Merge tag 'nolibc.2023.06.22a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull nolibc updates from Paul McKenney:

 - Add stackprotector support

 - Fix RISC-V load-store instruction syntax to support 32-bit binaries,
   plus fixes for generic 32-bit support

 - Fix use of s390 sys_fork()

 - Add my_syscall6() for ARM

 - Support different platforms having different errno definitions

 - Fix ppoll/ppoll_time64 arguments (add the fifth argument)

 - Force use of little endian on MIPS

 - Improved testing, for example, better handling of different compilers
   and compiler versions, comparing nolibc behavior to that of libc, and
   additional test cases

 - Improve syntax and header ordering

 - Use existing <linux/reboot.h> instead of redefining constants

 - Add syscall()

* tag 'nolibc.2023.06.22a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (53 commits)
  selftests/nolibc: make sure gcc always use little endian on MIPS
  selftests/nolibc: also count skipped and failed tests in output
  selftests/nolibc: add new gettimeofday test cases
  selftests/nolibc: remove gettimeofday_bad1/2 completely
  selftests/nolibc: support two errnos with EXPECT_SYSER2()
  tools/nolibc: open: fix up compile warning for arm
  tools/nolibc: arm: add missing my_syscall6
  selftests/nolibc: use INT_MAX instead of __INT_MAX__
  selftests/nolibc: not include limits.h for nolibc
  selftests/nolibc: fix up compile warning with glibc on x86_64
  selftests/nolibc: allow specify extra arguments for qemu
  selftests/nolibc: remove test gettimeofday_null
  tools/nolibc: ensure fast64 integer types have 64 bits
  selftests/nolibc: test_fork: fix up duplicated print
  tools/nolibc: ppoll/ppoll_time64: add a missing argument
  selftests/nolibc: remove the duplicated gettimeofday_bad2
  selftests/nolibc: print name instead of number for EOVERFLOW
  tools/nolibc: support nanoseconds in stat()
  selftests/nolibc: prevent coredumps during test execution
  tools/nolibc: add support for prctl()
  ...

1 files 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
 
-/* 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);