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

---

Willy:

This uses intptr_t instead of uintptr_t as proposed because uintptr_t can not be negative. --- tools/include/nolibc/stdio.h | 60 ++++++++++++++++++++++++-------------------- 1 file changed, 33 insertions(+), 27 deletions(-)

diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h index 96ac8afc5aee..edf1009e9203 100644 --- a/tools/include/nolibc/stdio.h +++ b/tools/include/nolibc/stdio.h @@ -21,17 +21,40 @@ #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) + return NULL; + return (FILE*)(intptr_t)~fd; +} + +/* provides the fd from 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; +}

/* getc(), fgetc(), getchar() */

@@ -41,14 +64,8 @@ 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 +85,8 @@ 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 +107,7 @@ 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);

Thomas,

On Sun, Apr 02, 2023 at 01:02:44PM +0000, Thomas Weißschuh wrote:

vfprintf() is complex and so far did not have proper tests.

This series is based on the "dev" branch of the RCU tree.

I've just ran it with glibc to see:

$ gcc nolibc-test.c $ ./a.out vfprintf Running test 'vfprintf' 0 empty "" = "" [OK] 1 simple written(3) != read(0) [FAIL] 2 string written(3) != read(0) [FAIL] 3 number written(4) != read(0) [FAIL] 4 negnumber written(5) != read(0) [FAIL] 5 unsigned written(5) != read(0) [FAIL] 6 char written(1) != read(0) [FAIL] 7 hex written(1) != read(0) [FAIL] 8 pointer written(5) != 3 [FAIL] Errors during this test: 8

The main issue was that glibc uses buffered writes by default.

I could fix them with fflush() (which we don't have so it required an ifndef), and this also made me realize that we were missing an fclose() as well for compatibility with glibc. With this it got better:

Running test 'vfprintf' 0 empty "" = "" [OK] 1 simple "foo" = "foo" [OK] 2 string "foo" = "foo" [OK] 3 number "1234" = "1234" [OK] 4 negnumber "-1234" = "-1234" [OK] 5 unsigned "12345" = "12345" [OK] 6 char "c" = "c" [OK] 7 hex "f" = "f" [OK] 8 pointer written(5) != 3 [FAIL] Errors during this test: 1

This is caused by glibc emitting "(nil)" while we emit "0x0" for a NULL pointer since we use the same code as when dumping integers. I could fix that one as well by printing (void*)1 instead, which shows "0x1" for both.

This gives me the patch below on top of yours, which I think would make sense to integrate in this form or a simplified one if we manage to add fflush() and fclose() earlier.

What do you think ?

Thanks, Willy

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index 28a8d77078dc..2958dc3eca93 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -678,6 +678,7 @@ static int expect_vfprintf(int llen, size_t c, const char *expected, const char int ret, fd, w, r; char buf[100]; va_list args; + FILE *memfile;

fd = memfd_create("vfprintf", 0); if (fd == -1) { @@ -685,8 +686,14 @@ static int expect_vfprintf(int llen, size_t c, const char *expected, const char return 1; }

+ memfile = fdopen(fd, "w+"); + if (!memfile) { + pad_spc(llen, 64, "[FAIL]\n"); + return 1; + } + va_start(args, fmt); - w = vfprintf(fdopen(fd, "w+"), fmt, args); + w = vfprintf(memfile, fmt, args); va_end(args);

if (w != c) { @@ -695,12 +702,19 @@ static int expect_vfprintf(int llen, size_t c, const char *expected, const char return 1; }

+#ifndef _NOLIBC_STDIO_H + fflush(memfile); +#endif lseek(fd, 0, SEEK_SET);

r = read(fd, buf, sizeof(buf) - 1); buf[r] = '\0';

+#ifndef _NOLIBC_STDIO_H + fclose(memfile); +#else close(fd); +#endif

if (r != w) { llen += printf(" written(%d) != read(%d)", w, r); @@ -737,7 +751,7 @@ static int run_vfprintf(int min, int max) CASE_TEST(unsigned); EXPECT_VFPRINTF(5, "12345", "%u", 12345); break; CASE_TEST(char); EXPECT_VFPRINTF(1, "c", "%c", 'c'); break; CASE_TEST(hex); EXPECT_VFPRINTF(1, "f", "%x", 0xf); break; - CASE_TEST(pointer); EXPECT_VFPRINTF(3, "0x0", "%p", NULL); break; + CASE_TEST(pointer); EXPECT_VFPRINTF(3, "0x1", "%p", (void*)0x1); break; case __LINE__: return ret; /* must be last */ /* note: do not set any defaults so as to permit holes above */