From: Paul Eggert Date: Sun, 12 Sep 2010 21:26:31 +0000 (-0700) Subject: tar: live within system-supplied limits on file descriptors X-Git-Url: https://git.dogcows.com/gitweb?a=commitdiff_plain;h=8da503cad6e883b30c05749149084d24319063b4;p=chaz%2Ftar tar: live within system-supplied limits on file descriptors * NEWS: Note the change. Mention dirfd and fdopendir. * gnulib.modules: Add dirfd and fdopendir. The code was already using fdopendir; dirfd is a new need. * src/common.h (open_searchdir_flags, get_directory_entries): (subfile_open, restore_parent_fd, tar_stat_close): New decls. (check_exclusion_tags): Adjust signature to match code change. * src/create.c (IMPOSTOR_ERRNO): New constant. (check_exclusion_tags): First arg is now a struct tar_stat_info const *, not an fd. All callers changed. (dump_regular_file, dump_file0): A zero fd represents an unused slot, so play it safe if the fd member is zero here. A negative fd represents the negation of an errno value, so play it safe and do not assign -1 to fd merely because an open fails. (open_failure_recover, get_directory_entries, restore_parent_fd): (subfile_open): New functions. These help to recover from file descriptor exhaustion. (dump_dir, dump_file0): Use them. (dump_file0): Use tar_stat_close instead of rolling our own close. * src/incremen.c (scan_directory): Use get_directory_entries, subfile_open, etc., to recover from file descriptor exhaustion. * src/names.c (add_hierarchy_to_namelist): Likewise. (collect_and_sort_names): A negative fd represents the negation of an errno value, so play it safe and do not assign -1 to fd. * src/tar.c (decode_options): Set open_searchdir_flags. Add O_CLOEXEC to all the open flags. (tar_stat_close): New function, which knows how to deal with new convention for directory streams and file descriptors. Diagnose 'close' failures. (tar_stat_destroy): Use it. * src/tar.h (struct tar_stat_info): New member dirstream. fd now has the negative of an errno value, not merely -1, if the file could not be opened, so that failures to reopen directories are better-diagnosed later. * tests/Makefile.am (TESTSUITE_AT): Add extrac11.at. * tests/testsuite.at: Likewise. * tests/extrac11.at: New file. --- diff --git a/NEWS b/NEWS index b305f26..667fad8 100644 --- a/NEWS +++ b/NEWS @@ -1,4 +1,4 @@ -GNU tar NEWS - User visible changes. 2010-09-06 +GNU tar NEWS - User visible changes. 2010-09-12 Please send GNU tar bug reports to @@ -14,10 +14,14 @@ time stamps to the full resolution. ** More reliable directory traversal when creating archives Tar now checks for inconsistencies caused when a file system is -modified while tar is creating an archive. The new checks are -implemented via the openat, fstatat, and readlinkat calls standardized -by POSIX.1-2008. On an older system that lacks these calls, tar -emulates them at some cost in efficiency and reliability. +modified while tar is creating an archive. In the new approach, tar +maintains a cache of file descriptors to directories, so it uses more +file descriptors before, but it gracefully adjusts to system limits on +the number of file descriptors. The new checks are implemented via +the openat, dirfd, fdopendir, fstatat, and readlinkat calls +standardized by POSIX.1-2008. On an older system where these calls do +not exist or do not return useful results, tar emulates the calls at +some cost in efficiency and reliability. ** Spurious error diagnostics on broken pipe. diff --git a/gnulib.modules b/gnulib.modules index 6d25072..6530923 100644 --- a/gnulib.modules +++ b/gnulib.modules @@ -8,10 +8,12 @@ argp-version-etc backupfile closeout configmake +dirfd dirname error exclude exitfail +fdopendir fileblocks fnmatch-gnu fseeko diff --git a/src/common.h b/src/common.h index 5be282c..e908854 100644 --- a/src/common.h +++ b/src/common.h @@ -357,8 +357,9 @@ struct name GLOBAL dev_t ar_dev; GLOBAL ino_t ar_ino; -/* Flags for reading and fstatatting arbitrary files. */ +/* Flags for reading, searching, and fstatatting files. */ GLOBAL int open_read_flags; +GLOBAL int open_searchdir_flags; GLOBAL int fstatat_flags; GLOBAL int seek_option; @@ -452,6 +453,7 @@ enum dump_status void add_exclusion_tag (const char *name, enum exclusion_tag_type type, bool (*predicate) (int)); bool cachedir_file_p (int fd); +char *get_directory_entries (struct tar_stat_info *st); void create_archive (void); void pad_archive (off_t size_left); @@ -466,9 +468,11 @@ union block * write_extended (bool global, struct tar_stat_info *st, union block *start_private_header (const char *name, size_t size, time_t t); void write_eot (void); void check_links (void); +int subfile_open (struct tar_stat_info const *dir, char const *file, int flags); +void restore_parent_fd (struct tar_stat_info const *st); void exclusion_tag_warning (const char *dirname, const char *tagname, const char *message); -enum exclusion_tag_type check_exclusion_tags (int dirfd, +enum exclusion_tag_type check_exclusion_tags (struct tar_stat_info const *st, const char **tag_file_name); #define OFF_TO_CHARS(val, where) off_to_chars (val, where, sizeof (where)) @@ -685,6 +689,7 @@ void usage (int); int confirm (const char *message_action, const char *name); void tar_stat_init (struct tar_stat_info *st); +bool tar_stat_close (struct tar_stat_info *st); void tar_stat_destroy (struct tar_stat_info *st); void usage (int) __attribute__ ((noreturn)); int tar_timespec_cmp (struct timespec a, struct timespec b); diff --git a/src/create.c b/src/create.c index e137325..5e2171b 100644 --- a/src/create.c +++ b/src/create.c @@ -26,6 +26,10 @@ #include "common.h" #include +/* Error number to use when an impostor is discovered. + Pretend the impostor isn't there. */ +enum { IMPOSTOR_ERRNO = ENOENT }; + struct link { dev_t dev; @@ -72,13 +76,13 @@ exclusion_tag_warning (const char *dirname, const char *tagname, } enum exclusion_tag_type -check_exclusion_tags (int fd, char const **tag_file_name) +check_exclusion_tags (struct tar_stat_info const *st, char const **tag_file_name) { struct exclusion_tag *tag; for (tag = exclusion_tags; tag; tag = tag->next) { - int tagfd = openat (fd, tag->name, open_read_flags); + int tagfd = subfile_open (st, tag->name, open_read_flags); if (0 <= tagfd) { bool satisfied = !tag->predicate || tag->predicate (tagfd); @@ -1038,7 +1042,7 @@ dump_regular_file (int fd, struct tar_stat_info *st) memset (blk->buffer + size_left, 0, BLOCKSIZE - count); } - count = (fd < 0) ? bufsize : safe_read (fd, blk->buffer, bufsize); + count = (fd <= 0) ? bufsize : safe_read (fd, blk->buffer, bufsize); if (count == SAFE_READ_ERROR) { read_diag_details (st->orig_file_name, @@ -1159,7 +1163,7 @@ dump_dir0 (struct tar_stat_info *st, char const *directory) char *name_buf; size_t name_size; - switch (check_exclusion_tags (st->fd, &tag_file_name)) + switch (check_exclusion_tags (st, &tag_file_name)) { case exclusion_tag_all: /* Handled in dump_file0 */ @@ -1224,21 +1228,93 @@ ensure_slash (char **pstr) (*pstr)[len] = '\0'; } +/* If we just ran out of file descriptors, release a file descriptor + in the directory chain somewhere leading from DIR->parent->parent + up through the root. Return true if successful, false (preserving + errno == EMFILE) otherwise. + + Do not release DIR's file descriptor, or DIR's parent, as other + code assumes that they work. On some operating systems, another + process can claim file descriptor resources as we release them, and + some calls or their emulations require multiple file descriptors, + so callers should not give up if a single release doesn't work. */ + static bool -dump_dir (struct tar_stat_info *st) +open_failure_recover (struct tar_stat_info const *dir) +{ + if (errno == EMFILE && dir && dir->parent) + { + struct tar_stat_info *p; + for (p = dir->parent->parent; p; p = p->parent) + if (0 < p->fd && (! p->parent || p->parent->fd <= 0)) + { + tar_stat_close (p); + return true; + } + errno = EMFILE; + } + + return false; +} + +/* Return the directory entries of ST, in a dynamically allocated buffer, + each entry followed by '\0' and the last followed by an extra '\0'. + Return null on failure, setting errno. */ +char * +get_directory_entries (struct tar_stat_info *st) { - char *directory = 0; - int dupfd = dup (st->fd); - if (0 <= dupfd) + DIR *dirstream; + while (! (dirstream = fdopendir (st->fd)) && open_failure_recover (st)) + continue; + + if (! dirstream) + return 0; + else { - directory = fdsavedir (dupfd); - if (! directory) + char *entries = streamsavedir (dirstream); + int streamsavedir_errno = errno; + + int fd = dirfd (dirstream); + if (fd < 0) { - int e = errno; - close (dupfd); - errno = e; + /* The dirent.h implementation doesn't use file descriptors + for directory streams, so open the directory again. */ + char const *name = st->orig_file_name; + if (closedir (dirstream) != 0) + close_diag (name); + dirstream = 0; + fd = subfile_open (st->parent, + st->parent ? last_component (name) : name, + open_searchdir_flags); + if (fd < 0) + fd = - errno; + else + { + struct stat dirst; + if (! (fstat (fd, &dirst) == 0 + && st->stat.st_ino == dirst.st_ino + && st->stat.st_dev == dirst.st_dev)) + { + close (fd); + fd = - IMPOSTOR_ERRNO; + } + } } + + st->fd = fd; + st->dirstream = dirstream; + errno = streamsavedir_errno; + return entries; } +} + +/* Dump the directory ST. Return true if successful, false (emitting + diagnostics) otherwise. Get ST's entries, recurse through its + subdirectories, and clean up file descriptors afterwards. */ +static bool +dump_dir (struct tar_stat_info *st) +{ + char *directory = get_directory_entries (st); if (! directory) { savedir_diag (st->orig_file_name); @@ -1247,6 +1323,7 @@ dump_dir (struct tar_stat_info *st) dump_dir0 (st, directory); + restore_parent_fd (st); free (directory); return true; } @@ -1307,21 +1384,19 @@ create_archive (void) { if (! st.orig_file_name) { - st.orig_file_name = xstrdup (p->name); - st.fd = open (st.orig_file_name, - ((open_read_flags - O_RDONLY - + O_SEARCH) - | O_DIRECTORY)); - if (st.fd < 0) + int fd = open (p->name, open_searchdir_flags); + if (fd < 0) { open_diag (p->name); break; } - if (fstat (st.fd, &st.stat) != 0) + st.fd = fd; + if (fstat (fd, &st.stat) != 0) { stat_diag (p->name); break; } + st.orig_file_name = xstrdup (p->name); } if (buffer_size < plen + qlen) { @@ -1492,6 +1567,74 @@ check_links (void) } } +/* Assuming DIR is the working directory, open FILE, using FLAGS to + control the open. A null DIR means to use ".". If we are low on + file descriptors, try to release one or more from DIR's parents to + reuse it. */ +int +subfile_open (struct tar_stat_info const *dir, char const *file, int flags) +{ + int fd; + + static bool initialized; + if (! initialized) + { + /* Initialize any tables that might be needed when file + descriptors are exhausted, and whose initialization might + require a file descriptor. This includes the system message + catalog and tar's message catalog. */ + initialized = true; + strerror (ENOENT); + gettext (""); + } + + while ((fd = openat (dir ? dir->fd : AT_FDCWD, file, flags)) < 0 + && open_failure_recover (dir)) + continue; + return fd; +} + +/* Restore the file descriptor for ST->parent, if it was temporarily + closed to conserve file descriptors. On failure, set the file + descriptor to the negative of the corresponding errno value. Call + this every time a subdirectory is ascended from. */ +void +restore_parent_fd (struct tar_stat_info const *st) +{ + struct tar_stat_info *parent = st->parent; + if (parent && ! parent->fd) + { + int parentfd = openat (st->fd, "..", open_searchdir_flags); + struct stat parentstat; + + if (parentfd < 0) + parentfd = - errno; + else if (! (fstat (parentfd, &parentstat) == 0 + && parent->stat.st_ino == parentstat.st_ino + && parent->stat.st_dev == parentstat.st_dev)) + { + close (parentfd); + parentfd = IMPOSTOR_ERRNO; + } + + if (parentfd < 0) + { + int origfd = open (parent->orig_file_name, open_searchdir_flags); + if (0 <= origfd) + { + if (fstat (parentfd, &parentstat) == 0 + && parent->stat.st_ino == parentstat.st_ino + && parent->stat.st_dev == parentstat.st_dev) + parentfd = origfd; + else + close (origfd); + } + } + + parent->fd = parentfd; + } +} + /* Dump a single file, recursing on directories. ST is the file's status info, NAME its name relative to the parent directory, and P its full name (which may be relative to the working directory). */ @@ -1508,10 +1651,11 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p) struct timespec original_ctime; struct timespec restore_times[2]; off_t block_ordinal = -1; - int fd = -1; + int fd = 0; bool is_dir; - bool top_level = ! st->parent; - int parentfd = top_level ? AT_FDCWD : st->parent->fd; + struct tar_stat_info const *parent = st->parent; + bool top_level = ! parent; + int parentfd = top_level ? AT_FDCWD : parent->fd; void (*diag) (char const *) = 0; if (interactive_option && !confirm ("add", p)) @@ -1523,15 +1667,24 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p) transform_name (&st->file_name, XFORM_REGFILE); - if (fstatat (parentfd, name, &st->stat, fstatat_flags) != 0) + if (parentfd < 0 && ! top_level) + { + errno = - parentfd; + diag = open_diag; + } + else if (fstatat (parentfd, name, &st->stat, fstatat_flags) != 0) diag = stat_diag; else if (file_dumpable_p (&st->stat)) { - fd = st->fd = openat (parentfd, name, open_read_flags); + fd = subfile_open (parent, name, open_read_flags); if (fd < 0) diag = open_diag; - else if (fstat (fd, &st->stat) != 0) - diag = stat_diag; + else + { + st->fd = fd; + if (fstat (fd, &st->stat) != 0) + diag = stat_diag; + } } if (diag) { @@ -1600,7 +1753,7 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p) ensure_slash (&st->orig_file_name); ensure_slash (&st->file_name); - if (check_exclusion_tags (fd, &tag_file_name) == exclusion_tag_all) + if (check_exclusion_tags (st, &tag_file_name) == exclusion_tag_all) { exclusion_tag_warning (st->orig_file_name, tag_file_name, _("directory not dumped")); @@ -1608,12 +1761,15 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p) } ok = dump_dir (st); + + fd = st->fd; + parentfd = top_level ? AT_FDCWD : parent->fd; } else { enum dump_status status; - if (fd != -1 && sparse_option && ST_IS_SPARSE (st->stat)) + if (fd && sparse_option && ST_IS_SPARSE (st->stat)) { status = sparse_dump_file (fd, st); if (status == dump_status_not_implemented) @@ -1641,14 +1797,26 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p) if (ok) { - if ((fd < 0 - ? fstatat (parentfd, name, &final_stat, fstatat_flags) - : fstat (fd, &final_stat)) - != 0) + if (fd < 0) { - file_removed_diag (p, top_level, stat_diag); + errno = - fd; ok = false; } + else if (fd == 0) + { + if (parentfd < 0 && ! top_level) + { + errno = - parentfd; + ok = false; + } + else + ok = fstatat (parentfd, name, &final_stat, fstatat_flags) == 0; + } + else + ok = fstat (fd, &final_stat) == 0; + + if (! ok) + file_removed_diag (p, top_level, stat_diag); } if (ok) @@ -1669,16 +1837,7 @@ dump_file0 (struct tar_stat_info *st, char const *name, char const *p) utime_error (p); } - if (0 < fd) - { - if (close (fd) != 0) - { - close_diag (p); - ok = false; - } - st->fd = 0; - } - + ok &= tar_stat_close (st); if (ok && remove_files_option) queue_deferred_unlink (p, is_dir); diff --git a/src/incremen.c b/src/incremen.c index afd19af..c6d4f4c 100644 --- a/src/incremen.c +++ b/src/incremen.c @@ -426,7 +426,6 @@ procdir (const char *name_buffer, struct tar_stat_info *st, { struct directory *directory; struct stat *stat_data = &st->stat; - int fd = st->fd; dev_t device = st->parent ? st->parent->stat.st_dev : 0; bool nfs = NFS_FILE_STAT (*stat_data); @@ -566,7 +565,7 @@ procdir (const char *name_buffer, struct tar_stat_info *st, { const char *tag_file_name; - switch (check_exclusion_tags (fd, &tag_file_name)) + switch (check_exclusion_tags (st, &tag_file_name)) { case exclusion_tag_all: /* This warning can be duplicated by code in dump_file0, but only @@ -680,8 +679,7 @@ struct directory * scan_directory (struct tar_stat_info *st) { char const *dir = st->orig_file_name; - int fd = st->fd; - char *dirp = 0; + char *dirp = get_directory_entries (st); dev_t device = st->stat.st_dev; bool cmdline = ! st->parent; namebuf_t nbuf; @@ -689,18 +687,6 @@ scan_directory (struct tar_stat_info *st) struct directory *directory; char ch; - int dupfd = dup (fd); - if (0 <= dupfd) - { - dirp = fdsavedir (dupfd); - if (! dirp) - { - int e = errno; - close (dupfd); - errno = e; - } - } - if (! dirp) savedir_error (dir); @@ -734,19 +720,29 @@ scan_directory (struct tar_stat_info *st) *entry = 'N'; else { + int fd = st->fd; void (*diag) (char const *) = 0; struct tar_stat_info stsub; tar_stat_init (&stsub); - if (fstatat (fd, entry + 1, &stsub.stat, fstatat_flags) != 0) + if (fd < 0) + { + errno = - fd; + diag = open_diag; + } + else if (fstatat (fd, entry + 1, &stsub.stat, fstatat_flags) != 0) diag = stat_diag; else if (S_ISDIR (stsub.stat.st_mode)) { - stsub.fd = openat (fd, entry + 1, open_read_flags); - if (stsub.fd < 0) + int subfd = subfile_open (st, entry + 1, open_read_flags); + if (subfd < 0) diag = open_diag; - else if (fstat (stsub.fd, &stsub.stat) != 0) - diag = stat_diag; + else + { + stsub.fd = subfd; + if (fstat (subfd, &stsub.stat) != 0) + diag = stat_diag; + } } if (diag) @@ -762,7 +758,10 @@ scan_directory (struct tar_stat_info *st) else if (directory->children == ALL_CHILDREN) pd_flag |= PD_FORCE_CHILDREN | ALL_CHILDREN; *entry = 'D'; + + stsub.parent = st; procdir (full_name, &stsub, pd_flag, entry); + restore_parent_fd (&stsub); } else if (one_file_system_option && device != stsub.stat.st_dev) *entry = 'N'; diff --git a/src/names.c b/src/names.c index 2fc751d..c38ccb6 100644 --- a/src/names.c +++ b/src/names.c @@ -818,6 +818,7 @@ add_hierarchy_to_namelist (struct tar_stat_info *st, struct name *name) { struct name *np; struct tar_stat_info subdir; + int subfd; if (allocated_length <= name_length + string_length) { @@ -841,21 +842,32 @@ add_hierarchy_to_namelist (struct tar_stat_info *st, struct name *name) tar_stat_init (&subdir); subdir.parent = st; - subdir.fd = openat (st->fd, string + 1, - open_read_flags | O_DIRECTORY); - if (subdir.fd < 0) - open_diag (namebuf); - else if (fstat (subdir.fd, &subdir.stat) != 0) - stat_diag (namebuf); - else if (! (O_DIRECTORY || S_ISDIR (subdir.stat.st_mode))) + if (st->fd < 0) { - errno = ENOTDIR; - open_diag (namebuf); + subfd = -1; + errno = - st->fd; } + else + subfd = subfile_open (st, string + 1, + open_read_flags | O_DIRECTORY); + if (subfd < 0) + open_diag (namebuf); else { - subdir.orig_file_name = xstrdup (namebuf); - add_hierarchy_to_namelist (&subdir, np); + subdir.fd = subfd; + if (fstat (subfd, &subdir.stat) != 0) + stat_diag (namebuf); + else if (! (O_DIRECTORY || S_ISDIR (subdir.stat.st_mode))) + { + errno = ENOTDIR; + open_diag (namebuf); + } + else + { + subdir.orig_file_name = xstrdup (namebuf); + add_hierarchy_to_namelist (&subdir, np); + restore_parent_fd (&subdir); + } } tar_stat_destroy (&subdir); @@ -976,16 +988,20 @@ collect_and_sort_names (void) } if (S_ISDIR (st.stat.st_mode)) { - st.fd = open (name->name, open_read_flags | O_DIRECTORY); - if (st.fd < 0) + int dir_fd = open (name->name, open_read_flags | O_DIRECTORY); + if (dir_fd < 0) open_diag (name->name); - else if (fstat (st.fd, &st.stat) != 0) - stat_diag (name->name); - else if (O_DIRECTORY || S_ISDIR (st.stat.st_mode)) + else { - st.orig_file_name = xstrdup (name->name); - name->found_count++; - add_hierarchy_to_namelist (&st, name); + st.fd = dir_fd; + if (fstat (dir_fd, &st.stat) != 0) + stat_diag (name->name); + else if (O_DIRECTORY || S_ISDIR (st.stat.st_mode)) + { + st.orig_file_name = xstrdup (name->name); + name->found_count++; + add_hierarchy_to_namelist (&st, name); + } } } diff --git a/src/tar.c b/src/tar.c index ab53cec..6fd117c 100644 --- a/src/tar.c +++ b/src/tar.c @@ -2465,13 +2465,17 @@ decode_options (int argc, char **argv) if (recursive_unlink_option) old_files_option = UNLINK_FIRST_OLD_FILES; - /* Flags for accessing files to be copied into. POSIX says + /* Flags for accessing files to be read from or copied into. POSIX says O_NONBLOCK has unspecified effect on most types of files, but in practice it never harms and sometimes helps. */ - open_read_flags = - (O_RDONLY | O_BINARY | O_NOCTTY | O_NONBLOCK - | (dereference_option ? 0 : O_NOFOLLOW) - | (atime_preserve_option == system_atime_preserve ? O_NOATIME : 0)); + { + int base_open_flags = + (O_BINARY | O_CLOEXEC | O_NOCTTY | O_NONBLOCK + | (dereference_option ? 0 : O_NOFOLLOW) + | (atime_preserve_option == system_atime_preserve ? O_NOATIME : 0)); + open_read_flags = O_RDONLY | base_open_flags; + open_searchdir_flags = O_SEARCH | O_DIRECTORY | base_open_flags; + } fstatat_flags = dereference_option ? 0 : AT_SYMLINK_NOFOLLOW; if (subcommand_option == TEST_LABEL_SUBCOMMAND) @@ -2684,9 +2688,31 @@ tar_stat_init (struct tar_stat_info *st) memset (st, 0, sizeof (*st)); } +/* Close the stream or file descriptor associated with ST, and remove + all traces of it from ST. Return true if successful, false (with a + diagnostic) otherwise. */ +bool +tar_stat_close (struct tar_stat_info *st) +{ + int status = (st->dirstream ? closedir (st->dirstream) + : 0 < st->fd ? close (st->fd) + : 0); + st->dirstream = 0; + st->fd = 0; + + if (status == 0) + return true; + else + { + close_diag (st->orig_file_name); + return false; + } +} + void tar_stat_destroy (struct tar_stat_info *st) { + tar_stat_close (st); free (st->orig_file_name); free (st->file_name); free (st->link_name); @@ -2694,8 +2720,6 @@ tar_stat_destroy (struct tar_stat_info *st) free (st->gname); free (st->sparse_map); free (st->dumpdir); - if (0 < st->fd) - close (st->fd); xheader_destroy (&st->xhdr); memset (st, 0, sizeof (*st)); } diff --git a/src/tar.h b/src/tar.h index c35ba5d..ce9850c 100644 --- a/src/tar.h +++ b/src/tar.h @@ -322,12 +322,20 @@ struct tar_stat_info file is at the top level. */ struct tar_stat_info *parent; + /* Directory stream. If this is not null, it is in control of FD, + and should be closed instead of FD. */ + DIR *dirstream; + /* File descriptor, if creating an archive, and if a directory or a - regular file or a contiguous file. This is AT_FDCWD if it is the - working directory, which is possible only for a dummy parent node - just above the top level. It may be -1 if the file could not be - opened. Zero represents an otherwise-uninitialized value; - standard input is never used here. */ + regular file or a contiguous file. + + It is zero if no file descriptor is available, either because it + was never needed or because it was open and then closed to + conserve on file descriptors. (Standard input is never used + here, so zero cannot be a valid file descriptor.) + + It is negative if it could not be reopened after it was closed. + Negate it to find out what errno was when the reopen failed. */ int fd; }; diff --git a/tests/Makefile.am b/tests/Makefile.am index 4b70000..ea1c6ae 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -77,6 +77,7 @@ TESTSUITE_AT = \ extrac08.at\ extrac09.at\ extrac10.at\ + extrac11.at\ filerem01.at\ filerem02.at\ gzip.at\ diff --git a/tests/extrac11.at b/tests/extrac11.at new file mode 100644 index 0000000..9456695 --- /dev/null +++ b/tests/extrac11.at @@ -0,0 +1,77 @@ +# Process this file with autom4te to create testsuite. -*- Autotest -*- + +# Test suite for GNU tar. +# Copyright (C) 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, 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 Paul Eggert + +# Check that 'tar' works even in a file-descriptor-limited environment. + +AT_SETUP([scarce file descriptors]) +AT_KEYWORDS([extract extrac11]) + +AT_TAR_CHECK([ +dirs='a + a/b + a/b/c + a/b/c/d + a/b/c/d/e + a/b/c/d/e/f + a/b/c/d/e/f/g + a/b/c/d/e/f/g/h + a/b/c/d/e/f/g/h/i + a/b/c/d/e/f/g/h/i/j + a/b/c/d/e/f/g/h/i/j/k +' +files= +mkdir $dirs dest1 dest2 dest3 || exit +for dir in $dirs; do + for file in X Y Z; do + echo $file >$dir/$file || exit + files="$files $file" + done +done + +# Check that "ulimit" itself works. +((ulimit -n 100 && + tar -cf archive1.tar a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- && + tar -xf archive1.tar -C dest1 a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- + ) && + diff -r a dest1/a +) >/dev/null 2>&1 || + AT_SKIP_TEST + +# Another test that "ulimit" itself works: +# tar should fail when completely starved of file descriptors. +((ulimit -n 4 && + tar -cf archive2.tar a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- && + tar -xf archive2.tar -C dest2 a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- + ) && + diff -r a dest2/a +) >/dev/null 2>&1 && + AT_SKIP_TEST + +# Tar should work when there are few, but enough, file descriptors. +((ulimit -n 10 && + tar -cf archive3.tar a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- && + tar -xf archive3.tar -C dest3 a 3<&- 4<&- 5<&- 6<&- 7<&- 8<&- 9<&- + ) && + diff -r a dest3/a >/dev/null 2>&1 +) || { diff -r a dest3/a; exit 1; } +], +[0],[],[],[],[],[gnu]) + +AT_CLEANUP diff --git a/tests/testsuite.at b/tests/testsuite.at index 8866ed0..2b2bd6b 100644 --- a/tests/testsuite.at +++ b/tests/testsuite.at @@ -149,6 +149,7 @@ m4_include([extrac07.at]) m4_include([extrac08.at]) m4_include([extrac09.at]) m4_include([extrac10.at]) +m4_include([extrac11.at]) m4_include([label01.at]) m4_include([label02.at])