Class: Tep::Shell

Inherits:
Object
  • Object
show all
Defined in:
lib/tep/shell.rb

Constant Summary collapse

DEFAULT_MAX = 
65535

Class Method Summary collapse

Class Method Details

.read(path) ⇒ Object

Read a file's contents. Useful for /proc/loadavg, /proc/meminfo, /sys/class/thermal/.../temp, and similar small-text endpoints. Returns "" on open failure. Spinel's File.read now raises a CRuby-correct Errno on a missing/unreadable path (it used to silently return ""); we rescue here to preserve this helper's never-raise contract -- a handler reading /proc should get "" for an absent file, not a 502'd worker.



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# File 'lib/tep/shell.rb', line 44

def self.read(path)
  begin
    File.read(path)
  rescue => e
    ""
  end
end

.read_limited(path, max_bytes) ⇒ Object

Bounded read: slice after the fact. The cap is mostly a defensive cue -- callers that need it should be reading bounded /proc files anyway. Same never-raise contract as #read.



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# File 'lib/tep/shell.rb', line 55

def self.read_limited(path, max_bytes)
  out = ""
  begin
    out = File.read(path)
  rescue => e
    out = ""
  end
  out.length > max_bytes ? out[0, max_bytes] : out
end

.run(cmd) ⇒ Object

Run cmd via /bin/sh -c; return up to DEFAULT_MAX bytes of stdout as a string. Stderr is inherited (visible on the server's console / log). The command's exit status is discarded -- callers that need it can append ; echo "EX=$?" and parse the tail. + "" forces a Ruby-side copy of the static C buffer; see read below.



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# File 'lib/tep/shell.rb', line 26

def self.run(cmd)
  Sock.sphttp_shell_capture(cmd, DEFAULT_MAX) + ""
end

.run_limited(cmd, max_bytes) ⇒ Object

As above but with a caller-chosen byte cap. Lower caps are cheaper memory-wise; higher caps (up to the sphttp internal buffer of ~64KB) let longer outputs through.



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# File 'lib/tep/shell.rb', line 33

def self.run_limited(cmd, max_bytes)
  Sock.sphttp_shell_capture(cmd, max_bytes) + ""
end

.write(path, data) ⇒ Object

Write data to path (truncate + rewrite). Returns the byte count for symmetry with the old FFI shape; spinel's File.write is void, so we recover it from data.length.



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# File 'lib/tep/shell.rb', line 68

def self.write(path, data)
  File.write(path, data)
  data.length
end