[GRASS-dev] new v.support metadata module

[Paul Kelly]

Hello Markus

On Thu, 15 Mar 2007, Markus Neteler wrote:

> Known bug: long comments are crashing it, I don't know why (C string programming
> and me are somewhat orthogonal to each other) - please someone take a look.

G_strcat() does not enlarge the memory allocated for the string you are 
appending to - it just adds the new string on to the end but the memory 
bytes after the end were probably reserved for something else, so that is 
a problem. You could enlarge the space allocated for Map.head.line_3 using 
perhaps G_realloc() before appending the new comment to it, but IMHO that 
would be a bad idea too as it is bad to modify the internal parameters of 
the struct Map_info without using vector library functions to do it.

I think it would be better to use a temporary string for the new comment. 
Something like:

char *temp;

G_asprintf(&temp, "%s%s", Map.head.line_3, comment->answer);

Vect_set_comment(&Map, temp);

Then you are never messing directly with the internals of the Map_info 
struct and G_asprintf() will ensure enough memory is allocated to hold the 
two strings concatenated together.

But I wonder too should there not be a newline character in there 
somewhere as the documentation says the comment text is added to the next 
line? Also don't understand the second example where a space " " is 
appended to the comment?

Also it might be useful to have a flag that would totally over-write the 
comment rather than appending, with a big warning in the description of 
course.

Paul