lib/parse_ini.c

   1 #include "common.h"
   2 #include "parse_ini.h"
   3 #include "utils_base.h"
   4 #include <ctype.h>
   5
   6 /* np_ini_info contains the result of parsing a "locator" in the format
   7  * [stanza_name][@config_filename] (check_foo@/etc/foo.ini, for example)
   8  */
   9 typedef struct {
  10         char *file;
  11         char *stanza;
  12 } np_ini_info;
  13
  14 /* eat all characters from a FILE pointer until n is encountered */
  15 #define GOBBLE_TO(f, c, n) do { (c)=fgetc((f)); } while((c)!=EOF && (c)!=(n))
  16
  17 /* internal function that returns the constructed defaults options */
  18 static char* read_defaults(FILE *f, const char *stanza);
  19 /* internal function that converts a single line into options format */
  20 static int add_option(FILE *f, char **optbuf, size_t *bufsize);
  21
  22 /* parse_locator decomposes a string of the form
  23  *      [stanza][@filename]
  24  * into its seperate parts
  25  */
  26 static void parse_locator(const char *locator, const char *def_stanza, np_ini_info *i){
  27         size_t locator_len, stanza_len;
  28
  29         locator_len=strlen(locator);
  30         stanza_len=strcspn(locator, "@");
  31         /* if a non-default stanza is provided */
  32         if(stanza_len>0){
  33                 i->stanza=(char*)malloc(sizeof(char)*(stanza_len+1));
  34                 strncpy(i->stanza, locator, stanza_len);
  35                 i->stanza[stanza_len]='\0';
  36         } else { /* otherwise we use the default stanza */
  37                 i->stanza=strdup(def_stanza);
  38         }
  39         /* if there is no @file part */
  40         if(stanza_len==locator_len){
  41                 i->file=strdup(NP_DEFAULT_INI_PATH);
  42         } else {
  43                 i->file=strdup(&(locator[stanza_len+1]));
  44         }
  45
  46         if(i->file==NULL || i->stanza==NULL){
  47                 die(STATE_UNKNOWN, _("malloc() failed!\n"));
  48         }
  49 }
  50
  51 /* this is the externally visible function used by plugins */
  52 char* np_get_defaults(const char *locator, const char *default_section){
  53         FILE *inifile=NULL;
  54         char *defaults=NULL;
  55         np_ini_info i;
  56
  57         parse_locator(locator, default_section, &i);
  58         /* if a file was specified or if we're using the default file */
  59         if(i.file != NULL && strlen(i.file) > 0){
  60                 if(strcmp(i.file, "-")==0){
  61                         inifile=stdout;
  62                 } else {
  63                         inifile=fopen(i.file, "r");
  64                 }
  65                 if(inifile==NULL) die(STATE_UNKNOWN, _("Config file error"));
  66                 defaults=read_defaults(inifile, i.stanza);
  67                 free(i.file);
  68                 if(inifile!=stdout) fclose(inifile);
  69         }
  70         free(i.stanza);
  71         return defaults;
  72 }
  73
  74 /* read_defaults is where the meat of the parsing takes place.
  75  *
  76  * note that this may be called by a setuid binary, so we need to
  77  * be extra careful about user-supplied input (i.e. avoiding possible
  78  * format string vulnerabilities, etc)
  79  */
  80 static char* read_defaults(FILE *f, const char *stanza){
  81         int c;
  82         char *opts=NULL;
  83         size_t i, stanza_len, opts_buf_size=0;
  84         enum { NOSTANZA, WRONGSTANZA, RIGHTSTANZA } stanzastate=NOSTANZA;
  85
  86         stanza_len=strlen(stanza);
  87
  88         /* our little stanza-parsing state machine.  */
  89         while((c=fgetc(f))!=EOF){
  90                 /* gobble up leading whitespace */
  91                 if(isspace(c)) continue;
  92                 switch(c){
  93                         /* globble up coment lines */
  94                         case '#':
  95                                 GOBBLE_TO(f, c, '\n');
  96                                 break;
  97                         /* start of a stanza.  check to see if it matches */
  98                         case '[':
  99                                 stanzastate=WRONGSTANZA;
 100                                 for(i=0; i<stanza_len; i++){
 101                                         c=fgetc(f);
 102                                         /* nope, read to the end of the stanza header */
 103                                         if(c!=stanza[i]) {
 104                                                 GOBBLE_TO(f, c, ']');
 105                                                 break;
 106                                         }
 107                                 }
 108                                 /* if it matched up to here and the next char is ']'... */
 109                                 if(i==stanza_len){
 110                                         c=fgetc(f);
 111                                         if(c==']') stanzastate=RIGHTSTANZA;
 112                                 }
 113                                 break;
 114                         /* otherwise, we're in the body of a stanza or a parse error */
 115                         default:
 116                                 switch(stanzastate){
 117                                         /* we never found the start of the first stanza, so
 118                                          * we're dealing with a config error
 119                                          */
 120                                         case NOSTANZA:
 121                                                 die(STATE_UNKNOWN, _("Config file error"));
 122                                                 break;
 123                                         /* we're in a stanza, but for a different plugin */
 124                                         case WRONGSTANZA:
 125                                                 GOBBLE_TO(f, c, '\n');
 126                                                 break;
 127                                         /* okay, this is where we start taking the config */
 128                                         case RIGHTSTANZA:
 129                                                 ungetc(c, f);
 130                                                 if(add_option(f, &opts, &opts_buf_size)){
 131                                                         die(STATE_UNKNOWN, _("Config file error"));
 132                                                 }
 133                                                 break;
 134                                 }
 135                                 break;
 136                 }
 137         }
 138         return opts;
 139 }
 140
 141 /*
 142  * read one line of input in the format
 143  *      ^option[[:space:]]*(=[[:space:]]*value)?
 144  * and creates it as a cmdline argument
 145  *      --option[=value]
 146  * appending it to the string pointed to by optbuf (which will
 147  * be dynamically grown if needed)
 148  */
 149 static int add_option(FILE *f, char **optbuf, size_t *bufsize){
 150         char *newbuf=*optbuf;
 151         char *linebuf=NULL, *lineend=NULL, *optptr=NULL, *optend=NULL;
 152         char *eqptr=NULL, *valptr=NULL, *spaceptr=NULL, *valend=NULL;
 153         short done_reading=0, equals=0, value=0;
 154         size_t cfg_len=0, read_sz=8, linebuf_sz=0, read_pos=0, bs=*bufsize;
 155         size_t opt_len=0, val_len=0;
 156
 157         /* read one line from the file */
 158         while(!done_reading){
 159                 /* grow if necessary */
 160                 if(linebuf==NULL || read_pos+read_sz >= linebuf_sz){
 161                         linebuf_sz=(linebuf_sz>0)?linebuf_sz<<1:read_sz;
 162                         linebuf=realloc(linebuf, linebuf_sz);
 163                         if(linebuf==NULL) die(STATE_UNKNOWN, _("malloc() failed!\n"));
 164                 }
 165                 if(fgets(&linebuf[read_pos], read_sz, f)==NULL) done_reading=1;
 166                 else {
 167                         read_pos=strlen(linebuf);
 168                         if(linebuf[read_pos-1]=='\n') {
 169                                 linebuf[--read_pos]='\0';
 170                                 done_reading=1;
 171                         }
 172                 }
 173         }
 174         lineend=&linebuf[read_pos];
 175         /* all that to read one line.  isn't C fun? :) now comes the parsing :/ */
 176
 177         /* skip leading whitespace */
 178         for(optptr=linebuf; optptr<lineend && isspace(*optptr); optptr++);
 179         /* continue to '=' or EOL, watching for spaces that might precede it */
 180         for(eqptr=optptr; eqptr<lineend && *eqptr!='='; eqptr++){
 181                 if(isspace(*eqptr) && optend==NULL) optend=eqptr;
 182                 else optend=NULL;
 183         }
 184         if(optend==NULL) optend=eqptr;
 185         --optend;
 186         /* ^[[:space:]]*=foo is a syntax error */
 187         if(optptr==eqptr) die(STATE_UNKNOWN, _("Config file error\n"));
 188         /* continue from '=' to start of value or EOL */
 189         for(valptr=eqptr+1; valptr<lineend && isspace(*valptr); valptr++);
 190         /* continue to the end of value, watching for trailing space/comments */
 191         for(valend=valptr; valend<lineend; valend++){
 192                 if(isspace(*valend) && spaceptr==NULL) spaceptr=valend;
 193                 else if(*valend=='#') break;
 194                 else spaceptr=NULL;
 195         }
 196         if(spaceptr!=NULL) valend=spaceptr;
 197         --valend;
 198         /* calculate the length of "--foo" */
 199         opt_len=1+optend-optptr;
 200         cfg_len=2+(opt_len);
 201         /* if valptr<lineend then we have to also allocate space for "=bar" */
 202         if(valptr<lineend) {
 203                 equals=value=1;
 204                 val_len=1+valend-valptr;
 205                 cfg_len+=1+val_len;
 206         }
 207         /* if valptr==valend then we have "=" but no "bar" */
 208         else if (valptr==lineend) {
 209                 equals=1;
 210                 cfg_len+=1;
 211         }
 212
 213         /* okay, now we have all the info we need, so we grow the default opts
 214          * buffer if it's necessary, and put everything together.
 215          * (+2 is for a potential space and a null byte)
 216          */
 217         read_pos=(newbuf==NULL)?0:strlen(newbuf);
 218         if(newbuf==NULL || read_pos+cfg_len+2 >= bs){
 219                 bs=(bs>0)?(bs+cfg_len+2)<<1:cfg_len+1;
 220                 newbuf=realloc(newbuf, bs);
 221                 if(newbuf==NULL) die(STATE_UNKNOWN, _("malloc() failed!\n"));
 222         }
 223         if(read_pos>0) newbuf[read_pos++]=' ';
 224         strncpy(&newbuf[read_pos], "--", 2); read_pos+=2;
 225         strncpy(&newbuf[read_pos], optptr, opt_len); read_pos+=opt_len;
 226         if(equals) newbuf[read_pos++]='=';
 227         if(value) {
 228                 strncpy(&newbuf[read_pos], valptr, val_len); read_pos+=val_len;
 229         }
 230         newbuf[read_pos]='\0';
 231
 232         *optbuf=newbuf;
 233         *bufsize=bs;
 234
 235         free(linebuf);
 236         return 0;
 237 }
 238