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hostip: add locks around use of global buffer for alarm()

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When building with the sync name resolver and timeout ability we now
require thread-safety to be present to enable it.

Closes #11030
This commit is contained in:
Harry Sintonen 2023-04-25 09:22:26 +02:00 committed by Daniel Stenberg
parent 91b53efa4b
commit 13718030ad
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GPG Key ID: 5CC908FDB71E12C2
1 changed files with 15 additions and 4 deletions
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19
lib/hostip.c
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@ -70,12 +70,19 @@
#include <SystemConfiguration/SCDynamicStoreCopySpecific.h>
#endif
#if defined(CURLRES_SYNCH) && \
defined(HAVE_ALARM) && defined(SIGALRM) && defined(HAVE_SIGSETJMP)
#if defined(CURLRES_SYNCH) && \
defined(HAVE_ALARM) && \
defined(SIGALRM) && \
defined(HAVE_SIGSETJMP) && \
defined(GLOBAL_INIT_IS_THREADSAFE)
/* alarm-based timeouts can only be used with all the dependencies satisfied */
#define USE_ALARM_TIMEOUT
#endif
#ifdef USE_ALARM_TIMEOUT
#include "easy_lock.h"
#endif
#define MAX_HOSTCACHE_LEN (255 + 7) /* max FQDN + colon + port number + zero */
/*
@ -254,11 +261,12 @@ void Curl_hostcache_prune(struct Curl_easy *data)
Curl_share_unlock(data, CURL_LOCK_DATA_DNS);
}
#ifdef HAVE_SIGSETJMP
#ifdef USE_ALARM_TIMEOUT
/* Beware this is a global and unique instance. This is used to store the
return address that we can jump back to from inside a signal handler. This
is not thread-safe stuff. */
sigjmp_buf curl_jmpenv;
curl_simple_lock curl_jmpenv_lock;
#endif
/* lookup address, returns entry if found and not stale */
@ -832,7 +840,6 @@ enum resolve_t Curl_resolv(struct Curl_easy *data,
static
void alarmfunc(int sig)
{
/* this is for "-ansi -Wall -pedantic" to stop complaining! (rabe) */
(void)sig;
siglongjmp(curl_jmpenv, 1);
}
@ -912,6 +919,8 @@ enum resolve_t Curl_resolv_timeout(struct Curl_easy *data,
This should be the last thing we do before calling Curl_resolv(),
as otherwise we'd have to worry about variables that get modified
before we invoke Curl_resolv() (and thus use "volatile"). */
curl_simple_lock_lock(&curl_jmpenv_lock);
if(sigsetjmp(curl_jmpenv, 1)) {
/* this is coming from a siglongjmp() after an alarm signal */
failf(data, "name lookup timed out");
@ -980,6 +989,8 @@ clean_up:
#endif
#endif /* HAVE_SIGACTION */
curl_simple_lock_unlock(&curl_jmpenv_lock);
/* switch back the alarm() to either zero or to what it was before minus
the time we spent until now! */
if(prev_alarm) {