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      1 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/linux_util.h"
      6 
      7 #include <dirent.h>
      8 #include <errno.h>
      9 #include <glib.h>
     10 #include <stdlib.h>
     11 #include <sys/stat.h>
     12 #include <unistd.h>
     13 
     14 #include <vector>
     15 
     16 #include "base/command_line.h"
     17 #include "base/lock.h"
     18 #include "base/path_service.h"
     19 #include "base/process_util.h"
     20 #include "base/singleton.h"
     21 #include "base/string_util.h"
     22 #include "base/third_party/xdg_user_dirs/xdg_user_dir_lookup.h"
     23 
     24 namespace {
     25 
     26 class EnvironmentVariableGetterImpl
     27     : public base::EnvironmentVariableGetter {
     28  public:
     29   virtual bool Getenv(const char* variable_name, std::string* result) {
     30     const char* env_value = ::getenv(variable_name);
     31     if (env_value) {
     32       // Note that the variable may be defined but empty.
     33       *result = env_value;
     34       return true;
     35     }
     36     // Some commonly used variable names are uppercase while others
     37     // are lowercase, which is inconsistent. Let's try to be helpful
     38     // and look for a variable name with the reverse case.
     39     char first_char = variable_name[0];
     40     std::string alternate_case_var;
     41     if (first_char >= 'a' && first_char <= 'z')
     42       alternate_case_var = StringToUpperASCII(std::string(variable_name));
     43     else if (first_char >= 'A' && first_char <= 'Z')
     44       alternate_case_var = StringToLowerASCII(std::string(variable_name));
     45     else
     46       return false;
     47     env_value = ::getenv(alternate_case_var.c_str());
     48     if (env_value) {
     49       *result = env_value;
     50       return true;
     51     }
     52     return false;
     53   }
     54 };
     55 
     56 // Not needed for OS_CHROMEOS.
     57 #if defined(OS_LINUX)
     58 enum LinuxDistroState {
     59   STATE_DID_NOT_CHECK  = 0,
     60   STATE_CHECK_STARTED  = 1,
     61   STATE_CHECK_FINISHED = 2,
     62 };
     63 
     64 // Helper class for GetLinuxDistro().
     65 class LinuxDistroHelper {
     66  public:
     67   // Retrieves the Singleton.
     68   static LinuxDistroHelper* Get() {
     69     return Singleton<LinuxDistroHelper>::get();
     70   }
     71 
     72   // The simple state machine goes from:
     73   // STATE_DID_NOT_CHECK -> STATE_CHECK_STARTED -> STATE_CHECK_FINISHED.
     74   LinuxDistroHelper() : state_(STATE_DID_NOT_CHECK) {}
     75   ~LinuxDistroHelper() {}
     76 
     77   // Retrieve the current state, if we're in STATE_DID_NOT_CHECK,
     78   // we automatically move to STATE_CHECK_STARTED so nobody else will
     79   // do the check.
     80   LinuxDistroState State() {
     81     AutoLock scoped_lock(lock_);
     82     if (STATE_DID_NOT_CHECK == state_) {
     83       state_ = STATE_CHECK_STARTED;
     84       return STATE_DID_NOT_CHECK;
     85     }
     86     return state_;
     87   }
     88 
     89   // Indicate the check finished, move to STATE_CHECK_FINISHED.
     90   void CheckFinished() {
     91     AutoLock scoped_lock(lock_);
     92     DCHECK(state_ == STATE_CHECK_STARTED);
     93     state_ = STATE_CHECK_FINISHED;
     94   }
     95 
     96  private:
     97   Lock lock_;
     98   LinuxDistroState state_;
     99 };
    100 #endif  // if defined(OS_LINUX)
    101 
    102 // expected prefix of the target of the /proc/self/fd/%d link for a socket
    103 static const char kSocketLinkPrefix[] = "socket:[";
    104 
    105 // Parse a symlink in /proc/pid/fd/$x and return the inode number of the
    106 // socket.
    107 //   inode_out: (output) set to the inode number on success
    108 //   path: e.g. /proc/1234/fd/5 (must be a UNIX domain socket descriptor)
    109 //   log: if true, log messages about failure details
    110 bool ProcPathGetInode(ino_t* inode_out, const char* path, bool log = false) {
    111   DCHECK(inode_out);
    112   DCHECK(path);
    113 
    114   char buf[256];
    115   const ssize_t n = readlink(path, buf, sizeof(buf) - 1);
    116   if (n == -1) {
    117     if (log) {
    118       LOG(WARNING) << "Failed to read the inode number for a socket from /proc"
    119                       "(" << errno << ")";
    120     }
    121     return false;
    122   }
    123   buf[n] = 0;
    124 
    125   if (memcmp(kSocketLinkPrefix, buf, sizeof(kSocketLinkPrefix) - 1)) {
    126     if (log) {
    127       LOG(WARNING) << "The descriptor passed from the crashing process wasn't a"
    128                       " UNIX domain socket.";
    129     }
    130     return false;
    131   }
    132 
    133   char *endptr;
    134   const unsigned long long int inode_ul =
    135       strtoull(buf + sizeof(kSocketLinkPrefix) - 1, &endptr, 10);
    136   if (*endptr != ']')
    137     return false;
    138 
    139   if (inode_ul == ULLONG_MAX) {
    140     if (log) {
    141       LOG(WARNING) << "Failed to parse a socket's inode number: the number was "
    142                       "too large. Please report this bug: " << buf;
    143     }
    144     return false;
    145   }
    146 
    147   *inode_out = inode_ul;
    148   return true;
    149 }
    150 
    151 }  // anonymous namespace
    152 
    153 namespace base {
    154 
    155 uint8_t* BGRAToRGBA(const uint8_t* pixels, int width, int height, int stride) {
    156   if (stride == 0)
    157     stride = width * 4;
    158 
    159   uint8_t* new_pixels = static_cast<uint8_t*>(malloc(height * stride));
    160 
    161   // We have to copy the pixels and swap from BGRA to RGBA.
    162   for (int i = 0; i < height; ++i) {
    163     for (int j = 0; j < width; ++j) {
    164       int idx = i * stride + j * 4;
    165       new_pixels[idx] = pixels[idx + 2];
    166       new_pixels[idx + 1] = pixels[idx + 1];
    167       new_pixels[idx + 2] = pixels[idx];
    168       new_pixels[idx + 3] = pixels[idx + 3];
    169     }
    170   }
    171 
    172   return new_pixels;
    173 }
    174 
    175 // We use this static string to hold the Linux distro info. If we
    176 // crash, the crash handler code will send this in the crash dump.
    177 std::string linux_distro =
    178 #if defined(OS_CHROMEOS)
    179     "CrOS";
    180 #else  // if defined(OS_LINUX)
    181     "Unknown";
    182 #endif
    183 
    184 FilePath GetHomeDir(EnvironmentVariableGetter* env) {
    185   std::string home_dir;
    186   if (env->Getenv("HOME", &home_dir) && !home_dir.empty())
    187     return FilePath(home_dir);
    188 
    189   home_dir = g_get_home_dir();
    190   if (!home_dir.empty())
    191     return FilePath(home_dir);
    192 
    193   FilePath rv;
    194   if (PathService::Get(base::DIR_TEMP, &rv))
    195     return rv;
    196 
    197   // Last resort.
    198   return FilePath("/tmp");
    199 }
    200 
    201 std::string GetLinuxDistro() {
    202 #if defined(OS_CHROMEOS)
    203   return linux_distro;
    204 #else  // if defined(OS_LINUX)
    205   LinuxDistroHelper* distro_state_singleton = LinuxDistroHelper::Get();
    206   LinuxDistroState state = distro_state_singleton->State();
    207   if (STATE_DID_NOT_CHECK == state) {
    208     // We do this check only once per process. If it fails, there's
    209     // little reason to believe it will work if we attempt to run
    210     // lsb_release again.
    211     std::vector<std::string> argv;
    212     argv.push_back("lsb_release");
    213     argv.push_back("-d");
    214     std::string output;
    215     base::GetAppOutput(CommandLine(argv), &output);
    216     if (output.length() > 0) {
    217       // lsb_release -d should return: Description:<tab>Distro Info
    218       static const std::string field = "Description:\t";
    219       if (output.compare(0, field.length(), field) == 0) {
    220         linux_distro = output.substr(field.length());
    221         TrimWhitespaceASCII(linux_distro, TRIM_ALL, &linux_distro);
    222       }
    223     }
    224     distro_state_singleton->CheckFinished();
    225     return linux_distro;
    226   } else if (STATE_CHECK_STARTED == state) {
    227     // If the distro check above is in progress in some other thread, we're
    228     // not going to wait for the results.
    229     return "Unknown";
    230   } else {
    231     // In STATE_CHECK_FINISHED, no more writing to |linux_distro|.
    232     return linux_distro;
    233   }
    234 #endif
    235 }
    236 
    237 FilePath GetXDGDirectory(EnvironmentVariableGetter* env,
    238                          const char* env_name, const char* fallback_dir) {
    239   std::string env_value;
    240   if (env->Getenv(env_name, &env_value) && !env_value.empty())
    241     return FilePath(env_value);
    242   return GetHomeDir(env).Append(fallback_dir);
    243 }
    244 
    245 FilePath GetXDGUserDirectory(EnvironmentVariableGetter* env,
    246                              const char* dir_name, const char* fallback_dir) {
    247   char* xdg_dir = xdg_user_dir_lookup(dir_name);
    248   if (xdg_dir) {
    249     FilePath rv(xdg_dir);
    250     free(xdg_dir);
    251     return rv;
    252   }
    253   return GetHomeDir(env).Append(fallback_dir);
    254 }
    255 
    256 // static
    257 EnvironmentVariableGetter* EnvironmentVariableGetter::Create() {
    258   return new EnvironmentVariableGetterImpl();
    259 }
    260 
    261 DesktopEnvironment GetDesktopEnvironment(EnvironmentVariableGetter* env) {
    262   std::string desktop_session;
    263   if (env->Getenv("DESKTOP_SESSION", &desktop_session)) {
    264     if (desktop_session == "gnome")
    265       return DESKTOP_ENVIRONMENT_GNOME;
    266     else if (desktop_session == "kde4")
    267       return DESKTOP_ENVIRONMENT_KDE4;
    268     else if (desktop_session == "kde") {
    269       // This may mean KDE4 on newer systems, so we have to check.
    270       std::string dummy;
    271       if (env->Getenv("KDE_SESSION_VERSION", &dummy))
    272         return DESKTOP_ENVIRONMENT_KDE4;
    273       return DESKTOP_ENVIRONMENT_KDE3;
    274     }
    275   }
    276 
    277   // Fall back on some older environment variables.
    278   // Useful particularly in the DESKTOP_SESSION=default case.
    279   std::string dummy;
    280   if (env->Getenv("GNOME_DESKTOP_SESSION_ID", &dummy)) {
    281     return DESKTOP_ENVIRONMENT_GNOME;
    282   } else if (env->Getenv("KDE_FULL_SESSION", &dummy)) {
    283     if (env->Getenv("KDE_SESSION_VERSION", &dummy))
    284       return DESKTOP_ENVIRONMENT_KDE4;
    285     return DESKTOP_ENVIRONMENT_KDE3;
    286   }
    287 
    288   return DESKTOP_ENVIRONMENT_OTHER;
    289 }
    290 
    291 const char* GetDesktopEnvironmentName(DesktopEnvironment env) {
    292   switch (env) {
    293     case DESKTOP_ENVIRONMENT_OTHER:
    294       return NULL;
    295     case DESKTOP_ENVIRONMENT_GNOME:
    296       return "GNOME";
    297     case DESKTOP_ENVIRONMENT_KDE3:
    298       return "KDE3";
    299     case DESKTOP_ENVIRONMENT_KDE4:
    300       return "KDE4";
    301   }
    302   return NULL;
    303 }
    304 
    305 const char* GetDesktopEnvironmentName(EnvironmentVariableGetter* env) {
    306   return GetDesktopEnvironmentName(GetDesktopEnvironment(env));
    307 }
    308 
    309 bool FileDescriptorGetInode(ino_t* inode_out, int fd) {
    310   DCHECK(inode_out);
    311 
    312   struct stat buf;
    313   if (fstat(fd, &buf) < 0)
    314     return false;
    315 
    316   if (!S_ISSOCK(buf.st_mode))
    317     return false;
    318 
    319   *inode_out = buf.st_ino;
    320   return true;
    321 }
    322 
    323 bool FindProcessHoldingSocket(pid_t* pid_out, ino_t socket_inode) {
    324   DCHECK(pid_out);
    325   bool already_found = false;
    326 
    327   DIR* proc = opendir("/proc");
    328   if (!proc) {
    329     LOG(WARNING) << "Cannot open /proc";
    330     return false;
    331   }
    332 
    333   std::vector<pid_t> pids;
    334 
    335   struct dirent* dent;
    336   while ((dent = readdir(proc))) {
    337     char *endptr;
    338     const unsigned long int pid_ul = strtoul(dent->d_name, &endptr, 10);
    339     if (pid_ul == ULONG_MAX || *endptr)
    340       continue;
    341     pids.push_back(pid_ul);
    342   }
    343   closedir(proc);
    344 
    345   for (std::vector<pid_t>::const_iterator
    346        i = pids.begin(); i != pids.end(); ++i) {
    347     const pid_t current_pid = *i;
    348     char buf[256];
    349     snprintf(buf, sizeof(buf), "/proc/%d/fd", current_pid);
    350     DIR* fd = opendir(buf);
    351     if (!fd)
    352       continue;
    353 
    354     while ((dent = readdir(fd))) {
    355       if (snprintf(buf, sizeof(buf), "/proc/%d/fd/%s", current_pid,
    356                    dent->d_name) >= static_cast<int>(sizeof(buf))) {
    357         continue;
    358       }
    359 
    360       ino_t fd_inode;
    361       if (ProcPathGetInode(&fd_inode, buf)) {
    362         if (fd_inode == socket_inode) {
    363           if (already_found) {
    364             closedir(fd);
    365             return false;
    366           }
    367 
    368           already_found = true;
    369           *pid_out = current_pid;
    370           break;
    371         }
    372       }
    373     }
    374 
    375     closedir(fd);
    376   }
    377 
    378   return already_found;
    379 }
    380 
    381 }  // namespace base
    382