libs/newlib-cygwin
libs/newlib-cygwin
4
0
Fork 0
mirror of git://sourceware.org/git/newlib-cygwin.git synced 2025-02-22 00:38:06 +08:00
Code Issues Projects Releases Wiki Activity

Cygwin: mmap: refactor mmap_record::match

Browse Source 
Slightly simplify the code and add comments to explain what the
function does.  Add a version of this method with a new reference
parameter "contains" that is set to true if the chunk of this
mmap_record contains the given address range.

Signed-off-by: Ken Brown <kbrown@cornell.edu>
This commit is contained in:
Ken Brown 2024-12-27 15:30:12 -05:00
parent 2e4db338ac
commit 5495179332
1 changed files with 25 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
winsup/cygwin/mm/mmap.cc
View File

@ -338,6 +338,8 @@ class mmap_record
void init_page_map (mmap_record &r);
SIZE_T find_unused_pages (SIZE_T pages) const;
bool match (caddr_t addr, SIZE_T len, caddr_t &m_addr, SIZE_T &m_len,
bool &contains);
bool match (caddr_t addr, SIZE_T len, caddr_t &m_addr, SIZE_T &m_len);
off_t map_pages (SIZE_T len, int new_prot);
bool map_pages (caddr_t addr, SIZE_T len, int new_prot);
@ -418,25 +420,42 @@ mmap_record::find_unused_pages (SIZE_T pages) const
return (SIZE_T) -1;
}
/* Return true if the interval I from addr to addr + len intersects
the interval J of this mmap_record. The endpoint of the latter is
first rounded up to a page boundary. If there is an intersection,
then it is the interval from m_addr to m_addr + m_len. The
variable 'contains' is set to true if J contains I.
*/
bool
mmap_record::match (caddr_t addr, SIZE_T len, caddr_t &m_addr, SIZE_T &m_len)
mmap_record::match (caddr_t addr, SIZE_T len, caddr_t &m_addr, SIZE_T &m_len,
bool &contains)
{
caddr_t low = (addr >= get_address ()) ? addr : get_address ();
contains = false;
caddr_t low = MAX (addr, get_address ());
caddr_t high = get_address ();
if (filler ())
high += get_len ();
else
high += (PAGE_CNT (get_len ()) * wincap.page_size ());
high = (addr + len < high) ? addr + len : high;
high = MIN (addr + len, high);
if (low < high)
{
m_addr = low;
m_len = high - low;
/* I is contained in J iff their intersection equals I. */
contains = (addr == m_addr && len == m_len);
return true;
}
return false;
}
inline bool
mmap_record:: match (caddr_t addr, SIZE_T len, caddr_t &m_addr, SIZE_T &m_len)
{
bool contains;
return match (addr, len, m_addr, m_len, contains);
}
void
mmap_record::init_page_map (mmap_record &r)
{
@ -653,14 +672,14 @@ mmap_list::try_map (void *addr, size_t len, int new_prot, int flags, off_t off)
request, try to reset the protection on the requested area. */
caddr_t u_addr;
SIZE_T u_len;
bool contains;
LIST_FOREACH (rec, &recs, mr_next)
if (rec->match ((caddr_t) addr, len, u_addr, u_len))
if (rec->match ((caddr_t) addr, len, u_addr, u_len, contains))
break;
if (rec)
{
if (u_addr > (caddr_t) addr || u_addr + u_len < (caddr_t) addr + len
|| !rec->compatible_flags (flags))
if (!contains || !rec->compatible_flags (flags))
{
/* Partial match only, or access mode doesn't match. */
/* FIXME: Handle partial mappings gracefully if adjacent