* manual/stdio.texi: Document MTASC-safety properties.

1 files changed, 249 insertions, 0 deletions

diff --git a/manual/stdio.texi b/manual/stdio.texi
index 7957a2adfc..1161a9a90a 100644
--- a/manual/stdio.texi
+++ b/manual/stdio.texi
@@ -148,6 +148,8 @@ Everything described in this section is declared in the header file
 @comment stdio.h
 @comment ISO
 @deftypefun {FILE *} fopen (const char *@var{filename}, const char *@var{opentype})
+@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@acsmem{} @acsfd{} @aculock{}}}
+@c fopen may leak the list lock if cancelled within _IO_link_in.
 The @code{fopen} function opens a stream for I/O to the file
 @var{filename}, and returns a pointer to the stream.
 
@@ -265,6 +267,7 @@ Locks}.
 @comment stdio.h
 @comment Unix98
 @deftypefun {FILE *} fopen64 (const char *@var{filename}, const char *@var{opentype})
+@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@acsmem{} @acsfd{} @aculock{}}}
 This function is similar to @code{fopen} but the stream it returns a
 pointer for is opened using @code{open64}.  Therefore this stream can be
 used even on files larger than @math{2^31} bytes on 32 bit machines.
@@ -294,6 +297,16 @@ resource limit; @pxref{Limits on Resources}.
 @comment stdio.h
 @comment ISO
 @deftypefun {FILE *} freopen (const char *@var{filename}, const char *@var{opentype}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @acsfd{}}}
+@c Like most I/O operations, this one is guarded by a recursive lock,
+@c released even upon cancellation, but cancellation may leak file
+@c descriptors and leave the stream in an inconsistent state (e.g.,
+@c still bound to the closed descriptor).  Also, if the stream is
+@c part-way through a significant update (say running freopen) when a
+@c signal handler calls freopen again on the same stream, the result is
+@c likely to be an inconsistent stream, and the possibility of closing
+@c twice file descriptor number that the stream used to use, the second
+@c time when it might have already been reused by another thread.
 This function is like a combination of @code{fclose} and @code{fopen}.
 It first closes the stream referred to by @var{stream}, ignoring any
 errors that are detected in the process.  (Because errors are ignored,
@@ -320,6 +333,7 @@ interface replaces transparently the old interface.
 @comment stdio.h
 @comment Unix98
 @deftypefun {FILE *} freopen64 (const char *@var{filename}, const char *@var{opentype}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @acsfd{}}}
 This function is similar to @code{freopen}.  The only difference is that
 on 32 bit machine the stream returned is able to read beyond the
 @math{2^31} bytes limits imposed by the normal interface.  It should be
@@ -341,6 +355,7 @@ descriptor and these functions are also available in @theglibc{}.
 @comment stdio_ext.h
 @comment GNU
 @deftypefun int __freadable (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
 The @code{__freadable} function determines whether the stream
 @var{stream} was opened to allow reading.  In this case the return value
 is nonzero.  For write-only streams the function returns zero.
@@ -351,6 +366,7 @@ This function is declared in @file{stdio_ext.h}.
 @comment stdio_ext.h
 @comment GNU
 @deftypefun int __fwritable (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
 The @code{__fwritable} function determines whether the stream
 @var{stream} was opened to allow writing.  In this case the return value
 is nonzero.  For read-only streams the function returns zero.
@@ -364,6 +380,7 @@ They provide even finer-grained information.
 @comment stdio_ext.h
 @comment GNU
 @deftypefun int __freading (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
 The @code{__freading} function determines whether the stream
 @var{stream} was last read from or whether it is opened read-only.  In
 this case the return value is nonzero, otherwise it is zero.
@@ -377,6 +394,7 @@ This function is declared in @file{stdio_ext.h}.
 @comment stdio_ext.h
 @comment GNU
 @deftypefun int __fwriting (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
 The @code{__fwriting} function determines whether the stream
 @var{stream} was last written to or whether it is opened write-only.  In
 this case the return value is nonzero, otherwise it is zero.
@@ -396,6 +414,21 @@ cannot perform any additional operations on it.
 @comment stdio.h
 @comment ISO
 @deftypefun int fclose (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@ascuheap{} @asulock{}}@acunsafe{@aculock{} @acsmem{} @acsfd{}}}
+@c After fclose, it is undefined behavior to use the stream it points
+@c to.  Therefore, one must only call fclose when the stream is
+@c otherwise unused.  Concurrent uses started before will complete
+@c successfully because of the lock, which makes it MT-Safe.  Calling it
+@c from a signal handler is perfectly safe if the stream is known to be
+@c no longer used, which is a precondition for fclose to be safe in the
+@c first place; since this is no further requirement, fclose is safe for
+@c use in async signals too.  After calling fclose, you can no longer
+@c use the stream, not even to fclose it again, so its memory and file
+@c descriptor may leak if fclose is canceled before @c releasing them.
+@c That the stream must be unused and it becomes unused after the call
+@c is what would enable fclose to be AS- and AC-Safe while freopen
+@c isn't.  However, because of the possibility of leaving __gconv_lock
+@c taken upon cancellation, AC-Safety is lost.
 This function causes @var{stream} to be closed and the connection to
 the corresponding file to be broken.  Any buffered output is written
 and any buffered input is discarded.  The @code{fclose} function returns
@@ -418,6 +451,12 @@ another function.
 @comment stdio.h
 @comment GNU
 @deftypefun int fcloseall (void)
+@safety{@prelim{}@mtunsafe{@mtasurace{:streams}}@asunsafe{}@acsafe{}}
+@c Like fclose, using any previously-opened streams after fcloseall is
+@c undefined.  However, the implementation of fcloseall isn't equivalent
+@c to calling fclose for all streams: it just flushes and unbuffers all
+@c streams, without any locking.  It's the flushing without locking that
+@c makes it unsafe.
 This function causes all open streams of the process to be closed and
 the connection to corresponding files to be broken.  All buffered data
 is written and any buffered input is discarded.  The @code{fcloseall}
@@ -474,6 +513,9 @@ perform the stream locking in the application code.
 @comment stdio.h
 @comment POSIX
 @deftypefun void flockfile (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@assafe{}@acunsafe{@aculock{}}}
+@c There's no way to tell whether the lock was acquired before or after
+@c cancellation so as to unlock only when appropriate.
 The @code{flockfile} function acquires the internal locking object
 associated with the stream @var{stream}.  This ensures that no other
 thread can explicitly through @code{flockfile}/@code{ftrylockfile} or
@@ -485,6 +527,7 @@ thread will block until the lock is acquired.  An explicit call to
 @comment stdio.h
 @comment POSIX
 @deftypefun int ftrylockfile (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@assafe{}@acunsafe{@aculock{}}}
 The @code{ftrylockfile} function tries to acquire the internal locking
 object associated with the stream @var{stream} just like
 @code{flockfile}.  But unlike @code{flockfile} this function does not
@@ -496,6 +539,7 @@ another thread.
 @comment stdio.h
 @comment POSIX
 @deftypefun void funlockfile (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@assafe{}@acunsafe{@aculock{}}}
 The @code{funlockfile} function releases the internal locking object of
 the stream @var{stream}. The stream must have been locked before by a
 call to @code{flockfile} or a successful call of @code{ftrylockfile}.
@@ -621,6 +665,15 @@ was introduced in Solaris and is available in @theglibc{} as well.
 @comment stdio_ext.h
 @comment GNU
 @deftypefun int __fsetlocking (FILE *@var{stream}, int @var{type})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asulock{}}@acsafe{}}
+@c Changing the implicit-locking status of a stream while it's in use by
+@c another thread may cause a lock to be implicitly acquired and not
+@c released, or vice-versa.  This function should probably hold the lock
+@c while changing this setting, to make sure we don't change it while
+@c there are any concurrent uses.  Meanwhile, callers should acquire the
+@c lock themselves to be safe, and even concurrent uses with external
+@c locking will be fine, as long as functions that require external
+@c locking are not called without holding locks.
 
 The @code{__fsetlocking} function can be used to select whether the
 stream operations will implicitly acquire the locking object of the
@@ -725,6 +778,10 @@ will simply be strange or the application will simply crash.  The
 @comment wchar.h
 @comment ISO
 @deftypefun int fwide (FILE *@var{stream}, int @var{mode})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{}}}
+@c Querying is always safe, but changing the stream when it's in use
+@c upthread may be problematic.  Like most lock-acquiring functions,
+@c this one may leak the lock if canceled.
 
 The @code{fwide} function can be used to set and query the state of the
 orientation of the stream @var{stream}.  If the @var{mode} parameter has
@@ -811,6 +868,16 @@ These narrow streams functions are declared in the header file
 @comment stdio.h
 @comment ISO
 @deftypefun int fputc (int @var{c}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @aculock{}}}
+@c If the stream is in use when interrupted by a signal, the recursive
+@c lock won't help ensure the stream is consistent; indeed, if fputc
+@c gets a signal precisely before the post-incremented _IO_write_ptr
+@c value is stored, we may overwrite the interrupted write.  Conversely,
+@c depending on compiler optimizations, the incremented _IO_write_ptr
+@c may be stored before the character is stored in the buffer,
+@c corrupting the stream if async cancel hits between the two stores.
+@c There may be other reasons for AS- and AC-unsafety in the overflow
+@c cases.
 The @code{fputc} function converts the character @var{c} to type
 @code{unsigned char}, and writes it to the stream @var{stream}.
 @code{EOF} is returned if a write error occurs; otherwise the
@@ -820,6 +887,7 @@ character @var{c} is returned.
 @comment wchar.h
 @comment ISO
 @deftypefun wint_t fputwc (wchar_t @var{wc}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @aculock{}}}
 The @code{fputwc} function writes the wide character @var{wc} to the
 stream @var{stream}.  @code{WEOF} is returned if a write error occurs;
 otherwise the character @var{wc} is returned.
@@ -828,6 +896,10 @@ otherwise the character @var{wc} is returned.
 @comment stdio.h
 @comment POSIX
 @deftypefun int fputc_unlocked (int @var{c}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
+@c The unlocked functions can't possibly satisfy the MT-Safety
+@c requirements on their own, because they require external locking for
+@c safety.
 The @code{fputc_unlocked} function is equivalent to the @code{fputc}
 function except that it does not implicitly lock the stream.
 @end deftypefun
@@ -835,6 +907,7 @@ function except that it does not implicitly lock the stream.
 @comment wchar.h
 @comment POSIX
 @deftypefun wint_t fputwc_unlocked (wchar_t @var{wc}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{fputwc_unlocked} function is equivalent to the @code{fputwc}
 function except that it does not implicitly lock the stream.
 
@@ -844,6 +917,7 @@ This function is a GNU extension.
 @comment stdio.h
 @comment ISO
 @deftypefun int putc (int @var{c}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @aculock{}}}
 This is just like @code{fputc}, except that most systems implement it as
 a macro, making it faster.  One consequence is that it may evaluate the
 @var{stream} argument more than once, which is an exception to the
@@ -854,6 +928,7 @@ use for writing a single character.
 @comment wchar.h
 @comment ISO
 @deftypefun wint_t putwc (wchar_t @var{wc}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @aculock{}}}
 This is just like @code{fputwc}, except that it can be implement as
 a macro, making it faster.  One consequence is that it may evaluate the
 @var{stream} argument more than once, which is an exception to the
@@ -864,6 +939,7 @@ use for writing a single wide character.
 @comment stdio.h
 @comment POSIX
 @deftypefun int putc_unlocked (int @var{c}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{putc_unlocked} function is equivalent to the @code{putc}
 function except that it does not implicitly lock the stream.
 @end deftypefun
@@ -871,6 +947,7 @@ function except that it does not implicitly lock the stream.
 @comment wchar.h
 @comment GNU
 @deftypefun wint_t putwc_unlocked (wchar_t @var{wc}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{putwc_unlocked} function is equivalent to the @code{putwc}
 function except that it does not implicitly lock the stream.
 
@@ -880,6 +957,7 @@ This function is a GNU extension.
 @comment stdio.h
 @comment ISO
 @deftypefun int putchar (int @var{c})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @aculock{}}}
 The @code{putchar} function is equivalent to @code{putc} with
 @code{stdout} as the value of the @var{stream} argument.
 @end deftypefun
@@ -887,6 +965,7 @@ The @code{putchar} function is equivalent to @code{putc} with
 @comment wchar.h
 @comment ISO
 @deftypefun wint_t putwchar (wchar_t @var{wc})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @aculock{}}}
 The @code{putwchar} function is equivalent to @code{putwc} with
 @code{stdout} as the value of the @var{stream} argument.
 @end deftypefun
@@ -894,6 +973,7 @@ The @code{putwchar} function is equivalent to @code{putwc} with
 @comment stdio.h
 @comment POSIX
 @deftypefun int putchar_unlocked (int @var{c})
+@safety{@prelim{}@mtunsafe{@mtasurace{:stdout}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{putchar_unlocked} function is equivalent to the @code{putchar}
 function except that it does not implicitly lock the stream.
 @end deftypefun
@@ -901,6 +981,7 @@ function except that it does not implicitly lock the stream.
 @comment wchar.h
 @comment GNU
 @deftypefun wint_t putwchar_unlocked (wchar_t @var{wc})
+@safety{@prelim{}@mtunsafe{@mtasurace{:stdout}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{putwchar_unlocked} function is equivalent to the @code{putwchar}
 function except that it does not implicitly lock the stream.
 
@@ -910,6 +991,7 @@ This function is a GNU extension.
 @comment stdio.h
 @comment ISO
 @deftypefun int fputs (const char *@var{s}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @aculock{}}}
 The function @code{fputs} writes the string @var{s} to the stream
 @var{stream}.  The terminating null character is not written.
 This function does @emph{not} add a newline character, either.
@@ -933,6 +1015,7 @@ outputs the text @samp{Are you hungry?} followed by a newline.
 @comment wchar.h
 @comment ISO
 @deftypefun int fputws (const wchar_t *@var{ws}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{} @aculock{}}}
 The function @code{fputws} writes the wide character string @var{ws} to
 the stream @var{stream}.  The terminating null character is not written.
 This function does @emph{not} add a newline character, either.  It
@@ -945,6 +1028,7 @@ a non-negative value.
 @comment stdio.h
 @comment GNU
 @deftypefun int fputs_unlocked (const char *@var{s}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{fputs_unlocked} function is equivalent to the @code{fputs}
 function except that it does not implicitly lock the stream.
 
@@ -954,6 +1038,7 @@ This function is a GNU extension.
 @comment wchar.h
 @comment GNU
 @deftypefun int fputws_unlocked (const wchar_t *@var{ws}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{fputws_unlocked} function is equivalent to the @code{fputws}
 function except that it does not implicitly lock the stream.
 
@@ -963,6 +1048,7 @@ This function is a GNU extension.
 @comment stdio.h
 @comment ISO
 @deftypefun int puts (const char *@var{s})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 The @code{puts} function writes the string @var{s} to the stream
 @code{stdout} followed by a newline.  The terminating null character of
 the string is not written.  (Note that @code{fputs} does @emph{not}
@@ -982,6 +1068,7 @@ outputs the text @samp{This is a message.} followed by a newline.
 @comment stdio.h
 @comment SVID
 @deftypefun int putw (int @var{w}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 This function writes the word @var{w} (that is, an @code{int}) to
 @var{stream}.  It is provided for compatibility with SVID, but we
 recommend you use @code{fwrite} instead (@pxref{Block Input/Output}).
@@ -1014,6 +1101,11 @@ it will fit in a @samp{char} variable without loss of information.
 @comment stdio.h
 @comment ISO
 @deftypefun int fgetc (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
+@c Same caveats as fputc, but instead of losing a write in case of async
+@c signals, we may read the same character more than once, and the
+@c stream may be left in odd states due to cancellation in the underflow
+@c cases.
 This function reads the next character as an @code{unsigned char} from
 the stream @var{stream} and returns its value, converted to an
 @code{int}.  If an end-of-file condition or read error occurs,
@@ -1023,6 +1115,7 @@ the stream @var{stream} and returns its value, converted to an
 @comment wchar.h
 @comment ISO
 @deftypefun wint_t fgetwc (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 This function reads the next wide character from the stream @var{stream}
 and returns its value.  If an end-of-file condition or read error
 occurs, @code{WEOF} is returned instead.
@@ -1031,6 +1124,7 @@ occurs, @code{WEOF} is returned instead.
 @comment stdio.h
 @comment POSIX
 @deftypefun int fgetc_unlocked (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{fgetc_unlocked} function is equivalent to the @code{fgetc}
 function except that it does not implicitly lock the stream.
 @end deftypefun
@@ -1038,6 +1132,7 @@ function except that it does not implicitly lock the stream.
 @comment wchar.h
 @comment GNU
 @deftypefun wint_t fgetwc_unlocked (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{fgetwc_unlocked} function is equivalent to the @code{fgetwc}
 function except that it does not implicitly lock the stream.
 
@@ -1047,6 +1142,7 @@ This function is a GNU extension.
 @comment stdio.h
 @comment ISO
 @deftypefun int getc (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 This is just like @code{fgetc}, except that it is permissible (and
 typical) for it to be implemented as a macro that evaluates the
 @var{stream} argument more than once.  @code{getc} is often highly
@@ -1057,6 +1153,7 @@ character.
 @comment wchar.h
 @comment ISO
 @deftypefun wint_t getwc (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 This is just like @code{fgetwc}, except that it is permissible for it to
 be implemented as a macro that evaluates the @var{stream} argument more
 than once.  @code{getwc} can be highly optimized, so it is usually the
@@ -1066,6 +1163,7 @@ best function to use to read a single wide character.
 @comment stdio.h
 @comment POSIX
 @deftypefun int getc_unlocked (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{getc_unlocked} function is equivalent to the @code{getc}
 function except that it does not implicitly lock the stream.
 @end deftypefun
@@ -1073,6 +1171,7 @@ function except that it does not implicitly lock the stream.
 @comment wchar.h
 @comment GNU
 @deftypefun wint_t getwc_unlocked (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{getwc_unlocked} function is equivalent to the @code{getwc}
 function except that it does not implicitly lock the stream.
 
@@ -1082,6 +1181,7 @@ This function is a GNU extension.
 @comment stdio.h
 @comment ISO
 @deftypefun int getchar (void)
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 The @code{getchar} function is equivalent to @code{getc} with @code{stdin}
 as the value of the @var{stream} argument.
 @end deftypefun
@@ -1089,6 +1189,7 @@ as the value of the @var{stream} argument.
 @comment wchar.h
 @comment ISO
 @deftypefun wint_t getwchar (void)
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 The @code{getwchar} function is equivalent to @code{getwc} with @code{stdin}
 as the value of the @var{stream} argument.
 @end deftypefun
@@ -1096,6 +1197,7 @@ as the value of the @var{stream} argument.
 @comment stdio.h
 @comment POSIX
 @deftypefun int getchar_unlocked (void)
+@safety{@prelim{}@mtunsafe{@mtasurace{:stdin}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{getchar_unlocked} function is equivalent to the @code{getchar}
 function except that it does not implicitly lock the stream.
 @end deftypefun
@@ -1103,6 +1205,7 @@ function except that it does not implicitly lock the stream.
 @comment wchar.h
 @comment GNU
 @deftypefun wint_t getwchar_unlocked (void)
+@safety{@prelim{}@mtunsafe{@mtasurace{:stdin}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{getwchar_unlocked} function is equivalent to the @code{getwchar}
 function except that it does not implicitly lock the stream.
 
@@ -1145,6 +1248,7 @@ y_or_n_p (const char *question)
 @comment stdio.h
 @comment SVID
 @deftypefun int getw (FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 This function reads a word (that is, an @code{int}) from @var{stream}.
 It's provided for compatibility with SVID.  We recommend you use
 @code{fread} instead (@pxref{Block Input/Output}).  Unlike @code{getc},
@@ -1173,6 +1277,12 @@ All these functions are declared in @file{stdio.h}.
 @comment stdio.h
 @comment GNU
 @deftypefun ssize_t getline (char **@var{lineptr}, size_t *@var{n}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{} @ascuheap{}}@acunsafe{@aculock{} @acucorrupt{} @acsmem{}}}
+@c Besides the usual possibility of getting an inconsistent stream in a
+@c signal handler or leaving it inconsistent in case of cancellation,
+@c the possibility of leaving a dangling pointer upon cancellation
+@c between reallocing the buffer at *lineptr and updating the pointer
+@c brings about another case of @acucorrupt.
 This function reads an entire line from @var{stream}, storing the text
 (including the newline and a terminating null character) in a buffer
 and storing the buffer address in @code{*@var{lineptr}}.
@@ -1208,6 +1318,8 @@ If an error occurs or end of file is reached without any bytes read,
 @comment stdio.h
 @comment GNU
 @deftypefun ssize_t getdelim (char **@var{lineptr}, size_t *@var{n}, int @var{delimiter}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{} @ascuheap{}}@acunsafe{@aculock{} @acucorrupt{} @acsmem{}}}
+@c See the getline @acucorrupt note.
 This function is like @code{getline} except that the character which
 tells it to stop reading is not necessarily newline.  The argument
 @var{delimiter} specifies the delimiter character; @code{getdelim} keeps
@@ -1232,6 +1344,7 @@ getline (char **lineptr, size_t *n, FILE *stream)
 @comment stdio.h
 @comment ISO
 @deftypefun {char *} fgets (char *@var{s}, int @var{count}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 The @code{fgets} function reads characters from the stream @var{stream}
 up to and including a newline character and stores them in the string
 @var{s}, adding a null character to mark the end of the string.  You
@@ -1255,6 +1368,7 @@ error message.  We recommend using @code{getline} instead of @code{fgets}.
 @comment wchar.h
 @comment ISO
 @deftypefun {wchar_t *} fgetws (wchar_t *@var{ws}, int @var{count}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 The @code{fgetws} function reads wide characters from the stream
 @var{stream} up to and including a newline character and stores them in
 the string @var{ws}, adding a null wide character to mark the end of the
@@ -1280,6 +1394,7 @@ message.
 @comment stdio.h
 @comment GNU
 @deftypefun {char *} fgets_unlocked (char *@var{s}, int @var{count}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{fgets_unlocked} function is equivalent to the @code{fgets}
 function except that it does not implicitly lock the stream.
 
@@ -1289,6 +1404,7 @@ This function is a GNU extension.
 @comment wchar.h
 @comment GNU
 @deftypefun {wchar_t *} fgetws_unlocked (wchar_t *@var{ws}, int @var{count}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{@mtsrace{:stream}}@asunsafe{@asucorrupt{}}@acunsafe{@acucorrupt{}}}
 The @code{fgetws_unlocked} function is equivalent to the @code{fgetws}
 function except that it does not implicitly lock the stream.
 
@@ -1298,6 +1414,7 @@ This function is a GNU extension.
 @comment stdio.h
 @comment ISO
 @deftypefn {Deprecated function} {char *} gets (char *@var{s})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 The function @code{gets} reads characters from the stream @code{stdin}
 up to the next newline character, and stores them in the string @var{s}.
 The newline character is discarded (note that this differs from the
@@ -1388,6 +1505,7 @@ reverses the action of @code{getc}.
 @comment stdio.h
 @comment ISO
 @deftypefun int ungetc (int @var{c}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 The @code{ungetc} function pushes back the character @var{c} onto the
 input stream @var{stream}.  So the next input from @var{stream} will
 read @var{c} before anything else.
@@ -1425,6 +1543,7 @@ will encounter end of file.
 @comment wchar.h
 @comment ISO
 @deftypefun wint_t ungetwc (wint_t @var{wc}, FILE *@var{stream})
+@safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acunsafe{@aculock{} @acucorrupt{}}}
 The @code{ungetwc} function behaves just like @code{ungetc} just that it
 pushes back