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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>
73 lines
2.4 KiB
Text
73 lines
2.4 KiB
Text
#
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# For a description of the syntax of this configuration file,
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# see the file kconfig-language.txt in the NuttX tools repository.
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#
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config SYSTEM_POPEN
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bool "popen()/pclose()/dpopen()/dpclose() Functions"
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default n
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select SCHED_WAITPID
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depends on PIPES
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---help---
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Enable support for the popen(), pclose(), dpopen(), and
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dpclose() interfaces.
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dpopen()/dpclose() are the descriptor-based counterparts
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of popen()/pclose(), analogous to how dprintf() relates
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to fprintf(). They return a raw file descriptor instead
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of a FILE stream, avoiding the stdio.h dependency.
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popen()/pclose() are thin wrappers around dpopen()/dpclose()
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that additionally wrap the fd in a FILE stream.
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When NSH is available (NSH_LIBRARY), commands are executed
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through the shell (sh -c command), supporting full shell
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syntax including pipes, redirects, and globbing.
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When NSH is not available, commands are executed directly
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via posix_spawnp(). The command string must be a simple
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"program arg1 arg2" form without shell syntax.
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if SYSTEM_POPEN
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config SYSTEM_POPEN_SHPATH
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string "Path to shell command"
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default "/bin/sh"
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depends on (SYSTEM_NSH=m || BUILD_KERNEL) && NSH_LIBRARY
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---help---
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This is the full path to the program in a mounted file system that
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implements the system() command. That is, a program that starts the
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NSH shell, executes one command (in argv[1]), then exits.
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config SYSTEM_POPEN_STACKSIZE
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int "Shell stack size"
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default DEFAULT_TASK_STACKSIZE
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---help---
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The size of stack allocated for the shell.
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NOTE: I needed to set the stack size quite large to get this example
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working on the simulated target (perhaps because of the 64-bit
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stack? Or perhaps that is a sneak call into the host libc that I
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have not caught). I assume that a smaller stack would be okay on
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real hardware, but I have not yet verified that.
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config SYSTEM_POPEN_PRIORITY
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int "Shell priority"
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default 100
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---help---
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The priority of the shell.
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config SYSTEM_POPEN_MAXARGUMENTS
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int "Maximum number of command arguments (no-shell mode)"
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default 7
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depends on !NSH_LIBRARY
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---help---
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When NSH is not available, dpopen()/popen() splits the command
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string by whitespace into an argv array. This sets the maximum
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number of arguments (excluding the program name and the
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terminating NULL).
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This is analogous to CONFIG_NSH_MAXARGUMENTS but applies
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only to the no-shell path.
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endif
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