(void *)) cfg_getch;
    new_cfg->getstr = (void *(*)(void *, size_t, void *)) cfg_getstr;
    new_cfg->close = (int (*)(void *)) cfg_close;
    new_cfg->line_number = 0;
    *ret_cfg = new_cfg;
    return APR_SUCCESS;
}


/* Allocate a ap_configfile_t handle with user defined functions and params */
AP_DECLARE(ap_configfile_t *) ap_pcfg_open_custom(apr_pool_t *p,
                       const char *descr,
                       void *param,
                       int(*getch)(void *param),
                       void *(*getstr) (void *buf, size_t bufsiz, void *param),
                       int(*close_func)(void *param))
{
    ap_configfile_t *new_cfg = apr_palloc(p, sizeof(*new_cfg));
#ifdef DEBUG
    ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, NULL,
                 "Opening config handler %s", descr);
#endif
    new_cfg->param = param;
    new_cfg->name = descr;
    new_cfg->getch = getch;
    new_cfg->getstr = getstr;
    new_cfg->close = close_func;
    new_cfg->line_number = 0;
    return new_cfg;
}
   
/* Read one character from a configfile_t */
AP_DECLARE(int) ap_cfg_getc(ap_configfile_t *cfp)
{
    register int ch = cfp->getch(cfp->param);
    if (ch == LF) 
        ++cfp->line_number;
    return ch;
}
  
/* Read one line from open ap_configfile_t, strip LF, increase line number */
/* If custom handler does not define a getstr() function, read char by char */
AP_DECLARE(int) ap_cfg_getline(char *buf, size_t bufsize, ap_configfile_t *cfp)
{
    /* If a "get string" function is defined, use it */
    if (cfp->getstr != NULL) {
        char *src, *dst;
        char *cp;
        char *cbuf = buf;
        size_t cbufsize = bufsize;

        while (1) {
            ++cfp->line_number;
            if (cfp->getstr(cbuf, cbufsize, cfp->param) == NULL)
                return 1;

            /*
             *  check for line continuation,
             *  i.e. match [^\\]\\[\r]\n only
             */
            cp = cbuf;
            while (cp < cbuf+cbufsize && *cp != '\0')
                cp++;
            if (cp > cbuf && cp[-1] == LF) {
                cp--;
                if (cp > cbuf && cp[-1] == CR)
                    cp--;
                if (cp > cbuf && cp[-1] == '\\') {
                    cp--;
                    if (!(cp > cbuf && cp[-1] == '\\')) {
                        /*
                         * line continuation requested -
                         * then remove backslash and continue
                         */
                        cbufsize -= (cp-cbuf);
                        cbuf = cp;
                        continue;
                    }
                    else {
                        /* 
                         * no real continuation because escaped -
                         * then just remove escape character
                         */
                        for ( ; cp < cbuf+cbufsize && *cp != '\0'; cp++)
                            cp[0] = cp[1];
                    }   
                }
            }
            break;
        }

        /*
         * Leading and trailing white space is eliminated completely
         */
        src = buf;
        while (apr_isspace(*src))
            ++src;
        /* blast trailing whitespace */
        dst = &src[strlen(src)];
        while (--dst >= src && apr_isspace(*dst))
            *dst = '\0';
        /* Zap leading whitespace by shifting */
        if (src != buf)
            for (dst = buf; (*dst++ = *src++) != '\0'; )
                ;

#ifdef DEBUG_CFG_LINES
        ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, NULL, "Read config: %s", buf);
#endif
        return 0;
    } else {
        /* No "get string" function defined; read character by character */