support MY_NOSYMLINKS in my_delete()

Author: vuvova

mysys/my_delete.c

@@ -21,6 +21,12 @@
 static int my_win_unlink(const char *name);
 #endif
 
+CREATE_NOSYMLINK_FUNCTION(
+  unlink_nosymlinks(const char *pathname),
+  unlinkat(dfd, filename, 0),
+  unlink(pathname)
+);
+
 int my_delete(const char *name, myf MyFlags)
 {
   int err;
@@ -30,7 +36,10 @@ int my_delete(const char *name, myf MyFlags)
 #ifdef _WIN32
   err = my_win_unlink(name);
 #else
-  err = unlink(name);
+  if (MyFlags & MY_NOSYMLINKS)
+    err= unlink_nosymlinks(name);
+  else
+    err= unlink(name);
 #endif
 
   if(err)

mysys/my_open.c

@@ -18,11 +18,11 @@
 #include <m_string.h>
 #include <errno.h>
 
-#if !defined(O_PATH) && defined(O_EXEC) /* FreeBSD */
-#define O_PATH O_EXEC
-#endif
-
-static int open_nosymlinks(const char *pathname, int flags, int mode);
+CREATE_NOSYMLINK_FUNCTION(
+  open_nosymlinks(const char *pathname, int flags, int mode),
+  openat(dfd, filename, O_NOFOLLOW | flags, mode),
+  open(pathname, O_NOFOLLOW | flags, mode)
+);
 
 /*
   Open a file
@@ -182,81 +182,3 @@ void my_print_open_files(void)
 }
 
 #endif
-
-/**
-  like open(), but with symlinks are not accepted anywhere in the path
-
-  This is used for opening symlinked tables for DATA/INDEX DIRECTORY.
-  The paths there have been realpath()-ed. So, we can assume here that
-
-  * `pathname` is an absolute path
-  * no '.', '..', and '//' in the path
-  * file exists
-*/
-static int open_nosymlinks(const char *pathname, int flags, int mode)
-{
-#ifndef O_PATH
-#ifdef HAVE_REALPATH
-  char buf[PATH_MAX+1];
-  if (realpath(pathname, buf) == NULL)
-    return -1;
-  if (strcmp(pathname, buf))
-  {
-    errno= ENOTDIR;
-    return -1;
-  }
-#endif
-  return open(pathname, flags, mode | O_NOFOLLOW);
-#else
-
-  char buf[PATH_MAX+1];
-  char *s= buf, *e= buf+1, *end= strnmov(buf, pathname, sizeof(buf));
-  int fd, dfd= -1;
-
-  if (*end)
-  {
-    errno= ENAMETOOLONG;
-    return -1;
-  }
-
-  if (*s != '/') /* not an absolute path */
-  {
-    errno= ENOENT;
-    return -1;
-  }
-
-  for (;;)
-  {
-    if (*e == '/') /* '//' in the path */
-    {
-      errno= ENOENT;
-      goto err;
-    }
-    while (*e && *e != '/')
-      e++;
-    *e= 0;
-    if (!memcmp(s, ".", 2) || !memcmp(s, "..", 3))
-    {
-      errno= ENOENT;
-      goto err;
-    }
-
-    fd = openat(dfd, s, O_NOFOLLOW | (e < end ? O_PATH : flags), mode);
-    if (fd < 0)
-      goto err;
-
-    if (dfd >= 0)
-      close(dfd);
-
-    dfd= fd;
-    s= ++e;
-
-    if (e >= end)
-      return fd;
-  }
-err:
-  if (dfd >= 0)
-    close(dfd);
-  return -1;
-#endif
-}

mysys/my_symlink.c

@@ -177,3 +177,78 @@ int my_realpath(char *to, const char *filename, myf MyFlags)
 #endif
   return 0;
 }
+
+#ifdef HAVE_OPEN_PARENT_DIR_NOSYMLINKS
+/** opens the parent dir. walks the path, and does not resolve symlinks
+
+   returns the pointer to the file name (basename) within the pathname
+   or NULL in case of an error
+
+   stores the parent dir (dirname) file descriptor in pdfd.
+   It can be -1 even if there was no error!
+
+   This is used for symlinked tables for DATA/INDEX DIRECTORY.
+   The paths there have been realpath()-ed. So, we can assume here that
+
+    * `pathname` is an absolute path
+    * no '.', '..', and '//' in the path
+    * file exists
+*/
+
+const char *my_open_parent_dir_nosymlinks(const char *pathname, int *pdfd)
+{
+  char buf[PATH_MAX+1];
+  char *s= buf, *e= buf+1, *end= strnmov(buf, pathname, sizeof(buf));
+  int fd, dfd= -1;
+
+  if (*end)
+  {
+    errno= ENAMETOOLONG;
+    return NULL;
+  }
+
+  if (*s != '/') /* not an absolute path */
+  {
+    errno= ENOENT;
+    return NULL;
+  }
+
+  for (;;)
+  {
+    if (*e == '/') /* '//' in the path */
+    {
+      errno= ENOENT;
+      goto err;
+    }
+    while (*e && *e != '/')
+      e++;
+    *e= 0;
+
+    if (!memcmp(s, ".", 2) || !memcmp(s, "..", 3))
+    {
+      errno= ENOENT;
+      goto err;
+    }
+
+    if (++e >= end)
+    {
+      *pdfd= dfd;
+      return pathname + (s - buf);
+    }
+
+    fd = openat(dfd, s, O_NOFOLLOW | O_PATH);
+    if (fd < 0)
+      goto err;
+
+    if (dfd >= 0)
+      close(dfd);
+
+    dfd= fd;
+    s= e;
+  }
+err:
+  if (dfd >= 0)
+    close(dfd);
+  return NULL;
+}
+#endif

mysys/mysys_priv.h

@@ -89,6 +89,34 @@ void sf_free(void *ptr);
 
 void my_error_unregister_all(void);
 
+#if !defined(O_PATH) && defined(O_EXEC) /* FreeBSD */
+#define O_PATH O_EXEC
+#endif
+
+#ifdef O_PATH
+#define HAVE_OPEN_PARENT_DIR_NOSYMLINKS
+const char *my_open_parent_dir_nosymlinks(const char *pathname, int *pdfd);
+#define NOSYMLINK_FUNCTION_BODY(AT,NOAT)                                \
+  int dfd, res;                                                         \
+  const char *filename= my_open_parent_dir_nosymlinks(pathname, &dfd);  \
+  if (filename == NULL) return -1;                                      \
+  res= AT;                                                              \
+  if (dfd >= 0) close(dfd);                                             \
+  return res;
+#elif defined(HAVE_REALPATH)
+#define NOSYMLINK_FUNCTION_BODY(AT,NOAT)                                \
+  char buf[PATH_MAX+1];                                                 \
+  if (realpath(pathname, buf) == NULL) return -1;                       \
+  if (strcmp(pathname, buf)) { errno= ENOTDIR; return -1; }             \
+  return NOAT;
+#else
+#define NOSYMLINK_FUNCTION_BODY(AT,NOAT)                                \
+  return NOAT;
+#endif
+
+#define CREATE_NOSYMLINK_FUNCTION(PROTO,AT,NOAT)                        \
+static int PROTO { NOSYMLINK_FUNCTION_BODY(AT,NOAT) }
+
 #ifdef _WIN32
 #include <sys/stat.h>
 /* my_winfile.c exports, should not be used outside mysys */