autofs-5.1.8 - add autofs_strerror_r() helper for musl

From: Fabian Groffen <grobian@gentoo.org>

If using musl libc the XSI-compliant variant strerror_r() which returns
an integer instead of a pointer so add a helper function to handle this
case.

Signed-off-by: Fabian Groffen <grobian@gentoo.org>
Signed-off-by: Ian Kent <raven@themaw.net>
---
 CHANGELOG           |    1 +
 include/automount.h |    5 +++++
 lib/log.c           |   10 ++++++++++
 3 files changed, 16 insertions(+)

diff --git a/CHANGELOG b/CHANGELOG
index 2e84b954..4f4ee181 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -24,6 +24,7 @@
 - musl: add missing include to hash.h for _WORDSIZE.
 - musl: add missing include to log.h for pid_t.
 - musl: define _SWORD_TYPE.
+- add autofs_strerror_r() helper for musl.
 
 19/10/2021 autofs-5.1.8
 - add xdr_exports().
diff --git a/include/automount.h b/include/automount.h
index 947ed16d..d2d05d89 100644
--- a/include/automount.h
+++ b/include/automount.h
@@ -43,6 +43,11 @@
 
 #define ENABLE_CORES	1
 
+#ifndef __GLIBC__
+# define strerror_r(N,B,S) autofs_strerror_r(N,B,S)
+char *autofs_strerror_r(int errnum, char *buf, size_t buflen);  /* GNU */
+#endif
+
 /* We MUST have the paths to mount(8) and umount(8) */
 #ifndef HAVE_MOUNT
 #error Failed to locate mount(8)!
diff --git a/lib/log.c b/lib/log.c
index d1edef28..43eccc07 100644
--- a/lib/log.c
+++ b/lib/log.c
@@ -367,3 +367,13 @@ pid_t log_pidinfo(struct autofs_point *ap, pid_t pid, char *label) {
 
 	return ppid;
 }
+
+#ifndef __GLIBC__
+# undef strerror_r
+char *autofs_strerror_r(int errnum, char *buf, size_t buflen) {
+	int s = strerror_r(errnum, buf, buflen);
+	if (s)
+		return NULL;
+	return buf;
+}
+#endif