Fix #3 Add support for relative dates

Date formats

        Two date formats are allowed for dates arguments (-d , -m) :
        - the same than in the logfile
        - relative from now prefixing the argument with '#-' and given a unit
                - y : year
                - M : Month
                - d : day
                - h : hour
                - m : min
                - s : sec

src/include/ttail_init.h

@@ -44,6 +44,27 @@ POSIX) ",NULL},\
 	{"",NULL}\
 }
 
+#define TTAIL_HELP_TEXT "\tLOGFILES\n\t\tLogfiles, can take '-' as value to \
+tell ttail to read from stdin instead of files\n\n\
+Date formats\n\n\
+\tTwo date formats are allowed for dates arguments (-d , -m) :\n\
+\t- the same than in the logfile\n\
+\t- relative from now prefixing the argument with '#-' and given a unit\n\
+\t\t- y : year\n\
+\t\t- M : Month\n\
+\t\t- d : day\n\
+\t\t- h : hour\n\
+\t\t- m : min\n\
+\t\t- s : sec\n\
+"
+
+#define TTAIL_NORMDATE(ttail,tm,FIELD) {\
+	if(ttail->flag & TTAIL_FLAG_DATE_MIN && (tm)->FIELD == -1)\
+	{ ttail->date_min.FIELD = -1; }\
+	if(ttail->flag & TTAIL_FLAG_DATE_MAX && (tm)->FIELD == -1)\
+	{ ttail->date_max.FIELD = -1; }\
+}
+
 /**<! Print help & usage */
 void usage();
 
@@ -220,6 +241,50 @@ int ttail_set_flag_re_ci(ttail_t*);
  */
 int ttail_set_dates(ttail_t*, char*[2]);
 
+/**@brief Set a date using format or format detection
+ *
+ *@param ttail_t ttail instance
+ *@param char*[2] dates {min,max} both can be NULL
+ *@param int c the date id to handle
+ *@return -1 if error 0 else
+ */
+int _ttail_set_date_fmt(ttail_t*, char*, int);
+
+/**@brief Set a date relative from now
+ *
+ *Relative date formats are "-#", an integer followed by a unit. Regcognized
+ *units are :
+ *- y[ear]
+ *- M[onth]
+ *- d[ay]
+ *- h[our]
+ *- m[in]
+ *- s[ec]
+ *
+ *Examples :
+ *- -#2s
+ *- -#3Month
+ *@param ttail_t ttail instance
+ *@param char*[2] dates {min,max} both can be NULL
+ *@param int c the date id to handle
+ *@return -1 if error 0 else
+ *@todo checks
+ */
+int _ttail_set_date_relative(ttail_t*, char*, int);
+
+/**@brief Normalize dates
+ *
+ *When dates are relatives from now all the struct tm fields are set. In 
+ *logfiles year or seconds can be missing from date format. In those case we 
+ *have to set to -1 missing fields
+ *@note must be called after arg parsing, ttail_set_dates() calls and
+ *ttail_format_guess() calls
+ *@param ttail_t* An initialized ttail_t
+ *@return -1 if error 0 else
+ *@todo checks
+ */
+int _ttail_norm_dates(ttail_t*);
+
 /**@brief Attempt to guess a dateformat
  *@param ttail_t* ttail if manage to guess set the ttail_t.fmt
  *@param const char* date as a dtring

src/ttail_init.c

@@ -29,8 +29,7 @@ void usage()
 		printf("\t\t%s\n\n", help[i][0]);
 		i++;
 	}
-	printf("\tLOGFILES\n\t\tLogfiles, can take '-' as value to tell ttail \
-to read from stdin instead of files\n");
+	printf(TTAIL_HELP_TEXT);
 }
 
 ttail_t *ttail_init(int argc, char **argv)
@@ -398,33 +397,19 @@ int ttail_set_dates(ttail_t* res, char* dates[2])
 		{
 			continue;
 		}
-		if(!(res->flag & TTAIL_FLAG_FORMAT))
+		date = dates[c];
+		if(!strncmp(date, "#-", 2))
 		{
-			/* no format specified */
-			ret = ttail_format_guess(res, dates[c],
-				c==0?&(res->date_min):&(res->date_max));
-			if(ret < 0)
-			{
-				fprintf(stderr, "Unable to guess format for \
-date '%s'\n", dates[c]);
-				return -1;
-			}
-			res->flag |= c?TTAIL_FLAG_DATE_MAX:TTAIL_FLAG_DATE_MIN;
-			continue;
+			/* relative date */
+			ret = _ttail_set_date_relative(res, date, c);
 		}
-		date = strptime(dates[c], res->fmt, 
-			c==0?&(res->date_min):&(res->date_max));
-		if(!date)
+		else
 		{
-			fprintf(stderr, "Unable to parse date-%s '%s' with \
-format '%s'\n", c==0?"min":"max", dates[c], res->fmt);
-			return -1;
+			/* date from format */
+			ret = _ttail_set_date_fmt(res, date, c);
 		}
-		else if(*date != '\0')
+		if(ret < 0)
 		{
-			fprintf(stderr, "Leading caracters for date-%s : '%s' \
-is not matched in '%s'\n",\
-				c==0?"min":"max", date, dates[c]);
 			return -1;
 		}
 		res->flag |= c?TTAIL_FLAG_DATE_MAX:TTAIL_FLAG_DATE_MIN;
@@ -436,6 +421,217 @@ is not matched in '%s'\n",\
 	return 0;
 }
 
+int _ttail_set_date_fmt(ttail_t* res, char* date, int c)
+{
+	int ret;
+	char *endp;
+
+	if(!(res->flag & TTAIL_FLAG_FORMAT))
+	{
+		/* no format specified */
+		ret = ttail_format_guess(res, date,
+			c==0?&(res->date_min):&(res->date_max));
+		if(ret < 0)
+		{
+			fprintf(stderr, "Unable to guess format for \
+date '%s'\n", date);
+			return -1;
+		}
+		res->flag |= c?TTAIL_FLAG_DATE_MAX:TTAIL_FLAG_DATE_MIN;
+		return 0;
+	}
+	endp = strptime(date, res->fmt, 
+		c==0?&(res->date_min):&(res->date_max));
+	if(!endp)
+	{
+		fprintf(stderr, "Unable to parse date-%s '%s' with \
+format '%s'\n", c==0?"min":"max", date, res->fmt);
+		return -1;
+	}
+	else if(*endp != '\0')
+	{
+		fprintf(stderr, "Leading caracters for date-%s : '%s' \
+is not matched in '%s'\n",\
+			c==0?"min":"max", endp, date);
+		return -1;
+	}
+	return 0;
+}
+int _ttail_set_date_relative(ttail_t* res, char* date, int c)
+{
+	time_t now;
+	char *unit;
+	int value;
+	struct tm *tm, *tm_p;
+	short mod;
+	
+	tm = c==0?&(res->date_min):&(res->date_max);
+	ttail_tm_init(tm);
+	if(time(&now) < 0)
+	{
+		fprintf(stderr, "Unable to retrieve time using time()\n");
+		return -1;
+	}
+	if(!(tm_p = localtime(&now)))
+	{
+		fprintf(stderr, "Unable to retrieve localtime using localtime()\n");
+		return -1;
+	}
+
+	memcpy(tm, tm_p, sizeof(struct tm));
+
+	mod = 0;
+	unit = NULL;
+	value = (int)strtol(date+2, &unit, 10);
+	switch(*unit)
+	{
+		case 's':
+			if(*(unit+1) == '\0' || !strcmp(unit, "sec"))
+			{
+				tm->tm_sec -= value;
+				if(tm->tm_sec < 0)
+				{
+					mod = 1;
+					value = abs(tm->tm_sec);
+					tm->tm_sec = 60 - (value % 60);
+					value /= 60;
+					value++;
+				}
+				if(!mod)
+				{
+					break;
+				}
+			}
+		case 'm':
+			if(mod || *(unit+1) == '\0' || !strcmp(unit, "min"))
+			{
+				mod = 0;
+				tm->tm_min -= value;
+				if(tm->tm_min < 0)
+				{
+					mod = 1;
+					value = abs(tm->tm_min);
+					tm->tm_min = 60 - (value % 60);
+					value /= 60;
+					value++;
+					printf("Value left : %d\n", value);
+				}
+				if(!mod)
+				{
+					break;
+				}
+			}
+		case 'h':
+			if(mod || *(unit+1) == '\0' || !strcmp(unit, "hour"))
+			{
+				mod = 0;
+				tm->tm_hour -= value;
+				if(tm->tm_hour < 0)
+				{
+					mod = 1;
+					value = abs(tm->tm_hour);
+					tm->tm_hour = 24 - (value % 24);
+					value /= 24;
+					value++;
+				}
+				if(!mod)
+				{
+					break;
+				}
+			}
+		case 'd':
+			if(mod || *(unit+1) == '\0' || !strcmp(unit, "day"))
+			{
+				mod = 0;
+				tm->tm_mday -= value;
+				if(tm->tm_mday < 0)
+				{
+					mod = 1;
+					value = abs(tm->tm_mday);
+					tm->tm_mday = 31 - (value % 31);
+					value /= 31;
+					value++;
+				}
+				if(!mod)
+				{
+					break;
+				}
+			}
+		case 'M':
+			if(*(unit+1) == '\0' || !strcmp(unit, "Month"))
+			{
+				mod = 0;
+				tm->tm_mon -= value;
+				if(tm->tm_mon < 0)
+				{
+					mod = 1;
+					value = abs(tm->tm_mon);
+					tm->tm_mon = 12 - (value % 12);
+					value /= 12;
+					value++;
+				}
+				if(!mod)
+				{
+					break;
+				}
+			}
+		case 'y':
+			if(mod || *(unit+1) == '\0' || !strcmp(unit, "year"))
+			{
+				tm->tm_year -= value;
+				break;
+			}
+		default:
+			fprintf(stderr,"Invalid relative date '%s'\n", date);
+			return -1;
+	}
+	return 0;
+
+}
+
+int _ttail_norm_dates(ttail_t* ttail)
+{
+	struct tm *tm_p, tm;
+	/* Huge buffer but no way to make a difference between error and
+	   buffer too small using strftime */
+	char date[4096], *endp;
+	size_t date_len;
+	time_t now;
+
+	if(time(&now) < 0)
+	{
+		perror("Unable to retrieve time using time()\n");
+		return -1;
+	}
+	if(!(tm_p = localtime(&now)))
+	{
+		perror("Unable to retrieve localtime using localtime()\n");
+		return -1;
+	}
+	if(!(date_len = strftime(date, sizeof(date), ttail->fmt, tm_p)))
+	{
+		fprintf(stderr, "Unable to print the current date using strftime()\n");
+		return -1;
+	}
+	ttail_tm_init(&tm);
+	endp = strptime(date, ttail->fmt, &tm);
+	if(!endp || *endp != '\0')
+	{
+		fprintf(stderr, "An error occured, unable to strptime() a date\
+we just strftime() !\n");
+		exit(EXIT_FAILURE);
+	}
+	
+	TTAIL_NORMDATE(ttail, &tm, tm_sec);
+	TTAIL_NORMDATE(ttail, &tm, tm_min);
+	TTAIL_NORMDATE(ttail, &tm, tm_hour);
+	TTAIL_NORMDATE(ttail, &tm, tm_mday);
+	TTAIL_NORMDATE(ttail, &tm, tm_mon);
+	TTAIL_NORMDATE(ttail, &tm, tm_year);
+	
+	return 0;
+}
+
 int ttail_format_guess(ttail_t* t, const char* date_str, struct tm* tm)
 {
 	int i, res;