stdio: Make legacy nano printf code at least compile

keith-packard · keith-packard · commit e060e1db5c4e · 2025-04-19T08:31:45.000-07:00
Remove 'struct _reent' dregs. Add __nothrow as needed to stdio.h. Clean
up some simple compiler warnings about undefined behavior.

There are many gaps in standards conformance with this; making it pass
the test suite would be a significant effort. But, at least it builds
again.

Signed-off-by: Keith Packard &lt;keithp@keithp.com&gt;
diff --git a/newlib/libc/stdio/nano-vfprintf.c b/newlib/libc/stdio/nano-vfprintf.c
@@ -617,7 +617,7 @@ VFPRINTF (
 	      n = 0;
 	    }
 	  else
-            n = _printf_float (data, &prt_data, fp, pfunc, &ap_copy);
+            n = _printf_float (&prt_data, fp, pfunc, &ap_copy);
 	}
       else
 #endif
diff --git a/newlib/libc/stdio/nano-vfprintf_float.c b/newlib/libc/stdio/nano-vfprintf_float.c
@@ -63,13 +63,14 @@ int __exponent (char *p0, int exp, int fmtch);
    [aAeEfFgG]; if it is [aA], then the return string lives in BUF,
    otherwise the return value shares the mprec reentrant storage.  */
 char *
-__cvt (struct _reent *data, _PRINTF_FLOAT_TYPE value, int ndigits, int flags,
+__cvt (_PRINTF_FLOAT_TYPE value, int ndigits, int flags,
        char *sign, int *decpt, int ch, int *length, char *buf)
 {
   int mode, dsgn;
   char *digits, *bp, *rve;
   union double_union tmp;
 
+  (void) buf;
   tmp.d = value;
   /* This will check for "< 0" and "-0.0".  */
   if (word0 (tmp) & Sign_bit)
@@ -160,10 +161,9 @@ __exponent (char *p0, int exp, int fmtch)
 
 /* Decode and print floating point number specified by "eEfgG".  */
 int
-_printf_float (struct _reent *data,
-	       struct _prt_data_t *pdata,
+_printf_float (struct _prt_data_t *pdata,
 	       FILE * fp,
-	       int (*pfunc) (struct _reent *, FILE *, const char *,
+	       int (*pfunc) (FILE *, const char *,
 			     size_t len), va_list * ap)
 {
 #define _fpvalue (pdata->_double_)
@@ -178,8 +178,7 @@ _printf_float (struct _reent *data,
   int expsize = 0;
   /* Actual number of digits returned by cvt.  */
   int ndig = 0;
-  char *cp;
-  int n;
+  char *cp = NULL;
   /* Field size expanded by dprec(not for _printf_float).  */
   int realsz;
   char code = pdata->code;
@@ -234,7 +233,7 @@ _printf_float (struct _reent *data,
 
   pdata->flags |= FPT;
 
-  cp = __cvt (data, _fpvalue, pdata->prec, pdata->flags, &softsign,
+  cp = __cvt (_fpvalue, pdata->prec, pdata->flags, &softsign,
 	      &expt, code, &ndig, cp);
 
   if (code == 'g' || code == 'G')
@@ -285,7 +284,7 @@ _printf_float (struct _reent *data,
   if (softsign)
     pdata->l_buf[0] = '-';
 print_float:
-  if (_printf_common (data, pdata, &realsz, fp, pfunc) == -1)
+  if (_printf_common (pdata, &realsz, fp, pfunc) == -1)
     goto error;
 
   if ((pdata->flags & FPT) == 0)
diff --git a/newlib/libc/stdio/nano-vfscanf.c b/newlib/libc/stdio/nano-vfscanf.c
@@ -397,7 +397,7 @@ _SVFSCANF (
 	ret = _scanf_i (&scan_data, fp, &ap_copy);
 #ifdef __IO_FLOATING_POINT
       else if (_scanf_float)
-	ret = _scanf_float (rptr, &scan_data, fp, &ap_copy);
+	ret = _scanf_float (&scan_data, fp, &ap_copy);
 #endif
 
       if (ret == MATCH_FAILURE)
diff --git a/newlib/libc/stdio/nano-vfscanf_float.c b/newlib/libc/stdio/nano-vfscanf_float.c
@@ -32,8 +32,7 @@
 
 #ifdef __IO_FLOATING_POINT
 int
-_scanf_float (struct _reent *rptr,
-	      struct _scan_data_t *pdata,
+_scanf_float (struct _scan_data_t *pdata,
 	      FILE *fp, va_list *ap)
 {
   int c;
@@ -84,7 +83,7 @@ _scanf_float (struct _reent *rptr,
 		}
 	      goto fskip;
 	    }
-	/* Fall through.  */
+          __fallthrough;
 	case '1':
 	case '2':
 	case '3':
@@ -212,7 +211,7 @@ _scanf_float (struct _reent *rptr,
       ++pdata->nread;
       if (--fp->_r > 0)
 	fp->_p++;
-      else if (pdata->pfn_refill (rptr, fp))
+      else if (pdata->pfn_refill (fp))
 	/* "EOF".  */
 	break;
     }
@@ -234,7 +233,7 @@ _scanf_float (struct _reent *rptr,
 	 guarantee that in all implementations of ungetc.  */
       while (p > pdata->buf)
 	{
-	  pdata->pfn_ungetc (rptr, *--p, fp); /* "[-+nNaA]".  */
+	  pdata->pfn_ungetc (*--p, fp); /* "[-+nNaA]".  */
 	  --pdata->nread;
 	}
       return MATCH_FAILURE;
@@ -248,14 +247,14 @@ _scanf_float (struct _reent *rptr,
       if (infcount >= 3) /* valid 'inf', but short of 'infinity'.  */
 	while (infcount-- > 3)
 	  {
-	    pdata->pfn_ungetc (rptr, *--p, fp); /* "[iInNtT]".  */
+	    pdata->pfn_ungetc (*--p, fp); /* "[iInNtT]".  */
 	    --pdata->nread;
 	  }
       else
         {
 	  while (p > pdata->buf)
 	    {
-	      pdata->pfn_ungetc (rptr, *--p, fp); /* "[-+iInN]".  */
+	      pdata->pfn_ungetc (*--p, fp); /* "[-+iInN]".  */
 	      --pdata->nread;
 	    }
 	  return MATCH_FAILURE;
@@ -271,7 +270,7 @@ _scanf_float (struct _reent *rptr,
 	  /* No digits at all.  */
 	  while (p > pdata->buf)
 	    {
-	      pdata->pfn_ungetc (rptr, *--p, fp); /* "[-+.]".  */
+	      pdata->pfn_ungetc (*--p, fp); /* "[-+.]".  */
 	      --pdata->nread;
 	    }
 	  return MATCH_FAILURE;
@@ -281,11 +280,11 @@ _scanf_float (struct _reent *rptr,
       --pdata->nread;
       if (c != 'e' && c != 'E')
 	{
-	  pdata->pfn_ungetc (rptr, c, fp); /* "[-+]".  */
+	  pdata->pfn_ungetc (c, fp); /* "[-+]".  */
 	  c = *--p;
 	  --pdata->nread;
 	}
-      pdata->pfn_ungetc (rptr, c, fp); /* "[eE]".  */
+      pdata->pfn_ungetc (c, fp); /* "[eE]".  */
     }
   if ((pdata->flags & SUPPRESS) == 0)
     {
diff --git a/newlib/libc/stdio/stdio.h b/newlib/libc/stdio/stdio.h
@@ -446,7 +446,7 @@ int	siprintf (char *, const char *, ...)
                __picolibc_format(__printf__, 2, 3) __nothrow;
 #define __i_sprintf siprintf
 int	siscanf (const char *, const char *, ...)
-               __picolibc_format(__scanf__,  2, 3);
+               __picolibc_format(__scanf__,  2, 3) __nothrow;
 int	sniprintf (char *, size_t, const char *, ...)
                __picolibc_format(__printf__, 3, 4) __nothrow;
 #define  __i_snprintf sniprintf
@@ -467,9 +467,9 @@ int	viprintf (const char *, va_list)
 int	viscanf (const char *, va_list)
                __picolibc_format(__scanf__,  1, 0);
 int	vsiprintf (char *, const char *, va_list)
-               __picolibc_format(__printf__, 2, 0);
+               __picolibc_format(__printf__, 2, 0) __nothrow;
 int	vsiscanf (const char *, const char *, va_list)
-               __picolibc_format(__scanf__,  2, 0);
+               __picolibc_format(__scanf__,  2, 0) __nothrow;
 int	vsniprintf (char *, size_t, const char *, va_list)
                __picolibc_format(__printf__, 3, 0) __nothrow;
 #endif /* __MISC_VISIBLE */

Original file line number	Diff line number	Diff line change
`@@ -617,7 +617,7 @@ VFPRINTF (`
`617`	`617`	`n = 0;`
`618`	`618`	`}`
`619`	`619`	`else`
`620`		`- n = _printf_float (data, &prt_data, fp, pfunc, &ap_copy);`
	`620`	`+ n = _printf_float (&prt_data, fp, pfunc, &ap_copy);`
`621`	`621`	`}`
`622`	`622`	`else`
`623`	`623`	`#endif`
Original file line number	Diff line number	Diff line change
`@@ -32,8 +32,7 @@`
`32`	`32`
`33`	`33`	`#ifdef __IO_FLOATING_POINT`
`34`	`34`	`int`
`35`		`-_scanf_float (struct _reent *rptr,`
`36`		`- struct _scan_data_t *pdata,`
	`35`	`+_scanf_float (struct _scan_data_t *pdata,`
`37`	`36`	`FILE fp, va_list ap)`
`38`	`37`	`{`
`39`	`38`	`int c;`
`@@ -84,7 +83,7 @@ _scanf_float (struct _reent *rptr,`
`84`	`83`	`}`
`85`	`84`	`goto fskip;`
`86`	`85`	`}`
`87`		`- /* Fall through. */`
	`86`	`+ __fallthrough;`
`88`	`87`	`case '1':`
`89`	`88`	`case '2':`
`90`	`89`	`case '3':`
`@@ -212,7 +211,7 @@ _scanf_float (struct _reent *rptr,`
`212`	`211`	`++pdata->nread;`
`213`	`212`	`if (--fp->_r > 0)`
`214`	`213`	`fp->_p++;`
`215`		`- else if (pdata->pfn_refill (rptr, fp))`
	`214`	`+ else if (pdata->pfn_refill (fp))`
`216`	`215`	`/* "EOF". */`
`217`	`216`	`break;`
`218`	`217`	`}`
`@@ -234,7 +233,7 @@ _scanf_float (struct _reent *rptr,`
`234`	`233`	`guarantee that in all implementations of ungetc. */`
`235`	`234`	`while (p > pdata->buf)`
`236`	`235`	`{`
`237`		`- pdata->pfn_ungetc (rptr, --p, fp); / "[-+nNaA]". */`
	`236`	`+ pdata->pfn_ungetc (--p, fp); / "[-+nNaA]". */`
`238`	`237`	`--pdata->nread;`
`239`	`238`	`}`
`240`	`239`	`return MATCH_FAILURE;`
`@@ -248,14 +247,14 @@ _scanf_float (struct _reent *rptr,`
`248`	`247`	`if (infcount >= 3) /* valid 'inf', but short of 'infinity'. */`
`249`	`248`	`while (infcount-- > 3)`
`250`	`249`	`{`
`251`		`- pdata->pfn_ungetc (rptr, --p, fp); / "[iInNtT]". */`
	`250`	`+ pdata->pfn_ungetc (--p, fp); / "[iInNtT]". */`
`252`	`251`	`--pdata->nread;`
`253`	`252`	`}`
`254`	`253`	`else`
`255`	`254`	`{`
`256`	`255`	`while (p > pdata->buf)`
`257`	`256`	`{`
`258`		`- pdata->pfn_ungetc (rptr, --p, fp); / "[-+iInN]". */`
	`257`	`+ pdata->pfn_ungetc (--p, fp); / "[-+iInN]". */`
`259`	`258`	`--pdata->nread;`
`260`	`259`	`}`
`261`	`260`	`return MATCH_FAILURE;`
`@@ -271,7 +270,7 @@ _scanf_float (struct _reent *rptr,`
`271`	`270`	`/* No digits at all. */`
`272`	`271`	`while (p > pdata->buf)`
`273`	`272`	`{`
`274`		`- pdata->pfn_ungetc (rptr, --p, fp); / "[-+.]". */`
	`273`	`+ pdata->pfn_ungetc (--p, fp); / "[-+.]". */`
`275`	`274`	`--pdata->nread;`
`276`	`275`	`}`
`277`	`276`	`return MATCH_FAILURE;`
`@@ -281,11 +280,11 @@ _scanf_float (struct _reent *rptr,`
`281`	`280`	`--pdata->nread;`
`282`	`281`	`if (c != 'e' && c != 'E')`
`283`	`282`	`{`
`284`		`- pdata->pfn_ungetc (rptr, c, fp); /* "[-+]". */`
	`283`	`+ pdata->pfn_ungetc (c, fp); /* "[-+]". */`
`285`	`284`	`c = *--p;`
`286`	`285`	`--pdata->nread;`
`287`	`286`	`}`
`288`		`- pdata->pfn_ungetc (rptr, c, fp); /* "[eE]". */`
	`287`	`+ pdata->pfn_ungetc (c, fp); /* "[eE]". */`
`289`	`288`	`}`
`290`	`289`	`if ((pdata->flags & SUPPRESS) == 0)`
`291`	`290`	`{`