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newlib: implement _fstat_r stub for console

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When CONFIG_VFS_SUPPORT_IO is disabled, _read_r and _write_r
implementations in syscalls.c are used to provide console I/O via
esp_rom_uart_tx_one_char/esp_rom_uart_rx_one_char.

When newlib opens a (FILE*) stream, it calls fstat to check if the
underlying file is character-oriented. In this case, it configures the
stream to use line buffering. Otherwise (or if fstat fails) the stream
is opened as block buffered.

Since fstat wasn't provided, stdin/stdout/stderr streams got opened in
block buffered mode. For console, we need line buffered output so that
the stream buffer is flushed each time a complete line (ending with
'\n') is sent to stdout or stderr.

Fix by implementing _fstat_r stub, setting st->st_mdoe=S_IFCHR.
This commit is contained in:
Ivan Grokhotkov
2021-09-15 14:49:57 +02:00
parent 3c0d892d43
commit 3d91e6d993
1 changed files with 15 additions and 2 deletions
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17
components/newlib/syscalls.c
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@ -17,6 +17,7 @@
#include <stdarg.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <reent.h>
#include <sys/fcntl.h>
@ -64,6 +65,18 @@ ssize_t _read_r_console(struct _reent *r, int fd, void * data, size_t size)
return -1;
}
static ssize_t _fstat_r_console(struct _reent *r, int fd, struct stat * st)
{
if (fd == STDOUT_FILENO || fd == STDERR_FILENO) {
memset(st, 0, sizeof(*st));
/* This needs to be set so that stdout and stderr are line buffered. */
st->st_mode = S_IFCHR;
return 0;
}
__errno_r(r) = EBADF;
return -1;
}
/* The following weak definitions of syscalls will be used unless
* another definition is provided. That definition may come from
@ -73,6 +86,8 @@ ssize_t _read_r(struct _reent *r, int fd, void * dst, size_t size)
__attribute__((weak,alias("_read_r_console")));
ssize_t _write_r(struct _reent *r, int fd, const void * data, size_t size)
__attribute__((weak,alias("_write_r_console")));
int _fstat_r (struct _reent *r, int fd, struct stat *st)
__attribute__((weak,alias("_fstat_r_console")));
/* The aliases below are to "syscall_not_implemented", which
@ -90,8 +105,6 @@ off_t _lseek_r(struct _reent *r, int fd, off_t size, int mode)
__attribute__((weak,alias("syscall_not_implemented")));
int _fcntl_r(struct _reent *r, int fd, int cmd, int arg)
__attribute__((weak,alias("syscall_not_implemented")));
int _fstat_r(struct _reent *r, int fd, struct stat * st)
__attribute__((weak,alias("syscall_not_implemented")));
int _stat_r(struct _reent *r, const char * path, struct stat * st)
__attribute__((weak,alias("syscall_not_implemented")));
int _link_r(struct _reent *r, const char* n1, const char* n2)