When NSH_LIBRARY is not available, dpopen()/popen() can still execute
commands by splitting the command string by whitespace and calling
posix_spawnp() directly. Shell syntax (pipes, redirects, globbing)
is not supported in this mode.
Add CONFIG_SYSTEM_POPEN_MAXARGUMENTS (default 7) to control the
argv array size for the no-shell path.
Remove the hard dependency on NSH_LIBRARY from SYSTEM_POPEN so the
feature can be used in minimal configurations without a shell.
Signed-off-by: cuiziwei <cuiziwei@xiaomi.com>
Add dpopen()/dpclose() as the descriptor-based counterpart of
popen()/pclose(), analogous to how dprintf() relates to fprintf().
dpopen() returns a raw file descriptor instead of a FILE stream,
avoiding the stdio.h dependency for callers that only need an fd.
Refactor popen() as a thin wrapper: dpopen() + fdopen() + FILE
container. All pipe creation and process spawning logic now lives
in dpopen.c.
Also remove the hard dependency on NSH_LIBRARY from SYSTEM_POPEN.
When NSH is available, commands are executed through sh -c with full
shell syntax support. When NSH is not available, commands are split
by whitespace and executed directly via posix_spawnp().
Add CONFIG_SYSTEM_POPEN_MAXARGUMENTS (default 7) to control the
argv array size for the no-shell path.
Signed-off-by: cuiziwei <cuiziwei@xiaomi.com>
