select: return error from "lethal" poll/select errors

Adds two new error codes: CURLE_UNRECOVERABLE_POLL and
CURLM_UNRECOVERABLE_POLL one each for the easy and the multi interfaces.

Reported-by: Harry Sintonen
Fixes #8921
Closes #8961

docs/libcurl/libcurl-errors.3

@@ -265,6 +265,8 @@ QUIC connection error. This error may be caused by an SSL library error. QUIC
 is the protocol used for HTTP/3 transfers.
 .IP "CURLE_SSL_CLIENTCERT (98)"
 SSL Client Certificate required.
+.IP "CURLE_UNRECOVERABLE_POLL (99)"
+An internal call to poll() or select() returned error that is not recoverable.
 .IP "CURLE_OBSOLETE*"
 These error codes will never be returned. They were used in an old libcurl
 version and are currently unused.
@@ -309,6 +311,8 @@ Wakeup is unavailable or failed.
 A function was called with a bad parameter.
 .IP "CURLM_ABORTED_BY_CALLBACK (11)"
 A multi handle callback returned error.
+.IP "CURLM_UNRECOVERABLE_POLL (12)"
+An internal call to poll() or select() returned error that is not recoverable.
 .SH "CURLSHcode"
 The "share" interface will return a CURLSHcode to indicate when an error has
 occurred. Also consider \fIcurl_share_strerror(3)\fP.

docs/libcurl/symbols-in-versions

@@ -320,6 +320,7 @@ CURLE_TFTP_UNKNOWNID            7.15.0
 CURLE_TOO_MANY_REDIRECTS        7.5
 CURLE_UNKNOWN_OPTION            7.21.5
 CURLE_UNKNOWN_TELNET_OPTION     7.7           7.21.5
+CURLE_UNRECOVERABLE_POLL        7.84.0
 CURLE_UNSUPPORTED_PROTOCOL      7.1
 CURLE_UPLOAD_FAILED             7.16.3
 CURLE_URL_MALFORMAT             7.1
@@ -523,6 +524,7 @@ CURLM_OK                        7.9.6
 CURLM_OUT_OF_MEMORY             7.9.6
 CURLM_RECURSIVE_API_CALL        7.59.0
 CURLM_UNKNOWN_OPTION            7.15.4
+CURLM_UNRECOVERABLE_POLL        7.84.0
 CURLM_WAKEUP_FAILURE            7.68.0
 CURLMIMEOPT_FORMESCAPE          7.81.0
 CURLMOPT_CHUNK_LENGTH_PENALTY_SIZE 7.30.0

include/curl/curl.h

@@ -613,6 +613,7 @@ typedef enum {
   CURLE_QUIC_CONNECT_ERROR,      /* 96 - QUIC connection error */
   CURLE_PROXY,                   /* 97 - proxy handshake error */
   CURLE_SSL_CLIENTCERT,          /* 98 - client-side certificate required */
+  CURLE_UNRECOVERABLE_POLL,      /* 99 - poll/select returned fatal error */
   CURL_LAST /* never use! */
 } CURLcode;
 

include/curl/multi.h

@@ -7,7 +7,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2021, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2022, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -75,6 +75,7 @@ typedef enum {
   CURLM_WAKEUP_FAILURE,  /* wakeup is unavailable or failed */
   CURLM_BAD_FUNCTION_ARGUMENT, /* function called with a bad parameter */
   CURLM_ABORTED_BY_CALLBACK,
+  CURLM_UNRECOVERABLE_POLL,
   CURLM_LAST
 } CURLMcode;
 

lib/asyn-ares.c

@@ -306,7 +306,7 @@ int Curl_resolver_getsock(struct Curl_easy *data,
  * 2) wait for the timeout period to check for action on ares' sockets.
  * 3) tell ares to act on all the sockets marked as "with action"
  *
- * return number of sockets it worked on
+ * return number of sockets it worked on, or -1 on error
  */
 
 static int waitperform(struct Curl_easy *data, timediff_t timeout_ms)
@@ -338,8 +338,11 @@ static int waitperform(struct Curl_easy *data, timediff_t timeout_ms)
       break;
   }
 
-  if(num)
+  if(num) {
     nfds = Curl_poll(pfd, num, timeout_ms);
+    if(nfds < 0)
+      return -1;
+  }
   else
     nfds = 0;
 
@@ -376,7 +379,8 @@ CURLcode Curl_resolver_is_resolved(struct Curl_easy *data,
   DEBUGASSERT(dns);
   *dns = NULL;
 
-  waitperform(data, 0);
+  if(waitperform(data, 0) < 0)
+    return CURLE_UNRECOVERABLE_POLL;
 
 #ifndef HAVE_CARES_GETADDRINFO
   /* Now that we've checked for any last minute results above, see if there are
@@ -475,7 +479,8 @@ CURLcode Curl_resolver_wait_resolv(struct Curl_easy *data,
     else
       timeout_ms = 1000;
 
-    waitperform(data, timeout_ms);
+    if(waitperform(data, timeout_ms) < 0)
+      return CURLE_UNRECOVERABLE_POLL;
     result = Curl_resolver_is_resolved(data, entry);
 
     if(result || data->state.async.done)

lib/easy.c

@@ -549,6 +549,8 @@ static CURLcode wait_or_timeout(struct Curl_multi *multi, struct events *ev)
 
     /* wait for activity or timeout */
     pollrc = Curl_poll(fds, numfds, ev->ms);
+    if(pollrc < 0)
+      return CURLE_UNRECOVERABLE_POLL;
 
     after = Curl_now();
 

lib/multi.c

@@ -1312,6 +1312,8 @@ static CURLMcode multi_wait(struct Curl_multi *multi,
 #else
     pollrc = Curl_poll(ufds, nfds, timeout_ms); /* wait... */
 #endif
+    if(pollrc < 0)
+      return CURLM_UNRECOVERABLE_POLL;
 
     if(pollrc > 0) {
       retcode = pollrc;

lib/select.c

@@ -352,8 +352,12 @@ int Curl_poll(struct pollfd ufds[], unsigned int nfds, timediff_t timeout_ms)
      value).
   */
   r = our_select(maxfd, &fds_read, &fds_write, &fds_err, timeout_ms);
-  if(r <= 0)
+  if(r <= 0) {
+    if((r == -1) && (SOCKERRNO == EINTR))
+      /* make EINTR from select or poll not a "lethal" error */
+      r = 0;
     return r;
+  }
 
   r = 0;
   for(i = 0; i < nfds; i++) {

lib/strerror.c

@@ -317,6 +317,9 @@ curl_easy_strerror(CURLcode error)
   case CURLE_SSL_CLIENTCERT:
     return "SSL Client Certificate required";
 
+  case CURLE_UNRECOVERABLE_POLL:
+    return "Unrecoverable error in select/poll";
+
     /* error codes not used by current libcurl */
   case CURLE_OBSOLETE20:
   case CURLE_OBSOLETE24:
@@ -400,6 +403,9 @@ curl_multi_strerror(CURLMcode error)
   case CURLM_ABORTED_BY_CALLBACK:
     return "Operation was aborted by an application callback";
 
+  case CURLM_UNRECOVERABLE_POLL:
+    return "Unrecoverable error in select/poll";
+
   case CURLM_LAST:
     break;
   }

tests/data/test1538

@@ -131,7 +131,8 @@ e95: HTTP/3 error
 e96: QUIC connection error
 e97: proxy handshake error
 e98: SSL Client Certificate required
-e99: Unknown error
+e99: Unrecoverable error in select/poll
+e100: Unknown error
 m-1: Please call curl_multi_perform() soon
 m0: No error
 m1: Invalid multi handle
@@ -145,7 +146,8 @@ m8: API function called from within callback
 m9: Wakeup is unavailable or failed
 m10: A libcurl function was given a bad argument
 m11: Operation was aborted by an application callback
-m12: Unknown error
+m12: Unrecoverable error in select/poll
+m13: Unknown error
 s0: No error
 s1: Unknown share option
 s2: Share currently in use