compat/cygwin.c

   1 #define CYGWIN_C
   2 #define WIN32_LEAN_AND_MEAN
   3 #include <sys/stat.h>
   4 #include <sys/errno.h>
   5 #include "win32.h"
   6 #include "../git-compat-util.h"
   7 #include "../cache.h" /* to read configuration */
   8
   9 /*
  10  * Return POSIX permission bits, regardless of core.ignorecygwinfstricks
  11  */
  12 int cygwin_get_st_mode_bits(const char *path, int *mode)
  13 {
  14         struct stat st;
  15         if (lstat(path, &st) < 0)
  16                 return -1;
  17         *mode = st.st_mode;
  18         return 0;
  19 }
  20
  21 static inline void filetime_to_timespec(const FILETIME *ft, struct timespec *ts)
  22 {
  23         long long winTime = ((long long)ft->dwHighDateTime << 32) +
  24                         ft->dwLowDateTime;
  25         winTime -= 116444736000000000LL; /* Windows to Unix Epoch conversion */
  26         /* convert 100-nsecond interval to seconds and nanoseconds */
  27         ts->tv_sec = (time_t)(winTime/10000000);
  28         ts->tv_nsec = (long)(winTime - ts->tv_sec*10000000LL) * 100;
  29 }
  30
  31 #define size_to_blocks(s) (((s)+511)/512)
  32
  33 /* do_stat is a common implementation for cygwin_lstat and cygwin_stat.
  34  *
  35  * To simplify its logic, in the case of cygwin symlinks, this implementation
  36  * falls back to the cygwin version of stat/lstat, which is provided as the
  37  * last argument.
  38  */
  39 static int do_stat(const char *file_name, struct stat *buf, stat_fn_t cygstat)
  40 {
  41         WIN32_FILE_ATTRIBUTE_DATA fdata;
  42
  43         if (file_name[0] == '/')
  44                 return cygstat (file_name, buf);
  45
  46         if (!(errno = get_file_attr(file_name, &fdata))) {
  47                 /*
  48                  * If the system attribute is set and it is not a directory then
  49                  * it could be a symbol link created in the nowinsymlinks mode.
  50                  * Normally, Cygwin works in the winsymlinks mode, so this situation
  51                  * is very unlikely. For the sake of simplicity of our code, let's
  52                  * Cygwin to handle it.
  53                  */
  54                 if ((fdata.dwFileAttributes & FILE_ATTRIBUTE_SYSTEM) &&
  55                     !(fdata.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY))
  56                         return cygstat(file_name, buf);
  57
  58                 /* fill out the stat structure */
  59                 buf->st_dev = buf->st_rdev = 0; /* not used by Git */
  60                 buf->st_ino = 0;
  61                 buf->st_mode = file_attr_to_st_mode(fdata.dwFileAttributes);
  62                 buf->st_nlink = 1;
  63                 buf->st_uid = buf->st_gid = 0;
  64 #ifdef __CYGWIN_USE_BIG_TYPES__
  65                 buf->st_size = ((_off64_t)fdata.nFileSizeHigh << 32) +
  66                         fdata.nFileSizeLow;
  67 #else
  68                 buf->st_size = (off_t)fdata.nFileSizeLow;
  69 #endif
  70                 buf->st_blocks = size_to_blocks(buf->st_size);
  71                 filetime_to_timespec(&fdata.ftLastAccessTime, &buf->st_atim);
  72                 filetime_to_timespec(&fdata.ftLastWriteTime, &buf->st_mtim);
  73                 filetime_to_timespec(&fdata.ftCreationTime, &buf->st_ctim);
  74                 return 0;
  75         } else if (errno == ENOENT) {
  76                 /*
  77                  * In the winsymlinks mode (which is the default), Cygwin
  78                  * emulates symbol links using Windows shortcut files. These
  79                  * files are formed by adding .lnk extension. So, if we have
  80                  * not found the specified file name, it could be that it is
  81                  * a symbol link. Let's Cygwin to deal with that.
  82                  */
  83                 return cygstat(file_name, buf);
  84         }
  85         return -1;
  86 }
  87
  88 /* We provide our own lstat/stat functions, since the provided Cygwin versions
  89  * of these functions are too slow. These stat functions are tailored for Git's
  90  * usage, and therefore they are not meant to be complete and correct emulation
  91  * of lstat/stat functionality.
  92  */
  93 static int cygwin_lstat(const char *path, struct stat *buf)
  94 {
  95         return do_stat(path, buf, lstat);
  96 }
  97
  98 static int cygwin_stat(const char *path, struct stat *buf)
  99 {
 100         return do_stat(path, buf, stat);
 101 }
 102
 103
 104 /*
 105  * At start up, we are trying to determine whether Win32 API or cygwin stat
 106  * functions should be used. The choice is determined by core.ignorecygwinfstricks.
 107  * Reading this option is not always possible immediately as git_dir may
 108  * not be set yet. So until it is set, use cygwin lstat/stat functions.
 109  * However, if core.filemode is set, we must use the Cygwin posix
 110  * stat/lstat as the Windows stat functions do not determine posix filemode.
 111  *
 112  * Note that git_cygwin_config() does NOT call git_default_config() and this
 113  * is deliberate.  Many commands read from config to establish initial
 114  * values in variables and later tweak them from elsewhere (e.g. command line).
 115  * init_stat() is called lazily on demand, typically much late in the program,
 116  * and calling git_default_config() from here would break such variables.
 117  */
 118 static int native_stat = 1;
 119 static int core_filemode = 1; /* matches trust_executable_bit default */
 120
 121 static int git_cygwin_config(const char *var, const char *value, void *cb)
 122 {
 123         if (!strcmp(var, "core.ignorecygwinfstricks"))
 124                 native_stat = git_config_bool(var, value);
 125         else if (!strcmp(var, "core.filemode"))
 126                 core_filemode = git_config_bool(var, value);
 127         return 0;
 128 }
 129
 130 static int init_stat(void)
 131 {
 132         if (have_git_dir() && git_config(git_cygwin_config,NULL)) {
 133                 if (!core_filemode && native_stat) {
 134                         cygwin_stat_fn = cygwin_stat;
 135                         cygwin_lstat_fn = cygwin_lstat;
 136                 } else {
 137                         cygwin_stat_fn = stat;
 138                         cygwin_lstat_fn = lstat;
 139                 }
 140                 return 0;
 141         }
 142         return 1;
 143 }
 144
 145 static int cygwin_stat_stub(const char *file_name, struct stat *buf)
 146 {
 147         return (init_stat() ? stat : *cygwin_stat_fn)(file_name, buf);
 148 }
 149
 150 static int cygwin_lstat_stub(const char *file_name, struct stat *buf)
 151 {
 152         return (init_stat() ? lstat : *cygwin_lstat_fn)(file_name, buf);
 153 }
 154
 155 stat_fn_t cygwin_stat_fn = cygwin_stat_stub;
 156 stat_fn_t cygwin_lstat_fn = cygwin_lstat_stub;
 157