params.c

   1 /* This modules is based on the params.c module from Samba, written by Karl Auer
   2    and much modifed by Christopher Hertel. */
   3
   4 /*
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, visit the http://fsf.org website.
  17  */
  18
  19 /* -------------------------------------------------------------------------- **
  20  *
  21  * Module name: params
  22  *
  23  * -------------------------------------------------------------------------- **
  24  *
  25  *  This module performs lexical analysis and initial parsing of a
  26  *  Windows-like parameter file.  It recognizes and handles four token
  27  *  types:  section-name, parameter-name, parameter-value, and
  28  *  end-of-file.  Comments and line continuation are handled
  29  *  internally.
  30  *
  31  *  The entry point to the module is function pm_process().  This
  32  *  function opens the source file, calls the Parse() function to parse
  33  *  the input, and then closes the file when either the EOF is reached
  34  *  or a fatal error is encountered.
  35  *
  36  *  A sample parameter file might look like this:
  37  *
  38  *  [section one]
  39  *  parameter one = value string
  40  *  parameter two = another value
  41  *  [section two]
  42  *  new parameter = some value or t'other
  43  *
  44  *  The parameter file is divided into sections by section headers:
  45  *  section names enclosed in square brackets (eg. [section one]).
  46  *  Each section contains parameter lines, each of which consist of a
  47  *  parameter name and value delimited by an equal sign.  Roughly, the
  48  *  syntax is:
  49  *
  50  *    <file>            :==  { <section> } EOF
  51  *
  52  *    <section>         :==  <section header> { <parameter line> }
  53  *
  54  *    <section header>  :==  '[' NAME ']'
  55  *
  56  *    <parameter line>  :==  NAME '=' VALUE '\n'
  57  *
  58  *  Blank lines and comment lines are ignored.  Comment lines are lines
  59  *  beginning with either a semicolon (';') or a pound sign ('#').
  60  *
  61  *  All whitespace in section names and parameter names is compressed
  62  *  to single spaces.  Leading and trailing whitespace is stipped from
  63  *  both names and values.
  64  *
  65  *  Only the first equals sign in a parameter line is significant.
  66  *  Parameter values may contain equals signs, square brackets and
  67  *  semicolons.  Internal whitespace is retained in parameter values,
  68  *  with the exception of the '\r' character, which is stripped for
  69  *  historic reasons.  Parameter names may not start with a left square
  70  *  bracket, an equal sign, a pound sign, or a semicolon, because these
  71  *  are used to identify other tokens.
  72  *
  73  * -------------------------------------------------------------------------- **
  74  */
  75
  76 #include "rsync.h"
  77 #include "ifuncs.h"
  78
  79 /* -------------------------------------------------------------------------- **
  80  * Constants...
  81  */
  82
  83 #define BUFR_INC 1024
  84
  85
  86 /* -------------------------------------------------------------------------- **
  87  * Variables...
  88  *
  89  *  bufr        - pointer to a global buffer.  This is probably a kludge,
  90  *                but it was the nicest kludge I could think of (for now).
  91  *  bSize       - The size of the global buffer <bufr>.
  92  */
  93
  94 static char *bufr  = NULL;
  95 static int   bSize = 0;
  96
  97 /* -------------------------------------------------------------------------- **
  98  * Functions...
  99  */
 100
 101 static int EatWhitespace( FILE *InFile )
 102   /* ------------------------------------------------------------------------ **
 103    * Scan past whitespace (see ctype(3C)) and return the first non-whitespace
 104    * character, or newline, or EOF.
 105    *
 106    *  Input:  InFile  - Input source.
 107    *
 108    *  Output: The next non-whitespace character in the input stream.
 109    *
 110    *  Notes:  Because the config files use a line-oriented grammar, we
 111    *          explicitly exclude the newline character from the list of
 112    *          whitespace characters.
 113    *        - Note that both EOF (-1) and the nul character ('\0') are
 114    *          considered end-of-file markers.
 115    *
 116    * ------------------------------------------------------------------------ **
 117    */
 118   {
 119   int c;
 120
 121   for( c = getc( InFile ); isspace( c ) && ('\n' != c); c = getc( InFile ) )
 122     ;
 123   return( c );
 124   } /* EatWhitespace */
 125
 126 static int EatComment( FILE *InFile )
 127   /* ------------------------------------------------------------------------ **
 128    * Scan to the end of a comment.
 129    *
 130    *  Input:  InFile  - Input source.
 131    *
 132    *  Output: The character that marks the end of the comment.  Normally,
 133    *          this will be a newline, but it *might* be an EOF.
 134    *
 135    *  Notes:  Because the config files use a line-oriented grammar, we
 136    *          explicitly exclude the newline character from the list of
 137    *          whitespace characters.
 138    *        - Note that both EOF (-1) and the nul character ('\0') are
 139    *          considered end-of-file markers.
 140    *
 141    * ------------------------------------------------------------------------ **
 142    */
 143   {
 144   int c;
 145
 146   for( c = getc( InFile ); ('\n'!=c) && (EOF!=c) && (c>0); c = getc( InFile ) )
 147     ;
 148   return( c );
 149   } /* EatComment */
 150
 151 static int Continuation( char *line, int pos )
 152   /* ------------------------------------------------------------------------ **
 153    * Scan backards within a string to discover if the last non-whitespace
 154    * character is a line-continuation character ('\\').
 155    *
 156    *  Input:  line  - A pointer to a buffer containing the string to be
 157    *                  scanned.
 158    *          pos   - This is taken to be the offset of the end of the
 159    *                  string.  This position is *not* scanned.
 160    *
 161    *  Output: The offset of the '\\' character if it was found, or -1 to
 162    *          indicate that it was not.
 163    *
 164    * ------------------------------------------------------------------------ **
 165    */
 166   {
 167   pos--;
 168   while( pos >= 0 && isSpace(line + pos) )
 169      pos--;
 170
 171   return( ((pos >= 0) && ('\\' == line[pos])) ? pos : -1 );
 172   } /* Continuation */
 173
 174
 175 static BOOL Section( FILE *InFile, BOOL (*sfunc)(char *) )
 176   /* ------------------------------------------------------------------------ **
 177    * Scan a section name, and pass the name to function sfunc().
 178    *
 179    *  Input:  InFile  - Input source.
 180    *          sfunc   - Pointer to the function to be called if the section
 181    *                    name is successfully read.
 182    *
 183    *  Output: True if the section name was read and True was returned from
 184    *          <sfunc>.  False if <sfunc> failed or if a lexical error was
 185    *          encountered.
 186    *
 187    * ------------------------------------------------------------------------ **
 188    */
 189   {
 190   int   c;
 191   int   i;
 192   int   end;
 193   char *func  = "params.c:Section() -";
 194
 195   i = 0;      /* <i> is the offset of the next free byte in bufr[] and  */
 196   end = 0;    /* <end> is the current "end of string" offset.  In most  */
 197               /* cases these will be the same, but if the last          */
 198               /* character written to bufr[] is a space, then <end>     */
 199               /* will be one less than <i>.                             */
 200
 201   c = EatWhitespace( InFile );    /* We've already got the '['.  Scan */
 202                                   /* past initial white space.        */
 203
 204   while( (EOF != c) && (c > 0) )
 205     {
 206
 207     /* Check that the buffer is big enough for the next character. */
 208     if( i > (bSize - 2) )
 209       {
 210       bSize += BUFR_INC;
 211       bufr   = realloc_array( bufr, char, bSize );
 212       if( NULL == bufr )
 213         {
 214         rprintf(FERROR, "%s Memory re-allocation failure.", func);
 215         return( False );
 216         }
 217       }
 218
 219     /* Handle a single character. */
 220     switch( c )
 221       {
 222       case ']':                       /* Found the closing bracket.         */
 223         bufr[end] = '\0';
 224         if( 0 == end )                  /* Don't allow an empty name.       */
 225           {
 226           rprintf(FERROR, "%s Empty section name in configuration file.\n", func );
 227           return( False );
 228           }
 229         if( !sfunc( bufr ) )            /* Got a valid name.  Deal with it. */
 230           return( False );
 231         (void)EatComment( InFile );     /* Finish off the line.             */
 232         return( True );
 233
 234       case '\n':                      /* Got newline before closing ']'.    */
 235         i = Continuation( bufr, i );    /* Check for line continuation.     */
 236         if( i < 0 )
 237           {
 238           bufr[end] = '\0';
 239           rprintf(FERROR, "%s Badly formed line in configuration file: %s\n",
 240                    func, bufr );
 241           return( False );
 242           }
 243         end = ( (i > 0) && (' ' == bufr[i - 1]) ) ? (i - 1) : (i);
 244         c = getc( InFile );             /* Continue with next line.         */
 245         break;
 246
 247       default:                        /* All else are a valid name chars.   */
 248         if( isspace( c ) )              /* One space per whitespace region. */
 249           {
 250           bufr[end] = ' ';
 251           i = end + 1;
 252           c = EatWhitespace( InFile );
 253           }
 254         else                            /* All others copy verbatim.        */
 255           {
 256           bufr[i++] = c;
 257           end = i;
 258           c = getc( InFile );
 259           }
 260       }
 261     }
 262
 263   /* We arrive here if we've met the EOF before the closing bracket. */
 264   rprintf(FERROR, "%s Unexpected EOF in the configuration file: %s\n", func, bufr );
 265   return( False );
 266   } /* Section */
 267
 268 static BOOL Parameter( FILE *InFile, BOOL (*pfunc)(char *, char *), int c )
 269   /* ------------------------------------------------------------------------ **
 270    * Scan a parameter name and value, and pass these two fields to pfunc().
 271    *
 272    *  Input:  InFile  - The input source.
 273    *          pfunc   - A pointer to the function that will be called to
 274    *                    process the parameter, once it has been scanned.
 275    *          c       - The first character of the parameter name, which
 276    *                    would have been read by Parse().  Unlike a comment
 277    *                    line or a section header, there is no lead-in
 278    *                    character that can be discarded.
 279    *
 280    *  Output: True if the parameter name and value were scanned and processed
 281    *          successfully, else False.
 282    *
 283    *  Notes:  This function is in two parts.  The first loop scans the
 284    *          parameter name.  Internal whitespace is compressed, and an
 285    *          equal sign (=) terminates the token.  Leading and trailing
 286    *          whitespace is discarded.  The second loop scans the parameter
 287    *          value.  When both have been successfully identified, they are
 288    *          passed to pfunc() for processing.
 289    *
 290    * ------------------------------------------------------------------------ **
 291    */
 292   {
 293   int   i       = 0;    /* Position within bufr. */
 294   int   end     = 0;    /* bufr[end] is current end-of-string. */
 295   int   vstart  = 0;    /* Starting position of the parameter value. */
 296   char *func    = "params.c:Parameter() -";
 297
 298   /* Read the parameter name. */
 299   while( 0 == vstart )  /* Loop until we've found the start of the value. */
 300     {
 301
 302     if( i > (bSize - 2) )       /* Ensure there's space for next char.    */
 303       {
 304       bSize += BUFR_INC;
 305       bufr   = realloc_array( bufr, char, bSize );
 306       if( NULL == bufr )
 307         {
 308         rprintf(FERROR, "%s Memory re-allocation failure.", func) ;
 309         return( False );
 310         }
 311       }
 312
 313     switch( c )
 314       {
 315       case '=':                 /* Equal sign marks end of param name. */
 316         if( 0 == end )              /* Don't allow an empty name.      */
 317           {
 318           rprintf(FERROR, "%s Invalid parameter name in config. file.\n", func );
 319           return( False );
 320           }
 321         bufr[end++] = '\0';         /* Mark end of string & advance.   */
 322         i       = end;              /* New string starts here.         */
 323         vstart  = end;              /* New string is parameter value.  */
 324         bufr[i] = '\0';             /* New string is nul, for now.     */
 325         break;
 326
 327       case '\n':                /* Find continuation char, else error. */
 328         i = Continuation( bufr, i );
 329         if( i < 0 )
 330           {
 331           bufr[end] = '\0';
 332           rprintf(FERROR, "%s Ignoring badly formed line in configuration file: %s\n",
 333                    func, bufr );
 334           return( True );
 335           }
 336         end = ( (i > 0) && (' ' == bufr[i - 1]) ) ? (i - 1) : (i);
 337         c = getc( InFile );       /* Read past eoln.                   */
 338         break;
 339
 340       case '\0':                /* Shouldn't have EOF within param name. */
 341       case EOF:
 342         bufr[i] = '\0';
 343         rprintf(FERROR, "%s Unexpected end-of-file at: %s\n", func, bufr );
 344         return( True );
 345
 346       default:
 347         if( isspace( c ) )     /* One ' ' per whitespace region.       */
 348           {
 349           bufr[end] = ' ';
 350           i = end + 1;
 351           c = EatWhitespace( InFile );
 352           }
 353         else                   /* All others verbatim.                 */
 354           {
 355           bufr[i++] = c;
 356           end = i;
 357           c = getc( InFile );
 358           }
 359       }
 360     }
 361
 362   /* Now parse the value. */
 363   c = EatWhitespace( InFile );  /* Again, trim leading whitespace. */
 364   while( (EOF !=c) && (c > 0) )
 365     {
 366
 367     if( i > (bSize - 2) )       /* Make sure there's enough room. */
 368       {
 369       bSize += BUFR_INC;
 370       bufr   = realloc_array( bufr, char, bSize );
 371       if( NULL == bufr )
 372         {
 373         rprintf(FERROR, "%s Memory re-allocation failure.", func) ;
 374         return( False );
 375         }
 376       }
 377
 378     switch( c )
 379       {
 380       case '\r':              /* Explicitly remove '\r' because the older */
 381         c = getc( InFile );   /* version called fgets_slash() which also  */
 382         break;                /* removes them.                            */
 383
 384       case '\n':              /* Marks end of value unless there's a '\'. */
 385         i = Continuation( bufr, i );
 386         if( i < 0 )
 387           c = 0;
 388         else
 389           {
 390           for( end = i; end >= 0 && isSpace(bufr + end); end-- )
 391             ;
 392           c = getc( InFile );
 393           }
 394         break;
 395
 396       default:               /* All others verbatim.  Note that spaces do */
 397         bufr[i++] = c;       /* not advance <end>.  This allows trimming  */
 398         if( !isspace( c ) )  /* of whitespace at the end of the line.     */
 399           end = i;
 400         c = getc( InFile );
 401         break;
 402       }
 403     }
 404   bufr[end] = '\0';          /* End of value. */
 405
 406   return( pfunc( bufr, &bufr[vstart] ) );   /* Pass name & value to pfunc().  */
 407   } /* Parameter */
 408
 409 static BOOL Parse( FILE *InFile,
 410                    BOOL (*sfunc)(char *),
 411                    BOOL (*pfunc)(char *, char *) )
 412   /* ------------------------------------------------------------------------ **
 413    * Scan & parse the input.
 414    *
 415    *  Input:  InFile  - Input source.
 416    *          sfunc   - Function to be called when a section name is scanned.
 417    *                    See Section().
 418    *          pfunc   - Function to be called when a parameter is scanned.
 419    *                    See Parameter().
 420    *
 421    *  Output: True if the file was successfully scanned, else False.
 422    *
 423    *  Notes:  The input can be viewed in terms of 'lines'.  There are four
 424    *          types of lines:
 425    *            Blank      - May contain whitespace, otherwise empty.
 426    *            Comment    - First non-whitespace character is a ';' or '#'.
 427    *                         The remainder of the line is ignored.
 428    *            Section    - First non-whitespace character is a '['.
 429    *            Parameter  - The default case.
 430    *
 431    * ------------------------------------------------------------------------ **
 432    */
 433   {
 434   int    c;
 435
 436   c = EatWhitespace( InFile );
 437   while( (EOF != c) && (c > 0) )
 438     {
 439     switch( c )
 440       {
 441       case '\n':                        /* Blank line. */
 442         c = EatWhitespace( InFile );
 443         break;
 444
 445       case ';':                         /* Comment line. */
 446       case '#':
 447         c = EatComment( InFile );
 448         break;
 449
 450       case '[':                         /* Section Header. */
 451               if (!sfunc) return True;
 452               if( !Section( InFile, sfunc ) )
 453                       return( False );
 454               c = EatWhitespace( InFile );
 455               break;
 456
 457       case '\\':                        /* Bogus backslash. */
 458         c = EatWhitespace( InFile );
 459         break;
 460
 461       default:                          /* Parameter line. */
 462         if( !Parameter( InFile, pfunc, c ) )
 463           return( False );
 464         c = EatWhitespace( InFile );
 465         break;
 466       }
 467     }
 468   return( True );
 469   } /* Parse */
 470
 471 static FILE *OpenConfFile( char *FileName )
 472   /* ------------------------------------------------------------------------ **
 473    * Open a configuration file.
 474    *
 475    *  Input:  FileName  - The pathname of the config file to be opened.
 476    *
 477    *  Output: A pointer of type (FILE *) to the opened file, or NULL if the
 478    *          file could not be opened.
 479    *
 480    * ------------------------------------------------------------------------ **
 481    */
 482   {
 483   FILE *OpenedFile;
 484   char *func = "params.c:OpenConfFile() -";
 485
 486   if( NULL == FileName || 0 == *FileName )
 487     {
 488     rprintf(FERROR,"%s No configuration filename specified.\n", func);
 489     return( NULL );
 490     }
 491
 492   OpenedFile = fopen( FileName, "r" );
 493   if( NULL == OpenedFile )
 494     {
 495     rsyserr(FERROR, errno, "unable to open configuration file \"%s\"",
 496             FileName);
 497     }
 498
 499   return( OpenedFile );
 500   } /* OpenConfFile */
 501
 502 BOOL pm_process( char *FileName,
 503                  BOOL (*sfunc)(char *),
 504                  BOOL (*pfunc)(char *, char *) )
 505   /* ------------------------------------------------------------------------ **
 506    * Process the named parameter file.
 507    *
 508    *  Input:  FileName  - The pathname of the parameter file to be opened.
 509    *          sfunc     - A pointer to a function that will be called when
 510    *                      a section name is discovered.
 511    *          pfunc     - A pointer to a function that will be called when
 512    *                      a parameter name and value are discovered.
 513    *
 514    *  Output: TRUE if the file was successfully parsed, else FALSE.
 515    *
 516    * ------------------------------------------------------------------------ **
 517    */
 518   {
 519   int   result;
 520   FILE *InFile;
 521   char *func = "params.c:pm_process() -";
 522
 523   InFile = OpenConfFile( FileName );          /* Open the config file. */
 524   if( NULL == InFile )
 525     return( False );
 526
 527   if( NULL != bufr )                          /* If we already have a buffer */
 528     result = Parse( InFile, sfunc, pfunc );   /* (recursive call), then just */
 529                                               /* use it.                     */
 530
 531   else                                        /* If we don't have a buffer   */
 532     {                                         /* allocate one, then parse,   */
 533     bSize = BUFR_INC;                         /* then free.                  */
 534     bufr = new_array( char, bSize );
 535     if( NULL == bufr )
 536       {
 537       rprintf(FERROR,"%s memory allocation failure.\n", func);
 538       fclose(InFile);
 539       return( False );
 540       }
 541     result = Parse( InFile, sfunc, pfunc );
 542     free( bufr );
 543     bufr  = NULL;
 544     bSize = 0;
 545     }
 546
 547   fclose(InFile);
 548
 549   if( !result )                               /* Generic failure. */
 550     {
 551     rprintf(FERROR,"%s Failed.  Error returned from params.c:parse().\n", func);
 552     return( False );
 553     }
 554
 555   return( True );                             /* Generic success. */
 556   } /* pm_process */
 557
 558 /* -------------------------------------------------------------------------- */
 559