compat/cygwin.c

   1 #define WIN32_LEAN_AND_MEAN
   2 #include "../git-compat-util.h"
   3 #include "win32.h"
   4 #include "../cache.h" /* to read configuration */
   5
   6 static inline void filetime_to_timespec(const FILETIME *ft, struct timespec *ts)
   7 {
   8         long long winTime = ((long long)ft->dwHighDateTime << 32) +
   9                         ft->dwLowDateTime;
  10         winTime -= 116444736000000000LL; /* Windows to Unix Epoch conversion */
  11         /* convert 100-nsecond interval to seconds and nanoseconds */
  12         ts->tv_sec = (time_t)(winTime/10000000);
  13         ts->tv_nsec = (long)(winTime - ts->tv_sec*10000000LL) * 100;
  14 }
  15
  16 #define size_to_blocks(s) (((s)+511)/512)
  17
  18 /* do_stat is a common implementation for cygwin_lstat and cygwin_stat.
  19  *
  20  * To simplify its logic, in the case of cygwin symlinks, this implementation
  21  * falls back to the cygwin version of stat/lstat, which is provided as the
  22  * last argument.
  23  */
  24 static int do_stat(const char *file_name, struct stat *buf, stat_fn_t cygstat)
  25 {
  26         WIN32_FILE_ATTRIBUTE_DATA fdata;
  27
  28         if (file_name[0] == '/')
  29                 return cygstat (file_name, buf);
  30
  31         if (!(errno = get_file_attr(file_name, &fdata))) {
  32                 /*
  33                  * If the system attribute is set and it is not a directory then
  34                  * it could be a symbol link created in the nowinsymlinks mode.
  35                  * Normally, Cygwin works in the winsymlinks mode, so this situation
  36                  * is very unlikely. For the sake of simplicity of our code, let's
  37                  * Cygwin to handle it.
  38                  */
  39                 if ((fdata.dwFileAttributes & FILE_ATTRIBUTE_SYSTEM) &&
  40                     !(fdata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY))
  41                         return cygstat(file_name, buf);
  42
  43                 /* fill out the stat structure */
  44                 buf->st_dev = buf->st_rdev = 0; /* not used by Git */
  45                 buf->st_ino = 0;
  46                 buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes);
  47                 buf->st_nlink = 1;
  48                 buf->st_uid = buf->st_gid = 0;
  49 #ifdef __CYGWIN_USE_BIG_TYPES__
  50                 buf->st_size = ((_off64_t)fdata.nFileSizeHigh << 32) +
  51                         fdata.nFileSizeLow;
  52 #else
  53                 buf->st_size = (off_t)fdata.nFileSizeLow;
  54 #endif
  55                 buf->st_blocks = size_to_blocks(buf->st_size);
  56                 filetime_to_timespec(&fdata.ftLastAccessTime, &buf->st_atim);
  57                 filetime_to_timespec(&fdata.ftLastWriteTime, &buf->st_mtim);
  58                 filetime_to_timespec(&fdata.ftCreationTime, &buf->st_ctim);
  59                 return 0;
  60         } else if (errno == ENOENT) {
  61                 /*
  62                  * In the winsymlinks mode (which is the default), Cygwin
  63                  * emulates symbol links using Windows shortcut files. These
  64                  * files are formed by adding .lnk extension. So, if we have
  65                  * not found the specified file name, it could be that it is
  66                  * a symbol link. Let's Cygwin to deal with that.
  67                  */
  68                 return cygstat(file_name, buf);
  69         }
  70         return -1;
  71 }
  72
  73 /* We provide our own lstat/stat functions, since the provided Cygwin versions
  74  * of these functions are too slow. These stat functions are tailored for Git's
  75  * usage, and therefore they are not meant to be complete and correct emulation
  76  * of lstat/stat functionality.
  77  */
  78 static int cygwin_lstat(const char *path, struct stat *buf)
  79 {
  80         return do_stat(path, buf, lstat);
  81 }
  82
  83 static int cygwin_stat(const char *path, struct stat *buf)
  84 {
  85         return do_stat(path, buf, stat);
  86 }
  87
  88
  89 /*
  90  * At start up, we are trying to determine whether Win32 API or cygwin stat
  91  * functions should be used. The choice is determined by core.ignorecygwinfstricks.
  92  * Reading this option is not always possible immediately as git_dir may be
  93  * not be set yet. So until it is set, use cygwin lstat/stat functions.
  94  * However, if core.filemode is set, we must use the Cygwin posix
  95  * stat/lstat as the Windows stat fuctions do not determine posix filemode.
  96  *
  97  * Note that git_cygwin_config() does NOT call git_default_config() and this
  98  * is deliberate.  Many commands read from config to establish initial
  99  * values in variables and later tweak them from elsewhere (e.g. command line).
 100  * init_stat() is called lazily on demand, typically much late in the program,
 101  * and calling git_default_config() from here would break such variables.
 102  */
 103 static int native_stat = 1;
 104 static int core_filemode;
 105
 106 static int git_cygwin_config(const char *var, const char *value, void *cb)
 107 {
 108         if (!strcmp(var, "core.ignorecygwinfstricks"))
 109                 native_stat = git_config_bool(var, value);
 110         else if (!strcmp(var, "core.filemode"))
 111                 core_filemode = git_config_bool(var, value);
 112         return 0;
 113 }
 114
 115 static int init_stat(void)
 116 {
 117         if (have_git_dir()) {
 118                 git_config(git_cygwin_config, NULL);
 119                 if (!core_filemode && native_stat) {
 120                         cygwin_stat_fn = cygwin_stat;
 121                         cygwin_lstat_fn = cygwin_lstat;
 122                 } else {
 123                         cygwin_stat_fn = stat;
 124                         cygwin_lstat_fn = lstat;
 125                 }
 126                 return 0;
 127         }
 128         return 1;
 129 }
 130
 131 static int cygwin_stat_stub(const char *file_name, struct stat *buf)
 132 {
 133         return (init_stat() ? stat : *cygwin_stat_fn)(file_name, buf);
 134 }
 135
 136 static int cygwin_lstat_stub(const char *file_name, struct stat *buf)
 137 {
 138         return (init_stat() ? lstat : *cygwin_lstat_fn)(file_name, buf);
 139 }
 140
 141 stat_fn_t cygwin_stat_fn = cygwin_stat_stub;
 142 stat_fn_t cygwin_lstat_fn = cygwin_lstat_stub;
 143