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Description: Use /dev/null in invalidate_fd to avoid infinite loop in OpenSSL
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Thanks to Andy Bakun / @thwarted for identifying the issue and
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suggesting the /dev/null workaround.
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Author: Aaron Stone <aaron@serendipity.cx>
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Origin: upstream,https://github.com/brianmario/mysql2/commit/fc30a7c056e63517f5f66702016941b3902ec0b6.patch
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Reviewed-by: Cédric Boutillier <boutil@debian.org>
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Last-Update: 2014-08-24
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--- a/ext/mysql2/client.c
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+++ b/ext/mysql2/client.c
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@@ -167,26 +167,30 @@
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#ifndef _WIN32
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/*
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- * Redirect clientfd to a dummy socket for mysql_close to
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- * write, shutdown, and close on as a no-op.
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- * We do this hack because we want to call mysql_close to release
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- * memory, but do not want mysql_close to drop connections in the
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- * parent if the socket got shared in fork.
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+ * Redirect clientfd to /dev/null for mysql_close and SSL_close to write,
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+ * shutdown, and close. The hack is needed to prevent shutdown() from breaking
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+ * a socket that may be in use by the parent or other processes after fork.
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+ *
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+ * /dev/null is used to absorb writes; previously a dummy socket was used, but
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+ * it could not abosrb writes and caused openssl to go into an infinite loop.
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+ *
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* Returns Qtrue or Qfalse (success or failure)
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+ *
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+ * Note: if this function is needed on Windows, use "nul" instead of "/dev/null"
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*/
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static VALUE invalidate_fd(int clientfd)
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{
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#ifdef SOCK_CLOEXEC
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/* Atomically set CLOEXEC on the new FD in case another thread forks */
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- int sockfd = socket(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
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+ int sockfd = open("/dev/null", O_RDWR | O_CLOEXEC);
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if (sockfd < 0) {
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/* Maybe SOCK_CLOEXEC is defined but not available on this kernel */
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- int sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
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+ int sockfd = open("/dev/null", O_RDWR);
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fcntl(sockfd, F_SETFD, FD_CLOEXEC);
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}
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#else
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/* Well we don't have SOCK_CLOEXEC, so just set FD_CLOEXEC quickly */
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- int sockfd = socket(AF_UNIX, SOCK_STREAM, 0);
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+ int sockfd = open("/dev/null", O_RDWR);
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fcntl(sockfd, F_SETFD, FD_CLOEXEC);
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#endif
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