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

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;
+}

lib/parse_ini.h

@@ -0,0 +1,19 @@
+#ifndef _PARSE_INI_H_
+#define _PARSE_INI_H_
+
+/*
+ * parse_ini.h: routines for loading nagios-plugin defaults from ini
+ * configuration files.
+ */
+
+/* NP_DEFAULT_INI_PATH: compile-time default location for ini file */
+#ifndef NP_DEFAULT_INI_PATH
+# define NP_DEFAULT_INI_PATH "/etc/nagios-plugins/plugins.ini"
+#endif /* NP_DEFAULT_INI_PATH */
+
+/* np_load_defaults: load the default configuration (if present) for
+ * a plugin from the ini file
+ */
+char* np_get_defaults(const char *locator, const char *default_section);
+
+#endif /* _PARSE_INI_H_ */