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2022-06-20tools/nolibc/stdio: Add format attribute to enable printf warningsAlviro Iskandar Setiawan
When we use printf and fprintf functions from the nolibc, we don't get any warning from the compiler if we have the wrong arguments. For example, the following calls will compile silently: ``` printf("%s %s\n", "aaa"); fprintf(stdout, "%s %s\n", "xxx", 1); ``` (Note the wrong arguments). Those calls are undefined behavior. The compiler can help us warn about the above mistakes by adding a `printf` format attribute to those functions declaration. This patch adds it, and now it yields these warnings for those mistakes: ``` warning: format `%s` expects a matching `char *` argument [-Wformat=] warning: format `%s` expects argument of type `char *`, but argument 4 has type `int` [-Wformat=] ``` [ ammarfaizi2: Simplify the attribute placement. ] Signed-off-by: Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org> Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org> Acked-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: add support for '%p' to vfprintf()Willy Tarreau
%p remains quite useful in test code, and the code path can easily be merged with the existing "%x" thus only adds ~50 bytes, thus let's add it. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: make printf(%s) accept NULLWilly Tarreau
It's often convenient to support this, especially in test programs where a NULL may correspond to an allocation error or a non-existing value. Let's make printf("%s") support being passed a NULL. In this case it prints "(null)" like glibc's printf(). Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/errno: extract errno.h from sys.hWilly Tarreau
This allows us to provide a minimal errno.h to ease porting applications that use it. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: add perror() to report the errno valueWilly Tarreau
It doesn't contain the text for the error codes, but instead displays "errno=" followed by the errno value. Just like the regular errno, if a non-empty message is passed, it's placed followed with ": " on the output before the errno code. The message is emitted on stderr. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: add a minimal [vf]printf() implementationWilly Tarreau
This adds a minimal vfprintf() implementation as well as the commonly used fprintf() and printf() that rely on it. For now the function supports: - formats: %s, %c, %u, %d, %x - modifiers: %l and %ll - unknown chars are considered as modifiers and are ignored It is designed to remain minimalist, despite this printf() is 549 bytes on x86_64. It would be wise not to add too many formats. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: add fwrite() to stdioWilly Tarreau
We'll use it to write substrings. It relies on a simpler _fwrite() that only takes one size. fputs() was also modified to rely on it. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: add stdin/stdout/stderr and fget*/fput* functionsWilly Tarreau
The standard puts() function always emits the trailing LF which makes it unconvenient for small string concatenation. fputs() ought to be used instead but it requires a FILE*. This adds 3 dummy FILE* values (stdin, stdout, stderr) which are in fact pointers to struct FILE of one byte. We reserve 3 pointer values for them, -3, -2 and -1, so that they are ordered, easing the tests and mapping to integer. >From this, fgetc(), fputc(), fgets() and fputs() were implemented, and the previous putchar() and getchar() now remap to these. The standard getc() and putc() macros were also implemented as pointing to these ones. There is absolutely no buffering, fgetc() and fgets() read one byte at a time, fputc() writes one byte at a time, and only fputs() which knows the string's length writes all of it at once. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: add a minimal set of stdio functionsWilly Tarreau
This only provides getchar(), putchar(), and puts(). Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>