X-Git-Url: https://git.cworth.org/git?p=tar;a=blobdiff_plain;f=gnu%2Fat-func2.c;fp=gnu%2Fat-func2.c;h=41501172494de47a55d803950669417ef021fd5d;hp=0000000000000000000000000000000000000000;hb=de7372b23c3da92fbfaea2d1ac592f0b2ba87914;hpb=fbbfb9406a82e647ce27b6462b11a802fa48f31a
diff --git a/gnu/at-func2.c b/gnu/at-func2.c
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+++ b/gnu/at-func2.c
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+/* -*- buffer-read-only: t -*- vi: set ro: */
+/* DO NOT EDIT! GENERATED AUTOMATICALLY! */
+/* Define an at-style functions like linkat or renameat.
+ Copyright (C) 2006, 2009-2010 Free Software Foundation, Inc.
+
+ 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; either version 3 of the License, or
+ (at your option) any later version.
+
+ 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, see . */
+
+/* written by Jim Meyering and Eric Blake */
+
+#include
+
+#include "openat-priv.h"
+
+#include
+#include
+#include
+#include
+
+#include "dirname.h" /* solely for definition of IS_ABSOLUTE_FILE_NAME */
+#include "filenamecat.h"
+#include "openat.h"
+#include "same-inode.h"
+#include "save-cwd.h"
+
+/* Call FUNC to operate on a pair of files, where FILE1 is relative to FD1,
+ and FILE2 is relative to FD2. If possible, do it without changing the
+ working directory. Otherwise, resort to using save_cwd/fchdir,
+ FUNC, restore_cwd (up to two times). If either the save_cwd or the
+ restore_cwd fails, then give a diagnostic and exit nonzero. */
+int
+at_func2 (int fd1, char const *file1,
+ int fd2, char const *file2,
+ int (*func) (char const *file1, char const *file2))
+{
+ struct saved_cwd saved_cwd;
+ int saved_errno;
+ int err;
+ char *file1_alt;
+ char *file2_alt;
+ struct stat st1;
+ struct stat st2;
+
+ /* There are 16 possible scenarios, based on whether an fd is
+ AT_FDCWD or real, and whether a file is absolute or relative:
+
+ fd1 file1 fd2 file2 action
+ 0 cwd abs cwd abs direct call
+ 1 cwd abs cwd rel direct call
+ 2 cwd abs fd abs direct call
+ 3 cwd abs fd rel chdir to fd2
+ 4 cwd rel cwd abs direct call
+ 5 cwd rel cwd rel direct call
+ 6 cwd rel fd abs direct call
+ 7 cwd rel fd rel convert file1 to abs, then case 3
+ 8 fd abs cwd abs direct call
+ 9 fd abs cwd rel direct call
+ 10 fd abs fd abs direct call
+ 11 fd abs fd rel chdir to fd2
+ 12 fd rel cwd abs chdir to fd1
+ 13 fd rel cwd rel convert file2 to abs, then case 12
+ 14 fd rel fd abs chdir to fd1
+ 15a fd1 rel fd1 rel chdir to fd1
+ 15b fd1 rel fd2 rel chdir to fd1, then case 7
+
+ Try some optimizations to reduce fd to AT_FDCWD, or to at least
+ avoid converting an absolute name or doing a double chdir. */
+
+ if ((fd1 == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file1))
+ && (fd2 == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file2)))
+ return func (file1, file2); /* Case 0-2, 4-6, 8-10. */
+
+ /* If /proc/self/fd works, we don't need any stat or chdir. */
+ {
+ char proc_buf1[OPENAT_BUFFER_SIZE];
+ char *proc_file1 = ((fd1 == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file1))
+ ? (char *) file1
+ : openat_proc_name (proc_buf1, fd1, file1));
+ if (proc_file1)
+ {
+ char proc_buf2[OPENAT_BUFFER_SIZE];
+ char *proc_file2 = ((fd2 == AT_FDCWD || IS_ABSOLUTE_FILE_NAME (file2))
+ ? (char *) file2
+ : openat_proc_name (proc_buf2, fd2, file2));
+ if (proc_file2)
+ {
+ int proc_result = func (proc_file1, proc_file2);
+ int proc_errno = errno;
+ if (proc_file1 != proc_buf1 && proc_file1 != file1)
+ free (proc_file1);
+ if (proc_file2 != proc_buf2 && proc_file2 != file2)
+ free (proc_file2);
+ /* If the syscall succeeds, or if it fails with an unexpected
+ errno value, then return right away. Otherwise, fall through
+ and resort to using save_cwd/restore_cwd. */
+ if (0 <= proc_result)
+ return proc_result;
+ if (! EXPECTED_ERRNO (proc_errno))
+ {
+ errno = proc_errno;
+ return proc_result;
+ }
+ }
+ else if (proc_file1 != proc_buf1 && proc_file1 != file1)
+ free (proc_file1);
+ }
+ }
+
+ /* Cases 3, 7, 11-15 remain. Time to normalize directory fds, if
+ possible. */
+ if (IS_ABSOLUTE_FILE_NAME (file1))
+ fd1 = AT_FDCWD; /* Case 11 reduced to 3. */
+ else if (IS_ABSOLUTE_FILE_NAME (file2))
+ fd2 = AT_FDCWD; /* Case 14 reduced to 12. */
+
+ /* Cases 3, 7, 12, 13, 15 remain. */
+
+ if (fd1 == AT_FDCWD) /* Cases 3, 7. */
+ {
+ if (stat (".", &st1) == -1 || fstat (fd2, &st2) == -1)
+ return -1;
+ if (!S_ISDIR (st2.st_mode))
+ {
+ errno = ENOTDIR;
+ return -1;
+ }
+ if (SAME_INODE (st1, st2)) /* Reduced to cases 1, 5. */
+ return func (file1, file2);
+ }
+ else if (fd2 == AT_FDCWD) /* Cases 12, 13. */
+ {
+ if (stat (".", &st2) == -1 || fstat (fd1, &st1) == -1)
+ return -1;
+ if (!S_ISDIR (st1.st_mode))
+ {
+ errno = ENOTDIR;
+ return -1;
+ }
+ if (SAME_INODE (st1, st2)) /* Reduced to cases 4, 5. */
+ return func (file1, file2);
+ }
+ else if (fd1 != fd2) /* Case 15b. */
+ {
+ if (fstat (fd1, &st1) == -1 || fstat (fd2, &st2) == -1)
+ return -1;
+ if (!S_ISDIR (st1.st_mode) || !S_ISDIR (st2.st_mode))
+ {
+ errno = ENOTDIR;
+ return -1;
+ }
+ if (SAME_INODE (st1, st2)) /* Reduced to case 15a. */
+ {
+ fd2 = fd1;
+ if (stat (".", &st1) == 0 && SAME_INODE (st1, st2))
+ return func (file1, file2); /* Further reduced to case 5. */
+ }
+ }
+ else /* Case 15a. */
+ {
+ if (fstat (fd1, &st1) == -1)
+ return -1;
+ if (!S_ISDIR (st1.st_mode))
+ {
+ errno = ENOTDIR;
+ return -1;
+ }
+ if (stat (".", &st2) == 0 && SAME_INODE (st1, st2))
+ return func (file1, file2); /* Reduced to case 5. */
+ }
+
+ /* Cases 3, 7, 12, 13, 15a, 15b remain. With all reductions in
+ place, it is time to start changing directories. */
+
+ if (save_cwd (&saved_cwd) != 0)
+ openat_save_fail (errno);
+
+ if (fd1 != AT_FDCWD && fd2 != AT_FDCWD && fd1 != fd2) /* Case 15b. */
+ {
+ if (fchdir (fd1) != 0)
+ {
+ saved_errno = errno;
+ free_cwd (&saved_cwd);
+ errno = saved_errno;
+ return -1;
+ }
+ fd1 = AT_FDCWD; /* Reduced to case 7. */
+ }
+
+ /* Cases 3, 7, 12, 13, 15a remain. Convert one relative name to
+ absolute, if necessary. */
+
+ file1_alt = (char *) file1;
+ file2_alt = (char *) file2;
+
+ if (fd1 == AT_FDCWD && !IS_ABSOLUTE_FILE_NAME (file1)) /* Case 7. */
+ {
+ /* It would be nicer to use:
+ file1_alt = file_name_concat (xgetcwd (), file1, NULL);
+ but libraries should not call xalloc_die. */
+ char *cwd = getcwd (NULL, 0);
+ if (!cwd)
+ {
+ saved_errno = errno;
+ free_cwd (&saved_cwd);
+ errno = saved_errno;
+ return -1;
+ }
+ file1_alt = mfile_name_concat (cwd, file1, NULL);
+ if (!file1_alt)
+ {
+ saved_errno = errno;
+ free (cwd);
+ free_cwd (&saved_cwd);
+ errno = saved_errno;
+ return -1;
+ }
+ free (cwd); /* Reduced to case 3. */
+ }
+ else if (fd2 == AT_FDCWD && !IS_ABSOLUTE_FILE_NAME (file2)) /* Case 13. */
+ {
+ char *cwd = getcwd (NULL, 0);
+ if (!cwd)
+ {
+ saved_errno = errno;
+ free_cwd (&saved_cwd);
+ errno = saved_errno;
+ return -1;
+ }
+ file2_alt = mfile_name_concat (cwd, file2, NULL);
+ if (!file2_alt)
+ {
+ saved_errno = errno;
+ free (cwd);
+ free_cwd (&saved_cwd);
+ errno = saved_errno;
+ return -1;
+ }
+ free (cwd); /* Reduced to case 12. */
+ }
+
+ /* Cases 3, 12, 15a remain. Change to the correct directory. */
+ if (fchdir (fd1 == AT_FDCWD ? fd2 : fd1) != 0)
+ {
+ saved_errno = errno;
+ free_cwd (&saved_cwd);
+ if (file1 != file1_alt)
+ free (file1_alt);
+ else if (file2 != file2_alt)
+ free (file2_alt);
+ errno = saved_errno;
+ return -1;
+ }
+
+ /* Finally safe to perform the user's function, then clean up. */
+
+ err = func (file1_alt, file2_alt);
+ saved_errno = (err < 0 ? errno : 0);
+
+ if (file1 != file1_alt)
+ free (file1_alt);
+ else if (file2 != file2_alt)
+ free (file2_alt);
+
+ if (restore_cwd (&saved_cwd) != 0)
+ openat_restore_fail (errno);
+
+ free_cwd (&saved_cwd);
+
+ if (saved_errno)
+ errno = saved_errno;
+ return err;
+}
+#undef CALL_FUNC
+#undef FUNC_RESULT