initial version of ini file parsing routines in C

git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@1610 f882894a-f735-0410-b71e-b25c423dba1c

1 files changed, 247 insertions, 0 deletions

diff --git a/lib/parse_ini.c b/lib/parse_ini.c
new file mode 100644
index 0000000..5155b6d
--- /dev/null
+++ b/lib/parse_ini.c
@@ -0,0 +1,247 @@
+#include "common.h"
+#include "parse_ini.h"
+#include "utils_base.h"
+#include <ctype.h>
+
+/* np_ini_info contains the result of parsing a "locator" in the format
+ * [stanza_name][@config_filename] (check_foo@/etc/foo.ini, for example)
+ */
+typedef struct {
+        char *file;
+        char *stanza;
+} np_ini_info;
+
+/* eat all characters from a FILE pointer until n is encountered */
+#define GOBBLE_TO(f, c, n) do { (c)=fgetc((f)); } while((c)!=EOF && (c)!=(n))
+
+/* internal function that returns the constructed defaults options */
+static char* read_defaults(FILE *f, const char *stanza);
+/* internal function that converts a single line into options format */
+static int add_option(FILE *f, char **optbuf, size_t *bufsize);
+
+/* parse_locator decomposes a string of the form
+ *      [stanza][@filename]
+ * into its seperate parts
+ */
+static void parse_locator(const char *locator, const char *def_stanza, np_ini_info *i){
+        size_t locator_len, stanza_len;
+
+        locator_len=strlen(locator);
+        stanza_len=strcspn(locator, "@");
+        /* if a non-default stanza is provided */
+        if(stanza_len>0){
+                i->stanza=(char*)malloc(sizeof(char)*(stanza_len+1));
+                strncpy(i->stanza, locator, stanza_len);
+                i->stanza[stanza_len]='\0';
+        } else { /* otherwise we use the default stanza */
+                i->stanza=strdup(def_stanza);
+        }
+        /* if there is no @file part */
+        if(stanza_len==locator_len){
+                i->file=strdup(NP_DEFAULT_INI_PATH);
+        } else {
+                i->file=strdup(&(locator[stanza_len+1]));
+        }
+        
+        if(i->file==NULL || i->stanza==NULL){
+                die(STATE_UNKNOWN, _("malloc() failed!\n"));
+        }
+}
+
+/* this is the externally visible function used by plugins */
+char* np_get_defaults(const char *locator, const char *default_section){
+        FILE *inifile=NULL;
+        char *defaults=NULL;
+        np_ini_info i;
+
+        parse_locator(locator, default_section, &i);
+        /* if a file was specified or if we're using the default file */
+        if(i.file != NULL && strlen(i.file) > 0){
+                if(strcmp(i.file, "-")==0){
+                        inifile=stdout;
+                } else {
+                        inifile=fopen(i.file, "r");
+                }
+                if(inifile==NULL) die(STATE_UNKNOWN, _("Config file error"));
+                defaults=read_defaults(inifile, i.stanza);
+                free(i.file);
+                if(inifile!=stdout) fclose(inifile);
+        }
+        free(i.stanza);
+        return defaults;        
+}
+
+/* read_defaults is where the meat of the parsing takes place.
+ *
+ * note that this may be called by a setuid binary, so we need to
+ * be extra careful about user-supplied input (i.e. avoiding possible
+ * format string vulnerabilities, etc)
+ */
+static char* read_defaults(FILE *f, const char *stanza){
+        int c;
+        char *opts=NULL;
+        size_t i, stanza_len, opts_buf_size=0;
+        enum { NOSTANZA, WRONGSTANZA, RIGHTSTANZA } stanzastate=NOSTANZA;
+
+        stanza_len=strlen(stanza);
+
+        /* our little stanza-parsing state machine.  */
+        while((c=fgetc(f))!=EOF){
+                /* gobble up leading whitespace */
+                if(isspace(c)) continue;
+                switch(c){
+                        /* globble up coment lines */
+                        case '#':
+                                GOBBLE_TO(f, c, '\n');
+                                break;
+                        /* start of a stanza.  check to see if it matches */
+                        case '[':
+                                stanzastate=WRONGSTANZA;
+                                for(i=0; i<stanza_len; i++){
+                                        c=fgetc(f);
+                                        /* nope, read to the end of the stanza header */
+                                        if(c!=stanza[i]) {
+                                                GOBBLE_TO(f, c, ']');
+                                                break;
+                                        }
+                                }
+                                /* if it matched up to here and the next char is ']'... */
+                                if(i==stanza_len){
+                                        c=fgetc(f);
+                                        if(c==']') stanzastate=RIGHTSTANZA;
+                                }
+                                break;
+                        /* otherwise, we're in the body of a stanza or a parse error */
+                        default:
+                                switch(stanzastate){
+                                        /* we never found the start of the first stanza, so
+                                         * we're dealing with a config error 
+                                         */
+                                        case NOSTANZA:
+                                                die(STATE_UNKNOWN, _("Config file error"));
+                                                break;
+                                        /* we're in a stanza, but for a different plugin */
+                                        case WRONGSTANZA:
+                                                GOBBLE_TO(f, c, '\n');
+                                                break;
+                                        /* okay, this is where we start taking the config */
+                                        case RIGHTSTANZA:
+                                                ungetc(c, f);
+                                                if(add_option(f, &opts, &opts_buf_size)){
+                                                        die(STATE_UNKNOWN, _("Config file error"));
+                                                }
+                                                break;
+                                }
+                                break;
+                }
+        }
+        return opts;
+}
+
+/*
+ * read one line of input in the format
+ *      ^option[[:space:]]*(=[[:space:]]*value)?
+ * and creates it as a cmdline argument
+ *      --option[=value]
+ * appending it to the string pointed to by optbuf (which will
+ * be dynamically grown if needed)
+ */
+static int add_option(FILE *f, char **optbuf, size_t *bufsize){
+        char *newbuf=*optbuf;
+        char *linebuf=NULL, *lineend=NULL, *optptr=NULL, *optend=NULL;
+        char *eqptr=NULL, *valptr=NULL, *spaceptr=NULL, *valend=NULL;
+        short done_reading=0, equals=0, value=0;
+        size_t cfg_len=0, read_sz=8, linebuf_sz=0, read_pos=0, bs=*bufsize;
+        size_t opt_len=0, val_len=0;
+
+        /* read one line from the file */
+        while(!done_reading){
+                /* grow if necessary */
+                if(linebuf==NULL || read_pos+read_sz >= linebuf_sz){
+                        linebuf_sz=(linebuf_sz>0)?linebuf_sz<<1:read_sz;
+                        linebuf=realloc(linebuf, linebuf_sz);
+                        if(linebuf==NULL) die(STATE_UNKNOWN, _("malloc() failed!\n"));
+                }
+                if(fgets(&linebuf[read_pos], read_sz, f)==NULL) done_reading=1;
+                else {
+                        read_pos=strlen(linebuf);
+                        if(linebuf[read_pos-1]=='\n') {
+                                linebuf[--read_pos]='\0';
+                                done_reading=1;
+                        }
+                }
+        }
+        lineend=&linebuf[read_pos];
+        /* all that to read one line.  isn't C fun? :) now comes the parsing :/ */
+
+        /* skip leading whitespace */
+        for(optptr=linebuf; optptr<lineend && isspace(*optptr); optptr++);
+        /* continue to '=' or EOL, watching for spaces that might precede it */
+        for(eqptr=optptr; eqptr<lineend && *eqptr!='='; eqptr++){
+                if(isspace(*eqptr) && optend==NULL) optend=eqptr;
+                else optend=NULL;
+        }
+        if(optend==NULL) optend=eqptr;
+        --optend;
+        /* ^[[:space:]]*=foo is a syntax error */
+        if(optptr==eqptr) die(STATE_UNKNOWN, _("Config file error\n"));
+        /* continue from '=' to start of value or EOL */
+        for(valptr=eqptr+1; valptr<lineend && isspace(*valptr); valptr++);
+        /* continue to the end of value, watching for trailing space/comments */
+        for(valend=valptr; valend<lineend; valend++){
+                if(isspace(*valend) && spaceptr==NULL) spaceptr=valend;
+                else if(*valend=='#') break;
+                else spaceptr=NULL;
+        }
+        if(spaceptr!=NULL) valend=spaceptr;
+        --valend;
+        /* calculate the length of "--foo" */
+        opt_len=1+optend-optptr;
+        cfg_len=2+(opt_len);
+        /* if valptr<lineend then we have to also allocate space for "=bar" */
+        if(valptr<lineend) {
+                equals=value=1;
+                val_len=1+valend-valptr;
+                cfg_len+=1+val_len;
+        }
+        /* if valptr==valend then we have "=" but no "bar" */
+        else if (valptr==lineend) {
+                equals=1;
+                cfg_len+=1;
+        }
+
+        /* okay, now we have all the info we need, so we grow the default opts
+         * buffer if it's necessary, and put everything together.
+         * (+2 is for a potential space and a null byte)
+         */
+        read_pos=(newbuf==NULL)?0:strlen(newbuf);
+        if(newbuf==NULL || read_pos+cfg_len+2 >= bs){
+                bs=(bs>0)?(bs+cfg_len+2)<<1:cfg_len+1;
+                newbuf=realloc(newbuf, bs);
+                if(newbuf==NULL) die(STATE_UNKNOWN, _("malloc() failed!\n"));
+        }
+        if(read_pos>0) newbuf[read_pos++]=' ';
+        strncpy(&newbuf[read_pos], "--", 2); read_pos+=2;
+        strncpy(&newbuf[read_pos], optptr, opt_len); read_pos+=opt_len;
+        if(equals) newbuf[read_pos++]='=';
+        if(value) {
+                strncpy(&newbuf[read_pos], valptr, val_len); read_pos+=val_len;
+        }
+        newbuf[read_pos]='\0';
+
+        *optbuf=newbuf;
+        *bufsize=bs;
+
+        free(linebuf);
+        return 0;
+}
+
+int main(){
+        char *optstr=NULL;
+        optstr=np_get_defaults("check_foo@./foo.ini", "check_bar");
+        if(optstr!=NULL) {
+                printf("optstr:\n\t%s\n", optstr);
+                free(optstr);
+        }
+        return 0;
+}