lib/clean-temp.h

   1 /* Temporary directories and temporary files with automatic cleanup.
   2    Copyright (C) 2006, 2011-2020 Free Software Foundation, Inc.
   3    Written by Bruno Haible <bruno@clisp.org>, 2006.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _CLEAN_TEMP_H
  19 #define _CLEAN_TEMP_H
  20
  21 #include <stdbool.h>
  22 #include <stdio.h>
  23 #include <sys/types.h>
  24
  25 #ifdef __cplusplus
  26 extern "C" {
  27 #endif
  28
  29
  30 /* Temporary directories and temporary files should be automatically removed
  31    when the program exits either normally or through a fatal signal.  We can't
  32    rely on the "unlink before close" idiom, because it works only on Unix and
  33    also - if no signal blocking is used - leaves a time window where a fatal
  34    signal would not clean up the temporary file.
  35
  36    Also, open file descriptors need to be closed before the temporary files
  37    and the temporary directories can be removed, because only on Unix
  38    (excluding Cygwin) can one remove directories containing open files.
  39
  40    This module provides support for
  41      - temporary directories and temporary files inside these temporary
  42        directories,
  43      - temporary files without temporary directories.
  44    The temporary directories and files are automatically cleaned up (at the
  45    latest) when the program exits or dies from a fatal signal such as SIGINT,
  46    SIGTERM, SIGHUP, but not if it dies from a fatal signal such as SIGQUIT,
  47    SIGKILL, or SIGABRT, SIGSEGV, SIGBUS, SIGILL, SIGFPE.
  48
  49    For the cleanup in the normal case, programs that use this module need to
  50    call 'cleanup_temp_dir' for each successful return of 'create_temp_dir'.
  51    The cleanup in the case of a fatal signal such as SIGINT, SIGTERM, SIGHUP,
  52    is done entirely automatically by the functions of this module.
  53
  54    Limitations: Files or directories can still be left over if
  55      - the program is dies from a fatal signal such as SIGQUIT, SIGKILL, or
  56        SIGABRT, SIGSEGV, SIGBUS, SIGILL, SIGFPE, or
  57      - in a multithreaded program, the fatal signal handler is already running
  58        while another thread of the program creates a new temporary directory
  59        or temporary file, or
  60      - on native Windows, some temporary files are used by a subprocess while
  61        the fatal signal interrupts the program.
  62  */
  63
  64
  65 /* ============= Temporary files without temporary directories ============= */
  66
  67 /* Register the given ABSOLUTE_FILE_NAME as being a file that needs to be
  68    removed.
  69    Should be called before the file ABSOLUTE_FILE_NAME is created.  */
  70 extern void register_temporary_file (const char *absolute_file_name);
  71
  72 /* Unregister the given ABSOLUTE_FILE_NAME as being a file that needs to be
  73    removed.
  74    Should be called when the file ABSOLUTE_FILE_NAME could not be created.  */
  75 extern void unregister_temporary_file (const char *absolute_file_name);
  76
  77 /* Remove the given ABSOLUTE_FILE_NAME and unregister it.
  78    CLEANUP_VERBOSE determines whether errors are reported to standard error.
  79    Return 0 upon success, or -1 if there was some problem.  */
  80 extern int cleanup_temporary_file (const char *absolute_file_name,
  81                                    bool cleanup_verbose);
  82
  83 /* ========= Temporary directories and temporary files inside them ========= */
  84
  85 struct temp_dir
  86 {
  87   /* The absolute pathname of the directory.  */
  88   const char * const dir_name;
  89   /* Whether errors during explicit cleanup are reported to standard error.  */
  90   bool cleanup_verbose;
  91   /* More fields are present here, but not public.  */
  92 };
  93
  94 /* Create a temporary directory.
  95    PREFIX is used as a prefix for the name of the temporary directory. It
  96    should be short and still give an indication about the program.
  97    PARENTDIR can be used to specify the parent directory; if NULL, a default
  98    parent directory is used (either $TMPDIR or /tmp or similar).
  99    CLEANUP_VERBOSE determines whether errors during explicit cleanup are
 100    reported to standard error.
 101    Return a fresh 'struct temp_dir' on success.  Upon error, an error message
 102    is shown and NULL is returned.  */
 103 extern struct temp_dir * create_temp_dir (const char *prefix,
 104                                           const char *parentdir,
 105                                           bool cleanup_verbose);
 106
 107 /* Register the given ABSOLUTE_FILE_NAME as being a file inside DIR, that
 108    needs to be removed before DIR can be removed.
 109    Should be called before the file ABSOLUTE_FILE_NAME is created.  */
 110 extern void register_temp_file (struct temp_dir *dir,
 111                                 const char *absolute_file_name);
 112
 113 /* Unregister the given ABSOLUTE_FILE_NAME as being a file inside DIR, that
 114    needs to be removed before DIR can be removed.
 115    Should be called when the file ABSOLUTE_FILE_NAME could not be created.  */
 116 extern void unregister_temp_file (struct temp_dir *dir,
 117                                   const char *absolute_file_name);
 118
 119 /* Register the given ABSOLUTE_DIR_NAME as being a subdirectory inside DIR,
 120    that needs to be removed before DIR can be removed.
 121    Should be called before the subdirectory ABSOLUTE_DIR_NAME is created.  */
 122 extern void register_temp_subdir (struct temp_dir *dir,
 123                                   const char *absolute_dir_name);
 124
 125 /* Unregister the given ABSOLUTE_DIR_NAME as being a subdirectory inside DIR,
 126    that needs to be removed before DIR can be removed.
 127    Should be called when the subdirectory ABSOLUTE_DIR_NAME could not be
 128    created.  */
 129 extern void unregister_temp_subdir (struct temp_dir *dir,
 130                                     const char *absolute_dir_name);
 131
 132 /* Remove the given ABSOLUTE_FILE_NAME and unregister it.
 133    Return 0 upon success, or -1 if there was some problem.  */
 134 extern int cleanup_temp_file (struct temp_dir *dir,
 135                               const char *absolute_file_name);
 136
 137 /* Remove the given ABSOLUTE_DIR_NAME and unregister it.
 138    Return 0 upon success, or -1 if there was some problem.  */
 139 extern int cleanup_temp_subdir (struct temp_dir *dir,
 140                                 const char *absolute_dir_name);
 141
 142 /* Remove all registered files and subdirectories inside DIR.
 143    Return 0 upon success, or -1 if there was some problem.  */
 144 extern int cleanup_temp_dir_contents (struct temp_dir *dir);
 145
 146 /* Remove all registered files and subdirectories inside DIR and DIR itself.
 147    DIR cannot be used any more after this call.
 148    Return 0 upon success, or -1 if there was some problem.  */
 149 extern int cleanup_temp_dir (struct temp_dir *dir);
 150
 151 /* ================== Opening and closing temporary files ================== */
 152
 153 /* Open a temporary file in a temporary directory.
 154    FILE_NAME must already have been passed to register_temp_file.
 155    Registers the resulting file descriptor to be closed.
 156    DELETE_ON_CLOSE indicates whether the file can be deleted when the resulting
 157    file descriptor or stream is closed.  */
 158 extern int open_temp (const char *file_name, int flags, mode_t mode,
 159                       bool delete_on_close);
 160 extern FILE * fopen_temp (const char *file_name, const char *mode,
 161                           bool delete_on_close);
 162
 163 /* Open a temporary file, generating its name based on FILE_NAME_TMPL.
 164    FILE_NAME_TMPL must match the rules for mk[s]temp (i.e. end in "XXXXXX",
 165    possibly with a suffix).  The name constructed does not exist at the time
 166    of the call.  FILE_NAME_TMPL is overwritten with the result.
 167    A safe choice for MODE is S_IRUSR | S_IWUSR, a.k.a. 0600.
 168    Registers the file for deletion.
 169    Opens the file, with the given FLAGS and mode MODE.
 170    Registers the resulting file descriptor to be closed.  */
 171 extern int gen_register_open_temp (char *file_name_tmpl, int suffixlen,
 172                                    int flags, mode_t mode);
 173
 174 /* Close a temporary file.
 175    FD must have been returned by open_temp or gen_register_open_temp.
 176    Unregisters the previously registered file descriptor.  */
 177 extern int close_temp (int fd);
 178
 179 /* Close a temporary file.
 180    FP must have been returned by fopen_temp, or by fdopen on a file descriptor
 181    returned by open_temp or gen_register_open_temp.
 182    Unregisters the previously registered file descriptor.  */
 183 extern int fclose_temp (FILE *fp);
 184
 185 /* Like fwriteerror.
 186    FP must have been returned by fopen_temp, or by fdopen on a file descriptor
 187    returned by open_temp or gen_register_open_temp.
 188    Unregisters the previously registered file descriptor.  */
 189 extern int fwriteerror_temp (FILE *fp);
 190
 191 /* Like close_stream.
 192    FP must have been returned by fopen_temp, or by fdopen on a file descriptor
 193    returned by open_temp or gen_register_open_temp.
 194    Unregisters the previously registered file descriptor.  */
 195 extern int close_stream_temp (FILE *fp);
 196
 197
 198 #ifdef __cplusplus
 199 }
 200 #endif
 201
 202 #endif /* _CLEAN_TEMP_H */