Added appending packages and overwriting package data if it is the same length

lib/solvitdb.lua

@@ -27,6 +27,59 @@ local function readPat(handle, patLength)
   return packages
 end
 
+local function insert(readHandle, writeHandle, data)
+  --NOTE: writeHandle must be in append ("a") mode
+  local chunkLength = 512
+  if #data > 512 then
+    chunkLength = #data
+  end
+  buf2 = data
+  while true do
+    buf1 = readHandle:read(chunkLength)
+    writeHandle:write(buf2)
+    if not buf1 then
+      break
+    end
+    buf2 = buf1
+  end
+end
+
+local function remove(filePath, location, length)
+  local chunkLength = 512
+  if length > 512 then
+    chunkLength = length
+  end
+  -- The file has to get shortened, so I have no choice but to do these shenanigans
+  local readHandle = assert(fs.open(filePath, "r"))
+  local tmpFilePath = filePath .. ".tmp"
+  local writeHandle = assert(fs.open(tmpFilePath, "w"))
+  local i = 0
+  while true do
+    local readAmount = chunkLength
+    if readAmount > location - i then
+      readAmount = location - i
+    end
+    if readAmount == 0 then
+      break
+    end
+    local data = readHandle:read(readAmount)
+    i = i + readAmount
+    assert(writeHandle:write(data))
+  end
+  readHandle:seek(length)
+  while true do
+    local data = readHandle:read(chunkLength)
+    if not data then
+      break
+    end
+    assert(writeHandle:write(data))
+  end
+  readHandle:close()
+  writeHandle:close()
+  fs.rename(tmpFilePath, filePath)
+  fs.remove(tmpFilePath)
+end
+
 function solvitdb.create(path)
   checkArg(1, path, "string")
   local handle = assert(fs.open(path, "w"))
@@ -38,7 +91,30 @@ function solvitdb.set(path, name, data)
   checkArg(1, path, "string")
   checkArg(2, name, "string")
   checkArg(3, data, "table")
-  local handle = checkValidityAndOpen(path)
+  local readHandle, patLength = checkValidityAndOpen(path)
+  local pat = readPat(readHandle, patLength)
+  if pat[name] then
+
+  else
+    local writeHandle = assert(fs.open(path, "a"))
+    writeHandle:seek("end")
+    local newPackageLocation = writeHandle:seek() - patLength - 8
+    if newPackageLocation > 4294967295 then
+      -- The above is the 32 bit unsigned integer limit
+      error("DB too large")
+    end
+    writeHandle:write("Pdguess-what-time-it-is;its-soup-time.\n")
+    writeHandle:seek("set", patLength + 8) -- + 8 because that's the length of the header
+    local patData = ("%s.%s;"):format(name, string.pack("<I4", newPackageLocation))
+    insert(readHandle, writeHandle, patData)
+    local newPatLength = patLength + #patData
+    writeHandle:seek("set", 0)
+    if newPatLength > 4294967295 then
+      error("PAT too large")
+    end
+    writeHandle:write(string.pack("<I4", newPatLength))
+    writeHandle:close()
+  end
 end
 
 function solvitdb.get(path, name)
@@ -46,7 +122,9 @@ function solvitdb.get(path, name)
   checkArg(2, name, "string")
   local handle, patLength = checkValidityAndOpen(path)
   local pat = readPat(handle, patLength)
-  assert(pat[name], "could not find package in PAT")
+  if not pat[name] then
+    return nil
+  end
   handle:seek(pat[name])
   local data, tmpdata = ""
   repeat
@@ -89,6 +167,7 @@ function solvitdb.get(path, name)
       table.insert(seriesOutput, seriesItem)
     end
   end
+  handle:close()
   return output
 end