New function: strerror

* configure (have_strerror_r): New variable.
Detect whether we have strerror_r and which flavor:
GNU or POSIX. Define HAVE_STRERROR_GNU or HAVE_STRERROR_POSIX
in config.h.

* sysif.c (strerror_wrap): New function.
(sysif_init): Register strerror intrinsic.

* txr.1: Documented.

3 files changed, 65 insertions, 0 deletions

diff --git a/configure b/configure
index 07d8d5a8..7ea5bea0 100755
--- a/configure
+++ b/configure
@@ -173,6 +173,7 @@ have_unistd=
 have_sys_stat=
 have_sys_types=
 have_sys_time=
+have_strerror_r=
 have_makedev=
 have_syslog=
 have_glob=
@@ -2022,6 +2023,37 @@ else
 fi
 
 #
+# errno stuff
+#
+
+printf "Checking for strerror_r ..."
+
+for type in int 'char *' ; do
+  cat > conftest.c <<!
+#include <string.h>
+
+int main(int argc, char **argv)
+{
+  $type (*fp)(int, char *, size_t) = strerror_r;
+  return 0;
+}
+!
+  if conftest EXTRA_FLAGS=-Werror=incompatible-pointer-types ; then
+    if [ "$type" = int ] ; then
+      printf "yes (POSIX)\n"
+      printf "#define HAVE_STRERROR_POSIX 1\n" >> config.h
+    else
+      printf "yes (GNU)\n"
+      printf "#define HAVE_STRERROR_GNU 1\n" >> config.h
+    fi
+    have_strerror_r=y
+    break
+  fi
+done
+
+[ $have_strerror_r ] || printf "no\n"
+
+#
 # fcntl
 #
 
diff --git a/sysif.c b/sysif.c
index 3f25bb7e..701a1eed 100644
--- a/sysif.c
+++ b/sysif.c
@@ -141,6 +141,21 @@ static val errno_wrap(val newval)
   return oldval;
 }
 
+static val strerror_wrap(val errnum)
+{
+  val self = lit("strerror");
+  int eno = c_int(errnum, self);
+#if HAVE_STRERROR_POSIX
+  char buf[128];
+  return strerror_r(eno, buf, sizeof buf) >= 0 ? string_utf8(buf) : nil;
+#elif HAVE_STRERROR_GNU
+  char buf[128];
+  return string_utf8(strerror_r(eno, buf, sizeof buf));
+#else
+  return string_utf8(strerror(eno));
+#endif
+}
+
 #if HAVE_DAEMON
 static val daemon_wrap(val nochdir, val noclose)
 {
@@ -2327,6 +2342,7 @@ void sysif_init(void)
   reg_varl(intern(lit("exdev"), user_package), num_fast(EXDEV));
 
   reg_fun(intern(lit("errno"), user_package), func_n1o(errno_wrap, 0));
+  reg_fun(intern(lit("strerror"), user_package), func_n1o(strerror_wrap, 0));
   reg_fun(intern(lit("exit"), user_package), func_n1(exit_wrap));
   reg_fun(intern(lit("at-exit-call"), user_package), func_n1(at_exit_call));
   reg_fun(intern(lit("at-exit-do-not-call"), user_package), func_n1(at_exit_do_not_call));
diff --git a/txr.1 b/txr.1
index 8d30662c..229d50ae 100644
--- a/txr.1
+++ b/txr.1
@@ -58584,6 +58584,23 @@ The place form of
 .code errno
 does not take an argument.
 
+.coNP Function @ strerror
+.synb
+.mets (strerror << errno-value )
+.syne
+.desc
+The
+.code strerror
+returns a character string which provides the host platform's description
+of the integer
+.meta errno-value
+obtained from the
+.code errno
+function.
+
+If the host platform fails to provide a descripion, the function returns
+.codn nil .
+
 .coNP Function @ exit
 .synb
 .mets (exit << status )