X-Git-Url: https://git.dogcows.com/gitweb?a=blobdiff_plain;f=src%2Fmisc.c;h=d94791f66a4f357d0fe542cc6dcd15b5bd197de2;hb=4bde4f39d08f000f7e63a832b08a2525c1262f84;hp=15161ae97e2beffcc6d2fa092491430a9b335583;hpb=fc5e44c99c98d764463f21a12c2c3ef1f0ba8ac7;p=chaz%2Ftar diff --git a/src/misc.c b/src/misc.c index 15161ae..d94791f 100644 --- a/src/misc.c +++ b/src/misc.c @@ -21,7 +21,6 @@ #include #include "common.h" #include -#include #include #include #include @@ -432,7 +431,7 @@ safer_rmdir (const char *file_name) return -1; } - return rmdir (file_name); + return unlinkat (chdir_fd, file_name, AT_REMOVEDIR); } /* Remove FILE_NAME, returning 1 on success. If FILE_NAME is a directory, @@ -452,7 +451,7 @@ remove_any_file (const char *file_name, enum remove_option option) if (try_unlink_first) { - if (unlink (file_name) == 0) + if (unlinkat (chdir_fd, file_name, 0) == 0) return 1; /* POSIX 1003.1-2001 requires EPERM when attempting to unlink a @@ -468,7 +467,7 @@ remove_any_file (const char *file_name, enum remove_option option) switch (errno) { case ENOTDIR: - return !try_unlink_first && unlink (file_name) == 0; + return !try_unlink_first && unlinkat (chdir_fd, file_name, 0) == 0; case 0: case EEXIST: @@ -545,7 +544,7 @@ maybe_backup_file (const char *file_name, bool this_is_the_archive) if (this_is_the_archive && _remdev (file_name)) return true; - if (stat (file_name, &file_stat)) + if (fstatat (chdir_fd, file_name, &file_stat, 0)) { if (errno == ENOENT) return true; @@ -565,7 +564,8 @@ maybe_backup_file (const char *file_name, bool this_is_the_archive) if (! after_backup_name) xalloc_die (); - if (rename (before_backup_name, after_backup_name) == 0) + if (renameat (chdir_fd, before_backup_name, chdir_fd, after_backup_name) + == 0) { if (verbose_option) fprintf (stdlis, _("Renaming %s to %s\n"), @@ -592,7 +592,8 @@ undo_last_backup (void) { if (after_backup_name) { - if (rename (after_backup_name, before_backup_name) != 0) + if (renameat (chdir_fd, after_backup_name, chdir_fd, before_backup_name) + != 0) { int e = errno; ERROR ((0, e, _("%s: Cannot rename to %s"), @@ -611,7 +612,7 @@ undo_last_backup (void) int deref_stat (bool deref, char const *name, struct stat *buf) { - return deref ? stat (name, buf) : lstat (name, buf); + return fstatat (chdir_fd, name, buf, deref ? 0 : AT_SYMLINK_NOFOLLOW); } /* Set FD's (i.e., assuming the working directory is PARENTFD, FILE's) @@ -633,13 +634,10 @@ struct wd /* The directory's name. */ char const *name; - /* A negative value if no attempt has been made to save the - directory, 0 if it was saved successfully, and a positive errno - value if it was not saved successfully. */ - int err; - - /* The saved version of the directory, if ERR == 0. */ - struct saved_cwd saved_cwd; + /* If nonzero, the file descriptor of the directory, or AT_FDCWD if + the working directory. If zero, the directory needs to be opened + to be used. */ + int fd; }; /* A vector of chdir targets. wd[0] is the initial working directory. */ @@ -651,6 +649,19 @@ static size_t wd_count; /* The allocated size of the vector. */ static size_t wd_alloc; +/* The maximum number of chdir targets with open directories. + Don't make it too large, as many operating systems have a small + limit on the number of open file descriptors. Also, the current + implementation does not scale well. */ +enum { CHDIR_CACHE_SIZE = 16 }; + +/* Indexes into WD of chdir targets with open file descriptors, sorted + most-recently used first. Zero indexes are unused. */ +static int wdcache[CHDIR_CACHE_SIZE]; + +/* Number of nonzero entries in WDCACHE. */ +static size_t wdcache_count; + int chdir_count () { @@ -677,7 +688,7 @@ chdir_arg (char const *dir) if (! wd_count) { wd[wd_count].name = "."; - wd[wd_count].err = -1; + wd[wd_count].fd = AT_FDCWD; wd_count++; } } @@ -694,66 +705,76 @@ chdir_arg (char const *dir) } wd[wd_count].name = dir; - wd[wd_count].err = -1; + wd[wd_count].fd = 0; return wd_count++; } /* Index of current directory. */ int chdir_current; -/* Change to directory I. If I is 0, change to the initial working - directory; otherwise, I must be a value returned by chdir_arg. */ +/* Value suitable for use as the first argument to openat, and in + similar locations for fstatat, etc. This is an open file + descriptor, or AT_FDCWD if the working directory is current. It is + valid until the next invocation of chdir_do. */ +int chdir_fd = AT_FDCWD; + +/* Change to directory I, in a virtual way. This does not actually + invoke chdir; it merely sets chdir_fd to an int suitable as the + first argument for openat, etc. If I is 0, change to the initial + working directory; otherwise, I must be a value returned by + chdir_arg. */ void chdir_do (int i) { if (chdir_current != i) { - struct wd *prev = &wd[chdir_current]; + static size_t counter; struct wd *curr = &wd[i]; + int fd = curr->fd; - if (prev->err < 0) + if (! fd) { - prev->err = 0; - if (save_cwd (&prev->saved_cwd) != 0) - prev->err = errno; - else if (0 <= prev->saved_cwd.desc) + if (! IS_ABSOLUTE_FILE_NAME (curr->name)) + chdir_do (i - 1); + fd = openat (chdir_fd, curr->name, open_searchdir_flags); + if (fd < 0) + open_fatal (curr->name); + + curr->fd = fd; + + /* Add I to the cache, tossing out the lowest-ranking entry if the + cache is full. */ + if (wdcache_count < CHDIR_CACHE_SIZE) + wdcache[wdcache_count++] = i; + else { - /* Make sure we still have at least one descriptor available. */ - int fd1 = prev->saved_cwd.desc; - int fd2 = dup (fd1); - if (0 <= fd2) - close (fd2); - else if (errno == EMFILE) - { - /* Force restore_cwd to use chdir_long. */ - close (fd1); - prev->saved_cwd.desc = -1; - prev->saved_cwd.name = xgetcwd (); - if (! prev->saved_cwd.name) - prev->err = errno; - } - else - prev->err = errno; + struct wd *stale = &wd[wdcache[CHDIR_CACHE_SIZE - 1]]; + if (close (stale->fd) != 0) + close_diag (stale->name); + stale->fd = 0; + wdcache[CHDIR_CACHE_SIZE - 1] = i; } } - if (0 <= curr->err) + if (0 < fd) { - int err = curr->err; - if (err == 0 && restore_cwd (&curr->saved_cwd) != 0) - err = errno; - if (err) - FATAL_ERROR ((0, err, _("Cannot restore working directory"))); - } - else - { - if (i && ! ISSLASH (curr->name[0])) - chdir_do (i - 1); - if (chdir (curr->name) != 0) - chdir_fatal (curr->name); + /* Move the i value to the front of the cache. This is + O(CHDIR_CACHE_SIZE), but the cache is small. */ + size_t ci; + int prev = wdcache[0]; + for (ci = 1; prev != i; ci++) + { + int curr = wdcache[ci]; + wdcache[ci] = prev; + if (curr == i) + break; + prev = curr; + } + wdcache[0] = i; } chdir_current = i; + chdir_fd = fd; } }