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Merge "adb: win32: file descriptor reliability improvements"

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Elliott Hughes 2015-08-04 00:50:43 +00:00 • committed by Gerrit Code Review
commit feacf20d1e
1 changed files with 27 additions and 20 deletions
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47
adb/sysdeps_win32.cpp
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@ -203,7 +203,7 @@ typedef struct FHRec_
static adb_mutex_t _win32_lock; static adb_mutex_t _win32_lock;
static FHRec _win32_fhs[ WIN32_MAX_FHS ]; static FHRec _win32_fhs[ WIN32_MAX_FHS ];
static int _win32_fh_count; static int _win32_fh_next; // where to start search for free FHRec
static FH static FH
_fh_from_int( int fd, const char* func ) _fh_from_int( int fd, const char* func )
@ -212,7 +212,7 @@ _fh_from_int( int fd, const char* func )
fd -= WIN32_FH_BASE; fd -= WIN32_FH_BASE;
if (fd < 0 || fd >= _win32_fh_count) { if (fd < 0 || fd >= WIN32_MAX_FHS) {
D( "_fh_from_int: invalid fd %d passed to %s\n", fd + WIN32_FH_BASE, D( "_fh_from_int: invalid fd %d passed to %s\n", fd + WIN32_FH_BASE,
func ); func );
errno = EBADF; errno = EBADF;
@ -244,28 +244,32 @@ _fh_to_int( FH f )
static FH static FH
_fh_alloc( FHClass clazz ) _fh_alloc( FHClass clazz )
{ {
int nn;
FH f = NULL; FH f = NULL;
adb_mutex_lock( &_win32_lock ); adb_mutex_lock( &_win32_lock );
if (_win32_fh_count < WIN32_MAX_FHS) { // Search entire array, starting from _win32_fh_next.
f = &_win32_fhs[ _win32_fh_count++ ]; for (int nn = 0; nn < WIN32_MAX_FHS; nn++) {
goto Exit; // Keep incrementing _win32_fh_next to avoid giving out an index that
} // was recently closed, to try to avoid use-after-free.
const int index = _win32_fh_next++;
for (nn = 0; nn < WIN32_MAX_FHS; nn++) { // Handle wrap-around of _win32_fh_next.
if ( _win32_fhs[nn].clazz == NULL) { if (_win32_fh_next == WIN32_MAX_FHS) {
f = &_win32_fhs[nn]; _win32_fh_next = 0;
}
if (_win32_fhs[index].clazz == NULL) {
f = &_win32_fhs[index];
goto Exit; goto Exit;
} }
} }
D( "_fh_alloc: no more free file descriptors\n" ); D( "_fh_alloc: no more free file descriptors\n" );
errno = EMFILE; // Too many open files
Exit: Exit:
if (f) { if (f) {
f->clazz = clazz; f->clazz = clazz;
f->used = 1; f->used = 1;
f->eof = 0; f->eof = 0;
f->name[0] = '\0';
clazz->_fh_init(f); clazz->_fh_init(f);
} }
adb_mutex_unlock( &_win32_lock ); adb_mutex_unlock( &_win32_lock );
@ -276,12 +280,17 @@ Exit:
static int static int
_fh_close( FH f ) _fh_close( FH f )
{ {
if ( f->used ) { // Use lock so that closing only happens once and so that _fh_alloc can't
// allocate a FH that we're in the middle of closing.
adb_mutex_lock(&_win32_lock);
if (f->used) {
f->clazz->_fh_close( f ); f->clazz->_fh_close( f );
f->used = 0; f->name[0] = '\0';
f->eof = 0; f->eof = 0;
f->clazz = NULL; f->used = 0;
f->clazz = NULL;
} }
adb_mutex_unlock(&_win32_lock);
return 0; return 0;
} }
@ -404,7 +413,6 @@ int adb_open(const char* path, int options)
f = _fh_alloc( &_fh_file_class ); f = _fh_alloc( &_fh_file_class );
if ( !f ) { if ( !f ) {
errno = ENOMEM;
return -1; return -1;
} }
@ -446,7 +454,6 @@ int adb_creat(const char* path, int mode)
f = _fh_alloc( &_fh_file_class ); f = _fh_alloc( &_fh_file_class );
if ( !f ) { if ( !f ) {
errno = ENOMEM;
return -1; return -1;
} }