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msvcrt: Avoid using global critical section while allocating new file descriptors.

This commit is contained in:
Piotr Caban 2015-06-10 18:12:53 +02:00 committed by Alexandre Julliard
parent e7fc237088
commit 6ed69c107f
1 changed files with 47 additions and 99 deletions
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146
dlls/msvcrt/file.c
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@ -114,9 +114,6 @@ ioinfo * MSVCRT___pioinfo[MSVCRT_MAX_FILES/MSVCRT_FD_BLOCK_SIZE] = { 0 };
*/ */
ioinfo MSVCRT___badioinfo = { INVALID_HANDLE_VALUE, WX_TEXT }; ioinfo MSVCRT___badioinfo = { INVALID_HANDLE_VALUE, WX_TEXT };
static int MSVCRT_fdstart = 3; /* first unallocated fd */
static int MSVCRT_fdend = 3; /* highest allocated fd */
typedef struct { typedef struct {
MSVCRT_FILE file; MSVCRT_FILE file;
CRITICAL_SECTION crit; CRITICAL_SECTION crit;
@ -143,12 +140,9 @@ static const ULONGLONG WCBAT = TOUL('b') << 32 | TOUL('a') << 16 | TOUL('t');
static const ULONGLONG WCCMD = TOUL('c') << 32 | TOUL('m') << 16 | TOUL('d'); static const ULONGLONG WCCMD = TOUL('c') << 32 | TOUL('m') << 16 | TOUL('d');
static const ULONGLONG WCCOM = TOUL('c') << 32 | TOUL('o') << 16 | TOUL('m'); static const ULONGLONG WCCOM = TOUL('c') << 32 | TOUL('o') << 16 | TOUL('m');
/* This critical section protects the tables MSVCRT___pioinfo and MSVCRT_fstreams, /* This critical section protects the MSVCRT_fstreams table
* and their related indexes, MSVCRT_fdstart, MSVCRT_fdend, * and MSVCRT_stream_idx from race conditions. It also
* and MSVCRT_stream_idx, from race conditions. * protects fd critical sections creation code.
* It doesn't protect against race conditions manipulating the underlying files
* or flags; doing so would probably be better accomplished with per-file
* protection, rather than locking the whole table for every change.
*/ */
static CRITICAL_SECTION MSVCRT_file_cs; static CRITICAL_SECTION MSVCRT_file_cs;
static CRITICAL_SECTION_DEBUG MSVCRT_file_cs_debug = static CRITICAL_SECTION_DEBUG MSVCRT_file_cs_debug =
@ -257,19 +251,24 @@ static inline ioinfo* get_ioinfo_nolock(int fd)
return ret + (fd%MSVCRT_FD_BLOCK_SIZE); return ret + (fd%MSVCRT_FD_BLOCK_SIZE);
} }
static inline void init_ioinfo_cs(ioinfo *info)
{
if(!(info->exflag & EF_CRIT_INIT)) {
LOCK_FILES();
if(!(info->exflag & EF_CRIT_INIT)) {
InitializeCriticalSection(&info->crit);
info->exflag |= EF_CRIT_INIT;
}
UNLOCK_FILES();
}
}
static inline ioinfo* get_ioinfo(int fd) static inline ioinfo* get_ioinfo(int fd)
{ {
ioinfo *ret = get_ioinfo_nolock(fd); ioinfo *ret = get_ioinfo_nolock(fd);
if(ret == &MSVCRT___badioinfo) if(ret == &MSVCRT___badioinfo)
return ret; return ret;
if(!(ret->exflag & EF_CRIT_INIT)) { init_ioinfo_cs(ret);
LOCK_FILES();
if(!(ret->exflag & EF_CRIT_INIT)) {
InitializeCriticalSection(&ret->crit);
ret->exflag |= EF_CRIT_INIT;
}
UNLOCK_FILES();
}
EnterCriticalSection(&ret->crit); EnterCriticalSection(&ret->crit);
return ret; return ret;
} }
@ -301,77 +300,49 @@ static inline BOOL alloc_pioinfo_block(int fd)
static inline ioinfo* get_ioinfo_alloc_fd(int fd) static inline ioinfo* get_ioinfo_alloc_fd(int fd)
{ {
ioinfo *ret, *info; ioinfo *ret;
ret = get_ioinfo(fd); ret = get_ioinfo(fd);
if(ret != &MSVCRT___badioinfo) if(ret != &MSVCRT___badioinfo)
{
LOCK_FILES();
/* locate next free slot */
if (fd == MSVCRT_fdstart && fd == MSVCRT_fdend)
MSVCRT_fdstart = MSVCRT_fdend + 1;
else if (fd == MSVCRT_fdstart)
{
MSVCRT_fdstart++;
while (MSVCRT_fdstart < MSVCRT_fdend &&
((info = get_ioinfo_nolock(MSVCRT_fdstart))->exflag & EF_CRIT_INIT))
{
if (TryEnterCriticalSection(&info->crit))
{
if (info->handle == INVALID_HANDLE_VALUE)
{
LeaveCriticalSection(&info->crit);
break;
}
LeaveCriticalSection(&info->crit);
}
MSVCRT_fdstart++;
}
}
/* update last fd in use */
if (fd >= MSVCRT_fdend)
MSVCRT_fdend = fd + 1;
TRACE("fdstart is %d, fdend is %d\n", MSVCRT_fdstart, MSVCRT_fdend);
UNLOCK_FILES();
return ret; return ret;
}
if(!alloc_pioinfo_block(fd)) if(!alloc_pioinfo_block(fd))
return &MSVCRT___badioinfo; return &MSVCRT___badioinfo;
ret = get_ioinfo(fd); return get_ioinfo(fd);
if(ret == &MSVCRT___badioinfo) }
return ret;
LOCK_FILES(); static inline ioinfo* get_ioinfo_alloc(int *fd)
/* locate next free slot */ {
if (fd == MSVCRT_fdstart && fd == MSVCRT_fdend) int i;
MSVCRT_fdstart = MSVCRT_fdend + 1;
else if (fd == MSVCRT_fdstart) *fd = -1;
for(i=0; i<MSVCRT_MAX_FILES; i++)
{ {
MSVCRT_fdstart++; ioinfo *info = get_ioinfo_nolock(i);
while (MSVCRT_fdstart < MSVCRT_fdend &&
((info = get_ioinfo_nolock(MSVCRT_fdstart))->exflag & EF_CRIT_INIT)) if(info == &MSVCRT___badioinfo)
{ {
if (TryEnterCriticalSection(&info->crit)) if(!alloc_pioinfo_block(i))
return &MSVCRT___badioinfo;
info = get_ioinfo_nolock(i);
}
init_ioinfo_cs(info);
if(TryEnterCriticalSection(&info->crit))
{
if(info->handle == INVALID_HANDLE_VALUE)
{ {
if (info->handle == INVALID_HANDLE_VALUE) *fd = i;
{ return info;
LeaveCriticalSection(&info->crit);
break;
}
LeaveCriticalSection(&info->crit);
} }
MSVCRT_fdstart++; LeaveCriticalSection(&info->crit);
} }
} }
/* update last fd in use */
if (fd >= MSVCRT_fdend)
MSVCRT_fdend = fd + 1;
TRACE("fdstart is %d, fdend is %d\n", MSVCRT_fdstart, MSVCRT_fdend);
UNLOCK_FILES();
return ret; WARN(":files exhausted!\n");
*MSVCRT__errno() = MSVCRT_ENFILE;
return &MSVCRT___badioinfo;
} }
static inline void release_ioinfo(ioinfo *info) static inline void release_ioinfo(ioinfo *info)
@ -434,13 +405,6 @@ static void msvcrt_free_fd(int fd)
} }
} }
release_ioinfo(fdinfo); release_ioinfo(fdinfo);
LOCK_FILES();
if (fd == MSVCRT_fdend - 1)
MSVCRT_fdend--;
if (fd < MSVCRT_fdstart)
MSVCRT_fdstart = fd;
UNLOCK_FILES();
} }
static void msvcrt_set_fd(ioinfo *fdinfo, HANDLE hand, int flag) static void msvcrt_set_fd(ioinfo *fdinfo, HANDLE hand, int flag)
@ -463,23 +427,11 @@ static void msvcrt_set_fd(ioinfo *fdinfo, HANDLE hand, int flag)
/* INTERNAL: Allocate an fd slot from a Win32 HANDLE */ /* INTERNAL: Allocate an fd slot from a Win32 HANDLE */
static int msvcrt_alloc_fd(HANDLE hand, int flag) static int msvcrt_alloc_fd(HANDLE hand, int flag)
{ {
ioinfo *info;
int fd; int fd;
ioinfo *info = get_ioinfo_alloc(&fd);
LOCK_FILES();
fd = MSVCRT_fdstart;
TRACE(":handle (%p) allocating fd (%d)\n", hand, fd); TRACE(":handle (%p) allocating fd (%d)\n", hand, fd);
if (fd >= MSVCRT_MAX_FILES)
{
UNLOCK_FILES();
WARN(":files exhausted!\n");
*MSVCRT__errno() = MSVCRT_ENFILE;
return -1;
}
info = get_ioinfo_alloc_fd(fd);
UNLOCK_FILES();
if(info == &MSVCRT___badioinfo) if(info == &MSVCRT___badioinfo)
return -1; return -1;
@ -623,9 +575,6 @@ void msvcrt_init_io(void)
wxflag_ptr++; handle_ptr++; wxflag_ptr++; handle_ptr++;
} }
MSVCRT_fdend = max( 3, count );
for (MSVCRT_fdstart = 3; MSVCRT_fdstart < MSVCRT_fdend; MSVCRT_fdstart++)
if (get_ioinfo_nolock(MSVCRT_fdstart)->handle == INVALID_HANDLE_VALUE) break;
} }
fdinfo = get_ioinfo_alloc_fd(MSVCRT_STDIN_FILENO); fdinfo = get_ioinfo_alloc_fd(MSVCRT_STDIN_FILENO);
@ -1147,14 +1096,13 @@ int CDECL MSVCRT__dup2(int od, int nd)
int CDECL MSVCRT__dup(int od) int CDECL MSVCRT__dup(int od)
{ {
int fd, ret; int fd, ret;
ioinfo *info = get_ioinfo_alloc(&fd);
LOCK_FILES();
fd = MSVCRT_fdstart;
if (MSVCRT__dup2(od, fd) == 0) if (MSVCRT__dup2(od, fd) == 0)
ret = fd; ret = fd;
else else
ret = -1; ret = -1;
UNLOCK_FILES(); release_ioinfo(info);
return ret; return ret;
} }
@ -4377,7 +4325,7 @@ MSVCRT_FILE* CDECL MSVCRT__wfreopen(const MSVCRT_wchar_t *path, const MSVCRT_wch
TRACE(":path (%s) mode (%s) file (%p) fd (%d)\n", debugstr_w(path), debugstr_w(mode), file, file ? file->_file : -1); TRACE(":path (%s) mode (%s) file (%p) fd (%d)\n", debugstr_w(path), debugstr_w(mode), file, file ? file->_file : -1);
LOCK_FILES(); LOCK_FILES();
if (!file || ((fd = file->_file) < 0) || fd > MSVCRT_fdend) if (!file || ((fd = file->_file) < 0))
file = NULL; file = NULL;
else else
{ {