Added in file locking.

3 files changed, 124 insertions, 86 deletions

diff --git a/README.md b/README.md
index a046042..ea58c61 100644
--- a/README.md
+++ b/README.md
@@ -104,7 +104,7 @@ lpm --help
 ### Linux -> Windows
 
 ```
-./build.sh clean && CC=x86_64-w64-mingw32-gcc AR=x86_64-w64-mingw32-gcc-ar WINDRES=x86_64-w64-mingw32-windres 
+./build.sh clean && CC=x86_64-w64-mingw32-gcc AR=x86_64-w64-mingw32-gcc-ar WINDRES=x86_64-w64-mingw32-windres \
 CMAKE_DEFAULT_FLAGS="-DCMAKE_FIND_ROOT_PATH_MODE_PROGRAM=NEVER\ -DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY=NEVER -DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE=NEVER -DCMAKE_POSITION_INDEPENDENT_CODE=ON -DCMAKE_SYSTEM_NAME=Windows -DCMAKE_SYSTEM_INCLUDE_PATH=/usr/share/mingw-w64/include"\
   GIT2_CONFIGURE="-DDLLTOOL=x86_64-w64-mingw32-dlltool" ./build.sh -DLPM_STATIC -DLPM_VERSION='"'$VERSION-x86_64-windows-`git rev-parse --short HEAD`'"'
 ```
diff --git a/src/lpm.c b/src/lpm.c
index f2e9799..eb17e3b 100644
--- a/src/lpm.c
+++ b/src/lpm.c
@@ -24,6 +24,7 @@
 #include <fcntl.h>
 
 #include <sys/stat.h>
+#include <sys/file.h>
 #include <git2.h>
 #include <mbedtls/sha256.h>
 #include <mbedtls/x509.h>
@@ -98,38 +99,43 @@ int lpm_chmod(lua_State* L) {
   return 0;
 }
 
-/** BEGIN STOLEN LITE CODE **/
 #if _WIN32
-static LPWSTR utfconv_utf8towc(const char *str) {
-  LPWSTR output;
+static LPCWSTR lua_toutf16(lua_State* L, const char* str) {
+  if (str && str[0] == 0)
+    return L"";
   int len = MultiByteToWideChar(CP_UTF8, 0, str, -1, NULL, 0);
-  if (len == 0)
-    return NULL;
-  output = (LPWSTR) malloc(sizeof(WCHAR) * len);
-  if (output == NULL)
-    return NULL;
-  len = MultiByteToWideChar(CP_UTF8, 0, str, -1, output, len);
-  if (len == 0) {
-    free(output);
-    return NULL;
+  if (len > 0) {
+    LPWSTR output = (LPWSTR) malloc(sizeof(WCHAR) * len);
+    if (output) {
+      len = MultiByteToWideChar(CP_UTF8, 0, str, -1, output, len);
+      if (len > 0) {
+        lua_pushlstring(L, (char*)output, len * 2);
+        free(output);
+        return (LPCWSTR)lua_tostring(L, -1);
+      }
+      free(output);
+    }
   }
-  return output;
+  luaL_error(L, "can't convert utf8 string");
+  return NULL;
 }
 
-static char *utfconv_wctoutf8(LPCWSTR str) {
-  char *output;
+static const char* lua_toutf8(lua_State* L, LPCWSTR str) {
   int len = WideCharToMultiByte(CP_UTF8, 0, str, -1, NULL, 0, NULL, NULL);
-  if (len == 0)
-    return NULL;
-  output = (char *) malloc(sizeof(char) * len);
-  if (output == NULL)
-    return NULL;
-  len = WideCharToMultiByte(CP_UTF8, 0, str, -1, output, len, NULL, NULL);
-  if (len == 0) {
-    free(output);
-    return NULL;
+  if (len > 0) {
+    char* output = (char *) malloc(sizeof(char) * len);
+    if (output) {
+      len = WideCharToMultiByte(CP_UTF8, 0, str, -1, output, len, NULL, NULL);
+      if (len) {
+        lua_pushlstring(L, output, len);
+        free(output);
+        return lua_tostring(L, -1);
+      }
+      free(output);
+    }
   }
-  return output;
+  luaL_error(L, "can't convert utf16 string");
+  return NULL;
 }
 #endif
 
@@ -141,22 +147,16 @@ static int lpm_ls(lua_State *L) {
   lua_pushstring(L, path[0] == 0 || strchr("\\/", path[strlen(path) - 1]) != NULL ? "*" : "\\*");
   lua_concat(L, 2);
   path = lua_tostring(L, -1);
-
-  LPWSTR wpath = utfconv_utf8towc(path);
-  if (wpath == NULL)
-    return luaL_error(L, "can't ls %s: invalid utf8 character conversion", path);
     
   WIN32_FIND_DATAW fd;
-  HANDLE find_handle = FindFirstFileExW(wpath, FindExInfoBasic, &fd, FindExSearchNameMatch, NULL, 0);
-  free(wpath);
+  HANDLE find_handle = FindFirstFileExW(lua_toutf16(L, path), FindExInfoBasic, &fd, FindExSearchNameMatch, NULL, 0);
   if (find_handle == INVALID_HANDLE_VALUE)
     return luaL_error(L, "can't ls %s: %d", path, GetLastError());
   char mbpath[MAX_PATH * 4]; // utf-8 spans 4 bytes at most
   int len, i = 1;
   lua_newtable(L);
 
-  do
-  {
+  do {
     if (wcscmp(fd.cFileName, L".") == 0) { continue; }
     if (wcscmp(fd.cFileName, L"..") == 0) { continue; }
 
@@ -193,10 +193,7 @@ static int lpm_ls(lua_State *L) {
 static int lpm_rmdir(lua_State *L) {
   const char *path = luaL_checkstring(L, 1);
 #ifdef _WIN32
-  LPWSTR wpath = utfconv_utf8towc(path);
-  int deleted = RemoveDirectoryW(wpath);
-  free(wpath);
-  if (!deleted)
+  if (!RemoveDirectoryW(lua_toutf16(L, path)))
     return luaL_error(L, "can't rmdir %s: %d", path, GetLastError());
 #else
   if (remove(path))
@@ -208,11 +205,7 @@ static int lpm_rmdir(lua_State *L) {
 static int lpm_mkdir(lua_State *L) {
   const char *path = luaL_checkstring(L, 1);
 #ifdef _WIN32
-  LPWSTR wpath = utfconv_utf8towc(path);
-  if (wpath == NULL)
-    return luaL_error(L, "can't mkdir %s: invalid utf8 character conversion", path);
-  int err = _wmkdir(wpath);
-  free(wpath);
+  int err = _wmkdir(lua_toutf16(L, path));
 #else
   int err = mkdir(path, S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
 #endif
@@ -223,29 +216,25 @@ static int lpm_mkdir(lua_State *L) {
 
 static int lpm_stat(lua_State *L) {
   const char *path = luaL_checkstring(L, 1);
-  lua_newtable(L);
 #ifdef _WIN32
   #define realpath(x, y) _wfullpath(y, x, MAX_PATH)
   struct _stat s;
-  LPWSTR wpath = utfconv_utf8towc(path);
-  if (wpath == NULL)
-    return luaL_error(L, "can't stat %s: invalid utf8 character conversion", path);
+  LPCWSTR wpath = lua_toutf16(L, path);
   int err = _wstat(wpath, &s);
-  LPWSTR wfullpath = realpath(wpath, NULL);
-  free(wpath);
+  LPCWSTR wfullpath = realpath(wpath, NULL);
   if (!wfullpath) return 0;
-  char *abs_path = utfconv_wctoutf8(wfullpath);
-  free(wfullpath);
+  const char *abs_path = lua_toutf8(L, wfullpath);
 #else
   struct stat s;
   int err = lstat(path, &s);
-  char *abs_path = realpath(path, NULL);
+  const char *abs_path = realpath(path, NULL);
 #endif
   if (err || !abs_path) {
     lua_pushnil(L);
     lua_pushstring(L, strerror(errno));
     return 2;
   }
+  lua_newtable(L);
   lua_pushstring(L, abs_path); lua_setfield(L, -2, "abs_path");
   lua_pushvalue(L, 1); lua_setfield(L, -2, "path");
 
@@ -658,7 +647,7 @@ static int lpm_extract(lua_State* L) {
       tar.close = gzip_close;*/
       char buffer[8192];
       int len = strlen(src);
-      strncpy(actual_src, src, len - 3);
+      strncpy(actual_src, src, min(len - 3, PATH_MAX));
       actual_src[len-3] = 0;
       FILE* file = fopen(actual_src, "wb");
       while (1) {
@@ -951,6 +940,41 @@ static int lpm_pwd(lua_State* L) {
   return 1;
 }
 
+int lpm_flock(lua_State* L) {
+  const char* path = luaL_checkstring(L, 1);
+  luaL_checktype(L, 2, LUA_TFUNCTION);
+  #ifdef _WIN32
+    HANDLE file = CreateFileW(lua_toutf16(L, path), FILE_SHARE_READ, FILE_SHARE_READ, 0, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, 0);
+    if (!file || file == INVALID_HANDLE_VALUE)
+      return luaL_error(L, "can't open for flock %s: %d", path, GetLastError());
+    OVERLAPPED overlapped = {0};
+    if (!LockFileEx(file, LOCKFILE_EXCLUSIVE_LOCK, 0, 0, 1, &overlapped)) {
+      CloseHandle(file);
+      return luaL_error(L, "can't flock %s: %d", path, GetLastError());
+    }
+  #else 
+    int fd = open(path, 0);
+    if (fd == -1)
+      return luaL_error(L, "can't flock %s: %s", path, strerror(errno));
+    if (flock(fd, LOCK_EX) == -1) {
+      close(fd);
+      return luaL_error(L, "can't acquire exclusive lock on %s: %s", strerror(errno));
+    }
+  #endif
+  lua_pushvalue(L, 2);
+  lua_pushvalue(L, 1);
+  int err = lua_pcall(L, 1, 0, 0);
+  #ifdef _WIN32
+    UnlockFile(file, 0, 0, 1, 0);
+    CloseHandle(file);
+  #else
+    close(fd);
+  #endif
+  if (err)
+    return lua_error(L);
+  return 0;
+}
+
 static const luaL_Reg system_lib[] = {
   { "ls",        lpm_ls    },    // Returns an array of files.
   { "stat",      lpm_stat  },    // Returns info about a single file.
@@ -969,6 +993,7 @@ static const luaL_Reg system_lib[] = {
   { "certs",     lpm_certs },    // Sets the SSL certificate chain folder/file.
   { "chdir",     lpm_chdir },    // Changes directory. Only use for --post actions.
   { "pwd",       lpm_pwd },      // Gets existing directory. Only use for --post actions.
+  { "flock",     lpm_flock },    // Locks a file.
   { NULL,        NULL }
 };
 
diff --git a/src/lpm.lua b/src/lpm.lua
index 5089463..33929b0 100644
--- a/src/lpm.lua
+++ b/src/lpm.lua
@@ -455,6 +455,13 @@ end
 
 local HOME, USERDIR, CACHEDIR, JSON, VERBOSE, MOD_VERSION, QUIET, FORCE, AUTO_PULL_REMOTES, ARCH, ASSUME_YES, NO_INSTALL_OPTIONAL, TMPDIR, DATADIR, BINARY, POST, repositories, lite_xls, system_bottle, progress_bar_label, write_progress_bar
 
+local function engage_locks(func)
+  if not system.stat(USERDIR) then common.mkdirp(USERDIR) end
+  local lockfile = USERDIR .. PATHSEP .. ".lock"
+  if not system.stat(lockfile) then common.write(lockfile, "") end
+  system.flock(lockfile, func)
+end
+
 local Plugin, Repository, LiteXL, Bottle = {}, {}, {}, {}
 
 local actions, warnings = {}, {}
@@ -1817,44 +1824,48 @@ in any circumstance unless explicitly supplied.
   end
 
   -- Base setup; initialize default repos if applicable, read them in. Determine Lite XL system binary if not specified, and pull in a list of all local lite-xl's.
-  lpm_repo_init()
-  repositories, lite_xls = {}, {}
-  if system.stat(CACHEDIR .. PATHSEP .. "repos" .. PATHSEP .. "list") then
-    for url in io.lines(CACHEDIR .. PATHSEP .. "repos" .. PATHSEP .. "list") do
-      table.insert(repositories, Repository.url(url))
-      repositories[#repositories]:parse_manifest()
+  engage_locks(function()
+    lpm_repo_init()
+    repositories, lite_xls = {}, {}
+    if system.stat(CACHEDIR .. PATHSEP .. "repos" .. PATHSEP .. "list") then
+      for url in io.lines(CACHEDIR .. PATHSEP .. "repos" .. PATHSEP .. "list") do
+        table.insert(repositories, Repository.url(url))
+        repositories[#repositories]:parse_manifest()
+      end
     end
-  end
-  if system.stat(CACHEDIR .. PATHSEP .. "lite_xls" .. PATHSEP .. ARCH .. PATHSEP .. "locals.json") then
-    for i, lite_xl in ipairs(json.decode(common.read(CACHEDIR .. PATHSEP .. "lite_xls" .. PATHSEP .. ARCH .. PATHSEP .. "locals.json"))) do
-      table.insert(lite_xls, LiteXL.new(nil, { version = lite_xl.version, mod_version = lite_xl.mod_version, path = lite_xl.path, tags = { "local" } }))
+    if system.stat(CACHEDIR .. PATHSEP .. "lite_xls" .. PATHSEP .. ARCH .. PATHSEP .. "locals.json") then
+      for i, lite_xl in ipairs(json.decode(common.read(CACHEDIR .. PATHSEP .. "lite_xls" .. PATHSEP .. ARCH .. PATHSEP .. "locals.json"))) do
+        table.insert(lite_xls, LiteXL.new(nil, { version = lite_xl.version, mod_version = lite_xl.mod_version, path = lite_xl.path, tags = { "local" } }))
+      end
     end
-  end
-  local lite_xl_binary = BINARY or common.path("lite-xl")
-  if lite_xl_binary then
-    local stat = system.stat(lite_xl_binary)
-    if not stat then error("can't find lite-xl binary " .. lite_xl_binary) end
-    lite_xl_binary = stat.symlink or lite_xl_binary
-    local directory = common.dirname(lite_xl_binary)
-    local hash = system.hash(lite_xl_binary, "file")
-    local system_lite_xl = common.first(common.concat(common.flat_map(repositories, function(r) return r.lite_xls end), lite_xls), function(lite_xl) return lite_xl.local_path == directory end)
-    if not system_lite_xl then 
-      system_lite_xl = common.first(lite_xls, function(e) return e.version == "system" end)
-      if system_lite_xl then error("can't find existing system lite (does " .. system_lite_xl.binary_path .. " exist? was it moved?); run `lpm purge`, or specify --binary and --datadir.") end
-      system_lite_xl = LiteXL.new(nil, { datadir_path = DATADIR, binary_path = BINARY, mod_version = MOD_VERSION or 3, version = "system", tags = { "system", "local" } })
-      table.insert(lite_xls, system_lite_xl)
-      lpm_lite_xl_save()
+    local lite_xl_binary = BINARY or common.path("lite-xl")
+    if lite_xl_binary then
+      local stat = system.stat(lite_xl_binary)
+      if not stat then error("can't find lite-xl binary " .. lite_xl_binary) end
+      lite_xl_binary = stat.symlink or lite_xl_binary
+      local directory = common.dirname(lite_xl_binary)
+      local hash = system.hash(lite_xl_binary, "file")
+      local system_lite_xl = common.first(common.concat(common.flat_map(repositories, function(r) return r.lite_xls end), lite_xls), function(lite_xl) return lite_xl.local_path == directory end)
+      if not system_lite_xl then 
+        system_lite_xl = common.first(lite_xls, function(e) return e.version == "system" end)
+        if system_lite_xl then error("can't find existing system lite (does " .. system_lite_xl.binary_path .. " exist? was it moved?); run `lpm purge`, or specify --binary and --datadir.") end
+        system_lite_xl = LiteXL.new(nil, { datadir_path = DATADIR, binary_path = BINARY, mod_version = MOD_VERSION or 3, version = "system", tags = { "system", "local" } })
+        table.insert(lite_xls, system_lite_xl)
+        lpm_lite_xl_save()
+      else
+        table.insert(system_lite_xl.tags, "system")
+      end
+      system_bottle = Bottle.new(system_lite_xl, nil, true) 
     else
-      table.insert(system_lite_xl.tags, "system")
+      system_bottle = Bottle.new(LiteXL.new(nil, { mod_version = MOD_VERSION or 3, version = "system", tags = { "system", "local" } }), nil, true)
     end
-    system_bottle = Bottle.new(system_lite_xl, nil, true) 
-  else
-    system_bottle = Bottle.new(LiteXL.new(nil, { mod_version = MOD_VERSION or 3, version = "system", tags = { "system", "local" } }), nil, true)
-  end
-  if not system_bottle then system_bottle = Bottle.new(nil, nil, true) end
+    if not system_bottle then system_bottle = Bottle.new(nil, nil, true) end
+  end)
   
   if ARGS[2] ~= '-' then
-    run_command(ARGS)
+    engage_locks(function()
+      run_command(ARGS)
+    end)
   else
     while true do
       local line = io.stdin:read("*line")
@@ -1868,7 +1879,9 @@ in any circumstance unless explicitly supplied.
         s = e + 1
       end
       xpcall(function()
-        run_command(args)
+        engage_locks(function()
+          run_command(args)
+        end)
       end, error_handler)
       actions, warnings = {}, {}
     end