From: Willy Tarreau <w@1wt.eu>
To: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Mark Brown <broonie@kernel.org>,
linux-kernel@vger.kernel.org, Willy Tarreau <w@1wt.eu>
Subject: [PATCH 21/42] tools/nolibc/stdio: add a minimal [vf]printf() implementation
Date: Mon, 7 Feb 2022 17:23:33 +0100 [thread overview]
Message-ID: <20220207162354.14293-22-w@1wt.eu> (raw)
In-Reply-To: <20220207162354.14293-1-w@1wt.eu>
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>
---
tools/include/nolibc/stdio.h | 128 +++++++++++++++++++++++++++++++++++
1 file changed, 128 insertions(+)
diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
index 996bf89a30d2..a73cf24cb68d 100644
--- a/tools/include/nolibc/stdio.h
+++ b/tools/include/nolibc/stdio.h
@@ -7,6 +7,8 @@
#ifndef _NOLIBC_STDIO_H
#define _NOLIBC_STDIO_H
+#include <stdarg.h>
+
#include "std.h"
#include "arch.h"
#include "types.h"
@@ -158,4 +160,130 @@ char *fgets(char *s, int size, FILE *stream)
return ofs ? s : NULL;
}
+
+/* minimal vfprintf(). It supports the following formats:
+ * - %[l*]{d,u,c,x}
+ * - %s
+ * - unknown modifiers are ignored.
+ */
+static __attribute__((unused))
+int vfprintf(FILE *stream, const char *fmt, va_list args)
+{
+ char escape, lpref, c;
+ unsigned long long v;
+ unsigned int written;
+ size_t len, ofs;
+ char tmpbuf[21];
+ const char *outstr;
+
+ written = ofs = escape = lpref = 0;
+ while (1) {
+ c = fmt[ofs++];
+
+ if (escape) {
+ /* we're in an escape sequence, ofs == 1 */
+ escape = 0;
+ if (c == 'c' || c == 'd' || c == 'u' || c == 'x') {
+ if (lpref) {
+ if (lpref > 1)
+ v = va_arg(args, unsigned long long);
+ else
+ v = va_arg(args, unsigned long);
+ } else
+ v = va_arg(args, unsigned int);
+
+ if (c == 'd') {
+ /* sign-extend the value */
+ if (lpref == 0)
+ v = (long long)(int)v;
+ else if (lpref == 1)
+ v = (long long)(long)v;
+ }
+
+ switch (c) {
+ case 'd':
+ i64toa_r(v, tmpbuf);
+ break;
+ case 'u':
+ u64toa_r(v, tmpbuf);
+ break;
+ case 'x':
+ u64toh_r(v, tmpbuf);
+ break;
+ default: /* 'c' */
+ tmpbuf[0] = v;
+ tmpbuf[1] = 0;
+ break;
+ }
+ outstr = tmpbuf;
+ }
+ else if (c == 's') {
+ outstr = va_arg(args, char *);
+ }
+ else if (c == '%') {
+ /* queue it verbatim */
+ continue;
+ }
+ else {
+ /* modifiers or final 0 */
+ if (c == 'l') {
+ /* long format prefix, maintain the escape */
+ lpref++;
+ }
+ escape = 1;
+ goto do_escape;
+ }
+ len = strlen(outstr);
+ goto flush_str;
+ }
+
+ /* not an escape sequence */
+ if (c == 0 || c == '%') {
+ /* flush pending data on escape or end */
+ escape = 1;
+ lpref = 0;
+ outstr = fmt;
+ len = ofs - 1;
+ flush_str:
+ if (_fwrite(outstr, len, stream) != 0)
+ break;
+
+ written += len;
+ do_escape:
+ if (c == 0)
+ break;
+ fmt += ofs;
+ ofs = 0;
+ continue;
+ }
+
+ /* literal char, just queue it */
+ }
+ return written;
+}
+
+static __attribute__((unused))
+int fprintf(FILE *stream, const char *fmt, ...)
+{
+ va_list args;
+ int ret;
+
+ va_start(args, fmt);
+ ret = vfprintf(stream, fmt, args);
+ va_end(args);
+ return ret;
+}
+
+static __attribute__((unused))
+int printf(const char *fmt, ...)
+{
+ va_list args;
+ int ret;
+
+ va_start(args, fmt);
+ ret = vfprintf(stdout, fmt, args);
+ va_end(args);
+ return ret;
+}
+
#endif /* _NOLIBC_STDIO_H */
--
2.35.1
next prev parent reply other threads:[~2022-02-07 16:45 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-07 16:23 [PATCH 00/42] nolibc: update to resync with out-of-tree project Willy Tarreau
2022-02-07 16:23 ` [PATCH 01/42] tools/nolibc: use pselect6 on RISCV Willy Tarreau
2022-02-07 16:23 ` [PATCH 02/42] tools/nolibc: guard the main file against multiple inclusion Willy Tarreau
2022-02-07 16:23 ` [PATCH 03/42] tools/nolibc/std: move the standard type definitions to std.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 04/42] tools/nolibc/types: split syscall-specific definitions into their own files Willy Tarreau
2022-02-07 16:23 ` [PATCH 05/42] tools/nolibc/arch: split arch-specific code into individual files Willy Tarreau
2022-02-07 16:23 ` [PATCH 06/42] tools/nolibc/sys: split the syscall definitions into their own file Willy Tarreau
2022-02-07 16:23 ` [PATCH 07/42] tools/nolibc/stdlib: extract the stdlib-specific functions to " Willy Tarreau
2022-02-07 16:23 ` [PATCH 08/42] tools/nolibc/string: split the string functions into string.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 09/42] tools/nolibc/ctype: split the is* functions to ctype.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 10/42] tools/nolibc/ctype: add the missing is* functions Willy Tarreau
2022-02-07 16:23 ` [PATCH 11/42] tools/nolibc/types: move the FD_* functions to macros in types.h Willy Tarreau
2022-02-07 17:05 ` David Laight
2022-02-08 5:14 ` Willy Tarreau
2022-02-13 8:52 ` [PATCH v2 " Willy Tarreau
2022-02-07 16:23 ` [PATCH 12/42] tools/nolibc/types: make FD_SETSIZE configurable Willy Tarreau
2022-02-13 8:53 ` [PATCH v2 " Willy Tarreau
2022-02-14 20:17 ` Paul E. McKenney
2022-02-07 16:23 ` [PATCH 13/42] tools/nolibc/types: move makedev to types.h and make it a macro Willy Tarreau
2022-02-07 16:23 ` [PATCH 14/42] tools/nolibc/stdlib: move ltoa() to stdlib.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 15/42] tools/nolibc/stdlib: replace the ltoa() function with more efficient ones Willy Tarreau
2022-02-07 16:23 ` [PATCH 16/42] tools/nolibc/stdlib: add i64toa() and u64toa() Willy Tarreau
2022-02-07 16:23 ` [PATCH 17/42] tools/nolibc/stdlib: add utoh() and u64toh() Willy Tarreau
2022-02-07 16:23 ` [PATCH 18/42] tools/nolibc/stdio: add a minimal set of stdio functions Willy Tarreau
2022-02-07 16:23 ` [PATCH 19/42] tools/nolibc/stdio: add stdin/stdout/stderr and fget*/fput* functions Willy Tarreau
2022-02-07 16:23 ` [PATCH 20/42] tools/nolibc/stdio: add fwrite() to stdio Willy Tarreau
2022-02-07 16:23 ` Willy Tarreau [this message]
2022-02-07 16:23 ` [PATCH 22/42] tools/nolibc/types: define EXIT_SUCCESS and EXIT_FAILURE Willy Tarreau
2022-02-07 16:23 ` [PATCH 23/42] tools/nolibc/stdio: add perror() to report the errno value Willy Tarreau
2022-02-07 16:23 ` [PATCH 24/42] tools/nolibc/sys: make open() take a vararg on the 3rd argument Willy Tarreau
2022-02-07 16:23 ` [PATCH 25/42] tools/nolibc/stdlib: avoid a 64-bit shift in u64toh_r() Willy Tarreau
2022-02-07 16:23 ` [PATCH 26/42] tools/nolibc/stdlib: make raise() use the lower level syscalls only Willy Tarreau
2022-02-07 16:23 ` [PATCH 27/42] tools/nolibc/sys: make getpgrp(), getpid(), gettid() not set errno Willy Tarreau
2022-02-07 16:23 ` [PATCH 28/42] tools/nolibc/string: use unidirectional variants for memcpy() Willy Tarreau
2022-02-07 16:23 ` [PATCH 29/42] tools/nolibc/string: slightly simplify memmove() Willy Tarreau
2022-02-07 16:23 ` [PATCH 30/42] tools/nolibc/string: add strncpy() and strlcpy() Willy Tarreau
2022-02-07 16:23 ` [PATCH 31/42] tools/nolibc/string: add tiny versions of strncat() and strlcat() Willy Tarreau
2022-02-07 16:23 ` [PATCH 32/42] tools/nolibc: move exported functions to their own section Willy Tarreau
2022-02-07 16:23 ` [PATCH 33/42] tools/nolibc/arch: mark the _start symbol as weak Willy Tarreau
2022-02-07 16:23 ` [PATCH 34/42] tools/nolibc/types: define PATH_MAX and MAXPATHLEN Willy Tarreau
2022-02-07 16:23 ` [PATCH 35/42] tools/nolibc/string: export memset() and memmove() Willy Tarreau
2022-02-07 16:23 ` [PATCH 36/42] tools/nolibc/errno: extract errno.h from sys.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 37/42] tools/nolibc/unistd: extract msleep(), sleep(), tcsetpgrp() to unistd.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 38/42] tools/nolibc/unistd: add usleep() Willy Tarreau
2022-02-07 16:23 ` [PATCH 39/42] tools/nolibc/signal: move raise() to signal.h Willy Tarreau
2022-02-07 16:23 ` [PATCH 40/42] tools/nolibc/time: create time.h with time() Willy Tarreau
2022-02-07 16:23 ` [PATCH 41/42] tools/nolibc: also mention how to build by just setting the include path Willy Tarreau
2022-02-07 16:23 ` [PATCH 42/42] tools/nolibc/stdlib: implement abort() Willy Tarreau
2022-02-08 0:00 ` [PATCH 00/42] nolibc: update to resync with out-of-tree project Paul E. McKenney
2022-02-08 4:41 ` Willy Tarreau
2022-02-08 5:10 ` Paul E. McKenney
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