- From dce4683cbbe107a95f1f0d45fabc304acfb5d71a Mon Sep 17 00:00:00 2001
- From: Andreas Gruenbacher <agruen@gnu.org>
- Date: Mon, 15 Jul 2019 16:21:48 +0200
- Subject: Don't follow symlinks unless --follow-symlinks is given
-
- * src/inp.c (plan_a, plan_b), src/util.c (copy_to_fd, copy_file,
- append_to_file): Unless the --follow-symlinks option is given, open files with
- the O_NOFOLLOW flag to avoid following symlinks. So far, we were only doing
- that consistently for input files.
- * src/util.c (create_backup): When creating empty backup files, (re)create them
- with O_CREAT | O_EXCL to avoid following symlinks in that case as well.
- ---
- src/inp.c | 12 ++++++++++--
- src/util.c | 14 +++++++++++---
- 2 files changed, 21 insertions(+), 5 deletions(-)
-
- --- a/src/inp.c
- +++ b/src/inp.c
- @@ -238,8 +238,13 @@ plan_a (char const *filename)
- {
- if (S_ISREG (instat.st_mode))
- {
- - int ifd = safe_open (filename, O_RDONLY|binary_transput, 0);
- + int flags = O_RDONLY | binary_transput;
- size_t buffered = 0, n;
- + int ifd;
- +
- + if (! follow_symlinks)
- + flags |= O_NOFOLLOW;
- + ifd = safe_open (filename, flags, 0);
- if (ifd < 0)
- pfatal ("can't open file %s", quotearg (filename));
-
- @@ -340,6 +345,7 @@ plan_a (char const *filename)
- static void
- plan_b (char const *filename)
- {
- + int flags = O_RDONLY | binary_transput;
- int ifd;
- FILE *ifp;
- int c;
- @@ -353,7 +359,9 @@ plan_b (char const *filename)
-
- if (instat.st_size == 0)
- filename = NULL_DEVICE;
- - if ((ifd = safe_open (filename, O_RDONLY | binary_transput, 0)) < 0
- + if (! follow_symlinks)
- + flags |= O_NOFOLLOW;
- + if ((ifd = safe_open (filename, flags, 0)) < 0
- || ! (ifp = fdopen (ifd, binary_transput ? "rb" : "r")))
- pfatal ("Can't open file %s", quotearg (filename));
- if (TMPINNAME_needs_removal)
- --- a/src/util.c
- +++ b/src/util.c
- @@ -388,7 +388,7 @@ create_backup (char const *to, const str
-
- try_makedirs_errno = ENOENT;
- safe_unlink (bakname);
- - while ((fd = safe_open (bakname, O_CREAT | O_WRONLY | O_TRUNC, 0666)) < 0)
- + while ((fd = safe_open (bakname, O_CREAT | O_EXCL | O_WRONLY | O_TRUNC, 0666)) < 0)
- {
- if (errno != try_makedirs_errno)
- pfatal ("Can't create file %s", quotearg (bakname));
- @@ -579,10 +579,13 @@ create_file (char const *file, int open_
- static void
- copy_to_fd (const char *from, int tofd)
- {
- + int from_flags = O_RDONLY | O_BINARY;
- int fromfd;
- ssize_t i;
-
- - if ((fromfd = safe_open (from, O_RDONLY | O_BINARY, 0)) < 0)
- + if (! follow_symlinks)
- + from_flags |= O_NOFOLLOW;
- + if ((fromfd = safe_open (from, from_flags, 0)) < 0)
- pfatal ("Can't reopen file %s", quotearg (from));
- while ((i = read (fromfd, buf, bufsize)) != 0)
- {
- @@ -625,6 +628,8 @@ copy_file (char const *from, char const
- else
- {
- assert (S_ISREG (mode));
- + if (! follow_symlinks)
- + to_flags |= O_NOFOLLOW;
- tofd = create_file (to, O_WRONLY | O_BINARY | to_flags, mode,
- to_dir_known_to_exist);
- copy_to_fd (from, tofd);
- @@ -640,9 +645,12 @@ copy_file (char const *from, char const
- void
- append_to_file (char const *from, char const *to)
- {
- + int to_flags = O_WRONLY | O_APPEND | O_BINARY;
- int tofd;
-
- - if ((tofd = safe_open (to, O_WRONLY | O_BINARY | O_APPEND, 0)) < 0)
- + if (! follow_symlinks)
- + to_flags |= O_NOFOLLOW;
- + if ((tofd = safe_open (to, to_flags, 0)) < 0)
- pfatal ("Can't reopen file %s", quotearg (to));
- copy_to_fd (from, tofd);
- if (close (tofd) != 0)
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