Better error handling

Add some perror calls

src/ttail_search_files.c

 			(const struct tm**)ftm, 0);
 		if(ret)
 		{
+			if(t->verbose > 2)
+			{
+				fprintf(stderr, "Error while looking for \
+date-max\n");
+			}
 			goto _ttail_search_closest_files_err;
 		}
 		t->session->file.off_max.off++;
 			ret = _ttail_search_file_binary_search(t, in, ftm, min);
 			if(ret)
 			{
+				if(t->verbose > 2)
+				{
+					fprintf(stderr, "Error while \
+running binary search algorithm in '%s'\n", t->logfile_name[*id]);
+				}
 				*id = 0;
 				return ret;
 			}
 		if(cur > prev)
 		{
 			cur = _ttail_file_next_line(t->logfile[id]);
+			if(cur < 0)
+			{
+				/* not sure errno is really set */
+				perror("Error searching previous line");
+				return -1;
+			}
 		}
 		else
-		{
-			cur = _ttail_file_start_line(t->logfile[id]);
-		}
-		if(cur < -1)
 		{
 			cur = _ttail_file_start_line(t->logfile[id]);
 			if(cur < 0)
 			{
+				/* not sure errno is really set */
+				perror("Error searching previous line");
 				return -1;
 			}
 		}
 		ret = _ttail_file_cur_cmp(t, id, in, &cmpres);
 		if(ret < 0)
 		{
+			if(t->verbose > 2)
+			{
+				fprintf(stderr, "Error comparing a logline \
+to a date directly from a file\n");
+			}
 			return -1;
 		}
 		else if(cmpres == 0)
 	r=0;
 	buff = NULL;
 	s = getline(&buff, &r, f);
-	if(s == -1)
+	if(s < 0)
 	{
 		goto _ttail_file_next_line_err;
 	}
 		{
 			if(fseek(f, -1, SEEK_CUR)<0)
 			{
+				perror("Unable to set position in file");
 				goto _ttail_file_next_line_err;
 			}
 			break;
 
 	if((start = ftell(f)) < 0)
 	{
+		perror("Unable to get position in file");
 		return -1;
 	}
 	res = 0;
 	{
 		if(fseek(f, read_beg, SEEK_SET) < 0)
 		{
+			perror("Unable to set position in file");
 			return -1;
 		}
 		start = read_beg;
 		read_beg = start - read_sz;
 		if(fseek(f, read_beg, SEEK_SET) < 0)
 		{
+			perror("Unable to set position in file");
 			return -1;
 		}
 		last = -1; /* last pos we saw a '\n' */
 	}
 	if(fseek(f, res, SEEK_SET) < 0)
 	{
+		perror("Unable to set position in file");
 		return -1;
 	}
 	return res;