load.c

Linux下利用NTP协议的网络时间同步客户端

/*
 *  $Id: load.c,v 4.20 2007/02/04 22:17:39 bkorb Exp $
 *  Time-stamp:      "2007-02-04 11:54:57 bkorb"
 *
 *  This file contains the routines that deal with processing text strings
 *  for options, either from a NUL-terminated string passed in or from an
 *  rc/ini file.
 */

/*
 *  Automated Options copyright 1992-2007 Bruce Korb
 *
 *  Automated Options is free software.
 *  You may redistribute it and/or modify it under the terms of the
 *  GNU General Public License, as published by the Free Software
 *  Foundation; either version 2, or (at your option) any later version.
 *
 *  Automated Options is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with Automated Options.  See the file "COPYING".  If not,
 *  write to:  The Free Software Foundation, Inc.,
 *             51 Franklin Street, Fifth Floor,
 *             Boston, MA  02110-1301, USA.
 *
 * As a special exception, Bruce Korb gives permission for additional
 * uses of the text contained in his release of AutoOpts.
 *
 * The exception is that, if you link the AutoOpts library with other
 * files to produce an executable, this does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * Your use of that executable is in no way restricted on account of
 * linking the AutoOpts library code into it.
 *
 * This exception does not however invalidate any other reasons why
 * the executable file might be covered by the GNU General Public License.
 *
 * This exception applies only to the code released by Bruce Korb under
 * the name AutoOpts.  If you copy code from other sources under the
 * General Public License into a copy of AutoOpts, as the General Public
 * License permits, the exception does not apply to the code that you add
 * in this way.  To avoid misleading anyone as to the status of such
 * modified files, you must delete this exception notice from them.
 *
 * If you write modifications of your own for AutoOpts, it is your choice
 * whether to permit this exception to apply to your modifications.
 * If you do not wish that, delete this exception notice.
 */

tOptionLoadMode option_load_mode = OPTION_LOAD_UNCOOKED;

/* = = = START-STATIC-FORWARD = = = */
/* static forward declarations maintained by :mkfwd */
static ag_bool
insertProgramPath(
    char*   pzBuf,
    int     bufSize,
    tCC*    pzName,
    tCC*    pzProgPath );

static ag_bool
insertEnvVal(
    char*   pzBuf,
    int     bufSize,
    tCC*    pzName,
    tCC*    pzProgPath );

static char*
assembleArgValue( char* pzTxt, tOptionLoadMode mode );
/* = = = END-STATIC-FORWARD = = = */

/*=export_func  optionMakePath
 * private:
 *
 * what:  translate and construct a path
 * arg:   + char*       + pzBuf      + The result buffer +
 * arg:   + int         + bufSize    + The size of this buffer +
 * arg:   + char const* + pzName     + The input name +
 * arg:   + char const* + pzProgPath + The full path of the current program +
 *
 * ret-type: ag_bool
 * ret-desc: AG_TRUE if the name was handled, otherwise AG_FALSE.
 *           If the name does not start with ``$'', then it is handled
 *           simply by copying the input name to the output buffer and
 *           resolving the name with either @code{canonicalize_file_name(3GLIBC)}
 *           or @code{realpath(3C)}.
 *
 * doc:
 *
 *  This routine will copy the @code{pzName} input name into the @code{pzBuf}
 *  output buffer, carefully not exceeding @code{bufSize} bytes.  If the
 *  first character of the input name is a @code{'$'} character, then there
 *  is special handling:
 *  @*
 *  @code{$$} is replaced with the directory name of the @code{pzProgPath},
 *  searching @code{$PATH} if necessary.
 *  @*
 *  @code{$@} is replaced with the AutoGen package data installation directory
 *  (aka @code{pkgdatadir}).
 *  @*
 *  @code{$NAME} is replaced by the contents of the @code{NAME} environment
 *  variable.  If not found, the search fails.
 *
 *  Please note: both @code{$$} and @code{$NAME} must be at the start of the
 *     @code{pzName} string and must either be the entire string or be followed
 *     by the @code{'/'} (backslash on windows) character.
 *
 * err:  @code{AG_FALSE} is returned if:
 *       @*
 *       @bullet{} The input name exceeds @code{bufSize} bytes.
 *       @*
 *       @bullet{} @code{$$}, @code{$@@} or @code{$NAME} is not the full string
 *                 and the next character is not '/'.
 *       @*
 *       @bullet{} libopts was built without PKGDATADIR defined and @code{$@@}
 *                 was specified.
 *       @*
 *       @bullet{} @code{NAME} is not a known environment variable
 *       @*
 *       @bullet{} @code{canonicalize_file_name} or @code{realpath} return
 *                 errors (cannot resolve the resulting path).
=*/
ag_bool
optionMakePath(
    char*   pzBuf,
    int     bufSize,
    tCC*    pzName,
    tCC*    pzProgPath )
{
    size_t  name_len = strlen( pzName );

#   ifndef PKGDATADIR
#     define PKGDATADIR ""
#   endif

    tSCC    pkgdatadir[] = PKGDATADIR;

    ag_bool res = AG_TRUE;

    if (bufSize <= name_len)
        return AG_FALSE;

    /*
     *  IF not an environment variable, just copy the data
     */
    if (*pzName != '$') {
        tCC*  pzS = pzName;
        char* pzD = pzBuf;
        int   ct  = bufSize;

        for (;;) {
            if ( (*(pzD++) = *(pzS++)) == NUL)
                break;
            if (--ct <= 0)
                return AG_FALSE;
        }
    }

    /*
     *  IF the name starts with "$$", then it must be "$$" or
     *  it must start with "$$/".  In either event, replace the "$$"
     *  with the path to the executable and append a "/" character.
     */
    else switch (pzName[1]) {
    case NUL:
        return AG_FALSE;

    case '$':
        res = insertProgramPath( pzBuf, bufSize, pzName, pzProgPath );
        break;

    case '@':
        if (pkgdatadir[0] == NUL)
            return AG_FALSE;

        if (name_len + sizeof (pkgdatadir) > bufSize)
            return AG_FALSE;

        strcpy(pzBuf, pkgdatadir);
        strcpy(pzBuf + sizeof(pkgdatadir) - 1, pzName + 2);
        break;

    default:
        res = insertEnvVal( pzBuf, bufSize, pzName, pzProgPath );
    }

    if (! res)
        return AG_FALSE;

#if defined(HAVE_CANONICALIZE_FILE_NAME)
    {
        char* pz = canonicalize_file_name(pzBuf);
        if (pz == NULL)
            return AG_FALSE;
        if (strlen(pz) < bufSize)
            strcpy(pzBuf, pz);
        free(pz);
    }

#elif defined(HAVE_REALPATH)
    {
        char z[ PATH_MAX+1 ];

        if (realpath( pzBuf, z ) == NULL)
            return AG_FALSE;

        if (strlen(z) < bufSize)
            strcpy( pzBuf, z );
    }
#endif

    return AG_TRUE;
}


static ag_bool
insertProgramPath(
    char*   pzBuf,
    int     bufSize,
    tCC*    pzName,
    tCC*    pzProgPath )
{
    tCC*    pzPath;
    tCC*    pz;
    int     skip = 2;

    switch (pzName[2]) {
    case DIRCH:
        skip = 3;
    case NUL:
        break;
    default:
        return AG_FALSE;
    }

    /*
     *  See if the path is included in the program name.
     *  If it is, we're done.  Otherwise, we have to hunt
     *  for the program using "pathfind".
     */
    if (strchr( pzProgPath, DIRCH ) != NULL)
        pzPath = pzProgPath;
    else {
        pzPath = pathfind( getenv( "PATH" ), (char*)pzProgPath, "rx" );

        if (pzPath == NULL)
            return AG_FALSE;
    }

    pz = strrchr( pzPath, DIRCH );

    /*
     *  IF we cannot find a directory name separator,
     *  THEN we do not have a path name to our executable file.
     */
    if (pz == NULL)
        return AG_FALSE;

    pzName += skip;

    /*
     *  Concatenate the file name to the end of the executable path.
     *  The result may be either a file or a directory.
     */
    if ((pz - pzPath)+1 + strlen(pzName) >= bufSize)
        return AG_FALSE;

    memcpy( pzBuf, pzPath, (size_t)((pz - pzPath)+1) );
    strcpy( pzBuf + (pz - pzPath) + 1, pzName );

    /*
     *  If the "pzPath" path was gotten from "pathfind()", then it was
     *  allocated and we need to deallocate it.
     */
    if (pzPath != pzProgPath)
        free( (void*)pzPath );
    return AG_TRUE;
}