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| -rw-r--r-- | ChangeLog | 4 | ||||
| -rw-r--r-- | manual/filesys.texi | 222 |
2 files changed, 226 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog index 34c86cbf1c..74e6fa55de 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,9 @@ 2014-02-01 Alexandre Oliva <aoliva@redhat.com> + * manual/filesys.texi: Document MTASC-safety properties. + +2014-02-01 Alexandre Oliva <aoliva@redhat.com> + * manual/errno.texi: Document MTASC-safety properties. 2014-02-01 Alexandre Oliva <aoliva@redhat.com> diff --git a/manual/filesys.texi b/manual/filesys.texi index 459fb1f5ae..1c9d7d7707 100644 --- a/manual/filesys.texi +++ b/manual/filesys.texi @@ -58,6 +58,25 @@ Prototypes for these functions are declared in the header file @comment unistd.h @comment POSIX.1 @deftypefun {char *} getcwd (char *@var{buffer}, size_t @var{size}) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{}}} +@c If buffer is NULL, this function calls malloc and realloc, and, in +@c case of error, free. Linux offers a getcwd syscall that we use on +@c GNU/Linux systems, but it may fail if the pathname is too long. As a +@c fallback, and on other systems, the generic implementation opens each +@c parent directory with opendir, which allocates memory for the +@c directory stream with malloc. If a fstatat64 syscall is not +@c available, very deep directory trees may also have to malloc to build +@c longer sequences of ../../../... than those supported by a global +@c const read-only string. + +@c linux/__getcwd +@c posix/__getcwd +@c malloc/realloc/free if buffer is NULL, or if dir is too deep +@c lstat64 -> see its own entry +@c fstatat64 +@c direct syscall if possible, alloca+snprintf+*stat64 otherwise +@c openat64_not_cancel_3, close_not_cancel_no_status +@c __fdopendir, __opendir, __readdir, rewinddir The @code{getcwd} function returns an absolute file name representing the current working directory, storing it in the character array @var{buffer} that you provide. The @var{size} argument is how you tell @@ -116,6 +135,9 @@ software. @comment unistd.h @comment BSD @deftypefn {Deprecated Function} {char *} getwd (char *@var{buffer}) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @ascuintl{}}@acunsafe{@acsmem{} @acsfd{}}} +@c Besides the getcwd safety issues, it calls strerror_r on error, which +@c brings in all of the i18n issues. This is similar to @code{getcwd}, but has no way to specify the size of the buffer. @Theglibc{} provides @code{getwd} only for backwards compatibility with BSD. @@ -130,6 +152,9 @@ this function is deprecated. @comment unistd.h @comment GNU @deftypefun {char *} get_current_dir_name (void) +@safety{@prelim{}@mtsafe{@mtsenv{}}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{}}} +@c Besides getcwd, which this function calls as a fallback, it calls +@c getenv, with the potential thread-safety issues that brings about. @vindex PWD This @code{get_current_dir_name} function is basically equivalent to @w{@code{getcwd (NULL, 0)}}. The only difference is that the value of @@ -145,6 +170,7 @@ This function is a GNU extension. @comment unistd.h @comment POSIX.1 @deftypefun int chdir (const char *@var{filename}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This function is used to set the process's working directory to @var{filename}. @@ -158,6 +184,7 @@ file @var{filename} is not a directory. @comment unistd.h @comment XPG @deftypefun int fchdir (int @var{filedes}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This function is used to set the process's working directory to directory associated with the file descriptor @var{filedes}. @@ -294,12 +321,14 @@ values and @code{st_mode} values: @comment dirent.h @comment BSD @deftypefun int IFTODT (mode_t @var{mode}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This returns the @code{d_type} value corresponding to @var{mode}. @end deftypefun @comment dirent.h @comment BSD @deftypefun mode_t DTTOIF (int @var{dtype}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This returns the @code{st_mode} value corresponding to @var{dtype}. @end deftypefun @end table @@ -342,6 +371,9 @@ the following functions. @comment dirent.h @comment POSIX.1 @deftypefun {DIR *} opendir (const char *@var{dirname}) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{}}} +@c Besides the safe syscall, we have to allocate the DIR object with +@c __alloc_dir, that calls malloc. The @code{opendir} function opens and returns a directory stream for reading the directory whose file name is @var{dirname}. The stream has type @code{DIR *}. @@ -381,6 +413,8 @@ alternative interface can be used. @comment dirent.h @comment GNU @deftypefun {DIR *} fdopendir (int @var{fd}) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{}}} +@c The DIR object is allocated with __alloc_dir, that calls malloc. The @code{fdopendir} function works just like @code{opendir} but instead of taking a file name and opening a file descriptor for the directory the caller is required to provide a file descriptor. This @@ -425,6 +459,7 @@ access. @comment dirent.h @comment GNU @deftypefun int dirfd (DIR *@var{dirstream}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The function @code{dirfd} returns the file descriptor associated with the directory stream @var{dirstream}. This descriptor can be used until the directory is closed with @code{closedir}. If the directory stream @@ -443,6 +478,12 @@ symbols are declared in the header file @file{dirent.h}. @comment dirent.h @comment POSIX.1 @deftypefun {struct dirent *} readdir (DIR *@var{dirstream}) +@safety{@prelim{}@mtunsafe{@mtasurace{:dirstream}}@asunsafe{@asulock{}}@acunsafe{@aculock{}}} +@c This function holds dirstream's non-recursive lock, which brings +@c about the usual issues with locks and async signals and cancellation, +@c but the lock taking is not enough to make the returned value safe to +@c use, since it points to a stream's internal buffer that can be +@c overwritten by subsequent calls or even released by closedir. This function reads the next entry from the directory. It normally returns a pointer to a structure containing information about the file. This structure is associated with the @var{dirstream} handle @@ -478,6 +519,7 @@ locking if multiple threads access the same @var{dirstream}. @comment dirent.h @comment GNU @deftypefun int readdir_r (DIR *@var{dirstream}, struct dirent *@var{entry}, struct dirent **@var{result}) +@safety{@prelim{}@mtsafe{}@asunsafe{@asulock{}}@acunsafe{@aculock{}}} This function is a version of @code{readdir} which performs internal locking. Like @code{readdir} it returns the next entry from the directory. To prevent conflicts between simultaneously running @@ -549,6 +591,7 @@ of the last two functions. @comment dirent.h @comment LFS @deftypefun {struct dirent64 *} readdir64 (DIR *@var{dirstream}) +@safety{@prelim{}@mtunsafe{@mtasurace{:dirstream}}@asunsafe{@asulock{}}@acunsafe{@aculock{}}} The @code{readdir64} function is just like the @code{readdir} function except that it returns a pointer to a record of type @code{struct dirent64}. Some of the members of this data type (notably @code{d_ino}) @@ -560,6 +603,7 @@ In all other aspects this function is equivalent to @code{readdir}. @comment dirent.h @comment LFS @deftypefun int readdir64_r (DIR *@var{dirstream}, struct dirent64 *@var{entry}, struct dirent64 **@var{result}) +@safety{@prelim{}@mtsafe{}@asunsafe{@asulock{}}@acunsafe{@aculock{}}} The @code{readdir64_r} function is equivalent to the @code{readdir_r} function except that it takes parameters of base type @code{struct dirent64} instead of @code{struct dirent} in the second and third @@ -570,6 +614,10 @@ position. The same precautions mentioned in the documentation of @comment dirent.h @comment POSIX.1 @deftypefun int closedir (DIR *@var{dirstream}) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{/hurd}}@acunsafe{@acsmem{} @acsfd{} @aculock{/hurd}}} +@c No synchronization in the posix implementation, only in the hurd +@c one. This is regarded as safe because it is undefined behavior if +@c other threads could still be using the dir stream while it's closed. This function closes the directory stream @var{dirstream}. It returns @code{0} on success and @code{-1} on failure. @@ -609,6 +657,7 @@ declared in the header file @file{dirent.h}. @comment dirent.h @comment POSIX.1 @deftypefun void rewinddir (DIR *@var{dirstream}) +@safety{@prelim{}@mtsafe{}@asunsafe{@asulock{}}@acunsafe{@aculock{}}} The @code{rewinddir} function is used to reinitialize the directory stream @var{dirstream}, so that if you call @code{readdir} it returns information about the first entry in the directory again. This @@ -622,6 +671,10 @@ added or removed since you last called @code{opendir} or @comment dirent.h @comment BSD @deftypefun {long int} telldir (DIR *@var{dirstream}) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{/bsd} @asulock{/bsd}}@acunsafe{@acsmem{/bsd} @aculock{/bsd}}} +@c The implementation is safe on most platforms, but on BSD it uses +@c cookies, buckets and records, and the global array of pointers to +@c dynamically allocated records is guarded by a non-recursive lock. The @code{telldir} function returns the file position of the directory stream @var{dirstream}. You can use this value with @code{seekdir} to restore the directory stream to that position. @@ -630,6 +683,10 @@ restore the directory stream to that position. @comment dirent.h @comment BSD @deftypefun void seekdir (DIR *@var{dirstream}, long int @var{pos}) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{/bsd} @asulock{/bsd}}@acunsafe{@acsmem{/bsd} @aculock{/bsd}}} +@c The implementation is safe on most platforms, but on BSD it uses +@c cookies, buckets and records, and the global array of pointers to +@c dynamically allocated records is guarded by a non-recursive lock. The @code{seekdir} function sets the file position of the directory stream @var{dirstream} to @var{pos}. The value @var{pos} must be the result of a previous call to @code{telldir} on this particular stream; @@ -649,6 +706,19 @@ the result. @comment dirent.h @comment BSD/SVID @deftypefun int scandir (const char *@var{dir}, struct dirent ***@var{namelist}, int (*@var{selector}) (const struct dirent *), int (*@var{cmp}) (const struct dirent **, const struct dirent **)) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{}}} +@c The scandir function calls __opendirat, __readdir, and __closedir to +@c go over the named dir; malloc and realloc to allocate the namelist +@c and copies of each selected dirent, besides the selector, if given, +@c and qsort and the cmp functions if the latter is given. In spite of +@c the cleanup handler that releases memory and the file descriptor in +@c case of synchronous cancellation, an asynchronous cancellation may +@c still leak memory and a file descriptor. Although readdir is unsafe +@c in general, the use of an internal dir stream for sequential scanning +@c of the directory with copying of dirents before subsequent calls +@c makes the use safe, and the fact that the dir stream is private to +@c each scandir call does away with the lock issues in readdir and +@c closedir. The @code{scandir} function scans the contents of the directory selected by @var{dir}. The result in *@var{namelist} is an array of pointers to @@ -679,6 +749,8 @@ are very helpful for this purpose. @comment dirent.h @comment BSD/SVID @deftypefun int alphasort (const void *@var{a}, const void *@var{b}) +@safety{@prelim{}@mtsafe{@mtslocale{}}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{}}} +@c Calls strcoll. The @code{alphasort} function behaves like the @code{strcoll} function (@pxref{String/Array Comparison}). The difference is that the arguments are not string pointers but instead they are of type @@ -691,6 +763,9 @@ than zero depending on the order of the two entries @var{a} and @var{b}. @comment dirent.h @comment GNU @deftypefun int versionsort (const void *@var{a}, const void *@var{b}) +@safety{@prelim{}@mtsafe{@mtslocale{}}@assafe{}@acsafe{}} +@c Calls strverscmp, which will accesses the locale object multiple +@c times. The @code{versionsort} function is like @code{alphasort} except that it uses the @code{strverscmp} function internally. @end deftypefun @@ -703,6 +778,8 @@ dirent64}}. To use this we need a new function. @comment dirent.h @comment GNU @deftypefun int scandir64 (const char *@var{dir}, struct dirent64 ***@var{namelist}, int (*@var{selector}) (const struct dirent64 *), int (*@var{cmp}) (const struct dirent64 **, const struct dirent64 **)) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{}}} +@c See scandir. The @code{scandir64} function works like the @code{scandir} function except that the directory entries it returns are described by elements of type @w{@code{struct dirent64}}. The function pointed to by @@ -721,6 +798,8 @@ argument. Instead we provide the two replacement functions below. @comment dirent.h @comment GNU @deftypefun int alphasort64 (const void *@var{a}, const void *@var{b}) +@safety{@prelim{}@mtsafe{@mtslocale{}}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{}}} +@c See alphasort. The @code{alphasort64} function behaves like the @code{strcoll} function (@pxref{String/Array Comparison}). The difference is that the arguments are not string pointers but instead they are of type @@ -733,6 +812,8 @@ than zero depending on the order of the two entries @var{a} and @var{b}. @comment dirent.h @comment GNU @deftypefun int versionsort64 (const void *@var{a}, const void *@var{b}) +@safety{@prelim{}@mtsafe{@mtslocale{}}@assafe{}@acsafe{}} +@c See versionsort. The @code{versionsort64} function is like @code{alphasort64}, excepted that it uses the @code{strverscmp} function internally. @end deftypefun @@ -913,6 +994,8 @@ file was passed). @comment ftw.h @comment SVID @deftypefun int ftw (const char *@var{filename}, __ftw_func_t @var{func}, int @var{descriptors}) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{}}} +@c see nftw for safety details The @code{ftw} function calls the callback function given in the parameter @var{func} for every item which is found in the directory specified by @var{filename} and all directories below. The function @@ -963,6 +1046,7 @@ interface transparently replaces the old interface. @comment ftw.h @comment Unix98 @deftypefun int ftw64 (const char *@var{filename}, __ftw64_func_t @var{func}, int @var{descriptors}) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{}}} This function is similar to @code{ftw} but it can work on filesystems with large files. File information is reported using a variable of type @code{struct stat64} which is passed by reference to the callback @@ -976,6 +1060,17 @@ transparently replaces the old implementation. @comment ftw.h @comment XPG4.2 @deftypefun int nftw (const char *@var{filename}, __nftw_func_t @var{func}, int @var{descriptors}, int @var{flag}) +@safety{@prelim{}@mtsafe{@mtasscwd{}}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{} @acscwd{}}} +@c ftw_startup calls alloca, malloc, free, xstat/lxstat, tdestroy, and ftw_dir +@c if FTW_CHDIR, call open, and fchdir, or chdir and getcwd +@c ftw_dir calls open_dir_stream, readdir64, process_entry, closedir +@c if FTW_CHDIR, also calls fchdir +@c open_dir_stream calls malloc, realloc, readdir64, free, closedir, +@c then openat64_not_cancel_3 and fdopendir or opendir, then dirfd. +@c process_entry may cal realloc, fxstatat/lxstat/xstat, ftw_dir, and +@c find_object (tsearch) and add_object (tfind). +@c Since each invocation of *ftw uses its own private search tree, none +@c of the search tree concurrency issues apply. The @code{nftw} function works like the @code{ftw} functions. They call the callback function @var{func} for all items found in the directory @var{filename} and below. At most @var{descriptors} file descriptors @@ -1036,6 +1131,7 @@ interface transparently replaces the old interface. @comment ftw.h @comment Unix98 @deftypefun int nftw64 (const char *@var{filename}, __nftw64_func_t @var{func}, int @var{descriptors}, int @var{flag}) +@safety{@prelim{}@mtsafe{@mtasscwd{}}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{} @acscwd{}}} This function is similar to @code{nftw} but it can work on filesystems with large files. File information is reported using a variable of type @code{struct stat64} which is passed by reference to the callback @@ -1079,6 +1175,7 @@ file @file{unistd.h}. @comment unistd.h @comment POSIX.1 @deftypefun int link (const char *@var{oldname}, const char *@var{newname}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The @code{link} function makes a new link to the existing file named by @var{oldname}, under the new name @var{newname}. @@ -1186,6 +1283,7 @@ Prototypes for most of the functions listed in this section are in @comment unistd.h @comment BSD @deftypefun int symlink (const char *@var{oldname}, const char *@var{newname}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The @code{symlink} function makes a symbolic link to @var{oldname} named @var{newname}. @@ -1223,6 +1321,7 @@ exceeded. @comment unistd.h @comment BSD @deftypefun ssize_t readlink (const char *@var{filename}, char *@var{buffer}, size_t @var{size}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The @code{readlink} function gets the value of the symbolic link @var{filename}. The file name that the link points to is copied into @var{buffer}. This file name string is @emph{not} null-terminated; @@ -1282,6 +1381,8 @@ names can refer to the same inode. @comment stdlib.h @comment GNU @deftypefun {char *} canonicalize_file_name (const char *@var{name}) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{}}} +@c Calls realpath. The @code{canonicalize_file_name} function returns the absolute name of the file named by @var{name} which contains no @code{.}, @code{..} @@ -1323,6 +1424,8 @@ where the result is placed in. @comment stdlib.h @comment XPG @deftypefun {char *} realpath (const char *restrict @var{name}, char *restrict @var{resolved}) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{} @acsfd{}}} +@c Calls malloc, realloc, getcwd, lxstat64, readlink, alloca. A call to @code{realpath} where the @var{resolved} parameter is @code{NULL} behaves exactly like @code{canonicalize_file_name}. The @@ -1362,6 +1465,7 @@ then the file is deleted as well. If the file has other remaining names @comment unistd.h @comment POSIX.1 @deftypefun int unlink (const char *@var{filename}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The @code{unlink} function deletes the file name @var{filename}. If this is a file's sole name, the file itself is also deleted. (Actually, if any process has the file open when this happens, deletion is @@ -1404,6 +1508,7 @@ file system and can't be modified. @comment unistd.h @comment POSIX.1 @deftypefun int rmdir (const char *@var{filename}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} @cindex directories, deleting @cindex deleting a directory The @code{rmdir} function deletes a directory. The directory must be @@ -1431,6 +1536,8 @@ The prototype for this function is declared in the header file @comment stdio.h @comment ISO @deftypefun int remove (const char *@var{filename}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c Calls unlink and rmdir. This is the @w{ISO C} function to remove a file. It works like @code{unlink} for files and like @code{rmdir} for directories. @code{remove} is declared in @file{stdio.h}. @@ -1446,6 +1553,10 @@ The @code{rename} function is used to change a file's name. @comment stdio.h @comment ISO @deftypefun int rename (const char *@var{oldname}, const char *@var{newname}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c In the absence of a rename syscall, there's an emulation with link +@c and unlink, but it's racy, even more so if newname exists and is +@c unlinked first. The @code{rename} function renames the file @var{oldname} to @var{newname}. The file formerly accessible under the name @var{oldname} is afterwards accessible as @var{newname} instead. (If @@ -1541,6 +1652,7 @@ a shell command @code{mkdir} which does the same thing.) @comment sys/stat.h @comment POSIX.1 @deftypefun int mkdir (const char *@var{filename}, mode_t @var{mode}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The @code{mkdir} function creates a new, empty directory with name @var{filename}. @@ -1882,6 +1994,7 @@ header file @file{sys/stat.h}. @comment sys/stat.h @comment POSIX.1 @deftypefun int stat (const char *@var{filename}, struct stat *@var{buf}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The @code{stat} function returns information about the attributes of the file named by @w{@var{filename}} in the structure pointed to by @var{buf}. @@ -1908,6 +2021,7 @@ replaces the normal implementation. @comment sys/stat.h @comment Unix98 @deftypefun int stat64 (const char *@var{filename}, struct stat64 *@var{buf}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This function is similar to @code{stat} but it is also able to work on files larger than @math{2^31} bytes on 32-bit systems. To be able to do this the result is stored in a variable of type @code{struct stat64} to @@ -1921,6 +2035,7 @@ replaces the interface for small files on 32-bit machines. @comment sys/stat.h @comment POSIX.1 @deftypefun int fstat (int @var{filedes}, struct stat *@var{buf}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The @code{fstat} function is like @code{stat}, except that it takes an open file descriptor as an argument instead of a file name. @xref{Low-Level I/O}. @@ -1942,6 +2057,7 @@ replaces the normal implementation. @comment sys/stat.h @comment Unix98 @deftypefun int fstat64 (int @var{filedes}, struct stat64 *@var{buf}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This function is similar to @code{fstat} but is able to work on large files on 32-bit platforms. For large files the file descriptor @var{filedes} should be obtained by @code{open64} or @code{creat64}. @@ -1953,9 +2069,16 @@ function is available under the name @code{fstat} and so transparently replaces the interface for small files on 32-bit machines. @end deftypefun +@c fstatat will call alloca and snprintf if the syscall is not +@c available. +@c @safety{@mtsafe{}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{}}} + @comment sys/stat.h @comment BSD @deftypefun int lstat (const char *@var{filename}, struct stat *@var{buf}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c Direct system call through lxstat, sometimes with an xstat conv call +@c afterwards. The @code{lstat} function is like @code{stat}, except that it does not follow symbolic links. If @var{filename} is the name of a symbolic link, @code{lstat} returns information about the link itself; otherwise @@ -1969,6 +2092,9 @@ replaces the normal implementation. @comment sys/stat.h @comment Unix98 @deftypefun int lstat64 (const char *@var{filename}, struct stat64 *@var{buf}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c Direct system call through lxstat64, sometimes with an xstat conv +@c call afterwards. This function is similar to @code{lstat} but it is also able to work on files larger than @math{2^31} bytes on 32-bit systems. To be able to do this the result is stored in a variable of type @code{struct stat64} to @@ -2007,12 +2133,14 @@ that file: @comment sys/stat.h @comment POSIX @deftypefn Macro int S_ISDIR (mode_t @var{m}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This macro returns non-zero if the file is a directory. @end deftypefn @comment sys/stat.h @comment POSIX @deftypefn Macro int S_ISCHR (mode_t @var{m}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This macro returns non-zero if the file is a character special file (a device like a terminal). @end deftypefn @@ -2020,6 +2148,7 @@ device like a terminal). @comment sys/stat.h @comment POSIX @deftypefn Macro int S_ISBLK (mode_t @var{m}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This macro returns non-zero if the file is a block special file (a device like a disk). @end deftypefn @@ -2027,12 +2156,14 @@ like a disk). @comment sys/stat.h @comment POSIX @deftypefn Macro int S_ISREG (mode_t @var{m}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This macro returns non-zero if the file is a regular file. @end deftypefn @comment sys/stat.h @comment POSIX @deftypefn Macro int S_ISFIFO (mode_t @var{m}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This macro returns non-zero if the file is a FIFO special file, or a pipe. @xref{Pipes and FIFOs}. @end deftypefn @@ -2040,6 +2171,7 @@ pipe. @xref{Pipes and FIFOs}. @comment sys/stat.h @comment GNU @deftypefn Macro int S_ISLNK (mode_t @var{m}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This macro returns non-zero if the file is a symbolic link. @xref{Symbolic Links}. @end deftypefn @@ -2047,6 +2179,7 @@ This macro returns non-zero if the file is a symbolic link. @comment sys/stat.h @comment GNU @deftypefn Macro int S_ISSOCK (mode_t @var{m}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This macro returns non-zero if the file is a socket. @xref{Sockets}. @end deftypefn @@ -2129,6 +2262,7 @@ the whole @code{struct stat} structure. @comment sys/stat.h @comment POSIX @deftypefn Macro int S_TYPEISMQ (struct stat *@var{s}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} If the system implement POSIX message queues as distinct objects and the file is a message queue object, this macro returns a non-zero value. In all other cases the result is zero. @@ -2137,6 +2271,7 @@ In all other cases the result is zero. @comment sys/stat.h @comment POSIX @deftypefn Macro int S_TYPEISSEM (struct stat *@var{s}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} If the system implement POSIX semaphores as distinct objects and the file is a semaphore object, this macro returns a non-zero value. In all other cases the result is zero. @@ -2145,6 +2280,7 @@ In all other cases the result is zero. @comment sys/stat.h @comment POSIX @deftypefn Macro int S_TYPEISSHM (struct stat *@var{s}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} If the system implement POSIX shared memory objects as distinct objects and the file is a shared memory object, this macro returns a non-zero value. In all other cases the result is zero. @@ -2189,6 +2325,7 @@ The prototype for this function is declared in @file{unistd.h}. @comment unistd.h @comment POSIX.1 @deftypefun int chown (const char *@var{filename}, uid_t @var{owner}, gid_t @var{group}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The @code{chown} function changes the owner of the file @var{filename} to @var{owner}, and its group owner to @var{group}. @@ -2223,6 +2360,7 @@ The file is on a read-only file system. @comment unistd.h @comment BSD @deftypefun int fchown (int @var{filedes}, uid_t @var{owner}, gid_t @var{group}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This is like @code{chown}, except that it changes the owner of the open file with descriptor @var{filedes}. @@ -2502,6 +2640,7 @@ The functions in this section are declared in @file{sys/stat.h}. @comment sys/stat.h @comment POSIX.1 @deftypefun mode_t umask (mode_t @var{mask}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The @code{umask} function sets the file creation mask of the current process to @var{mask}, and returns the previous value of the file creation mask. @@ -2527,6 +2666,7 @@ you just want to read the mask value, because it is reentrant. @comment sys/stat.h @comment GNU @deftypefun mode_t getumask (void) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} Return the current value of the file creation mask for the current process. This function is a GNU extension and is only available on @gnuhurdsystems{}. @@ -2535,6 +2675,7 @@ process. This function is a GNU extension and is only available on @comment sys/stat.h @comment POSIX.1 @deftypefun int chmod (const char *@var{filename}, mode_t @var{mode}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The @code{chmod} function sets the access permission bits for the file named by @var{filename} to @var{mode}. @@ -2575,6 +2716,7 @@ for full details on the sticky bit. @comment sys/stat.h @comment BSD @deftypefun int fchmod (int @var{filedes}, mode_t @var{mode}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This is like @code{chmod}, except that it changes the permissions of the currently open file given by @var{filedes}. @@ -2645,6 +2787,7 @@ The symbols in this section are declared in @file{unistd.h}. @comment unistd.h @comment POSIX.1 @deftypefun int access (const char *@var{filename}, int @var{how}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The @code{access} function checks to see whether the file named by @var{filename} can be accessed in the way specified by the @var{how} argument. The @var{how} argument either can be the bitwise OR of the @@ -2765,6 +2908,9 @@ This is the modification time for the file. @comment utime.h @comment POSIX.1 @deftypefun int utime (const char *@var{filename}, const struct utimbuf *@var{times}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c In the absence of a utime syscall, it non-atomically converts times +@c to a struct timeval and calls utimes. This function is used to modify the file times associated with the file named @var{filename}. @@ -2816,6 +2962,10 @@ in the header file @file{sys/time.h}. @comment sys/time.h @comment BSD @deftypefun int utimes (const char *@var{filename}, const struct timeval @var{tvp}@t{[2]}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c In the absence of a utimes syscall, it non-atomically converts tvp +@c to struct timespec array and issues a utimensat syscall, or to +@c struct utimbuf and calls utime. This function sets the file access and modification times of the file @var{filename}. The new file access time is specified by @code{@var{tvp}[0]}, and the new modification time by @@ -2830,6 +2980,9 @@ function. @comment sys/time.h @comment BSD @deftypefun int lutimes (const char *@var{filename}, const struct timeval @var{tvp}@t{[2]}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c Since there's no lutimes syscall, it non-atomically converts tvp +@c to struct timespec array and issues a utimensat syscall. This function is like @code{utimes}, except that it does not follow symbolic links. If @var{filename} is the name of a symbolic link, @code{lutimes} sets the file access and modification times of the @@ -2846,6 +2999,10 @@ function. @comment sys/time.h @comment BSD @deftypefun int futimes (int @var{fd}, const struct timeval @var{tvp}@t{[2]}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c Since there's no futimes syscall, it non-atomically converts tvp +@c to struct timespec array and issues a utimensat syscall, falling back +@c to utimes on a /proc/self/fd symlink. This function is like @code{utimes}, except that it takes an open file descriptor as an argument instead of a file name. @xref{Low-Level I/O}. This function comes from FreeBSD, and is not available on all @@ -2900,6 +3057,8 @@ succeed, without actually accomplishing anything. @comment unistd.h @comment X/Open @deftypefun int truncate (const char *@var{filename}, off_t @var{length}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c In the absence of a truncate syscall, we use open and ftruncate. The @code{truncate} function changes the size of @var{filename} to @var{length}. If @var{length} is shorter than the previous length, data @@ -2944,6 +3103,8 @@ The operation was interrupted by a signal. @comment unistd.h @comment Unix98 @deftypefun int truncate64 (const char *@var{name}, off64_t @var{length}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c In the absence of a syscall, try truncate if length fits. This function is similar to the @code{truncate} function. The difference is that the @var{length} argument is 64 bits wide even on 32 bits machines, which allows the handling of files with sizes up to @@ -2957,6 +3118,7 @@ When the source file is compiled with @code{_FILE_OFFSET_BITS == 64} on a @comment unistd.h @comment POSIX @deftypefun int ftruncate (int @var{fd}, off_t @var{length}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This is like @code{truncate}, but it works on a file descriptor @var{fd} for an opened file instead of a file name to identify the object. The @@ -3021,6 +3183,8 @@ The operation was interrupted by a signal. @comment unistd.h @comment Unix98 @deftypefun int ftruncate64 (int @var{id}, off64_t @var{length}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c In the absence of a syscall, try ftruncate if length fits. This function is similar to the @code{ftruncate} function. The difference is that the @var{length} argument is 64 bits wide even on 32 bits machines which allows the handling of files with sizes up to @@ -3083,6 +3247,10 @@ The prototype for @code{mknod} is declared in @file{sys/stat.h}. @comment sys/stat.h @comment BSD @deftypefun int mknod (const char *@var{filename}, mode_t @var{mode}, dev_t @var{dev}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c Instead of issuing the syscall directly, we go through xmknod. +@c Although the internal xmknod takes a dev_t*, that could lead to +@c @mtsrace races, it's passed a pointer to mknod's dev. The @code{mknod} function makes a special file with name @var{filename}. The @var{mode} specifies the mode of the file, and may include the various special file bits, such as @code{S_IFCHR} (for a character special file) @@ -3134,6 +3302,20 @@ These facilities are declared in the header file @file{stdio.h}. @comment stdio.h @comment ISO @deftypefun {FILE *} tmpfile (void) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@acsmem{} @acsfd{} @aculock{}}} +@c The unsafety issues are those of fdopen, plus @acsfd because of the +@c open. +@c __path_search (internal buf, !dir, const pfx, !try_tmpdir) ok +@c libc_secure_genenv only if try_tmpdir +@c xstat64, strlen, strcmp, sprintf +@c __gen_tempname (internal tmpl, __GT_FILE) ok +@c strlen, memcmp, getpid, open/mkdir/lxstat64 ok +@c HP_TIMING_NOW if available ok +@c gettimeofday (!tz) first time, or every time if no HP_TIMING_NOW ok +@c static value is used and modified without synchronization ok +@c but the use is as a source of non-cryptographic randomness +@c with retries in case of collision, so it should be safe +@c unlink, fdopen This function creates a temporary binary file for update mode, as if by calling @code{fopen} with mode @code{"wb+"}. The file is deleted automatically when it is closed or when the program terminates. (On @@ -3150,6 +3332,7 @@ interface transparently replaces the old interface. @comment stdio.h @comment Unix98 @deftypefun {FILE *} tmpfile64 (void) +@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@acsmem{} @acsfd{} @aculock{}}} This function is similar to @code{tmpfile}, but the stream it returns a pointer to was opened using @code{tmpfile64}. Therefore this stream can be used for files larger than @math{2^31} bytes on 32-bit machines. @@ -3165,6 +3348,11 @@ and so transparently replaces the old interface. @comment stdio.h @comment ISO @deftypefun {char *} tmpnam (char *@var{result}) +@safety{@prelim{}@mtunsafe{@mtasurace{:tmpnam/!result}}@asunsafe{}@acsafe{}} +@c The passed-in buffer should not be modified concurrently with the +@c call. +@c __path_search (static or passed-in buf, !dir, !pfx, !try_tmpdir) ok +@c __gen_tempname (internal tmpl, __GT_NOCREATE) ok This function constructs and returns a valid file name that does not refer to any existing file. If the @var{result} argument is a null pointer, the return value is a pointer to an internal static string, @@ -3189,6 +3377,7 @@ opening the file you should use the @code{O_EXCL} flag. Using @comment stdio.h @comment GNU @deftypefun {char *} tmpnam_r (char *@var{result}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This function is nearly identical to the @code{tmpnam} function, except that if @var{result} is a null pointer it returns a null pointer. @@ -3225,6 +3414,13 @@ never less than @code{25}. @comment stdio.h @comment SVID @deftypefun {char *} tempnam (const char *@var{dir}, const char *@var{prefix}) +@safety{@prelim{}@mtsafe{@mtsenv{}}@asunsafe{@ascuheap{}}@acunsafe{@acsmem{}}} +@c There's no way (short of being setuid) to avoid getenv("TMPDIR"), +@c even with a non-NULL dir. +@c +@c __path_search (internal buf, dir, pfx, try_tmpdir) unsafe getenv +@c __gen_tempname (internal tmpl, __GT_NOCREATE) ok +@c strdup This function generates a unique temporary file name. If @var{prefix} is not a null pointer, up to five characters of this string are used as a prefix for the file name. The return value is a string newly @@ -3288,6 +3484,8 @@ string. These functions are declared in the header file @file{stdlib.h}. @comment stdlib.h @comment Unix @deftypefun {char *} mktemp (char *@var{template}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c __gen_tempname (caller tmpl, __GT_NOCREATE) ok The @code{mktemp} function generates a unique file name by modifying @var{template} as described above. If successful, it returns @var{template} as modified. If @code{mktemp} cannot find a unique file @@ -3306,6 +3504,8 @@ opening the file you should use the @code{O_EXCL} flag. Using @comment stdlib.h @comment BSD @deftypefun int mkstemp (char *@var{template}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{@acsfd{}}} +@c __gen_tempname (caller tmpl, __GT_FILE) ok The @code{mkstemp} function generates a unique file name just as @code{mktemp} does, but it also opens the file for you with @code{open} (@pxref{Opening and Closing Files}). If successful, it modifies @@ -3328,6 +3528,8 @@ new file and get an error if the file already exists. @comment stdlib.h @comment BSD @deftypefun {char *} mkdtemp (char *@var{template}) +@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} +@c __gen_tempname (caller tmpl, __GT_DIR) ok The @code{mkdtemp} function creates a directory with a unique name. If it succeeds, it overwrites @var{template} with the name of the directory, and returns @var{template}. As with @code{mktemp} and @@ -3349,3 +3551,23 @@ creation always works like @code{open} with @code{O_EXCL}. @xref{Creating Directories}. The @code{mkdtemp} function comes from OpenBSD. + +@c FIXME these are undocumented: +@c faccessat +@c fchmodat +@c fchownat +@c futimesat +@c fstatat (there's a commented-out safety assessment for this one) +@c linkat +@c mkdirat +@c mkfifoat +@c name_to_handle_at +@c openat +@c open_by_handle_at +@c readlinkat +@c renameat +@c scandirat +@c symlinkat +@c unlinkat +@c utimensat +@c mknodat |