Taken from https://salsa.debian.org/debian/libtirpc/-/raw/master/debian/patches/06-hurd-client-port.diff

Description: Fix client code for hurd, avoiding malloc overflow
 When trying to setup a inet connection, it happens the following:
 - in libtirp, src/clnt_vc.c, clnt_vc_create gets called
 - when trying to allocate vc_fd_locks, __rpc_dtbsize() is used as size
   for that array of fd locks
 - __rpc_dtbsize(), in src/rpc_generic.c, queries using rlimit the
   maximum (rlim_max) number of file descriptors (RLIMIT_NOFILE):
   - on Linux, the default is { rlim_cur = 1024, rlim_max = 4096 }
   - on kFreeBSD, the default is { rlim_cur = 1024, rlim_max = 1024 }
   - on Hurd, the default is { rlim_cur = 1024, rlim_max = RLIM_INFINITY }
  meaning that on Hurd the memory allocation fails (as
  __rpc_dtbsize() * sizeof(int) overflows and is negative)

 Change libtiprc so __rpc_dtbsize falls back on rlim_cur if rlim_max
 is unlimited.

 This patch fixes the client connection using inet sockets; local unix
 sockets are not working, for two reasons so far:
 - getpeername on them gives EOPNOTSUPP
 - SO_REUSEADDR is not implemented for them
Author: Pino Toscano <pino@debian.org>

Bug-Debian: http://bugs.debian.org/739674
Forwarded: no
Reviewed-By: Petter Reinholdtsen
Last-Update: 2014-03-03

--- a/src/rpc_generic.c
+++ b/src/rpc_generic.c
@@ -107,12 +107,17 @@
 {
 	static int tbsize;
 	struct rlimit rl;
+	rlim_t lim;
 
 	if (tbsize) {
 		return (tbsize);
 	}
 	if (getrlimit(RLIMIT_NOFILE, &rl) == 0) {
-		return (tbsize = (int)rl.rlim_max);
+		lim = rl.rlim_max;
+		if (lim == RLIM_INFINITY) {
+			lim = rl.rlim_cur;
+		}
+		return (tbsize = (int)lim);
 	}
 	/*
 	 * Something wrong.  I'll try to save face by returning a
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<div class='path'>path: <a href='/guix/log/?id=23fb3fa28004f7570a63b1a7cabce8dd0afac784'>root</a>/<a href='/guix/log/tests?id=23fb3fa28004f7570a63b1a7cabce8dd0afac784'>tests</a>/<a href='/guix/log/tests/substitute.scm?id=23fb3fa28004f7570a63b1a7cabce8dd0afac784'>substitute.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/tests/substitute.scm?id=23fb3fa28004f7570a63b1a7cabce8dd0afac784&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2021-04-09 17:46:38 +0200'>2021-04-09</span></td><td><a href='/guix/commit/tests/substitute.scm?id=2d73086262e1fb33cd0f0f16f74a495fe06b38aa'>daemon: 'guix substitute' replies on FD 4.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2021-01-16 11:51:03 +0000'>2021-01-16</span></td><td><a href='/guix/commit/tests/substitute.scm?id=681af17460fa34916ac40589cccdcca7222249af'>guix: Move narinfo code from substitute script to module.</a><span class='msg-avail'>...</span></td><td>Christopher Baines</td></tr>
<tr><td><span title='2020-12-19 23:25:01 +0100'>2020-12-19</span></td><td><a href='/guix/commit/tests/substitute.scm?id=77a1efed9e12ce0e2c470d7b0601ae70c72b010b'>tests: Check the mtime and permissions of substituted items.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-12-19 23:25:00 +0100'>2020-12-19</span></td><td><a href='/guix/commit/tests/substitute.scm?id=9dfa20a22ae0be3d3b01a7b3d422af97428c627e'>daemon: Let 'guix substitute' perform hash checks.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-12-08 22:30:08 +0100'>2020-12-08</span></td><td><a href='/guix/commit/tests/substitute.scm?id=711df9ef3c04a0e0d7e844bed4c6b260ea1f65c1'>daemon: Run 'guix substitute --substitute' as an agent.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-12-08 22:30:08 +0100'>2020-12-08</span></td><td><a href='/guix/commit/tests/substitute.scm?id=79c6614f58a57b985daf8940766319e440311db0'>daemon: Use 'Agent' to spawn 'guix substitute --query'.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-08-24 13:35:24 +0200'>2020-08-24</span></td><td><a href='/guix/commit/tests/substitute.scm?id=4c0c65acfade63ce0549115d19db4b639c1e9992'>Use "guile-zlib" and "guile-lzlib" instead of (guix config).</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>