将这段代码转换成lua语言typedef char PACKAGENAME; int getPID(const char *packageName) { int id = -1; DIR *dir; FILE *fp; char filename[64]; char cmdline[64]; struct dirent *entry; dir = opendir("/proc"); while ((entry = readdir(dir)) != NULL) { id = atoi(entry->d_name); if (id != 0) { sprintf(filename, "/proc/%d/cmdline", id); fp = fopen(filename, "r"); if (fp) { fgets(cmdline, sizeof(cmdline), fp); fclose(fp); if (strcmp(packageName, cmdline) == 0) { return id; } } } } closedir(dir); return -1; }

以下是将该代码转换为 Lua 语言的示例：

local ffi = require("ffi")
ffi.cdef[[
    typedef char PACKAGENAME;
    typedef struct DIR DIR;
    typedef struct dirent dirent;
    DIR *opendir(const char *name);
    dirent *readdir(DIR *dirp);
    int closedir(DIR *dirp);
    FILE *fopen(const char *path, const char *mode);
    int fclose(FILE *stream);
    char *fgets(char *s, int size, FILE *stream);
]]

function getPID(packageName)
    local id = -1
    local dir = ffi.C.opendir("/proc")
    if dir == nil then
        return id
    end
    local entry = ffi.new("dirent")
    local filename = ffi.new("char[?]", 64)
    local cmdline = ffi.new("char[?]", 64)
    repeat
        if ffi.C.readdir(dir, entry) == nil then
            break
        end
        id = tonumber(ffi.string(entry.d_name))
        if id ~= 0 then
            ffi.C.sprintf(filename, "/proc/%d/cmdline", id)
            local fp = ffi.C.fopen(filename, "r")
            if fp ~= nil then
                ffi.C.fgets(cmdline, 64, fp)
                ffi.C.fclose(fp)
                if ffi.string(cmdline) == packageName then
                    ffi.C.closedir(dir)
                    return id
                end
            end
        end
    until false
    ffi.C.closedir(dir)
    return -1
end