You may know that the strlen() function computes the length of the string *without" the \0 char !
Example : if buffer = "AAAAA[...]AAA" = 0x2001 buffer_size = strlen(buffer) = 0x2000. apr_mem_remap(Map, buffer_size+1) = will map 0x3000 see apr_mem_pager(). memcpy(Map->base, buffer, buffer_size); strlen(Map->base) = 0x2000 Regards, Michael Vergoz Le Jeudi 30 Juin 2005 00:41, Bruce Korb a écrit : > Michael Vergoz wrote: > > Hi Bruce, > > > > Yes > > Thank you! > > > because you must align the page to the biggest you can. > > ?? The problem is is that no matter how you align the thing, > if the last byte of the file is the last byte of a page, > then the next byte is unmapped. Consequently, when "strlen(3C)" > tries to determine if the next byte after the last valid byte > is NUL or not, it faults on a bad memory reference. There > are several solutions: > > Punt mmap and just read the file into an allocated buffer. > > mmap the file then figure out if the last byte is the last > byte of a page. If so, then mmap anonymous memory into > the fixed address following the last page of the text file. > I do this, but it is a real pain. I hate it. :-) Most > often, I just allocate and read the file 'cuz it is easier. > > > Have a look at : http://badcode.be/~descript/.apache/ > > > > Into function apr_mem_pager() : > > if you need 0x2001 (Size). > > <snip> > > ret = size; // ret = 0x2001 > > if((ret%_apr_mem_page_size) != 0) { // 0x0001 > > ret -= (ret%_apr_mem_page_size); // ret -= 0x0001 = 0x2000 > > ret += _apr_mem_page_size*map->pager; // ret += 0x1000*PAGER > > } > > </snip> > > Right. If "size" is 0x2000 exactly, the byte following the > mapping will be unmapped and "strlen(3C)" will fault. > That's the problem.$ > > > You may have a look at apr_mem_remap(). It will allow you to ask for a > > unaligned address. Then the engine will auto update the address > > alignment with a predefined pager (defined by the pager argument in > > apr_mem_map()). > > OK. So, if I check the file size and it is a multiple of a page size, > then I should ask for non-aligned mapping, otherwise an aligned mapping? > Better than messing around with anonymous pages on my own, but still..... > > Thanks. Regards, Bruce
