ln: Refuse deleting a directory entry by hardlinking it to itself.
Two pathnames refer to the same directory entry iff the directories match and the final components' names match. Example: (assuming file1 is an existing file) ln -f file1 file1 This now fails while leaving file1 intact. It used to delete file1 and then complain it cannot be linked because it is gone. With -i, this error is detected before the question is asked. MFC after: 2 weeks
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parent
9eb448a7e6
commit
5d66b54e27
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=206773
61
bin/ln/ln.c
61
bin/ln/ln.c
@ -172,6 +172,52 @@ main(int argc, char *argv[])
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exit(exitval);
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}
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/*
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* Two pathnames refer to the same directory entry if the directories match
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* and the final components' names match.
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*/
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static int
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samedirent(const char *path1, const char *path2)
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{
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const char *file1, *file2;
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char pathbuf[PATH_MAX];
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struct stat sb1, sb2;
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if (strcmp(path1, path2) == 0)
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return 1;
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file1 = strrchr(path1, '/');
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if (file1 != NULL)
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file1++;
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else
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file1 = path1;
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file2 = strrchr(path2, '/');
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if (file2 != NULL)
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file2++;
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else
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file2 = path2;
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if (strcmp(file1, file2) != 0)
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return 0;
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if (file1 - path1 >= PATH_MAX || file2 - path2 >= PATH_MAX)
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return 0;
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if (file1 == path1)
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memcpy(pathbuf, ".", 2);
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else {
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memcpy(pathbuf, path1, file1 - path1);
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pathbuf[file1 - path1] = '\0';
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}
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if (stat(pathbuf, &sb1) != 0)
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return 0;
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if (file2 == path2)
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memcpy(pathbuf, ".", 2);
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else {
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memcpy(pathbuf, path2, file2 - path2);
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pathbuf[file2 - path2] = '\0';
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}
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if (stat(pathbuf, &sb2) != 0)
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return 0;
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return sb1.st_dev == sb2.st_dev && sb1.st_ino == sb2.st_ino;
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}
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int
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linkit(const char *source, const char *target, int isdir)
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{
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@ -215,7 +261,6 @@ linkit(const char *source, const char *target, int isdir)
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target = path;
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}
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exists = !lstat(target, &sb);
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/*
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* If the link source doesn't exist, and a symbolic link was
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* requested, and -w was specified, give a warning.
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@ -242,8 +287,20 @@ linkit(const char *source, const char *target, int isdir)
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warn("warning: %s", source);
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}
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}
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/*
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* If the file exists, then unlink it forcibly if -f was specified
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* If the file exists, first check it is not the same directory entry.
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*/
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exists = !lstat(target, &sb);
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if (exists) {
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if (!sflag && samedirent(source, target)) {
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warnx("%s and %s are the same directory entry",
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source, target);
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return (1);
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}
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}
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/*
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* Then unlink it forcibly if -f was specified
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* and interactively if -i was specified.
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*/
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if (fflag && exists) {
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