From: Alex Colomar <alx.manpages@gmail.com>
To: Xi Ruoyao <xry111@xry111.site>, libc-alpha@sourceware.org
Cc: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>,
Carlos O'Donell <carlos@redhat.com>
Subject: Re: [PATCH] libio: Add nonnull attribute for most FILE * arguments in stdio.h
Date: Thu, 18 May 2023 20:06:00 +0200 [thread overview]
Message-ID: <d96fd93d-4e49-111b-175d-314ff38cc9f1@gmail.com> (raw)
In-Reply-To: <20230518172511.2130831-1-xry111@xry111.site>
[-- Attachment #1.1: Type: text/plain, Size: 19819 bytes --]
Hi Xi!
On 5/18/23 19:25, Xi Ruoyao via Libc-alpha wrote:
> During the review of a GCC analyzer test case, we found most stdio
> functions accepting a FILE * argument expect it to be nonnull and just
> segfault when the argument is NULL. Add nonnull attribute for them.
>
> setbuf is well defined when __stream is NULL so it's not touched.
>
> For fputs, fgets, fread, fwrite, fprintf, vfprintf, and their unlocked
> version, if __stream is empty but there is nothing to read or write,
> they don't segfault and I'm not sure if the standard allows such a use
> so I left them out.
> ---
> libio/stdio.h | 119 ++++++++++++++++++++++++++------------------------
> 1 file changed, 62 insertions(+), 57 deletions(-)
>
> diff --git a/libio/stdio.h b/libio/stdio.h
> index 4cf9f1c012..ae3d7295d4 100644
> --- a/libio/stdio.h
> +++ b/libio/stdio.h
> @@ -232,7 +232,7 @@ extern char *tempnam (const char *__dir, const char *__pfx)
>
> This function is a possible cancellation point and therefore not
> marked with __THROW. */
> -extern int fflush (FILE *__stream);
> +extern int fflush (FILE *__stream) __nonnull ((1));
flush(NULL) is well defined. It flushes all streams that can be
flushed. This reminds me that I should document that in the SYNOPSIS
section of the manual page; an oversight on my side.
>
> #ifdef __USE_MISC
> /* Faster versions when locking is not required.
> @@ -241,7 +241,7 @@ extern int fflush (FILE *__stream);
> cancellation point. But due to similarity with an POSIX interface
> or due to the implementation it is a cancellation point and
> therefore not marked with __THROW. */
> -extern int fflush_unlocked (FILE *__stream);
> +extern int fflush_unlocked (FILE *__stream) __nonnull ((1));
Without checking, I'll guess that fflush_unlocked(NULL) is also well
defined.
I didn't see any other similar cases, but I may have missed some; I
didn't revise them all thoroughly; please check.
> #endif
>
> #ifdef __USE_GNU
> @@ -278,7 +278,7 @@ extern FILE *__REDIRECT (fopen, (const char *__restrict __filename,
> extern FILE *__REDIRECT (freopen, (const char *__restrict __filename,
> const char *__restrict __modes,
> FILE *__restrict __stream), freopen64)
> - __wur;
> + __wur __nonnull ((3));
> # else
> # define fopen fopen64
> # define freopen freopen64
> @@ -335,16 +335,16 @@ extern void setbuf (FILE *__restrict __stream, char *__restrict __buf) __THROW;
> If BUF is not NULL, use N bytes of it for buffering;
> else allocate an internal buffer N bytes long. */
> extern int setvbuf (FILE *__restrict __stream, char *__restrict __buf,
> - int __modes, size_t __n) __THROW;
> + int __modes, size_t __n) __THROW __nonnull ((1));
>
> #ifdef __USE_MISC
> /* If BUF is NULL, make STREAM unbuffered.
> Else make it use SIZE bytes of BUF for buffering. */
> extern void setbuffer (FILE *__restrict __stream, char *__restrict __buf,
> - size_t __size) __THROW;
> + size_t __size) __THROW __nonnull ((1));
>
> /* Make STREAM line-buffered. */
> -extern void setlinebuf (FILE *__stream) __THROW;
> +extern void setlinebuf (FILE *__stream) __THROW __nonnull ((1));
> #endif
>
>
> @@ -418,7 +418,7 @@ extern int dprintf (int __fd, const char *__restrict __fmt, ...)
> This function is a possible cancellation point and therefore not
> marked with __THROW. */
> extern int fscanf (FILE *__restrict __stream,
> - const char *__restrict __format, ...) __wur;
> + const char *__restrict __format, ...) __wur __nonnull ((1));
> /* Read formatted input from stdin.
>
> This function is a possible cancellation point and therefore not
> @@ -439,7 +439,7 @@ extern int sscanf (const char *__restrict __s,
> # ifdef __REDIRECT
> extern int __REDIRECT (fscanf, (FILE *__restrict __stream,
> const char *__restrict __format, ...),
> - __isoc23_fscanf) __wur;
> + __isoc23_fscanf) __wur __nonnull ((1));
> extern int __REDIRECT (scanf, (const char *__restrict __format, ...),
> __isoc23_scanf) __wur;
> extern int __REDIRECT_NTH (sscanf, (const char *__restrict __s,
> @@ -447,7 +447,7 @@ extern int __REDIRECT_NTH (sscanf, (const char *__restrict __s,
> __isoc23_sscanf);
> # else
> extern int __isoc23_fscanf (FILE *__restrict __stream,
> - const char *__restrict __format, ...) __wur;
> + const char *__restrict __format, ...) __wur __nonnull ((1));
> extern int __isoc23_scanf (const char *__restrict __format, ...) __wur;
> extern int __isoc23_sscanf (const char *__restrict __s,
> const char *__restrict __format, ...) __THROW;
> @@ -459,7 +459,7 @@ extern int __isoc23_sscanf (const char *__restrict __s,
> # ifdef __REDIRECT
> extern int __REDIRECT (fscanf, (FILE *__restrict __stream,
> const char *__restrict __format, ...),
> - __isoc99_fscanf) __wur;
> + __isoc99_fscanf) __wur __nonnull ((1));
> extern int __REDIRECT (scanf, (const char *__restrict __format, ...),
> __isoc99_scanf) __wur;
> extern int __REDIRECT_NTH (sscanf, (const char *__restrict __s,
> @@ -467,7 +467,7 @@ extern int __REDIRECT_NTH (sscanf, (const char *__restrict __s,
> __isoc99_sscanf);
> # else
> extern int __isoc99_fscanf (FILE *__restrict __stream,
> - const char *__restrict __format, ...) __wur;
> + const char *__restrict __format, ...) __wur __nonnull ((1));
> extern int __isoc99_scanf (const char *__restrict __format, ...) __wur;
> extern int __isoc99_sscanf (const char *__restrict __s,
> const char *__restrict __format, ...) __THROW;
> @@ -485,7 +485,7 @@ extern int __isoc99_sscanf (const char *__restrict __s,
> marked with __THROW. */
> extern int vfscanf (FILE *__restrict __s, const char *__restrict __format,
> __gnuc_va_list __arg)
> - __attribute__ ((__format__ (__scanf__, 2, 0))) __wur;
> + __attribute__ ((__format__ (__scanf__, 2, 0))) __wur __nonnull ((1));
>
> /* Read formatted input from stdin into argument list ARG.
>
> @@ -508,7 +508,7 @@ extern int __REDIRECT (vfscanf,
> (FILE *__restrict __s,
> const char *__restrict __format, __gnuc_va_list __arg),
> __isoc23_vfscanf)
> - __attribute__ ((__format__ (__scanf__, 2, 0))) __wur;
> + __attribute__ ((__format__ (__scanf__, 2, 0))) __wur __nonnull ((1));
> extern int __REDIRECT (vscanf, (const char *__restrict __format,
> __gnuc_va_list __arg), __isoc23_vscanf)
> __attribute__ ((__format__ (__scanf__, 1, 0))) __wur;
> @@ -520,7 +520,7 @@ extern int __REDIRECT_NTH (vsscanf,
> # elif !defined __REDIRECT
> extern int __isoc23_vfscanf (FILE *__restrict __s,
> const char *__restrict __format,
> - __gnuc_va_list __arg) __wur;
> + __gnuc_va_list __arg) __wur __nonnull ((1));
> extern int __isoc23_vscanf (const char *__restrict __format,
> __gnuc_va_list __arg) __wur;
> extern int __isoc23_vsscanf (const char *__restrict __s,
> @@ -537,7 +537,7 @@ extern int __REDIRECT (vfscanf,
> (FILE *__restrict __s,
> const char *__restrict __format, __gnuc_va_list __arg),
> __isoc99_vfscanf)
> - __attribute__ ((__format__ (__scanf__, 2, 0))) __wur;
> + __attribute__ ((__format__ (__scanf__, 2, 0))) __wur __nonnull ((1));
> extern int __REDIRECT (vscanf, (const char *__restrict __format,
> __gnuc_va_list __arg), __isoc99_vscanf)
> __attribute__ ((__format__ (__scanf__, 1, 0))) __wur;
> @@ -549,7 +549,7 @@ extern int __REDIRECT_NTH (vsscanf,
> # elif !defined __REDIRECT
> extern int __isoc99_vfscanf (FILE *__restrict __s,
> const char *__restrict __format,
> - __gnuc_va_list __arg) __wur;
> + __gnuc_va_list __arg) __wur __nonnull ((1));
> extern int __isoc99_vscanf (const char *__restrict __format,
> __gnuc_va_list __arg) __wur;
> extern int __isoc99_vsscanf (const char *__restrict __s,
> @@ -568,8 +568,8 @@ extern int __isoc99_vsscanf (const char *__restrict __s,
>
> These functions are possible cancellation points and therefore not
> marked with __THROW. */
> -extern int fgetc (FILE *__stream);
> -extern int getc (FILE *__stream);
> +extern int fgetc (FILE *__stream) __nonnull ((1));
> +extern int getc (FILE *__stream) __nonnull ((1));
>
> /* Read a character from stdin.
>
> @@ -582,7 +582,7 @@ extern int getchar (void);
>
> These functions are possible cancellation points and therefore not
> marked with __THROW. */
> -extern int getc_unlocked (FILE *__stream);
> +extern int getc_unlocked (FILE *__stream) __nonnull ((1));
> extern int getchar_unlocked (void);
> #endif /* Use POSIX. */
>
> @@ -593,7 +593,7 @@ extern int getchar_unlocked (void);
> cancellation point. But due to similarity with an POSIX interface
> or due to the implementation it is a cancellation point and
> therefore not marked with __THROW. */
> -extern int fgetc_unlocked (FILE *__stream);
> +extern int fgetc_unlocked (FILE *__stream) __nonnull ((1));
> #endif /* Use MISC. */
>
>
> @@ -604,8 +604,8 @@ extern int fgetc_unlocked (FILE *__stream);
>
> These functions is a possible cancellation point and therefore not
Aside: here's a typo mixing plural and singular in the sentence (not
part of your commit). I'll prepare a patch for it.
> marked with __THROW. */
> -extern int fputc (int __c, FILE *__stream);
> -extern int putc (int __c, FILE *__stream);
> +extern int fputc (int __c, FILE *__stream) __nonnull ((2));
> +extern int putc (int __c, FILE *__stream) __nonnull ((2));
>
> /* Write a character to stdout.
>
> @@ -620,7 +620,7 @@ extern int putchar (int __c);
> cancellation point. But due to similarity with an POSIX interface
> or due to the implementation it is a cancellation point and
> therefore not marked with __THROW. */
> -extern int fputc_unlocked (int __c, FILE *__stream);
> +extern int fputc_unlocked (int __c, FILE *__stream) __nonnull ((2));
> #endif /* Use MISC. */
>
> #ifdef __USE_POSIX199506
> @@ -628,7 +628,7 @@ extern int fputc_unlocked (int __c, FILE *__stream);
>
> These functions are possible cancellation points and therefore not
> marked with __THROW. */
> -extern int putc_unlocked (int __c, FILE *__stream);
> +extern int putc_unlocked (int __c, FILE *__stream) __nonnull ((2));
> extern int putchar_unlocked (int __c);
> #endif /* Use POSIX. */
>
> @@ -636,10 +636,10 @@ extern int putchar_unlocked (int __c);
> #if defined __USE_MISC \
> || (defined __USE_XOPEN && !defined __USE_XOPEN2K)
> /* Get a word (int) from STREAM. */
> -extern int getw (FILE *__stream);
> +extern int getw (FILE *__stream) __nonnull ((1));
>
> /* Write a word (int) to STREAM. */
> -extern int putw (int __w, FILE *__stream);
> +extern int putw (int __w, FILE *__stream) __nonnull ((2));
> #endif
>
>
> @@ -689,10 +689,10 @@ extern char *fgets_unlocked (char *__restrict __s, int __n,
> therefore not marked with __THROW. */
> extern __ssize_t __getdelim (char **__restrict __lineptr,
> size_t *__restrict __n, int __delimiter,
> - FILE *__restrict __stream) __wur;
> + FILE *__restrict __stream) __wur __nonnull ((4));
> extern __ssize_t getdelim (char **__restrict __lineptr,
> size_t *__restrict __n, int __delimiter,
> - FILE *__restrict __stream) __wur;
> + FILE *__restrict __stream) __wur __nonnull ((4));
>
> /* Like `getdelim', but reads up to a newline.
>
> @@ -702,7 +702,7 @@ extern __ssize_t getdelim (char **__restrict __lineptr,
> therefore not marked with __THROW. */
> extern __ssize_t getline (char **__restrict __lineptr,
> size_t *__restrict __n,
> - FILE *__restrict __stream) __wur;
> + FILE *__restrict __stream) __wur __nonnull ((3));
> #endif
>
>
> @@ -723,7 +723,7 @@ extern int puts (const char *__s);
>
> This function is a possible cancellation point and therefore not
> marked with __THROW. */
> -extern int ungetc (int __c, FILE *__stream);
> +extern int ungetc (int __c, FILE *__stream) __nonnull ((2));
>
>
> /* Read chunks of generic data from STREAM.
> @@ -768,17 +768,17 @@ extern size_t fwrite_unlocked (const void *__restrict __ptr, size_t __size,
>
> This function is a possible cancellation point and therefore not
> marked with __THROW. */
> -extern int fseek (FILE *__stream, long int __off, int __whence);
> +extern int fseek (FILE *__stream, long int __off, int __whence) __nonnull ((1));
> /* Return the current position of STREAM.
>
> This function is a possible cancellation point and therefore not
> marked with __THROW. */
> -extern long int ftell (FILE *__stream) __wur;
> +extern long int ftell (FILE *__stream) __wur __nonnull ((1));
> /* Rewind to the beginning of STREAM.
>
> This function is a possible cancellation point and therefore not
> marked with __THROW. */
> -extern void rewind (FILE *__stream);
> +extern void rewind (FILE *__stream) __nonnull ((1));
>
> /* The Single Unix Specification, Version 2, specifies an alternative,
> more adequate interface for the two functions above which deal with
> @@ -791,18 +791,19 @@ extern void rewind (FILE *__stream);
>
> This function is a possible cancellation point and therefore not
> marked with __THROW. */
> -extern int fseeko (FILE *__stream, __off_t __off, int __whence);
> +extern int fseeko (FILE *__stream, __off_t __off, int __whence) __nonnull ((1));
> /* Return the current position of STREAM.
>
> This function is a possible cancellation point and therefore not
> marked with __THROW. */
> -extern __off_t ftello (FILE *__stream) __wur;
> +extern __off_t ftello (FILE *__stream) __wur __nonnull ((1));
> # else
> # ifdef __REDIRECT
> extern int __REDIRECT (fseeko,
> (FILE *__stream, __off64_t __off, int __whence),
> - fseeko64);
> -extern __off64_t __REDIRECT (ftello, (FILE *__stream), ftello64);
> + fseeko64) __nonnull ((1));
> +extern __off64_t __REDIRECT (ftello, (FILE *__stream), ftello64)
> + __nonnull ((1));
> # else
> # define fseeko fseeko64
> # define ftello ftello64
> @@ -815,18 +816,20 @@ extern __off64_t __REDIRECT (ftello, (FILE *__stream), ftello64);
>
> This function is a possible cancellation point and therefore not
> marked with __THROW. */
> -extern int fgetpos (FILE *__restrict __stream, fpos_t *__restrict __pos);
> +extern int fgetpos (FILE *__restrict __stream, fpos_t *__restrict __pos)
> + __nonnull ((1));
> /* Set STREAM's position.
>
> This function is a possible cancellation point and therefore not
> marked with __THROW. */
> -extern int fsetpos (FILE *__stream, const fpos_t *__pos);
> +extern int fsetpos (FILE *__stream, const fpos_t *__pos) __nonnull ((1));
> #else
> # ifdef __REDIRECT
> extern int __REDIRECT (fgetpos, (FILE *__restrict __stream,
> - fpos_t *__restrict __pos), fgetpos64);
> + fpos_t *__restrict __pos), fgetpos64) __nonnull ((1));
> extern int __REDIRECT (fsetpos,
> - (FILE *__stream, const fpos_t *__pos), fsetpos64);
> + (FILE *__stream, const fpos_t *__pos), fsetpos64)
> + __nonnull ((1));
> # else
> # define fgetpos fgetpos64
> # define fsetpos fsetpos64
> @@ -834,24 +837,26 @@ extern int __REDIRECT (fsetpos,
> #endif
>
> #ifdef __USE_LARGEFILE64
> -extern int fseeko64 (FILE *__stream, __off64_t __off, int __whence);
> -extern __off64_t ftello64 (FILE *__stream) __wur;
> -extern int fgetpos64 (FILE *__restrict __stream, fpos64_t *__restrict __pos);
> -extern int fsetpos64 (FILE *__stream, const fpos64_t *__pos);
> +extern int fseeko64 (FILE *__stream, __off64_t __off, int __whence)
> + __nonnull ((1));
> +extern __off64_t ftello64 (FILE *__stream) __wur __nonnull ((1));
> +extern int fgetpos64 (FILE *__restrict __stream, fpos64_t *__restrict __pos)
> + __nonnull ((1));
> +extern int fsetpos64 (FILE *__stream, const fpos64_t *__pos) __nonnull ((1));
> #endif
>
> /* Clear the error and EOF indicators for STREAM. */
> -extern void clearerr (FILE *__stream) __THROW;
> +extern void clearerr (FILE *__stream) __THROW __nonnull ((1));
> /* Return the EOF indicator for STREAM. */
> -extern int feof (FILE *__stream) __THROW __wur;
> +extern int feof (FILE *__stream) __THROW __wur __nonnull ((1));
> /* Return the error indicator for STREAM. */
> -extern int ferror (FILE *__stream) __THROW __wur;
> +extern int ferror (FILE *__stream) __THROW __wur __nonnull ((1));
>
> #ifdef __USE_MISC
> /* Faster versions when locking is not required. */
> -extern void clearerr_unlocked (FILE *__stream) __THROW;
> -extern int feof_unlocked (FILE *__stream) __THROW __wur;
> -extern int ferror_unlocked (FILE *__stream) __THROW __wur;
> +extern void clearerr_unlocked (FILE *__stream) __THROW __nonnull ((1));
> +extern int feof_unlocked (FILE *__stream) __THROW __wur __nonnull ((1));
> +extern int ferror_unlocked (FILE *__stream) __THROW __wur __nonnull ((1));
> #endif
>
>
> @@ -864,12 +869,12 @@ extern void perror (const char *__s) __COLD;
>
> #ifdef __USE_POSIX
> /* Return the system file descriptor for STREAM. */
> -extern int fileno (FILE *__stream) __THROW __wur;
> +extern int fileno (FILE *__stream) __THROW __wur __nonnull ((1));
> #endif /* Use POSIX. */
>
> #ifdef __USE_MISC
> /* Faster version when locking is not required. */
> -extern int fileno_unlocked (FILE *__stream) __THROW __wur;
> +extern int fileno_unlocked (FILE *__stream) __THROW __wur __nonnull ((1));
> #endif
>
>
> @@ -878,7 +883,7 @@ extern int fileno_unlocked (FILE *__stream) __THROW __wur;
>
> This function is a possible cancellation point and therefore not
> marked with __THROW. */
> -extern int pclose (FILE *__stream);
> +extern int pclose (FILE *__stream) __nonnull ((1));
You didn't patch fclose(3). Any reason? I guess it's similarly UB to
call fclose(NULL).
Cheers,
Alex
>
> /* Create a new stream connected to a pipe running the given command.
>
> @@ -922,14 +927,14 @@ extern int obstack_vprintf (struct obstack *__restrict __obstack,
> /* These are defined in POSIX.1:1996. */
>
> /* Acquire ownership of STREAM. */
> -extern void flockfile (FILE *__stream) __THROW;
> +extern void flockfile (FILE *__stream) __THROW __nonnull ((1));
>
> /* Try to acquire ownership of STREAM but do not block if it is not
> possible. */
> -extern int ftrylockfile (FILE *__stream) __THROW __wur;
> +extern int ftrylockfile (FILE *__stream) __THROW __wur __nonnull ((1));
>
> /* Relinquish the ownership granted for STREAM. */
> -extern void funlockfile (FILE *__stream) __THROW;
> +extern void funlockfile (FILE *__stream) __THROW __nonnull ((1));
> #endif /* POSIX */
>
> #if defined __USE_XOPEN && !defined __USE_XOPEN2K && !defined __USE_GNU
--
<http://www.alejandro-colomar.es/>
GPG key fingerprint: A9348594CE31283A826FBDD8D57633D441E25BB5
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next prev parent reply other threads:[~2023-05-18 18:06 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-18 17:25 Xi Ruoyao
2023-05-18 18:06 ` Alex Colomar [this message]
2023-05-18 18:29 ` Alex Colomar
2023-05-19 4:13 ` Xi Ruoyao
2023-05-19 5:21 ` Xi Ruoyao
2023-05-19 12:40 ` Alejandro Colomar
2023-05-19 13:03 ` Xi Ruoyao
2023-05-19 13:07 ` Alejandro Colomar
2023-05-18 18:56 ` Alejandro Colomar
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