nshlib: add relative image path support in boot command

[Junbo-Zheng]

Summary

cmd_boot passed the image path straight to boardctl(), which resolves it in a context that does not inherit the NSH shell cwd, so relative paths failed, and only absolute paths worked. Use nsh_getfullpath() to resolve relative paths against the cwd before calling boardctl().

Impact

• Users: boot <relative-path> now resolves against the NSH cwd;
  absolute-path behavior is unchanged.
• Build: None -- uses the existing nsh_getfullpath/nsh_freefullpath
  helpers, no new dependency.
• Hardware: None -- NSH command logic only, no board-specific code.
• Documentation: None.
• Security & Compatibility: None -- behavior extension; absolute
  paths behave exactly as before.

Testing

Local build on Cortex-M55 (enables CONFIG_BOARDCTL_BOOT_IMAGE); the boot ELF builds and the boot NSH command succeeds.

And the change follows the established nsh_getfullpath()/nsh_freefullpath() convention already used by the other NSH file-path commands. Representative upstream examples (the same pattern is also used by mv, ls, ln, mkdir, and every other NSH file-path command):

• cp (src) -- https://github.com/apache/nuttx-apps/blob/master/nshlib/nsh_fscmds.c#L1106
• cp (dest) -- https://github.com/apache/nuttx-apps/blob/master/nshlib/nsh_fscmds.c#L1113
• cat -- https://github.com/apache/nuttx-apps/blob/master/nshlib/nsh_fscmds.c#L854
• rm -- https://github.com/apache/nuttx-apps/blob/master/nshlib/nsh_fscmds.c#L2667

[cederom]

Thank you @Junbo-Zheng :-)

[acassis]

@Junbo-Zheng I think this feature needs Documentation

[cederom]

I also wonder about impact on firmware size, have you compared that @Junbo-Zheng ? Maybe we want this as an option if the function is not part of the firmware by default? I understand that cp, rm, cat can use relative paths but these can be disabled by default. If no impact then no problem :-)

[Junbo-Zheng]

@Junbo-Zheng I think this feature needs Documentation

@acassis Done, please review apache/nuttx#19553

[Junbo-Zheng]

I also wonder about impact on firmware size, have you compared that @Junbo-Zheng ? Maybe we want this as an option if the function is not part of the firmware by default? I understand that cp, rm, cat can use relative paths but these can be disabled by default. If no impact then no problem :-)

@cederom

The boot nsh command is already optional — it is gated by CONFIG_BOARDCTL_BOOT_IMAGE (opt-in) together with CONFIG_NSH_DISABLE_BOOT (opt-out), see nsh_syscmds.c#L404. Platforms that don't need image boot simply leave CONFIG_BOARDCTL_BOOT_IMAGE unset, and cmd_boot (along with its nsh_getfullpath() call) is not compiled in at all.

Local build with Arm GNU Toolchain 13.2.rel1

/home/mi/xiaomi/trunk [26-07-27_13:53:56] arm-none-eabi-gcc --version
arm-none-eabi-gcc (Arm GNU Toolchain 13.2.rel1 (Build arm-13.7)) 13.2.1 20231009
Copyright (C) 2023 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

• before

/home/mi/xiaomi/trunk/out [26-07-27_12:16:26] arm-none-eabi-size nuttx 
   text	   data	    bss	    dec	    hex	filename
 469784	  15352	49257896	49743032	2f704b8	nuttx

• after
  • CONFIG_BOARDCTL_BOOT_IMAGE=y
  • CONFIG_NSH_DISABLE_BOOT not set

/home/mi/xiaomi/trunk/out [26-07-27_12:18:43] arm-none-eabi-size nuttx 
   text	   data	    bss	    dec	    hex	filename
 469792	  15352	49257896	49743040	2f704c0	nuttx