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-rw-r--r--mysys/my_symlink.c266
1 files changed, 266 insertions, 0 deletions
diff --git a/mysys/my_symlink.c b/mysys/my_symlink.c
new file mode 100644
index 00000000..8238e501
--- /dev/null
+++ b/mysys/my_symlink.c
@@ -0,0 +1,266 @@
+/*
+ Copyright (c) 2001, 2011, Oracle and/or its affiliates
+ Copyright (c) 2010, 2022, MariaDB
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 of the License.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
+
+#include "mysys_priv.h"
+#include "mysys_err.h"
+#include <m_string.h>
+#include <errno.h>
+#ifdef HAVE_REALPATH
+#include <sys/param.h>
+#include <sys/stat.h>
+#endif
+
+static int always_valid(const char *filename __attribute__((unused)))
+{
+ return 0;
+}
+
+int (*mysys_test_invalid_symlink)(const char *filename)= always_valid;
+
+
+/*
+ Reads the content of a symbolic link
+ If the file is not a symbolic link, return the original file name in to.
+
+ RETURN
+ 0 If filename was a symlink, (to will be set to value of symlink)
+ 1 If filename was a normal file (to will be set to filename)
+ -1 on error.
+*/
+
+int my_readlink(char *to, const char *filename, myf MyFlags)
+{
+#ifndef HAVE_READLINK
+ strmov(to,filename);
+ return 1;
+#else
+ int result=0;
+ int length;
+ DBUG_ENTER("my_readlink");
+
+ if ((length=readlink(filename, to, FN_REFLEN-1)) < 0)
+ {
+ /* Don't give an error if this wasn't a symlink */
+ if ((my_errno=errno) == EINVAL)
+ {
+ result= 1;
+ strmov(to,filename);
+ }
+ else
+ {
+ if (MyFlags & MY_WME)
+ my_error(EE_CANT_READLINK, MYF(0), filename, errno);
+ result= -1;
+ }
+ }
+ else
+ to[length]=0;
+ DBUG_PRINT("exit" ,("result: %d", result));
+ DBUG_RETURN(result);
+#endif /* HAVE_READLINK */
+}
+
+
+/* Create a symbolic link */
+
+int my_symlink(const char *content, const char *linkname, myf MyFlags)
+{
+#ifndef HAVE_READLINK
+ return 0;
+#else
+ int result;
+ DBUG_ENTER("my_symlink");
+ DBUG_PRINT("enter",("content: %s linkname: %s", content, linkname));
+
+ result= 0;
+ if (symlink(content, linkname))
+ {
+ result= -1;
+ my_errno=errno;
+ if (MyFlags & MY_WME)
+ my_error(EE_CANT_SYMLINK, MYF(0), linkname, content, errno);
+ }
+ else if ((MyFlags & MY_SYNC_DIR) && my_sync_dir_by_file(linkname, MyFlags))
+ result= -1;
+ DBUG_RETURN(result);
+#endif /* HAVE_READLINK */
+}
+
+#if defined(SCO)
+#define BUFF_LEN 4097
+#elif defined(MAXPATHLEN)
+#define BUFF_LEN MAXPATHLEN
+#else
+#define BUFF_LEN FN_LEN
+#endif
+
+
+int my_is_symlink(const char *filename __attribute__((unused)))
+{
+#if defined (HAVE_LSTAT) && defined (S_ISLNK)
+ struct stat stat_buff;
+ if (lstat(filename, &stat_buff))
+ return 0;
+ MSAN_STAT_WORKAROUND(&stat_buff);
+ return !!S_ISLNK(stat_buff.st_mode);
+#elif defined (_WIN32)
+ DWORD dwAttr = GetFileAttributes(filename);
+ return (dwAttr != INVALID_FILE_ATTRIBUTES) &&
+ (dwAttr & FILE_ATTRIBUTE_REPARSE_POINT);
+#else /* No symlinks */
+ return 0;
+#endif
+}
+
+/*
+ Resolve all symbolic links in path
+ 'to' may be equal to 'filename'
+
+ to is guaranteed to never set to a string longer than FN_REFLEN
+ (including the end \0)
+
+ On error returns -1, unless error is file not found, in which case it
+ is 1.
+
+ Sets my_errno to specific error number.
+*/
+
+int my_realpath(char *to, const char *filename, myf MyFlags)
+{
+#if defined(HAVE_REALPATH) && !defined(HAVE_BROKEN_REALPATH)
+ int result=0;
+ char buff[BUFF_LEN];
+ char *ptr;
+ DBUG_ENTER("my_realpath");
+
+ DBUG_PRINT("info",("executing realpath"));
+ if ((ptr=realpath(filename,buff)))
+ strmake(to, ptr, FN_REFLEN-1);
+ else
+ {
+ /*
+ Realpath didn't work; Use my_load_path() which is a poor substitute
+ original name but will at least be able to resolve paths that starts
+ with '.'.
+ */
+ if (MyFlags)
+ DBUG_PRINT("error",("realpath failed with errno: %d", errno));
+ my_errno=errno;
+ if (MyFlags & MY_WME)
+ my_error(EE_REALPATH, MYF(0), filename, my_errno);
+ my_load_path(to, filename, NullS);
+ if (my_errno == ENOENT)
+ result= 1;
+ else
+ result= -1;
+ }
+ DBUG_RETURN(result);
+#elif defined(_WIN32)
+ int ret= GetFullPathName(filename,FN_REFLEN, to, NULL);
+ if (ret == 0 || ret > FN_REFLEN)
+ {
+ my_errno= (ret > FN_REFLEN) ? ENAMETOOLONG : GetLastError();
+ if (MyFlags & MY_WME)
+ my_error(EE_REALPATH, MYF(0), filename, my_errno);
+ /*
+ GetFullPathName didn't work : use my_load_path() which is a poor
+ substitute original name but will at least be able to resolve
+ paths that starts with '.'.
+ */
+ my_load_path(to, filename, NullS);
+ return -1;
+ }
+#else
+ my_load_path(to, filename, NullS);
+#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[FN_REFLEN + 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 | O_CLOEXEC);
+ if (fd < 0)
+ goto err;
+
+ if (dfd >= 0)
+ close(dfd);
+
+ dfd= fd;
+ s= e;
+ }
+err:
+ if (dfd >= 0)
+ close(dfd);
+ return NULL;
+}
+#endif