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McKenney" To: linux-kernel@vger.kernel.org Cc: gwml@vger.gnuweeb.org, kernel-team@meta.com, w@lwt.eu, =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , Willy Tarreau , "Paul E . McKenney" Subject: [PATCH v2 nolibc 06/15] tools/nolibc: implement fd-based FILE streams Date: Thu, 18 May 2023 07:55:12 -0700 Message-Id: <20230518145521.3806117-6-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <4817a4dc-69e6-4937-84d5-f2f630ff646c@paulmck-laptop> References: <4817a4dc-69e6-4937-84d5-f2f630ff646c@paulmck-laptop> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Thomas Wei=C3=9Fschuh This enables the usage of the stream APIs with arbitrary filedescriptors. It will be used by a future testcase. Signed-off-by: Thomas Wei=C3=9Fschuh Signed-off-by: Willy Tarreau Signed-off-by: Paul E. McKenney --- tools/include/nolibc/stdio.h | 95 ++++++++++++++++++++++++++---------- 1 file changed, 68 insertions(+), 27 deletions(-) diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h index 6cbbb52836a0..0eef91daf289 100644 --- a/tools/include/nolibc/stdio.h +++ b/tools/include/nolibc/stdio.h @@ -21,17 +21,75 @@ #define EOF (-1) #endif =20 -/* just define FILE as a non-empty type */ +/* just define FILE as a non-empty type. The value of the pointer gives + * the FD: FILE=3D~fd for fd>=3D0 or NULL for fd<0. This way positive FILE + * are immediately identified as abnormal entries (i.e. possible copies + * of valid pointers to something else). + */ typedef struct FILE { char dummy[1]; } FILE; =20 -/* We define the 3 common stdio files as constant invalid pointers that - * are easily recognized. - */ -static __attribute__((unused)) FILE* const stdin =3D (FILE*)-3; -static __attribute__((unused)) FILE* const stdout =3D (FILE*)-2; -static __attribute__((unused)) FILE* const stderr =3D (FILE*)-1; +static __attribute__((unused)) FILE* const stdin =3D (FILE*)(intptr_t)~ST= DIN_FILENO; +static __attribute__((unused)) FILE* const stdout =3D (FILE*)(intptr_t)~ST= DOUT_FILENO; +static __attribute__((unused)) FILE* const stderr =3D (FILE*)(intptr_t)~ST= DERR_FILENO; + +/* provides a FILE* equivalent of fd. The mode is ignored. */ +static __attribute__((unused)) +FILE *fdopen(int fd, const char *mode __attribute__((unused))) +{ + if (fd < 0) { + SET_ERRNO(EBADF); + return NULL; + } + return (FILE*)(intptr_t)~fd; +} + +/* provides the fd of stream. */ +static __attribute__((unused)) +int fileno(FILE *stream) +{ + intptr_t i =3D (intptr_t)stream; + + if (i >=3D 0) { + SET_ERRNO(EBADF); + return -1; + } + return ~i; +} + +/* flush a stream. */ +static __attribute__((unused)) +int fflush(FILE *stream) +{ + intptr_t i =3D (intptr_t)stream; + + /* NULL is valid here. */ + if (i > 0) { + SET_ERRNO(EBADF); + return -1; + } + + /* Don't do anything, nolibc does not support buffering. */ + return 0; +} + +/* flush a stream. */ +static __attribute__((unused)) +int fclose(FILE *stream) +{ + intptr_t i =3D (intptr_t)stream; + + if (i >=3D 0) { + SET_ERRNO(EBADF); + return -1; + } + + if (close(~i)) + return EOF; + + return 0; +} =20 /* getc(), fgetc(), getchar() */ =20 @@ -41,14 +99,8 @@ static __attribute__((unused)) int fgetc(FILE* stream) { unsigned char ch; - int fd; =20 - if (stream < stdin || stream > stderr) - return EOF; - - fd =3D 3 + (long)stream; - - if (read(fd, &ch, 1) <=3D 0) + if (read(fileno(stream), &ch, 1) <=3D 0) return EOF; return ch; } @@ -68,14 +120,8 @@ static __attribute__((unused)) int fputc(int c, FILE* stream) { unsigned char ch =3D c; - int fd; - - if (stream < stdin || stream > stderr) - return EOF; - - fd =3D 3 + (long)stream; =20 - if (write(fd, &ch, 1) <=3D 0) + if (write(fileno(stream), &ch, 1) <=3D 0) return EOF; return ch; } @@ -96,12 +142,7 @@ static __attribute__((unused)) int _fwrite(const void *buf, size_t size, FILE *stream) { ssize_t ret; - int fd; - - if (stream < stdin || stream > stderr) - return EOF; - - fd =3D 3 + (long)stream; + int fd =3D fileno(stream); =20 while (size) { ret =3D write(fd, buf, size); --=20 2.40.1