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tools/nolibc: implement fd-based FILE streams

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This enables the usage of the stream APIs with arbitrary filedescriptors.

It will be used by a future testcase.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Thomas Weißschuh
2023-04-02 20:48:05 +02:00
committed by Paul E. McKenney
parent e8842cf04e
commit 5df28c153d
1 changed files with 68 additions and 27 deletions
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95
tools/include/nolibc/stdio.h
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@ -21,17 +21,75 @@
#define EOF (-1)
#endif
/* 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=~fd for fd>=0 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;
/* We define the 3 common stdio files as constant invalid pointers that
* are easily recognized.
*/
static __attribute__((unused)) FILE* const stdin = (FILE*)-3;
static __attribute__((unused)) FILE* const stdout = (FILE*)-2;
static __attribute__((unused)) FILE* const stderr = (FILE*)-1;
static __attribute__((unused)) FILE* const stdin = (FILE*)(intptr_t)~STDIN_FILENO;
static __attribute__((unused)) FILE* const stdout = (FILE*)(intptr_t)~STDOUT_FILENO;
static __attribute__((unused)) FILE* const stderr = (FILE*)(intptr_t)~STDERR_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 = (intptr_t)stream;
if (i >= 0) {
SET_ERRNO(EBADF);
return -1;
}
return ~i;
}
/* flush a stream. */
static __attribute__((unused))
int fflush(FILE *stream)
{
intptr_t i = (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 = (intptr_t)stream;
if (i >= 0) {
SET_ERRNO(EBADF);
return -1;
}
if (close(~i))
return EOF;
return 0;
}
/* getc(), fgetc(), getchar() */
@ -41,14 +99,8 @@ static __attribute__((unused))
int fgetc(FILE* stream)
{
unsigned char ch;
int fd;
if (stream < stdin || stream > stderr)
return EOF;
fd = 3 + (long)stream;
if (read(fd, &ch, 1) <= 0)
if (read(fileno(stream), &ch, 1) <= 0)
return EOF;
return ch;
}
@ -68,14 +120,8 @@ static __attribute__((unused))
int fputc(int c, FILE* stream)
{
unsigned char ch = c;
int fd;
if (stream < stdin || stream > stderr)
return EOF;
fd = 3 + (long)stream;
if (write(fd, &ch, 1) <= 0)
if (write(fileno(stream), &ch, 1) <= 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 = 3 + (long)stream;
int fd = fileno(stream);
while (size) {
ret = write(fd, buf, size);