inject.py

f = open('feria.lsr', 'rb')
x = f.read()
f.close()

# Position of the strings data segment
pos = x[0x2c] | x[0x2d]<<8 | x[0x2e]<<16 | x[0x2f]<<24
# Length of the original segment
l = x[pos] | x[pos+1]<<8 | x[pos+2]<<16 | x[pos+3]<<24
# Number of 0-separated strings that should follow this number
num = x[pos+4] | x[pos+5]<<8 | x[pos+6]<<16 | x[pos+7]<<24

f = open('feria.txt', 'rb')
# Strip for newlines being added by text editors
y = f.read().strip()
f.close()

s = y.split(b'\r\n|\r\n')
if len(s) != num:
  print("Warning: expected %d strings, got %d!" %(num, len(s)))

# Re-encode all strings
for i in range(len(s)):
  j = s[i]
  try:
    j = j.decode('utf-8')
  except:
    print("Could not read item %d ('%s') as UTF-8" % (i, s[i]))
    exit()
  try:
    j = j.encode('shift-jis')
  except:
    print("Could not encode item %d ('%s') as Shift-JIS" % (i, s[i]))
    exit()
  s[i] = j + b'\0'

s = b''.join(s)
newLen = len(s)
offset = newLen - l

# Add the offset to known data pointers that point to data after strings
# 0x30 up to (and excluding) 0x64 are 32-bit integers pointing to
# locations after the strings.
b = list(x[:pos+8])
for i in range(0x30, 0x64, 4):
  v = b[i] | b[i+1]<<8 | b[i+2]<<16 | b[i+3]<<24
  v += offset
  b[i] = v & 0xff
  b[i+1] = (v & 0xff00) >> 8
  b[i+2] = (v & 0xff0000) >> 16
  b[i+3] = (v & 0xff000000) >> 24

b[pos] = newLen & 0xff
b[pos+1] = (newLen & 0xff00) >> 8
b[pos+2] = (newLen & 0xff0000) >> 16
b[pos+3] = (newLen & 0xff000000) >> 24

header = bytes(b)
footer = x[pos+l+8:]

f = open('feria_injected.lsr', 'wb')
f.write(header + s + footer)
f.close()