Merge branch 'master' of https://github.com/keplerproject/luarocks

16 files changed, 335 insertions, 428 deletions

diff --git a/Makefile.setup.inc b/Makefile.setup.inc
index 0a049bc4..092d0423 100644
--- a/Makefile.setup.inc
+++ b/Makefile.setup.inc
@@ -5,7 +5,7 @@ BINDIR ?= $(PREFIX)/bin
 LUADIR ?= $(PREFIX)/share/lua/$(LUA_VERSION)/
 
 BIN_FILES = luarocks luarocks-admin
-LUAROCKS_FILES = fs/unix/tools.lua fs/unix.lua fs/win32/tools.lua fs/win32.lua \
+LUAROCKS_FILES = fs/tools.lua fs/unix/tools.lua fs/unix.lua fs/win32/tools.lua fs/win32.lua \
 fs/lua.lua persist.lua list.lua require.lua repos.lua dir.lua make_manifest.lua \
 command_line.lua config_cmd.lua install.lua build/command.lua build/cmake.lua \
 build/make.lua build/builtin.lua fetch/cvs.lua fetch/git.lua fetch/sscm.lua \
diff --git a/src/luarocks/build.lua b/src/luarocks/build.lua
index a1aeb501..c62e4694 100644
--- a/src/luarocks/build.lua
+++ b/src/luarocks/build.lua
@@ -332,15 +332,7 @@ function build.build_rockspec(rockspec_file, need_to_fetch, minimal_mode, deps_m
    ok, err = manif.update_manifest(name, version, nil, deps_mode)
    if err then return nil, err end
 
-   local license = ""
-   if rockspec.description and rockspec.description.license then
-      license = ("(license: "..rockspec.description.license..")")
-   end
-
-   local root_dir = path.root_dir(cfg.rocks_dir)
-   util.printout(name.." "..version.." is now built and installed in "..root_dir.." "..license)
-   util.printout()
-   
+   util.announce_install(rockspec)
    util.remove_scheduled_function(rollback)
    return name, version
 end
diff --git a/src/luarocks/deps.lua b/src/luarocks/deps.lua
index 812e6d18..536b6c51 100644
--- a/src/luarocks/deps.lua
+++ b/src/luarocks/deps.lua
@@ -322,48 +322,32 @@ end
 -- @param dep table: A dependency parsed in table format.
 -- @param blacklist table: Versions that can't be accepted. Table where keys
 -- are program versions and values are 'true'.
--- @return table or nil: A table containing fields 'name' and 'version'
--- representing an installed rock which matches the given dependency,
+-- @return string or nil: latest installed version of the rock matching the dependency
 -- or nil if it could not be matched.
 local function match_dep(dep, blacklist, deps_mode)
    assert(type(dep) == "table")
 
-   local versions = cfg.rocks_provided[dep.name]
+   local versions
    if cfg.rocks_provided[dep.name] then
       -- provided rocks have higher priority than manifest's rocks
       versions = { cfg.rocks_provided[dep.name] }
    else
       versions = manif_core.get_versions(dep.name, deps_mode)
    end
-   if not versions then
-      return nil
-   end
-   if blacklist then
-      local i = 1
-      while versions[i] do
-         if blacklist[versions[i]] then
-            table.remove(versions, i)
-         else
-            i = i + 1
-         end
-      end
-   end
-   local candidates = {}
+
+   local latest_version
    for _, vstring in ipairs(versions) do
-      local version = deps.parse_version(vstring)
-      if deps.match_constraints(version, dep.constraints) then
-         table.insert(candidates, version)
+      if not blacklist or not blacklist[vstring] then
+         local version = deps.parse_version(vstring)
+         if deps.match_constraints(version, dep.constraints) then
+            if not latest_version or version > latest_version then
+               latest_version = version
+            end
+         end
       end
    end
-   if #candidates == 0 then
-      return nil
-   else
-      table.sort(candidates)
-      return {
-         name = dep.name,
-         version = candidates[#candidates].string
-      }
-   end
+
+   return latest_version and latest_version.string
 end
 
 --- Attempt to match dependencies of a rockspec to installed rocks.
@@ -386,7 +370,7 @@ function deps.match_deps(rockspec, blacklist, deps_mode)
       local found = match_dep(dep, blacklist and blacklist[dep.name] or nil, deps_mode)
       if found then
          if not cfg.rocks_provided[dep.name] then
-            matched[dep] = found
+            matched[dep] = {name = dep.name, version = found}
          end
       else
          if dep.constraints[1] and dep.constraints[1].no_upgrade then
@@ -410,6 +394,13 @@ local function values_set(tbl)
    return set
 end
 
+local function rock_status(name, deps_mode)
+   local search = require("luarocks.search")
+   local installed = match_dep(search.make_query(name), nil, deps_mode)
+   local installation_type = cfg.rocks_provided[name] and "provided by VM" or "installed"
+   return installed and installed.." "..installation_type or "not installed"
+end
+
 --- Check dependencies of a rock and attempt to install any missing ones.
 -- Packages are installed using the LuaRocks "install" command.
 -- Aborts the program if a dependency could not be fulfilled.
@@ -449,52 +440,53 @@ function deps.fulfill_dependencies(rockspec, deps_mode)
       end
    end
 
-   local _, missing, no_upgrade = deps.match_deps(rockspec, nil, deps_mode)
+   local first_missing_dep = true
 
-   if next(no_upgrade) then
-      util.printerr("Missing dependencies for "..rockspec.name.." "..rockspec.version..":")
-      for _, dep in pairs(no_upgrade) do
-         util.printerr(deps.show_dep(dep))
-      end
-      if next(missing) then
-         for _, dep in pairs(missing) do
-            util.printerr(deps.show_dep(dep))
+   for _, dep in ipairs(rockspec.dependencies) do
+      if not match_dep(dep, nil, deps_mode) then
+         if first_missing_dep then
+            util.printout(("Missing dependencies for %s %s:"):format(rockspec.name, rockspec.version))
+            first_missing_dep = false
          end
+
+         util.printout(("   %s (%s)"):format(deps.show_dep(dep), rock_status(dep.name, deps_mode)))
       end
-      util.printerr()
-      for _, dep in pairs(no_upgrade) do
-         util.printerr("This version of "..rockspec.name.." is designed for use with")
-         util.printerr(deps.show_dep(dep)..", but is configured to avoid upgrading it")
-         util.printerr("automatically. Please upgrade "..dep.name.." with")
-         util.printerr("   luarocks install "..dep.name)
-         util.printerr("or choose an older version of "..rockspec.name.." with")
-         util.printerr("   luarocks search "..rockspec.name)
-      end
-      return nil, "Failed matching dependencies."
    end
 
-   if next(missing) then
-      util.printerr()
-      util.printerr("Missing dependencies for "..rockspec.name..":")
-      for _, dep in pairs(missing) do
-         util.printerr(deps.show_dep(dep))
-      end
-      util.printerr()
-
-      for _, dep in pairs(missing) do
-         -- Double-check in case dependency was filled during recursion.
-         if not match_dep(dep, nil, deps_mode) then
-            local url, err = search.find_suitable_rock(dep)
-            if not url then
-               return nil, "Could not satisfy dependency "..deps.show_dep(dep)..": "..err
-            end
-            local ok, err, errcode = install.run(url, deps.deps_mode_to_flag(deps_mode))
-            if not ok then
-               return nil, "Failed installing dependency: "..url.." - "..err, errcode
-            end
+   first_missing_dep = true
+
+   for _, dep in ipairs(rockspec.dependencies) do
+      if not match_dep(dep, nil, deps_mode) then
+         if first_missing_dep then
+            util.printout()
+            first_missing_dep = false
+         end
+
+         util.printout(("%s %s depends on %s (%s)"):format(
+            rockspec.name, rockspec.version, deps.show_dep(dep), rock_status(dep.name, deps_mode)))
+
+         if dep.constraints[1] and dep.constraints[1].no_upgrade then
+            util.printerr("This version of "..rockspec.name.." is designed for use with")
+            util.printerr(deps.show_dep(dep)..", but is configured to avoid upgrading it")
+            util.printerr("automatically. Please upgrade "..dep.name.." with")
+            util.printerr("   luarocks install "..dep.name)
+            util.printerr("or choose an older version of "..rockspec.name.." with")
+            util.printerr("   luarocks search "..rockspec.name)
+            return nil, "Failed matching dependencies"
+         end
+
+         local url, search_err = search.find_suitable_rock(dep)
+         if not url then
+            return nil, "Could not satisfy dependency "..deps.show_dep(dep)..": "..search_err
+         end
+         util.printout("Installing "..url)
+         local ok, install_err, errcode = install.run(url, deps.deps_mode_to_flag(deps_mode))
+         if not ok then
+            return nil, "Failed installing dependency: "..url.." - "..install_err, errcode
          end
       end
    end
+
    return true
 end
 
diff --git a/src/luarocks/fs.lua b/src/luarocks/fs.lua
index 57302c7f..f3d86a13 100644
--- a/src/luarocks/fs.lua
+++ b/src/luarocks/fs.lua
@@ -68,7 +68,10 @@ load_fns(fs_lua)
 
 -- Load platform-specific fallbacks for missing Lua modules
 local ok, fs_plat_tools = pcall(require, "luarocks.fs."..loaded_platform..".tools")
-if ok and fs_plat_tools then load_fns(fs_plat_tools) end
+if ok and fs_plat_tools then
+   load_fns(fs_plat_tools)
+   load_fns(require("luarocks.fs.tools"))
+end
 
 
 return fs
diff --git a/src/luarocks/fs/tools.lua b/src/luarocks/fs/tools.lua
new file mode 100644
index 00000000..ed51b545
--- /dev/null
+++ b/src/luarocks/fs/tools.lua
@@ -0,0 +1,156 @@
+
+--- Common fs operations implemented with third-party tools.
+local tools = {}
+
+local fs = require("luarocks.fs")
+local dir = require("luarocks.dir")
+local cfg = require("luarocks.cfg")
+
+local vars = cfg.variables
+
+local dir_stack = {}
+
+--- Obtain current directory.
+-- Uses the module's internal directory stack.
+-- @return string: the absolute pathname of the current directory.
+function tools.current_dir()
+   local current = cfg.cache_pwd
+   if not current then
+      local pipe = io.popen(fs.quiet_stderr(fs.Q(vars.PWD)))
+      current = pipe:read("*l")
+      pipe:close()
+      cfg.cache_pwd = current
+   end
+   for _, directory in ipairs(dir_stack) do
+      current = fs.absolute_name(directory, current)
+   end
+   return current
+end
+
+--- Change the current directory.
+-- Uses the module's internal directory stack. This does not have exact
+-- semantics of chdir, as it does not handle errors the same way,
+-- but works well for our purposes for now.
+-- @param directory string: The directory to switch to.
+-- @return boolean or (nil, string): true if successful, (nil, error message) if failed.
+function tools.change_dir(directory)
+   assert(type(directory) == "string")
+   if fs.is_dir(directory) then
+      table.insert(dir_stack, directory)
+      return true
+   end
+   return nil, "directory not found: "..directory
+end
+
+--- Change directory to root.
+-- Allows leaving a directory (e.g. for deleting it) in
+-- a crossplatform way.
+function tools.change_dir_to_root()
+   table.insert(dir_stack, "/")
+end
+
+--- Change working directory to the previous in the directory stack.
+function tools.pop_dir()
+   local directory = table.remove(dir_stack)
+   return directory ~= nil
+end
+
+--- Run the given command.
+-- The command is executed in the current directory in the directory stack.
+-- @param cmd string: No quoting/escaping is applied to the command.
+-- @return boolean: true if command succeeds (status code 0), false
+-- otherwise.
+function tools.execute_string(cmd)
+   local current = fs.current_dir()
+   if not current then return false end
+   cmd = fs.command_at(current, cmd)
+   local code = os.execute(cmd)
+   if code == 0 or code == true then
+      return true
+   else
+      return false
+   end
+end
+
+--- Internal implementation function for fs.dir.
+-- Yields a filename on each iteration.
+-- @param at string: directory to list
+-- @return nil
+function tools.dir_iterator(at)
+   local pipe = io.popen(fs.command_at(at, fs.Q(vars.LS)))
+   for file in pipe:lines() do
+      if file ~= "." and file ~= ".." then
+         coroutine.yield(file)
+      end
+   end
+   pipe:close()
+end
+
+--- Download a remote file.
+-- @param url string: URL to be fetched.
+-- @param filename string or nil: this function attempts to detect the
+-- resulting local filename of the remote file as the basename of the URL;
+-- if that is not correct (due to a redirection, for example), the local
+-- filename can be given explicitly as this second argument.
+-- @return (boolean, string): true and the filename on success,
+-- false and the error message on failure.
+function tools.use_downloader(url, filename, cache)
+   assert(type(url) == "string")
+   assert(type(filename) == "string" or not filename)
+
+   filename = fs.absolute_name(filename or dir.base_name(url))
+
+   local ok
+   if cfg.downloader == "wget" then
+      local wget_cmd = fs.Q(vars.WGET).." "..vars.WGETNOCERTFLAG.." --no-cache --user-agent=\""..cfg.user_agent.." via wget\" --quiet "
+      if cfg.connection_timeout and cfg.connection_timeout > 0 then
+        wget_cmd = wget_cmd .. "--timeout="..tonumber(cfg.connection_timeout).." --tries=1 "
+      end
+      if cache then
+         -- --timestamping is incompatible with --output-document,
+         -- but that's not a problem for our use cases.
+         fs.change_dir(dir.dir_name(filename))
+         ok = fs.execute_quiet(wget_cmd.." --timestamping ", url)
+         fs.pop_dir()
+      elseif filename then
+         ok = fs.execute_quiet(wget_cmd.." --output-document ", filename, url)
+      else
+         ok = fs.execute_quiet(wget_cmd, url)
+      end
+   elseif cfg.downloader == "curl" then
+      local curl_cmd = fs.Q(vars.CURL).." "..vars.CURLNOCERTFLAG.." -f -L --user-agent \""..cfg.user_agent.." via curl\" "
+      if cfg.connection_timeout and cfg.connection_timeout > 0 then
+        curl_cmd = curl_cmd .. "--connect-timeout "..tonumber(cfg.connection_timeout).." "
+      end
+      ok = fs.execute_string(fs.quiet_stderr(curl_cmd..fs.Q(url).." > "..fs.Q(filename)))
+   end
+   if ok then
+      return true, filename
+   else
+      return false
+   end
+end
+
+local md5_cmd = {
+   md5sum = fs.Q(vars.MD5SUM),
+   openssl = fs.Q(vars.OPENSSL).." md5",
+   md5 = fs.Q(vars.MD5),
+}
+
+--- Get the MD5 checksum for a file.
+-- @param file string: The file to be computed.
+-- @return string: The MD5 checksum or nil + message
+function tools.get_md5(file)
+   local cmd = md5_cmd[cfg.md5checker]
+   if not cmd then return nil, "no MD5 checker command configured" end
+   local pipe = io.popen(cmd.." "..fs.Q(fs.absolute_name(file)))
+   local computed = pipe:read("*a")
+   pipe:close()
+   if computed then
+      computed = computed:match("("..("%x"):rep(32)..")")
+   end
+   if computed then return computed end
+   return nil, "Failed to compute MD5 hash for file "..tostring(fs.absolute_name(file))
+end
+
+return tools
diff --git a/src/luarocks/fs/unix.lua b/src/luarocks/fs/unix.lua
index e2cc825b..520b3e99 100644
--- a/src/luarocks/fs/unix.lua
+++ b/src/luarocks/fs/unix.lua
@@ -16,6 +16,13 @@ function unix.quiet(cmd)
    return cmd.." 1> /dev/null 2> /dev/null"
 end
 
+--- Annotate command string for execution with quiet stderr.
+-- @param cmd string: A command-line string.
+-- @return string: The command-line, with stderr silencing annotation.
+function unix.quiet_stderr(cmd)
+   return cmd.." 2> /dev/null"
+end
+
 --- Return an absolute pathname from a potentially relative one.
 -- @param pathname string: pathname to convert.
 -- @param relative_to string or nil: path to prepend when making
diff --git a/src/luarocks/fs/unix/tools.lua b/src/luarocks/fs/unix/tools.lua
index ab55897e..84bd53fd 100644
--- a/src/luarocks/fs/unix/tools.lua
+++ b/src/luarocks/fs/unix/tools.lua
@@ -7,74 +7,16 @@ local fs = require("luarocks.fs")
 local dir = require("luarocks.dir")
 local cfg = require("luarocks.cfg")
 
-local dir_stack = {}
-
 local vars = cfg.variables
 
-local function command_at(directory, cmd)
+--- Adds prefix to command to make it run from a directory.
+-- @param directory string: Path to a directory.
+-- @param cmd string: A command-line string.
+-- @return string: The command-line with prefix.
+function tools.command_at(directory, cmd)
    return "cd " .. fs.Q(fs.absolute_name(directory)) .. " && " .. cmd
 end
 
---- Obtain current directory.
--- Uses the module's internal directory stack.
--- @return string: the absolute pathname of the current directory.
-function tools.current_dir()
-   local current = cfg.cache_pwd
-   if not current then
-      local pipe = io.popen(fs.Q(vars.PWD).." 2> /dev/null")
-      current = pipe:read("*l")
-      pipe:close()
-      cfg.cache_pwd = current
-   end
-   for _, directory in ipairs(dir_stack) do
-      current = fs.absolute_name(directory, current)
-   end
-   return current
-end
-
---- Run the given command.
--- The command is executed in the current directory in the directory stack.
--- @param cmd string: No quoting/escaping is applied to the command.
--- @return boolean: true if command succeeds (status code 0), false
--- otherwise.
-function tools.execute_string(cmd)
-   local current = fs.current_dir()
-   if not current then return false end
-   local code, err = os.execute(command_at(current, cmd))
-   if code == 0 or code == true then
-      return true
-   else
-      return false
-   end
-end
-
---- Change the current directory.
--- Uses the module's internal directory stack. This does not have exact
--- semantics of chdir, as it does not handle errors the same way,
--- but works well for our purposes for now.
--- @param directory string: The directory to switch to.
-function tools.change_dir(directory)
-   assert(type(directory) == "string")
-   if fs.is_dir(directory) then
-      table.insert(dir_stack, directory)
-      return true
-   end
-   return nil, "directory not found: "..directory
-end
-
---- Change directory to root.
--- Allows leaving a directory (e.g. for deleting it) in
--- a crossplatform way.
-function tools.change_dir_to_root()
-   table.insert(dir_stack, "/")
-end
-
---- Change working directory to the previous in the directory stack.
-function tools.pop_dir()
-   local directory = table.remove(dir_stack)
-   return directory ~= nil
-end
-
 --- Create a directory if it does not already exist.
 -- If any of the higher levels in the path name does not exist
 -- too, they are created as well.
@@ -155,20 +97,6 @@ function tools.delete(arg)
    fs.execute_quiet(vars.RM, "-rf", arg)
 end
 
---- Internal implementation function for fs.dir.
--- Yields a filename on each iteration.
--- @param at string: directory to list
--- @return nil
-function tools.dir_iterator(at)
-   local pipe = io.popen(command_at(at, vars.LS))
-   for file in pipe:lines() do
-      if file ~= "." and file ~= ".." then
-         coroutine.yield(file)
-      end
-   end
-   pipe:close()
-end
-
 --- Recursively scan the contents of a directory.
 -- @param at string or nil: directory to scan (will be the current
 -- directory if none is given).
@@ -183,7 +111,7 @@ function tools.find(at)
       return {}
    end
    local result = {}
-   local pipe = io.popen(command_at(at, vars.FIND.." * 2>/dev/null"))
+   local pipe = io.popen(fs.command_at(at, fs.quiet_stderr(vars.FIND.." *")))
    for file in pipe:lines() do
       table.insert(result, file)
    end
@@ -232,51 +160,6 @@ function tools.is_file(file)
    return fs.execute(vars.TEST, "-f", file)
 end
 
---- Download a remote file.
--- @param url string: URL to be fetched.
--- @param filename string or nil: this function attempts to detect the
--- resulting local filename of the remote file as the basename of the URL;
--- if that is not correct (due to a redirection, for example), the local
--- filename can be given explicitly as this second argument.
--- @return (boolean, string): true and the filename on success,
--- false and the error message on failure.
-function tools.use_downloader(url, filename, cache)
-   assert(type(url) == "string")
-   assert(type(filename) == "string" or not filename)
-
-   filename = fs.absolute_name(filename or dir.base_name(url))
-
-   local ok
-   if cfg.downloader == "wget" then
-      local wget_cmd = fs.Q(vars.WGET).." "..vars.WGETNOCERTFLAG.." --no-cache --user-agent='"..cfg.user_agent.." via wget' --quiet "
-      if cfg.connection_timeout and cfg.connection_timeout > 0 then
-        wget_cmd = wget_cmd .. "--timeout="..tonumber(cfg.connection_timeout).." --tries=1 " 
-      end
-      if cache then
-         -- --timestamping is incompatible with --output-document,
-         -- but that's not a problem for our use cases.
-         fs.change_dir(dir.dir_name(filename))
-         ok = fs.execute_quiet(wget_cmd.." --timestamping ", url)
-         fs.pop_dir()
-      elseif filename then
-         ok = fs.execute_quiet(wget_cmd.." --output-document ", filename, url)
-      else
-         ok = fs.execute_quiet(wget_cmd, url)
-      end
-   elseif cfg.downloader == "curl" then
-      local curl_cmd = fs.Q(vars.CURL).." "..vars.CURLNOCERTFLAG.." -f -L --user-agent '"..cfg.user_agent.." via curl' "
-      if cfg.connection_timeout and cfg.connection_timeout > 0 then
-        curl_cmd = curl_cmd .. "--connect-timeout "..tonumber(cfg.connection_timeout).." " 
-      end
-      ok = fs.execute_string(curl_cmd..fs.Q(url).." 2> /dev/null 1> "..fs.Q(filename))
-   end
-   if ok then
-      return true, filename
-   else
-      return false
-   end
-end
-
 function tools.chmod(pathname, mode)
    if mode then 
       return fs.execute(vars.CHMOD, mode, pathname)
@@ -319,28 +202,6 @@ function tools.unpack_archive(archive)
    return true
 end
 
-local md5_cmd = {
-   md5sum = vars.MD5SUM,
-   openssl = vars.OPENSSL.." md5",
-   md5 = vars.MD5,
-}
-
---- Get the MD5 checksum for a file.
--- @param file string: The file to be computed.
--- @return string: The MD5 checksum
-function tools.get_md5(file)
-   local cmd = md5_cmd[cfg.md5checker]
-   if not cmd then return nil, "no MD5 checker command configured" end
-   local pipe = io.popen(cmd.." "..fs.Q(fs.absolute_name(file)))
-   local computed = pipe:read("*a")
-   pipe:close()
-   if computed then
-      computed = computed:match("("..("%x"):rep(32)..")")
-   end
-   if computed then return computed end
-   return nil, "Failed to compute MD5 hash for file "..tostring(fs.absolute_name(file))
-end
-
 function tools.get_permissions(filename)
    local pipe = io.popen(vars.STAT.." "..vars.STATFLAG.." "..fs.Q(filename))
    local ret = pipe:read("*l")
diff --git a/src/luarocks/fs/win32.lua b/src/luarocks/fs/win32.lua
index c14c421b..74f3ed69 100644
--- a/src/luarocks/fs/win32.lua
+++ b/src/luarocks/fs/win32.lua
@@ -27,6 +27,13 @@ function win32.quiet(cmd)
    return cmd.." 2> NUL 1> NUL"
 end
 
+--- Annotate command string for execution with quiet stderr.
+-- @param cmd string: A command-line string.
+-- @return string: The command-line, with stderr silencing annotation.
+function win32.quiet_stderr(cmd)
+   return cmd.." 2> NUL"
+end
+
 local drive_letter = "[%.a-zA-Z]?:?[\\/]"
 
 local win_escape_chars = {
diff --git a/src/luarocks/fs/win32/tools.lua b/src/luarocks/fs/win32/tools.lua
index b9dce85c..9cb6d47a 100644
--- a/src/luarocks/fs/win32/tools.lua
+++ b/src/luarocks/fs/win32/tools.lua
@@ -9,22 +9,13 @@ local fs = require("luarocks.fs")
 local dir = require("luarocks.dir")
 local cfg = require("luarocks.cfg")
 
-local dir_stack = {}
-
 local vars = cfg.variables
 
---- Strip the last extension of a filename.
--- Example: "foo.tar.gz" becomes "foo.tar".
--- If filename has no dots, returns it unchanged.
--- @param filename string: The file name to strip.
--- @return string: The stripped name.
-local function strip_extension(filename)
-   assert(type(filename) == "string")
-
-   return (filename:gsub("%.[^.]+$", "")) or filename
-end
-
-local function command_at(directory, cmd)
+--- Adds prefix to command to make it run from a directory.
+-- @param directory string: Path to a directory.
+-- @param cmd string: A command-line string.
+-- @return string: The command-line with prefix.
+function tools.command_at(directory, cmd)
    local drive = directory:match("^([A-Za-z]:)")
    cmd = "cd " .. fs.Q(directory) .. " & " .. cmd
    if drive then
@@ -33,68 +24,6 @@ local function command_at(directory, cmd)
    return cmd
 end
 
---- Obtain current directory.
--- Uses the module's internal directory stack.
--- @return string: the absolute pathname of the current directory.
-function tools.current_dir()
-   local current = cfg.cache_pwd
-   if not current then
-      local pipe = io.popen(fs.Q(vars.PWD).. " 2> NUL")
-      current = pipe:read("*l")
-      pipe:close()
-      cfg.cache_pwd = current
-   end
-   for _, directory in ipairs(dir_stack) do
-      current = fs.absolute_name(directory, current)
-   end
-   return current
-end
-
---- Run the given command.
--- The command is executed in the current directory in the directory stack.
--- @param cmd string: No quoting/escaping is applied to the command.
--- @return boolean: true if command succeeds (status code 0), false
--- otherwise.
-function tools.execute_string(cmd)
-   local current = fs.current_dir()
-   if not current then return false end
-   cmd = command_at(current, cmd)
-   local code = os.execute(cmd)
-   if code == 0 or code == true then
-      return true
-   else
-      return false
-   end
-end
-
---- Change the current directory.
--- Uses the module's internal directory stack. This does not have exact
--- semantics of chdir, as it does not handle errors the same way,
--- but works well for our purposes for now.
--- @param directory string: The directory to switch to.
--- @return boolean or (nil, string): true if successful, (nil, error message) if failed.
-function tools.change_dir(directory)
-   assert(type(directory) == "string")
-   if fs.is_dir(directory) then
-      table.insert(dir_stack, directory)
-      return true
-   end
-   return nil, "directory not found: "..directory
-end
-
---- Change directory to root.
--- Allows leaving a directory (e.g. for deleting it) in
--- a crossplatform way.
-function tools.change_dir_to_root()
-   table.insert(dir_stack, "/")
-end
-
---- Change working directory to the previous in the directory stack.
-function tools.pop_dir()
-   local directory = table.remove(dir_stack)
-   return directory ~= nil
-end
-
 --- Create a directory if it does not already exist.
 -- If any of the higher levels in the path name does not exist
 -- too, they are created as well.
@@ -168,20 +97,6 @@ function tools.delete(arg)
    fs.execute_quiet("if exist "..fs.Q(arg.."\\").." ( RMDIR /S /Q "..fs.Q(arg).." ) else ( DEL /Q /F "..fs.Q(arg).." )")
 end
 
---- Internal implementation function for fs.dir.
--- Yields a filename on each iteration.
--- @param at string: directory to list
--- @return nil
-function tools.dir_iterator(at)
-   local pipe = io.popen(command_at(at, fs.Q(vars.LS)))
-   for file in pipe:lines() do
-      if file ~= "." and file ~= ".." then
-         coroutine.yield(file)
-      end
-   end
-   pipe:close()
-end
-
 --- Recursively scan the contents of a directory.
 -- @param at string or nil: directory to scan (will be the current
 -- directory if none is given).
@@ -196,7 +111,7 @@ function tools.find(at)
       return {}
    end
    local result = {}
-   local pipe = io.popen(command_at(at, fs.Q(vars.FIND).." 2> NUL"))
+   local pipe = io.popen(fs.command_at(at, fs.quiet_stderr(fs.Q(vars.FIND))))
    for file in pipe:lines() do
       -- Windows find is a bit different
       local first_two = file:sub(1,2)
@@ -242,49 +157,14 @@ function tools.is_file(file)
    return fs.execute(fs.Q(vars.TEST).." -f", file)
 end
 
---- Download a remote file.
--- @param url string: URL to be fetched.
--- @param filename string or nil: this function attempts to detect the
--- resulting local filename of the remote file as the basename of the URL;
--- if that is not correct (due to a redirection, for example), the local
--- filename can be given explicitly as this second argument.
--- @return (boolean, string): true and the filename on success,
--- false and the error message on failure.
-function tools.use_downloader(url, filename, cache)
-   assert(type(url) == "string")
-   assert(type(filename) == "string" or not filename)
-
-   filename = fs.absolute_name(filename or dir.base_name(url))
-
-   local ok   
-   if cfg.downloader == "wget" then
-      local wget_cmd = fs.Q(vars.WGET).." "..vars.WGETNOCERTFLAG.." --no-cache --user-agent=\""..cfg.user_agent.." via wget\" --quiet "
-      if cfg.connection_timeout and cfg.connection_timeout > 0 then
-        wget_cmd = wget_cmd .. "--timeout="..tonumber(cfg.connection_timeout).." --tries=1 " 
-      end
-      if cache then
-         -- --timestamping is incompatible with --output-document,
-         -- but that's not a problem for our use cases.
-         fs.change_dir(dir.dir_name(filename))
-         ok = fs.execute_quiet(wget_cmd.." --timestamping ", url)
-         fs.pop_dir()
-      elseif filename then
-         ok = fs.execute_quiet(wget_cmd.." --output-document ", filename, url)
-      else
-         ok = fs.execute_quiet(wget_cmd, url)
-      end
-   elseif cfg.downloader == "curl" then
-      local curl_cmd = fs.Q(vars.CURL).." "..vars.CURLNOCERTFLAG.." -f -L --user-agent \""..cfg.user_agent.." via curl\" "
-      if cfg.connection_timeout and cfg.connection_timeout > 0 then
-        curl_cmd = curl_cmd .. "--connect-timeout "..tonumber(cfg.connection_timeout).." " 
-      end
-      ok = fs.execute_string(curl_cmd..fs.Q(url).." 2> NUL 1> "..fs.Q(filename))
-   end
-   if ok then
-      return true, filename
-   else
-      return false
-   end
+--- Strip the last extension of a filename.
+-- Example: "foo.tar.gz" becomes "foo.tar".
+-- If filename has no dots, returns it unchanged.
+-- @param filename string: The file name to strip.
+-- @return string: The stripped name.
+local function strip_extension(filename)
+   assert(type(filename) == "string")
+   return (filename:gsub("%.[^.]+$", "")) or filename
 end
 
 --- Uncompress gzip file.
@@ -334,28 +214,6 @@ function tools.unpack_archive(archive)
    return true
 end
 
-local md5_cmd = {
-   md5sum = fs.Q(vars.MD5SUM),
-   openssl = fs.Q(vars.OPENSSL).." md5",
-   md5 = fs.Q(vars.MD5),
-}
-
---- Get the MD5 checksum for a file.
--- @param file string: The file to be computed.
--- @return string: The MD5 checksum or nil + message
-function tools.get_md5(file)
-   local cmd = md5_cmd[cfg.md5checker]
-   if not cmd then return nil, "no MD5 checker command configured" end
-   local pipe = io.popen(cmd.." "..fs.Q(fs.absolute_name(file)))
-   local computed = pipe:read("*a")
-   pipe:close()
-   if computed then
-      computed = computed:match("("..("%x"):rep(32)..")")
-   end
-   if computed then return computed end
-   return nil, "Failed to compute MD5 hash for file "..tostring(fs.absolute_name(file))
-end
-
 --- Test for existance of a file.
 -- @param file string: filename to test
 -- @return boolean: true if file exists, false otherwise.
diff --git a/src/luarocks/install.lua b/src/luarocks/install.lua
index b6af43cc..e3ab6fac 100644
--- a/src/luarocks/install.lua
+++ b/src/luarocks/install.lua
@@ -98,15 +98,7 @@ function install.install_binary_rock(rock_file, deps_mode)
    ok, err = manif.update_manifest(name, version, nil, deps_mode)
    if err then return nil, err end
    
-   local license = ""
-   if rockspec.description.license then
-      license = ("(license: "..rockspec.description.license..")")
-   end
-
-   local root_dir = path.root_dir(cfg.rocks_dir)
-   util.printout()
-   util.printout(name.." "..version.." is now installed in "..root_dir.." "..license)
-   
+   util.announce_install(rockspec)
    util.remove_scheduled_function(rollback)
    return name, version
 end
@@ -168,7 +160,6 @@ function install.run(...)
    if not ok then return nil, err, cfg.errorcodes.PERMISSIONDENIED end
 
    if name:match("%.rockspec$") or name:match("%.src%.rock$") then
-      util.printout("Using "..name.."... switching to 'build' mode")
       local build = require("luarocks.build")
       return build.run(name, util.forward_flags(flags, "local", "keep", "deps-mode", "only-deps", "force", "force-fast"))
    elseif name:match("%.rock$") then
@@ -190,7 +181,7 @@ function install.run(...)
       if not url then
          return nil, err
       end
-      util.printout("Installing "..url.."...")
+      util.printout("Installing "..url)
       return install.run(url, util.forward_flags(flags))
    end
 end
diff --git a/src/luarocks/manif.lua b/src/luarocks/manif.lua
index 05621315..bc202be3 100644
--- a/src/luarocks/manif.lua
+++ b/src/luarocks/manif.lua
@@ -432,8 +432,6 @@ function manif.update_manifest(name, version, repo, deps_mode)
    
    if deps_mode == "none" then deps_mode = cfg.deps_mode end
 
-   util.printout("Updating manifest for "..repo)
-
    local manifest, err = manif.load_manifest(repo)
    if not manifest then
       util.printerr("No existing manifest. Attempting to rebuild...")
diff --git a/src/luarocks/repos.lua b/src/luarocks/repos.lua
index 66b1377f..b6d5825a 100644
--- a/src/luarocks/repos.lua
+++ b/src/luarocks/repos.lua
@@ -157,11 +157,10 @@ local function install_binary(source, target, name, version)
    assert(type(target) == "string")
    
    if fs.is_lua(source) then
-      repos.ok, repos.err = fs.wrap_script(source, target, name, version)
+      return fs.wrap_script(source, target, name, version)
    else
-      repos.ok, repos.err = fs.copy_binary(source, target)
+      return fs.copy_binary(source, target)
    end
-   return repos.ok, repos.err
 end
 
 local function resolve_conflict(target, deploy_dir, name, version)
diff --git a/src/luarocks/util.lua b/src/luarocks/util.lua
index 80f1684a..520625c0 100644
--- a/src/luarocks/util.lua
+++ b/src/luarocks/util.lua
@@ -506,6 +506,20 @@ function util.see_help(command, program)
    return "See '"..util.this_program(program or "luarocks")..' help'..(command and " "..command or "").."'."
 end
 
+function util.announce_install(rockspec)
+   local cfg = require("luarocks.cfg")
+   local path = require("luarocks.path")
+
+   local suffix = ""
+   if rockspec.description and rockspec.description.license then
+      suffix = " (license: "..rockspec.description.license..")"
+   end
+
+   local root_dir = path.root_dir(cfg.rocks_dir)
+   util.printout(rockspec.name.." "..rockspec.version.." is now installed in "..root_dir..suffix)
+   util.printout()
+end
+
 -- from http://lua-users.org/wiki/SplitJoin
 -- by PhilippeLhoste
 function util.split_string(str, delim, maxNb)
diff --git a/src/luarocks/write_rockspec.lua b/src/luarocks/write_rockspec.lua
index 972562c3..abfca322 100644
--- a/src/luarocks/write_rockspec.lua
+++ b/src/luarocks/write_rockspec.lua
@@ -12,14 +12,16 @@ local type_check = require("luarocks.type_check")
 local util = require("luarocks.util")
 
 write_rockspec.help_summary = "Write a template for a rockspec file."
-write_rockspec.help_arguments = "[--output=<file> ...] [<name>] [<version>] {<url>|<path>}"
+write_rockspec.help_arguments = "[--output=<file> ...] [<name>] [<version>] [<url>|<path>]"
 write_rockspec.help = [[
 This command writes an initial version of a rockspec file,
-based on an URL or a local path. You may use a relative path such as '.'.
-If a local path is given, name and version arguments are mandatory.
-For URLs, LuaRocks will attempt to infer name and version if not given.
-
-If a repository URL is given with no version, it creates an 'scm' rock.
+based on a name, a version, and a location (an URL or a local path).
+If only two arguments are given, the first one is considered the name and the
+second one is the location.
+If only one argument is given, it must be the location.
+If no arguments are given, current directory is used as location.
+LuaRocks will attempt to infer name and version if not given,
+using 'scm' as default version.
 
 Note that the generated file is a _starting point_ for writing a
 rockspec, and is not guaranteed to be complete or correct.
@@ -198,18 +200,17 @@ end
 
 function write_rockspec.run(...)
    local flags, name, version, url_or_dir = util.parse_flags(...)
-   
-   if not name then
-      return nil, "Missing arguments. "..util.see_help("write_rockspec")
-   end
 
-   if name and not version then
+   if not name then
+      url_or_dir = "."
+   elseif not version then
       url_or_dir = name
       name = nil
    elseif not url_or_dir then
       url_or_dir = version
+      version = nil
    end
-   
+
    if flags["tag"] then
       if not version then
          version = flags["tag"]:gsub("^v", "")
@@ -217,28 +218,25 @@ function write_rockspec.run(...)
    end
 
    local protocol, pathname = dir.split_url(url_or_dir)
-   if not fetch.is_basic_protocol(protocol) then
-      if not name then
-         name = dir.base_name(url_or_dir):gsub("%.[^.]+$", "")
+   if protocol == "file" then
+      if pathname == "." then
+         name = name or dir.base_name(fs.current_dir())
       end
-      if not version then
-         version = "scm"
-      end
-   elseif protocol ~= "file" then
+   elseif fetch.is_basic_protocol(protocol) then
       local filename = dir.base_name(url_or_dir)
       local newname, newversion = filename:match("(.*)-([^-]+)")
-      if (not name) and newname then
-         name = newname
-      end
-      if (not version) and newversion then
-         version = newversion:gsub(".[a-z]+$", ""):gsub(".tar$", "")
+      if newname then
+         name = name or newname
+         version = version or newversion:gsub("%.[a-z]+$", ""):gsub("%.tar$", "")
       end
-      if not (name and version) then
-         return nil, "Missing name and version arguments. "..util.see_help("write_rockspec")
-      end
-   elseif not version then
-      return nil, "Missing name and version arguments. "..util.see_help("write_rockspec")
+   else
+      name = name or dir.base_name(url_or_dir):gsub("%.[^.]+$", "")
+   end
+
+   if not name then
+      return nil, "Could not infer rock name. "..util.see_help("write_rockspec")
    end
+   version = version or "scm"
 
    local filename = flags["output"] or dir.path(fs.current_dir(), name:lower().."-"..version.."-1.rockspec")
    
diff --git a/test/testing.lua b/test/testing.lua
index c37293ee..1a837484 100644
--- a/test/testing.lua
+++ b/test/testing.lua
@@ -459,6 +459,25 @@ local tests = {
          and assert("lua-compat-5.2" == fetch.url_to_base_dir("https://github.com/hishamhm/lua-compat-5.2.tar.bz2"))
          and assert("parser.moon" == fetch.url_to_base_dir("git://github.com/Cirru/parser.moon"))
          and assert("v0.3" == fetch.url_to_base_dir("https://github.com/hishamhm/lua-compat-5.2/archive/v0.3"))
+   end,
+
+   -- Tests for https://github.com/keplerproject/luarocks/issues/552
+   test_install_break_dependencies_warning = function()
+      need_luasocket()
+      return run "$luarocks install say ${new_version_say}"
+         and run "$luarocks install luassert"
+         and run "$luarocks install say ${old_version_say}"
+   end,
+   test_install_break_dependencies_force = function()
+      need_luasocket()
+      return run "$luarocks install say ${new_version_say}"
+         and run "$luarocks install luassert"
+         and run "$luarocks install --force say ${old_version_say}"
+   end,
+   test_install_break_dependencies_force = function()
+      need_luasocket()
+      return run "$luarocks install say ${new_version_say}"
+         and run "$luarocks install luassert"
+         and run "$luarocks install --force-fast say ${old_version_say}"
    end
-   
 }
diff --git a/test/testing.sh b/test/testing.sh
index 5269e42a..f56f2aa9 100755
--- a/test/testing.sh
+++ b/test/testing.sh
@@ -179,6 +179,9 @@ srcdir_luasocket=luasocket-3.0-rc1
 version_cprint=0.1
 verrev_cprint=0.1-2
 
+new_version_say=1.2-1
+old_version_say=1.0-1
+
 version_luacov=0.11.0
 verrev_luacov=${version_luacov}-1
 version_lxsh=0.8.6
@@ -260,6 +263,9 @@ mkdir -p "$testing_server"
    get "$luarocks_repo/lua-path-0.2.3-1.src.rock"
    get "$luarocks_repo/lua-cjson-2.1.0-1.src.rock"
    get "$luarocks_repo/luacov-coveralls-0.1.1-1.src.rock"
+   get "$luarocks_repo/say-1.2-1.src.rock"
+   get "$luarocks_repo/say-1.0-1.src.rock"
+   get "$luarocks_repo/luassert-1.7.0-1.src.rock"
 )
 $luarocks_admin_nocov make_manifest "$testing_server"
 
@@ -358,7 +364,6 @@ fail_upload_noarg() { $luarocks upload; }
 fail_remove_noarg() { $luarocks remove; }
 fail_doc_noarg() { $luarocks doc; }
 fail_new_version_noarg() { $luarocks new_version; }
-fail_write_rockspec_noarg() { $luarocks write_rockspec; }
 
 fail_build_invalid() { $luarocks build invalid; }
 fail_download_invalid() { $luarocks download invalid; }
@@ -517,6 +522,9 @@ test_deps_mode_make_order() { $luarocks build --tree="$testing_sys_tree" lpeg &&
 test_deps_mode_make_order_sys() { $luarocks build --tree="$testing_tree" lpeg && rm -rf ./lxsh-${verrev_lxsh} && $luarocks download --source lxsh ${verrev_lxsh} && $luarocks unpack ./lxsh-${verrev_lxsh}.src.rock && cd lxsh-${verrev_lxsh}/lxsh-${version_lxsh}-1  && $luarocks make --tree="$testing_sys_tree" --deps-mode=order && cd ../.. && [ `$luarocks_noecho list --tree="$testing_tree" --porcelain lpeg | wc -l` = 1 ] && rm -rf ./lxsh-${verrev_lxsh}; }
 
 test_write_rockspec() { $luarocks write_rockspec git://github.com/keplerproject/luarocks; }
+test_write_rockspec_name() { $luarocks write_rockspec luarocks git://github.com/keplerproject/luarocks; }
+test_write_rockspec_name_version() { $luarocks write_rockspec luarocks 7.8.9 git://github.com/keplerproject/luarocks; }
+test_write_rockspec_current_dir() { $luarocks write_rockspec; }
 test_write_rockspec_tag() { $luarocks write_rockspec git://github.com/keplerproject/luarocks --tag=v2.3.0; }
 test_write_rockspec_lib() { $luarocks write_rockspec git://github.com/mbalmer/luafcgi --lib=fcgi --license="3-clause BSD" --lua-version=5.1,5.2; }
 test_write_rockspec_format() { $luarocks write_rockspec git://github.com/keplerproject/luarocks --rockspec-format=1.1 --lua-version=5.1,5.2; }
@@ -558,8 +566,12 @@ test_doc_list() { $luarocks install luacov; $luarocks doc luacov --list; }
 test_doc_local() { $luarocks install luacov; $luarocks doc luacov --local; }
 test_doc_porcelain() { $luarocks install luacov; $luarocks doc luacov --porcelain; }
 
-# Driver #########################################
+# Tests for https://github.com/keplerproject/luarocks/pull/552
+test_install_break_dependencies_warning() { need_luasocket; $luarocks install say ${new_version_say} && $luarocks install luassert && $luarocks install say ${old_version_say}; }
+test_install_break_dependencies_force() { need_luasocket; $luarocks install say ${new_version_say} && $luarocks install luassert && $luarocks install --force say ${old_version_say}; }
+test_install_break_dependencies_forcefast() { need_luasocket; $luarocks install say ${new_version_say} && $luarocks install luassert && $luarocks install --force-fast say ${old_version_say}; }
 
+# Driver #########################################
 run_tests() {
    grep "^test_$1.*(" < $testing_dir/testing.sh | cut -d'(' -f1 | while read test
    do