mescc: Mes C Library: Support GNU Tar: Add execlp.

* lib/posix/execl.c (vexec): New function.
(execl): Use it.
* lib/posix/execlp.c: New file.
* lib/libc+gnu.c: Include it.
* include/unistd.h (execlp): Declare.
* lib/tests/posix/90-execlp.c: New file.
* lib/tests/posix/90-execlp.stdout: New file.
* build-aux/check-mescc.sh: Test it.

build-aux/check-mescc.sh

@@ -192,6 +192,7 @@ scaffold/tests/84-struct-field-list
 scaffold/tests/85-sizeof
 lib/tests/dirent/90-readdir
 lib/tests/io/90-stat
+lib/tests/posix/90-execlp
 lib/tests/posix/90-unsetenv
 lib/tests/signal/90-signal
 lib/tests/stdio/90-fopen

include/unistd.h

@@ -62,6 +62,7 @@ unsigned int alarm (unsigned int seconds);
 int close (int fd);
 int execv (char const *file_name, char *const argv[]);
 int execl (char const *file_name, char const *arg, ...);
+int execlp (char const *file_name, char const *arg, ...);
 int execve (char const *file, char *const argv[], char *const env[]);
 int execvp (char const *file, char *const argv[]);
 int fork (void);

lib/libc+gnu.c

@@ -119,3 +119,6 @@
 #include <stub/rand.c>
 #include <stub/sigdelset.c>
 #include <stub/ttyname.c>
+
+// tar
+#include <posix/execlp.c>

lib/posix/execl.c

@@ -22,20 +22,13 @@
 #include <unistd.h>
 
 int
-execl (char const *file_name, char const *arg, ...)
+vexec (char const *file_name, va_list ap)
 {
-  if (__mes_debug () > 2)
-    {
-      eputs ("execl "); eputs (file_name); eputs ("\n");
-    }
+  char *arg = va_arg (ap, char const *);
   char *argv[1000];           // POSIX minimum 4096
   int i = 0;
 
-  va_list ap;
-  va_start (ap, arg);
-
   argv[i++] = file_name;
-  arg = va_arg (ap, char const *);
   while (arg)
     {
       argv[i++] = arg;
@@ -50,3 +43,18 @@ execl (char const *file_name, char const *arg, ...)
   va_end (ap);
   return r;
 }
+
+int
+execl (char const *file_name, char const *arg, ...)
+{
+  va_list ap;
+  int r;
+  va_start (ap, arg);
+  if (__mes_debug () > 2)
+    {
+      eputs ("execl "); eputs (file_name); eputs ("\n");
+    }
+  r = vexec (file_name, ap);
+  va_end (ap);
+  return r;
+}

lib/posix/execlp.c

@@ -0,0 +1,44 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2017,2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * GNU Mes is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <libmes.h>
+#include <unistd.h>
+
+int
+execlp (char const *file_name, char const *arg, ...)
+{
+  va_list ap;
+  int r;
+  va_start (ap, arg);
+  if (file_name[0] != '/')
+    file_name = search_path (file_name);
+  if (__mes_debug () > 2)
+    {
+      eputs ("execlp "); eputs (file_name ? file_name : "0"); eputs ("\n");
+    }
+  if (!file_name)
+    {
+      errno = ENOENT;
+      return -1;
+    }
+  r = vexec (file_name, ap);
+  va_end (ap);
+  return r;
+}

lib/tests/posix/90-execlp.c

@@ -0,0 +1,28 @@
+/* -*-comment-start: "//";comment-end:""-*-
+ * GNU Mes --- Maxwell Equations of Software
+ * Copyright © 2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+ *
+ * This file is part of GNU Mes.
+ *
+ * GNU Mes is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * GNU Mes is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "unistd.h"
+
+int
+main (int argc, char const *argv[])
+{
+  execlp ("echo", "echo", "Hello", "World!", 0);
+  return 0;
+}

lib/tests/posix/90-execlp.stdout

@@ -0,0 +1 @@
+Hello World!