3 files changed, 20 insertions, 13 deletions

diff --git a/src/luarocks/fs/lua.lua b/src/luarocks/fs/lua.lua
index 51cbee03..f9ec43ba 100644
--- a/src/luarocks/fs/lua.lua
+++ b/src/luarocks/fs/lua.lua
@@ -123,18 +123,18 @@ end
 --- Check the MD5 checksum for a file.
 -- @param file string: The file to be checked.
 -- @param md5sum string: The string with the expected MD5 checksum.
--- @return boolean: true if the MD5 checksum for 'file' equals 'md5sum', false if not
+-- @return boolean: true if the MD5 checksum for 'file' equals 'md5sum', false + msg if not
 -- or if it could not perform the check for any reason.
 function check_md5(file, md5sum)
    file = dir.normalize(file)
-   local computed = fs.get_md5(file)
+   local computed, msg = fs.get_md5(file)
    if not computed then
-      return false
+      return false, msg
    end
    if computed:match("^"..md5sum) then
       return true
    else
-      return false
+      return false, "Mismatch MD5 hash for file "..file
    end
 end
 
@@ -648,14 +648,15 @@ if md5_ok then
 
 --- Get the MD5 checksum for a file.
 -- @param file string: The file to be computed.
--- @return string: The MD5 checksum
+-- @return string: The MD5 checksum or nil + error
 function get_md5(file)
    file = fs.absolute_name(file)
    local file = io.open(file, "rb")
-   if not file then return false end
+   if not file then return nil, "Failed to compute MD5 hash for file "..file end
    local computed = md5.sumhexa(file:read("*a"))
    file:close()
-   return computed
+   if computed then return computed end
+   return nil, "Failed to compute MD5 hash for file "..file
 end
 
 end
diff --git a/src/luarocks/fs/unix/tools.lua b/src/luarocks/fs/unix/tools.lua
index e3468ab4..c857b093 100644
--- a/src/luarocks/fs/unix/tools.lua
+++ b/src/luarocks/fs/unix/tools.lua
@@ -328,8 +328,11 @@ function get_md5(file)
    local pipe = io.popen(cmd.." "..fs.absolute_name(file))
    local computed = pipe:read("*a")
    pipe:close()
-   if not computed then return nil end
-   return computed:match("("..("%x"):rep(32)..")")
+   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 get_permissions(filename)
diff --git a/src/luarocks/fs/win32/tools.lua b/src/luarocks/fs/win32/tools.lua
index 9aa76851..1c0131c7 100644
--- a/src/luarocks/fs/win32/tools.lua
+++ b/src/luarocks/fs/win32/tools.lua
@@ -353,15 +353,18 @@ local md5_cmd = {
 
 --- Get the MD5 checksum for a file.
 -- @param file string: The file to be computed.
--- @return string: The MD5 checksum
+-- @return string: The MD5 checksum or nil + message
 function get_md5(file)
    local cmd = md5_cmd[cfg.md5checker]
    if not cmd then return nil end
-   local pipe = io.popen(cmd.." "..fs.Q(fs.absolute_name(file)))
+   local pipe = io.popen(cmd.." "..fs.absolute_name(file))   -- should be in fs.Q()
    local computed = pipe:read("*a")
    pipe:close()
-   if not computed then return nil end
-   return computed:match("("..("%x"):rep(32)..")")
+   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.