[5/5] libs/libc: Build popen() without the check for the apps copy.

Documentation/os/libs/libc/index.rst

@@ -176,6 +176,7 @@ Implementation Details
    :maxdepth: 1
    :caption: Contents:
 
+   popen.rst
    search.rst
    stdbit.rst
    stream.rst

Documentation/os/libs/libc/popen.rst

@@ -0,0 +1,19 @@
+====================
+popen() and dpopen()
+====================
+
+libc has ``popen()``, ``pclose()``, ``dpopen()`` and ``dpclose()`` when
+``CONFIG_PIPES``, ``CONFIG_LIBC_EXECFUNCS`` and ``CONFIG_SCHED_WAITPID`` are
+enabled.
+
+``popen()`` starts ``sh -c command``.  With ``CONFIG_LIBC_ENVPATH``, ``PATH``
+gives the location of ``sh``; else it is ``/bin/sh``.  If there is no shell,
+the command is split at blanks and the program is started directly, without
+shell syntax.  The command starts with the ``posix_spawn()`` defaults for
+priority and stack size.  ``pclose()`` returns the termination status of the
+shell, as from ``waitpid()``.
+
+``dpopen()`` and ``dpclose()`` are NuttX extensions in ``unistd.h``.  They
+use a file descriptor instead of a stream.  ``dpopen()`` with ``O_RDWR``
+connects both the standard input and output of the command through a socket
+pair (needs ``CONFIG_NET_LOCAL`` and ``CONFIG_NET_LOCAL_STREAM``).

libs/libc/stdio/CMakeLists.txt

@@ -110,13 +110,11 @@ if(CONFIG_FILE_STREAM)
     lib_ungetwc.c
     lib_stdio_ext.c)
 
-  # popen() needs dpopen().  CONFIG_SYSTEM_POPEN selects the copy in
-  # apps/system/popen instead.
+  # popen() needs dpopen()
 
   if(CONFIG_PIPES
      AND CONFIG_LIBC_EXECFUNCS
-     AND CONFIG_SCHED_WAITPID
-     AND NOT CONFIG_SYSTEM_POPEN)
+     AND CONFIG_SCHED_WAITPID)
     list(APPEND SRCS lib_popen.c)
   endif()
 endif()

libs/libc/stdio/Make.defs

@@ -48,15 +48,12 @@ CSRCS += lib_setbuffer.c lib_fputwc.c lib_putwc.c lib_fputws.c
 CSRCS += lib_fopencookie.c lib_fmemopen.c lib_open_memstream.c lib_fgetwc.c
 CSRCS += lib_getwc.c lib_ungetwc.c lib_stdio_ext.c
 
-# popen() needs dpopen().  CONFIG_SYSTEM_POPEN selects the copy in
-# apps/system/popen instead.
+# popen() needs dpopen()
 
 ifeq ($(CONFIG_PIPES)$(CONFIG_LIBC_EXECFUNCS)$(CONFIG_SCHED_WAITPID),yyy)
-ifneq ($(CONFIG_SYSTEM_POPEN),y)
 CSRCS += lib_popen.c
 endif
 endif
-endif
 
 # Add the stdio directory to the build
 

libs/libc/unistd/CMakeLists.txt

@@ -127,13 +127,11 @@ if(CONFIG_PIPES)
   list(APPEND SRCS lib_pipe.c)
 endif()
 
-# dpopen() needs pipes, posix_spawn() and waitpid().  CONFIG_SYSTEM_POPEN
-# selects the copy in apps/system/popen instead.
+# dpopen() needs pipes, posix_spawn() and waitpid()
 
 if(CONFIG_PIPES
    AND CONFIG_LIBC_EXECFUNCS
-   AND CONFIG_SCHED_WAITPID
-   AND NOT CONFIG_SYSTEM_POPEN)
+   AND CONFIG_SCHED_WAITPID)
   list(APPEND SRCS lib_dpopen.c)
 endif()
 

libs/libc/unistd/Make.defs

@@ -77,14 +77,11 @@ ifeq ($(CONFIG_PIPES),y)
 CSRCS += lib_pipe.c
 endif
 
-# dpopen() needs pipes, posix_spawn() and waitpid().  CONFIG_SYSTEM_POPEN
-# selects the copy in apps/system/popen instead.
+# dpopen() needs pipes, posix_spawn() and waitpid()
 
 ifeq ($(CONFIG_PIPES)$(CONFIG_LIBC_EXECFUNCS)$(CONFIG_SCHED_WAITPID),yyy)
-ifneq ($(CONFIG_SYSTEM_POPEN),y)
 CSRCS += lib_dpopen.c
 endif
-endif
 
 # Add the unistd directory to the build