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Diffstat (limited to 'lib/clean-temp.c')
| -rw-r--r-- | lib/clean-temp.c | 793 |
1 files changed, 793 insertions, 0 deletions
diff --git a/lib/clean-temp.c b/lib/clean-temp.c new file mode 100644 index 0000000..1053312 --- /dev/null +++ b/lib/clean-temp.c @@ -0,0 +1,793 @@ +/* Temporary directories and temporary files with automatic cleanup. + Copyright (C) 2001, 2003, 2006-2007, 2009-2013 Free Software Foundation, + Inc. + Written by Bruno Haible <bruno@clisp.org>, 2006. + + 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 <http://www.gnu.org/licenses/>. */ + + +#include <config.h> + +/* Specification. */ +#include "clean-temp.h" + +#include <errno.h> +#include <fcntl.h> +#include <limits.h> +#include <stdbool.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ +# define WIN32_LEAN_AND_MEAN /* avoid including junk */ +# include <windows.h> +#endif + +#include "error.h" +#include "fatal-signal.h" +#include "pathmax.h" +#include "tmpdir.h" +#include "xalloc.h" +#include "xmalloca.h" +#include "gl_xlist.h" +#include "gl_linkedhash_list.h" +#include "gettext.h" +#if GNULIB_FWRITEERROR +# include "fwriteerror.h" +#endif +#if GNULIB_CLOSE_STREAM +# include "close-stream.h" +#endif +#if GNULIB_FCNTL_SAFER +# include "fcntl--.h" +#endif +#if GNULIB_FOPEN_SAFER +# include "stdio--.h" +#endif + +#define _(str) gettext (str) + +/* GNU Hurd doesn't have PATH_MAX. Use a fallback. + Temporary directory names are usually not that long. */ +#ifndef PATH_MAX +# define PATH_MAX 1024 +#endif + +#ifndef uintptr_t +# define uintptr_t unsigned long +#endif + +#if !GNULIB_FCNTL_SAFER +/* The results of open() in this file are not used with fchdir, + therefore save some unnecessary work in fchdir.c. */ +# undef open +# undef close +#endif + + +/* The use of 'volatile' in the types below (and ISO C 99 section 5.1.2.3.(5)) + ensure that while constructing or modifying the data structures, the field + values are written to memory in the order of the C statements. So the + signal handler can rely on these field values to be up to date. */ + + +/* Registry for a single temporary directory. + 'struct temp_dir' from the public header file overlaps with this. */ +struct tempdir +{ + /* The absolute pathname of the directory. */ + char * volatile dirname; + /* Whether errors during explicit cleanup are reported to standard error. */ + bool cleanup_verbose; + /* Absolute pathnames of subdirectories. */ + gl_list_t /* <char *> */ volatile subdirs; + /* Absolute pathnames of files. */ + gl_list_t /* <char *> */ volatile files; +}; + +/* List of all temporary directories. */ +static struct +{ + struct tempdir * volatile * volatile tempdir_list; + size_t volatile tempdir_count; + size_t tempdir_allocated; +} cleanup_list /* = { NULL, 0, 0 } */; + +/* List of all open file descriptors to temporary files. */ +static gl_list_t /* <int> */ volatile descriptors; + + +/* For the subdirs and for the files, we use a gl_list_t of type LINKEDHASH. + Why? We need a data structure that + + 1) Can contain an arbitrary number of 'char *' values. The strings + are compared via strcmp, not pointer comparison. + 2) Has insertion and deletion operations that are fast: ideally O(1), + or possibly O(log n). This is important for GNU sort, which may + create a large number of temporary files. + 3) Allows iteration through all elements from within a signal handler. + 4) May or may not allow duplicates. It doesn't matter here, since + any file or subdir can only be removed once. + + Criterion 1) would allow any gl_list_t or gl_oset_t implementation. + + Criterion 2) leaves only GL_LINKEDHASH_LIST, GL_TREEHASH_LIST, or + GL_TREE_OSET. + + Criterion 3) puts at disadvantage GL_TREEHASH_LIST and GL_TREE_OSET. + Namely, iteration through the elements of a binary tree requires access + to many ->left, ->right, ->parent pointers. However, the rebalancing + code for insertion and deletion in an AVL or red-black tree is so + complicated that we cannot assume that >left, ->right, ->parent pointers + are in a consistent state throughout these operations. Therefore, to + avoid a crash in the signal handler, all destructive operations to the + lists would have to be protected by a + block_fatal_signals (); + ... + unblock_fatal_signals (); + pair. Which causes extra system calls. + + Criterion 3) would also discourage GL_ARRAY_LIST and GL_CARRAY_LIST, + if they were not already excluded. Namely, these implementations use + xrealloc(), leaving a time window in which in the list->elements pointer + points to already deallocated memory. To avoid a crash in the signal + handler at such a moment, all destructive operations would have to + protected by block/unblock_fatal_signals (), in this case too. + + A list of type GL_LINKEDHASH_LIST without duplicates fulfills all + requirements: + 2) Insertion and deletion are O(1) on average. + 3) The gl_list_iterator, gl_list_iterator_next implementations do + not trigger memory allocations, nor other system calls, and are + therefore safe to be called from a signal handler. + Furthermore, since SIGNAL_SAFE_LIST is defined, the implementation + of the destructive functions ensures that the list structure is + safe to be traversed at any moment, even when interrupted by an + asynchronous signal. + */ + +/* String equality and hash code functions used by the lists. */ + +static bool +string_equals (const void *x1, const void *x2) +{ + const char *s1 = (const char *) x1; + const char *s2 = (const char *) x2; + return strcmp (s1, s2) == 0; +} + +#define SIZE_BITS (sizeof (size_t) * CHAR_BIT) + +/* A hash function for NUL-terminated char* strings using + the method described by Bruno Haible. + See http://www.haible.de/bruno/hashfunc.html. */ +static size_t +string_hash (const void *x) +{ + const char *s = (const char *) x; + size_t h = 0; + + for (; *s; s++) + h = *s + ((h << 9) | (h >> (SIZE_BITS - 9))); + + return h; +} + + +/* The signal handler. It gets called asynchronously. */ +static void +cleanup () +{ + size_t i; + + /* First close all file descriptors to temporary files. */ + { + gl_list_t fds = descriptors; + + if (fds != NULL) + { + gl_list_iterator_t iter; + const void *element; + + iter = gl_list_iterator (fds); + while (gl_list_iterator_next (&iter, &element, NULL)) + { + int fd = (int) (uintptr_t) element; + close (fd); + } + gl_list_iterator_free (&iter); + } + } + + for (i = 0; i < cleanup_list.tempdir_count; i++) + { + struct tempdir *dir = cleanup_list.tempdir_list[i]; + + if (dir != NULL) + { + gl_list_iterator_t iter; + const void *element; + + /* First cleanup the files in the subdirectories. */ + iter = gl_list_iterator (dir->files); + while (gl_list_iterator_next (&iter, &element, NULL)) + { + const char *file = (const char *) element; + unlink (file); + } + gl_list_iterator_free (&iter); + + /* Then cleanup the subdirectories. */ + iter = gl_list_iterator (dir->subdirs); + while (gl_list_iterator_next (&iter, &element, NULL)) + { + const char *subdir = (const char *) element; + rmdir (subdir); + } + gl_list_iterator_free (&iter); + + /* Then cleanup the temporary directory itself. */ + rmdir (dir->dirname); + } + } +} + +/* Create a temporary directory. + PREFIX is used as a prefix for the name of the temporary directory. It + should be short and still give an indication about the program. + PARENTDIR can be used to specify the parent directory; if NULL, a default + parent directory is used (either $TMPDIR or /tmp or similar). + CLEANUP_VERBOSE determines whether errors during explicit cleanup are + reported to standard error. + Return a fresh 'struct temp_dir' on success. Upon error, an error message + is shown and NULL is returned. */ +struct temp_dir * +create_temp_dir (const char *prefix, const char *parentdir, + bool cleanup_verbose) +{ + struct tempdir * volatile *tmpdirp = NULL; + struct tempdir *tmpdir; + size_t i; + char *xtemplate; + char *tmpdirname; + + /* See whether it can take the slot of an earlier temporary directory + already cleaned up. */ + for (i = 0; i < cleanup_list.tempdir_count; i++) + if (cleanup_list.tempdir_list[i] == NULL) + { + tmpdirp = &cleanup_list.tempdir_list[i]; + break; + } + if (tmpdirp == NULL) + { + /* See whether the array needs to be extended. */ + if (cleanup_list.tempdir_count == cleanup_list.tempdir_allocated) + { + /* Note that we cannot use xrealloc(), because then the cleanup() + function could access an already deallocated array. */ + struct tempdir * volatile *old_array = cleanup_list.tempdir_list; + size_t old_allocated = cleanup_list.tempdir_allocated; + size_t new_allocated = 2 * cleanup_list.tempdir_allocated + 1; + struct tempdir * volatile *new_array = + XNMALLOC (new_allocated, struct tempdir * volatile); + + if (old_allocated == 0) + /* First use of this facility. Register the cleanup handler. */ + at_fatal_signal (&cleanup); + else + { + /* Don't use memcpy() here, because memcpy takes non-volatile + arguments and is therefore not guaranteed to complete all + memory stores before the next statement. */ + size_t k; + + for (k = 0; k < old_allocated; k++) + new_array[k] = old_array[k]; + } + + cleanup_list.tempdir_list = new_array; + cleanup_list.tempdir_allocated = new_allocated; + + /* Now we can free the old array. */ + if (old_array != NULL) + free ((struct tempdir **) old_array); + } + + tmpdirp = &cleanup_list.tempdir_list[cleanup_list.tempdir_count]; + /* Initialize *tmpdirp before incrementing tempdir_count, so that + cleanup() will skip this entry before it is fully initialized. */ + *tmpdirp = NULL; + cleanup_list.tempdir_count++; + } + + /* Initialize a 'struct tempdir'. */ + tmpdir = XMALLOC (struct tempdir); + tmpdir->dirname = NULL; + tmpdir->cleanup_verbose = cleanup_verbose; + tmpdir->subdirs = gl_list_create_empty (GL_LINKEDHASH_LIST, + string_equals, string_hash, NULL, + false); + tmpdir->files = gl_list_create_empty (GL_LINKEDHASH_LIST, + string_equals, string_hash, NULL, + false); + + /* Create the temporary directory. */ + xtemplate = (char *) xmalloca (PATH_MAX); + if (path_search (xtemplate, PATH_MAX, parentdir, prefix, parentdir == NULL)) + { + error (0, errno, + _("cannot find a temporary directory, try setting $TMPDIR")); + goto quit; + } + block_fatal_signals (); + tmpdirname = mkdtemp (xtemplate); + if (tmpdirname != NULL) + { + tmpdir->dirname = tmpdirname; + *tmpdirp = tmpdir; + } + unblock_fatal_signals (); + if (tmpdirname == NULL) + { + error (0, errno, + _("cannot create a temporary directory using template \"%s\""), + xtemplate); + goto quit; + } + /* Replace tmpdir->dirname with a copy that has indefinite extent. + We cannot do this inside the block_fatal_signals/unblock_fatal_signals + block because then the cleanup handler would not remove the directory + if xstrdup fails. */ + tmpdir->dirname = xstrdup (tmpdirname); + freea (xtemplate); + return (struct temp_dir *) tmpdir; + + quit: + freea (xtemplate); + return NULL; +} + +/* Register the given ABSOLUTE_FILE_NAME as being a file inside DIR, that + needs to be removed before DIR can be removed. + Should be called before the file ABSOLUTE_FILE_NAME is created. */ +void +register_temp_file (struct temp_dir *dir, + const char *absolute_file_name) +{ + struct tempdir *tmpdir = (struct tempdir *)dir; + + /* Add absolute_file_name to tmpdir->files, without duplicates. */ + if (gl_list_search (tmpdir->files, absolute_file_name) == NULL) + gl_list_add_first (tmpdir->files, xstrdup (absolute_file_name)); +} + +/* Unregister the given ABSOLUTE_FILE_NAME as being a file inside DIR, that + needs to be removed before DIR can be removed. + Should be called when the file ABSOLUTE_FILE_NAME could not be created. */ +void +unregister_temp_file (struct temp_dir *dir, + const char *absolute_file_name) +{ + struct tempdir *tmpdir = (struct tempdir *)dir; + gl_list_t list = tmpdir->files; + gl_list_node_t node; + + node = gl_list_search (list, absolute_file_name); + if (node != NULL) + { + char *old_string = (char *) gl_list_node_value (list, node); + + gl_list_remove_node (list, node); + free (old_string); + } +} + +/* Register the given ABSOLUTE_DIR_NAME as being a subdirectory inside DIR, + that needs to be removed before DIR can be removed. + Should be called before the subdirectory ABSOLUTE_DIR_NAME is created. */ +void +register_temp_subdir (struct temp_dir *dir, + const char *absolute_dir_name) +{ + struct tempdir *tmpdir = (struct tempdir *)dir; + + /* Add absolute_dir_name to tmpdir->subdirs, without duplicates. */ + if (gl_list_search (tmpdir->subdirs, absolute_dir_name) == NULL) + gl_list_add_first (tmpdir->subdirs, xstrdup (absolute_dir_name)); +} + +/* Unregister the given ABSOLUTE_DIR_NAME as being a subdirectory inside DIR, + that needs to be removed before DIR can be removed. + Should be called when the subdirectory ABSOLUTE_DIR_NAME could not be + created. */ +void +unregister_temp_subdir (struct temp_dir *dir, + const char *absolute_dir_name) +{ + struct tempdir *tmpdir = (struct tempdir *)dir; + gl_list_t list = tmpdir->subdirs; + gl_list_node_t node; + + node = gl_list_search (list, absolute_dir_name); + if (node != NULL) + { + char *old_string = (char *) gl_list_node_value (list, node); + + gl_list_remove_node (list, node); + free (old_string); + } +} + +/* Remove a file, with optional error message. + Return 0 upon success, or -1 if there was some problem. */ +static int +do_unlink (struct temp_dir *dir, const char *absolute_file_name) +{ + if (unlink (absolute_file_name) < 0 && dir->cleanup_verbose + && errno != ENOENT) + { + error (0, errno, _("cannot remove temporary file %s"), absolute_file_name); + return -1; + } + return 0; +} + +/* Remove a directory, with optional error message. + Return 0 upon success, or -1 if there was some problem. */ +static int +do_rmdir (struct temp_dir *dir, const char *absolute_dir_name) +{ + if (rmdir (absolute_dir_name) < 0 && dir->cleanup_verbose + && errno != ENOENT) + { + error (0, errno, + _("cannot remove temporary directory %s"), absolute_dir_name); + return -1; + } + return 0; +} + +/* Remove the given ABSOLUTE_FILE_NAME and unregister it. + Return 0 upon success, or -1 if there was some problem. */ +int +cleanup_temp_file (struct temp_dir *dir, + const char *absolute_file_name) +{ + int err; + + err = do_unlink (dir, absolute_file_name); + unregister_temp_file (dir, absolute_file_name); + + return err; +} + +/* Remove the given ABSOLUTE_DIR_NAME and unregister it. + Return 0 upon success, or -1 if there was some problem. */ +int +cleanup_temp_subdir (struct temp_dir *dir, + const char *absolute_dir_name) +{ + int err; + + err = do_rmdir (dir, absolute_dir_name); + unregister_temp_subdir (dir, absolute_dir_name); + + return err; +} + +/* Remove all registered files and subdirectories inside DIR. + Return 0 upon success, or -1 if there was some problem. */ +int +cleanup_temp_dir_contents (struct temp_dir *dir) +{ + struct tempdir *tmpdir = (struct tempdir *)dir; + int err = 0; + gl_list_t list; + gl_list_iterator_t iter; + const void *element; + gl_list_node_t node; + + /* First cleanup the files in the subdirectories. */ + list = tmpdir->files; + iter = gl_list_iterator (list); + while (gl_list_iterator_next (&iter, &element, &node)) + { + char *file = (char *) element; + + err |= do_unlink (dir, file); + gl_list_remove_node (list, node); + /* Now only we can free file. */ + free (file); + } + gl_list_iterator_free (&iter); + + /* Then cleanup the subdirectories. */ + list = tmpdir->subdirs; + iter = gl_list_iterator (list); + while (gl_list_iterator_next (&iter, &element, &node)) + { + char *subdir = (char *) element; + + err |= do_rmdir (dir, subdir); + gl_list_remove_node (list, node); + /* Now only we can free subdir. */ + free (subdir); + } + gl_list_iterator_free (&iter); + + return err; +} + +/* Remove all registered files and subdirectories inside DIR and DIR itself. + DIR cannot be used any more after this call. + Return 0 upon success, or -1 if there was some problem. */ +int +cleanup_temp_dir (struct temp_dir *dir) +{ + struct tempdir *tmpdir = (struct tempdir *)dir; + int err = 0; + size_t i; + + err |= cleanup_temp_dir_contents (dir); + err |= do_rmdir (dir, tmpdir->dirname); + + for (i = 0; i < cleanup_list.tempdir_count; i++) + if (cleanup_list.tempdir_list[i] == tmpdir) + { + /* Remove cleanup_list.tempdir_list[i]. */ + if (i + 1 == cleanup_list.tempdir_count) + { + while (i > 0 && cleanup_list.tempdir_list[i - 1] == NULL) + i--; + cleanup_list.tempdir_count = i; + } + else + cleanup_list.tempdir_list[i] = NULL; + /* Now only we can free the tmpdir->dirname, tmpdir->subdirs, + tmpdir->files, and tmpdir itself. */ + gl_list_free (tmpdir->files); + gl_list_free (tmpdir->subdirs); + free (tmpdir->dirname); + free (tmpdir); + return err; + } + + /* The user passed an invalid DIR argument. */ + abort (); +} + + +#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ + +/* On Windows, opening a file with _O_TEMPORARY has the effect of passing + the FILE_FLAG_DELETE_ON_CLOSE flag to CreateFile(), which has the effect + of deleting the file when it is closed - even when the program crashes. + But (according to the Cygwin sources) it works only on Windows NT or newer. + So we cache the info whether we are running on Windows NT or newer. */ + +static bool +supports_delete_on_close () +{ + static int known; /* 1 = yes, -1 = no, 0 = unknown */ + /* M4 wants to close and later reopen a temporary file, so + delete-on-close must not be used. */ + known = -1; + if (!known) + { + OSVERSIONINFO v; + + /* According to + <http://msdn.microsoft.com/en-us/library/windows/desktop/ms724451(v=vs.85).aspx> + this structure must be initialised as follows: */ + v.dwOSVersionInfoSize = sizeof (OSVERSIONINFO); + + if (GetVersionEx (&v)) + known = (v.dwPlatformId == VER_PLATFORM_WIN32_NT ? 1 : -1); + else + known = -1; + } + return (known > 0); +} + +#endif + + +/* Register a file descriptor to be closed. */ +static void +register_fd (int fd) +{ + if (descriptors == NULL) + descriptors = gl_list_create_empty (GL_LINKEDHASH_LIST, NULL, NULL, NULL, + false); + gl_list_add_first (descriptors, (void *) (uintptr_t) fd); +} + +/* Unregister a file descriptor to be closed. */ +static void +unregister_fd (int fd) +{ + gl_list_t fds = descriptors; + gl_list_node_t node; + + if (fds == NULL) + /* descriptors should already contain fd. */ + abort (); + node = gl_list_search (fds, (void *) (uintptr_t) fd); + if (node == NULL) + /* descriptors should already contain fd. */ + abort (); + gl_list_remove_node (fds, node); +} + +/* Open a temporary file in a temporary directory. + Registers the resulting file descriptor to be closed. */ +int +open_temp (const char *file_name, int flags, mode_t mode) +{ + int fd; + int saved_errno; + + block_fatal_signals (); + /* Note: 'open' here is actually open() or open_safer(). */ +#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ + /* Use _O_TEMPORARY when possible, to increase the chances that the + temporary file is removed when the process crashes. */ + if (supports_delete_on_close ()) + fd = open (file_name, flags | _O_TEMPORARY, mode); + else +#endif + fd = open (file_name, flags, mode); + saved_errno = errno; + if (fd >= 0) + register_fd (fd); + unblock_fatal_signals (); + errno = saved_errno; + return fd; +} + +/* Open a temporary file in a temporary directory. + Registers the resulting file descriptor to be closed. */ +FILE * +fopen_temp (const char *file_name, const char *mode) +{ + FILE *fp; + int saved_errno; + + block_fatal_signals (); + /* Note: 'fopen' here is actually fopen() or fopen_safer(). */ +#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ + /* Use _O_TEMPORARY when possible, to increase the chances that the + temporary file is removed when the process crashes. */ + if (supports_delete_on_close ()) + { + size_t mode_len = strlen (mode); + char *augmented_mode = (char *) xmalloca (mode_len + 2); + memcpy (augmented_mode, mode, mode_len); + memcpy (augmented_mode + mode_len, "D", 2); + + fp = fopen (file_name, augmented_mode); + saved_errno = errno; + + freea (augmented_mode); + } + else +#endif + { + fp = fopen (file_name, mode); + saved_errno = errno; + } + if (fp != NULL) + { + /* It is sufficient to register fileno (fp) instead of the entire fp, + because at cleanup time there is no need to do an fflush (fp); a + close (fileno (fp)) will be enough. */ + int fd = fileno (fp); + if (!(fd >= 0)) + abort (); + register_fd (fd); + } + unblock_fatal_signals (); + errno = saved_errno; + return fp; +} + +/* Close a temporary file in a temporary directory. + Unregisters the previously registered file descriptor. */ +int +close_temp (int fd) +{ + if (fd >= 0) + { + /* No blocking of signals is needed here, since a double close of a + file descriptor is harmless. */ + int result = close (fd); + int saved_errno = errno; + + /* No race condition here: we assume a single-threaded program, hence + fd cannot be re-opened here. */ + + unregister_fd (fd); + + errno = saved_errno; + return result; + } + else + return close (fd); +} + +/* Close a temporary file in a temporary directory. + Unregisters the previously registered file descriptor. */ +int +fclose_temp (FILE *fp) +{ + int fd = fileno (fp); + /* No blocking of signals is needed here, since a double close of a + file descriptor is harmless. */ + int result = fclose (fp); + int saved_errno = errno; + + /* No race condition here: we assume a single-threaded program, hence + fd cannot be re-opened here. */ + + unregister_fd (fd); + + errno = saved_errno; + return result; +} + +#if GNULIB_FWRITEERROR +/* Like fwriteerror. + Unregisters the previously registered file descriptor. */ +int +fwriteerror_temp (FILE *fp) +{ + int fd = fileno (fp); + /* No blocking of signals is needed here, since a double close of a + file descriptor is harmless. */ + int result = fwriteerror (fp); + int saved_errno = errno; + + /* No race condition here: we assume a single-threaded program, hence + fd cannot be re-opened here. */ + + unregister_fd (fd); + + errno = saved_errno; + return result; +} +#endif + +#if GNULIB_CLOSE_STREAM +/* Like close_stream. + Unregisters the previously registered file descriptor. */ +int +close_stream_temp (FILE *fp) +{ + int fd = fileno (fp); + /* No blocking of signals is needed here, since a double close of a + file descriptor is harmless. */ + int result = close_stream (fp); + int saved_errno = errno; + + /* No race condition here: we assume a single-threaded program, hence + fd cannot be re-opened here. */ + + unregister_fd (fd); + + errno = saved_errno; + return result; +} +#endif |