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select: use timediff_t instead of time_t and int for timeout_ms
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Make all functions in select.[ch] take timeout_ms as timediff_t
which should always be large enough and signed on all platforms
to take all possible timeout values and avoid type conversions.

Reviewed-by: Jay Satiro
Reviewed-by: Daniel Stenberg

Replaces #5107 and partially #5262
Related to #5240 and #5286
Closes #5343
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@mback2k
mback2k committed May 30, 2020
1 parent 62314d6 commit 4a8f459
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Showing 2 changed files with 39 additions and 52 deletions.
85 changes: 36 additions & 49 deletions lib/select.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -74,7 +74,7 @@
* -1 = system call error, invalid timeout value, or interrupted
* 0 = specified timeout has elapsed
*/
int Curl_wait_ms(int timeout_ms)
int Curl_wait_ms(timediff_t timeout_ms)
{
int r = 0;

Expand All @@ -87,10 +87,20 @@ int Curl_wait_ms(int timeout_ms)
#if defined(MSDOS)
delay(timeout_ms);
#elif defined(USE_WINSOCK)
Sleep(timeout_ms);
/* prevent overflow, timeout_ms is typecast to ULONG/DWORD. */
#if TIMEDIFF_T_MAX > ULONG_MAX
if(timeout_ms > ULONG_MAX)
timeout_ms = ULONG_MAX;
#endif
Sleep((ULONG)timeout_ms);
#else
#if defined(HAVE_POLL_FINE)
r = poll(NULL, 0, timeout_ms);
/* prevent overflow, timeout_ms is typecast to int. */
#if TIMEDIFF_T_MAX > INT_MAX
if(timeout_ms > INT_MAX)
timeout_ms = INT_MAX;
#endif
r = poll(NULL, 0, (int)timeout_ms);
#else
{
struct timeval pending_tv;
Expand All @@ -116,44 +126,35 @@ int Curl_wait_ms(int timeout_ms)
* 0 = timeout
* N = number of signalled file descriptors
*/
int Curl_select(curl_socket_t maxfd,
fd_set *fds_read,
fd_set *fds_write,
fd_set *fds_err,
time_t timeout_ms) /* milliseconds to wait */
int Curl_select(curl_socket_t maxfd, /* highest socket number */
fd_set *fds_read, /* sockets ready for reading */
fd_set *fds_write, /* sockets ready for writing */
fd_set *fds_err, /* sockets with errors */
timediff_t timeout_ms) /* milliseconds to wait */
{
struct timeval pending_tv;
struct timeval *ptimeout;
int pending_ms;
int r;

#if SIZEOF_TIME_T != SIZEOF_INT
/* wrap-around precaution */
if(timeout_ms >= INT_MAX)
timeout_ms = INT_MAX;
#endif

#ifdef USE_WINSOCK
/* WinSock select() can't handle zero events. See the comment below. */
if((!fds_read || fds_read->fd_count == 0) &&
(!fds_write || fds_write->fd_count == 0) &&
(!fds_err || fds_err->fd_count == 0)) {
r = Curl_wait_ms((int)timeout_ms);
r = Curl_wait_ms(timeout_ms);
return r;
}
#endif

ptimeout = &pending_tv;

if(timeout_ms < 0) {
ptimeout = NULL;
}
else if(timeout_ms > 0) {
pending_ms = (int)timeout_ms;
pending_tv.tv_sec = pending_ms / 1000;
pending_tv.tv_usec = (pending_ms % 1000) * 1000;
pending_tv.tv_sec = timeout_ms / 1000;
pending_tv.tv_usec = (timeout_ms % 1000) * 1000;
}
else if(!timeout_ms) {
else {
pending_tv.tv_sec = 0;
pending_tv.tv_usec = 0;
}
Expand Down Expand Up @@ -204,11 +205,10 @@ int Curl_select(curl_socket_t maxfd,
int Curl_socket_check(curl_socket_t readfd0, /* two sockets to read from */
curl_socket_t readfd1,
curl_socket_t writefd, /* socket to write to */
timediff_t timeout_ms) /* milliseconds to wait */
timediff_t timeout_ms) /* milliseconds to wait */
{
#ifdef HAVE_POLL_FINE
struct pollfd pfd[3];
int pending_ms;
int num;
#else
fd_set fds_read;
Expand All @@ -219,20 +219,10 @@ int Curl_socket_check(curl_socket_t readfd0, /* two sockets to read from */
int r;
int ret;

/* prevent overflow. timeout_ms is typecast to time_t and int. */
#if TIMEDIFF_T_MAX > INT_MAX
if(timeout_ms > INT_MAX)
timeout_ms = INT_MAX;
#endif
#if INT_MAX > TIME_T_MAX
if(timeout_ms > (int)TIME_T_MAX)
timeout_ms = (int)TIME_T_MAX;
#endif

if((readfd0 == CURL_SOCKET_BAD) && (readfd1 == CURL_SOCKET_BAD) &&
(writefd == CURL_SOCKET_BAD)) {
/* no sockets, just wait */
r = Curl_wait_ms((int)timeout_ms);
r = Curl_wait_ms(timeout_ms);
return r;
}

Expand Down Expand Up @@ -263,18 +253,9 @@ int Curl_socket_check(curl_socket_t readfd0, /* two sockets to read from */
num++;
}

if(timeout_ms > 0)
pending_ms = (int)timeout_ms;
else if(timeout_ms < 0)
pending_ms = -1;
else
pending_ms = 0;
r = poll(pfd, num, pending_ms);

if(r < 0)
return -1;
if(r == 0)
return 0;
r = Curl_poll(pfd, num, timeout_ms);
if(r <= 0)
return r;

ret = 0;
num = 0;
Expand Down Expand Up @@ -340,7 +321,7 @@ int Curl_socket_check(curl_socket_t readfd0, /* two sockets to read from */
curl_socket_t is unsigned in such cases and thus -1 is the largest
value).
*/
r = Curl_select(maxfd, &fds_read, &fds_write, &fds_err, (time_t)timeout_ms);
r = Curl_select(maxfd, &fds_read, &fds_write, &fds_err, timeout_ms);

if(r < 0)
return -1;
Expand Down Expand Up @@ -386,7 +367,7 @@ int Curl_socket_check(curl_socket_t readfd0, /* two sockets to read from */
* 0 = timeout
* N = number of structures with non zero revent fields
*/
int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms)
int Curl_poll(struct pollfd ufds[], unsigned int nfds, timediff_t timeout_ms)
{
#ifdef HAVE_POLL_FINE
int pending_ms;
Expand All @@ -409,6 +390,7 @@ int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms)
}
}
if(fds_none) {
/* no sockets, just wait */
r = Curl_wait_ms(timeout_ms);
return r;
}
Expand All @@ -420,8 +402,13 @@ int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms)

#ifdef HAVE_POLL_FINE

/* prevent overflow, timeout_ms is typecast to int. */
#if TIMEDIFF_T_MAX > INT_MAX
if(timeout_ms > INT_MAX)
timeout_ms = INT_MAX;
#endif
if(timeout_ms > 0)
pending_ms = timeout_ms;
pending_ms = (int)timeout_ms;
else if(timeout_ms < 0)
pending_ms = -1;
else
Expand Down
6 changes: 3 additions & 3 deletions lib/select.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -76,7 +76,7 @@ int Curl_select(curl_socket_t maxfd,
fd_set *fds_read,
fd_set *fds_write,
fd_set *fds_err,
time_t timeout_ms);
timediff_t timeout_ms);

int Curl_socket_check(curl_socket_t readfd, curl_socket_t readfd2,
curl_socket_t writefd,
Expand All @@ -86,8 +86,8 @@ int Curl_socket_check(curl_socket_t readfd, curl_socket_t readfd2,
#define SOCKET_WRITABLE(x,z) \
Curl_socket_check(CURL_SOCKET_BAD, CURL_SOCKET_BAD, x, z)

int Curl_poll(struct pollfd ufds[], unsigned int nfds, int timeout_ms);
int Curl_wait_ms(int timeout_ms);
int Curl_poll(struct pollfd ufds[], unsigned int nfds, timediff_t timeout_ms);
int Curl_wait_ms(timediff_t timeout_ms);

#ifdef TPF
int tpf_select_libcurl(int maxfds, fd_set* reads, fd_set* writes,
Expand Down

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