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Join shm_pair.info and .segment of Windows shm implementation #8648

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40 changes: 12 additions & 28 deletions TSRM/tsrm_win32.c
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Original file line number Diff line number Diff line change
Expand Up @@ -69,10 +69,8 @@ static void tsrm_win32_dtor(tsrm_win32_globals *globals)

if (globals->shm) {
for (ptr = globals->shm; ptr < (globals->shm + globals->shm_size); ptr++) {
UnmapViewOfFile(ptr->addr);
CloseHandle(ptr->segment);
UnmapViewOfFile(ptr->descriptor);
CloseHandle(ptr->info);
CloseHandle(ptr->segment);
}
free(globals->shm);
}
Expand Down Expand Up @@ -610,26 +608,27 @@ TSRM_API int pclose(FILE *stream)
}/*}}}*/

#define SEGMENT_PREFIX "TSRM_SHM_SEGMENT:"
#define DESCRIPTOR_PREFIX "TSRM_SHM_DESCRIPTOR:"
#define INT_MIN_AS_STRING "-2147483648"

TSRM_API int shmget(key_t key, size_t size, int flags)
{/*{{{*/
shm_pair *shm;
char shm_segment[sizeof(SEGMENT_PREFIX INT_MIN_AS_STRING)], shm_info[sizeof(DESCRIPTOR_PREFIX INT_MIN_AS_STRING)];
char shm_segment[sizeof(SEGMENT_PREFIX INT_MIN_AS_STRING)];
HANDLE shm_handle = NULL, info_handle = NULL;
BOOL created = FALSE;

if (key != IPC_PRIVATE) {
snprintf(shm_segment, sizeof(shm_segment), SEGMENT_PREFIX "%d", key);
snprintf(shm_info, sizeof(shm_info), DESCRIPTOR_PREFIX "%d", key);

shm_handle = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, shm_segment);
info_handle = OpenFileMapping(FILE_MAP_ALL_ACCESS, FALSE, shm_info);
}

if (!shm_handle && !info_handle) {
if (!shm_handle) {
if (flags & IPC_CREAT) {
if (size > SIZE_MAX - sizeof(shm->descriptor)) {
return -1;
}
size += sizeof(shm->descriptor);
#if SIZEOF_SIZE_T == 8
DWORD high = size >> 32;
DWORD low = (DWORD)size;
Expand All @@ -638,39 +637,25 @@ TSRM_API int shmget(key_t key, size_t size, int flags)
DWORD low = size;
#endif
shm_handle = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, high, low, key == IPC_PRIVATE ? NULL : shm_segment);
info_handle = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0, sizeof(shm->descriptor), key == IPC_PRIVATE ? NULL : shm_info);
created = TRUE;
}
if (!shm_handle || !info_handle) {
if (shm_handle) {
CloseHandle(shm_handle);
}
if (info_handle) {
CloseHandle(info_handle);
}
if (!shm_handle) {
return -1;
}
} else {
if (flags & IPC_EXCL) {
if (shm_handle) {
CloseHandle(shm_handle);
}
if (info_handle) {
CloseHandle(info_handle);
}
CloseHandle(shm_handle);
return -1;
}
}

shm = shm_get(key, NULL);
if (!shm) {
CloseHandle(shm_handle);
CloseHandle(info_handle);
return -1;
}
shm->segment = shm_handle;
shm->info = info_handle;
shm->descriptor = MapViewOfFileEx(shm->info, FILE_MAP_ALL_ACCESS, 0, 0, 0, NULL);
shm->descriptor = MapViewOfFileEx(shm->segment, FILE_MAP_ALL_ACCESS, 0, 0, 0, NULL);

if (NULL != shm->descriptor && created) {
shm->descriptor->shm_perm.key = key;
Expand All @@ -691,7 +676,6 @@ TSRM_API int shmget(key_t key, size_t size, int flags)
CloseHandle(shm->segment);
}
UnmapViewOfFile(shm->descriptor);
CloseHandle(shm->info);
return -1;
}

Expand All @@ -706,7 +690,7 @@ TSRM_API void *shmat(int key, const void *shmaddr, int flags)
return (void*)-1;
}

shm->addr = MapViewOfFileEx(shm->segment, FILE_MAP_ALL_ACCESS, 0, 0, 0, NULL);
shm->addr = shm->descriptor + sizeof(shm->descriptor);
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The error handling here is wrong, if (NULL == shm->addr) { would be comparing shm->descriptor + sizeof(shm->descriptor); against NULL

As a result, this would start returning non-null.

At a quick glance, the rest of the pointer operations seemed normal

I suspect some part of this change is related to krakjoe/apcu#445 - apcu calls shmat in 3 places https://github.com/krakjoe/apcu/blob/v5.1.22/apc_shm.c#L72


if (NULL == shm->addr) {
int err = GetLastError();
Expand Down Expand Up @@ -734,7 +718,7 @@ TSRM_API int shmdt(const void *shmaddr)
shm->descriptor->shm_lpid = getpid();
shm->descriptor->shm_nattch--;

ret = UnmapViewOfFile(shm->addr) ? 0 : -1;
ret = 1;
if (!ret && shm->descriptor->shm_nattch <= 0) {
ret = UnmapViewOfFile(shm->descriptor) ? 0 : -1;
shm->descriptor = NULL;
Expand Down
1 change: 0 additions & 1 deletion TSRM/tsrm_win32.h
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Original file line number Diff line number Diff line change
Expand Up @@ -50,7 +50,6 @@ typedef struct {

typedef struct {
void *addr;
HANDLE info;
HANDLE segment;
struct shmid_ds *descriptor;
} shm_pair;
Expand Down