mpq_*_str: document and support the correct base range

3 files changed, 33 insertions, 11 deletions

diff --git a/ChangeLog b/ChangeLog
index 6d027e6b4..86885c20a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2018-05-04 Marco Bodrato <bodrato@mail.dm.unipi.it>
+
+	* doc/gmp.texi (mpq_*_str): Document the full base allowed range.
+	* mpq/get_str.c: Make all bases either work or return an error.
+
 2018-04-27  Niels Möller  <nisse@lysator.liu.se>
 
 	* mpn/generic/div_q.c (mpn_div_q): Replace dead code with ASSERT.
diff --git a/doc/gmp.texi b/doc/gmp.texi
index 9ebf2b082..15ce9ad85 100644
--- a/doc/gmp.texi
+++ b/doc/gmp.texi
@@ -14,7 +14,7 @@
 This manual describes how to install and use the GNU multiple precision
 arithmetic library, version @value{VERSION}.
 
-Copyright 1991, 1993-2016 Free Software Foundation, Inc.
+Copyright 1991, 1993-2016, 2018 Free Software Foundation, Inc.
 
 Permission is granted to copy, distribute and/or modify this document under
 the terms of the GNU Free Documentation License, Version 1.3 or any later
@@ -4365,9 +4365,14 @@ is exact.
 @end deftypefun
 
 @deftypefun {char *} mpq_get_str (char *@var{str}, int @var{base}, const mpq_t @var{op})
-Convert @var{op} to a string of digits in base @var{base}.  The base may vary
-from 2 to 36.  The string will be of the form @samp{num/den}, or if the
-denominator is 1 then just @samp{num}.
+Convert @var{op} to a string of digits in base @var{base}.  The base argument
+may vary from 2 to 62 or from @minus{}2 to @minus{}36.  The string will be of
+the form @samp{num/den}, or if the denominator is 1 then just @samp{num}.
+
+For @var{base} in the range 2..36, digits and lower-case letters are used; for
+@minus{}2..@minus{}36, digits and upper-case letters are used; for 37..62,
+digits, upper-case letters, and lower-case letters (in that significance order)
+are used.
 
 If @var{str} is @code{NULL}, the result string is allocated using the current
 allocation function (@pxref{Custom Allocation}).  The block will be
@@ -4535,9 +4540,15 @@ See also @ref{Formatted Output} and @ref{Formatted Input}.
 
 @deftypefun size_t mpq_out_str (FILE *@var{stream}, int @var{base}, const mpq_t @var{op})
 Output @var{op} on stdio stream @var{stream}, as a string of digits in base
-@var{base}.  The base may vary from 2 to 36.  Output is in the form
+@var{base}.  The base argument may vary from 2 to 62 or from @minus{}2 to
+@minus{}36. Output is in the form
 @samp{num/den} or if the denominator is 1 then just @samp{num}.
 
+For @var{base} in the range 2..36, digits and lower-case letters are used; for
+@minus{}2..@minus{}36, digits and upper-case letters are used; for 37..62,
+digits, upper-case letters, and lower-case letters (in that significance order)
+are used.
+
 Return the number of bytes written, or if an error occurred, return 0.
 @end deftypefun
 
@@ -4553,9 +4564,10 @@ space is not permitted within the string.  If the input might not be in
 canonical form, then @code{mpq_canonicalize} must be called (@pxref{Rational
 Number Functions}).
 
-The @var{base} can be between 2 and 36, or can be 0 in which case the leading
+The @var{base} can be between 2 and 62, or can be 0 in which case the leading
 characters of the string determine the base, @samp{0x} or @samp{0X} for
-hexadecimal, @samp{0} for octal, or decimal otherwise.  The leading characters
+hexadecimal, @code{0b} and @code{0B} for binary, @samp{0} for octal, or
+decimal otherwise.  The leading characters
 are examined separately for the numerator and denominator of a fraction, so
 for instance @samp{0x10/11} is @math{16/11}, whereas @samp{0x10/0x11} is
 @math{16/17}.
diff --git a/mpq/get_str.c b/mpq/get_str.c
index 881340fb9..d0cfb58dd 100644
--- a/mpq/get_str.c
+++ b/mpq/get_str.c
@@ -1,6 +1,6 @@
 /* mpq_get_str -- mpq to string conversion.
 
-Copyright 2001, 2002, 2006, 2011 Free Software Foundation, Inc.
+Copyright 2001, 2002, 2006, 2011, 2018 Free Software Foundation, Inc.
 
 This file is part of the GNU MP Library.
 
@@ -47,6 +47,8 @@ mpq_get_str (char *str, int base, mpq_srcptr q)
       /* This is an overestimate since we don't bother checking how much of
 	 the high limbs of num and den are used.  +2 for rounding up the
 	 chars per bit of num and den.  +3 for sign, slash and '\0'.  */
+      if (ABS(base) < 2)
+	base = 10;
       DIGITS_IN_BASE_PER_LIMB (str_alloc, ABSIZ(NUM(q)) + SIZ(DEN(q)), ABS(base));
       str_alloc += 6;
 
@@ -64,9 +66,12 @@ mpq_get_str (char *str, int base, mpq_srcptr q)
 
   ASSERT (len == strlen(str));
   ASSERT (str_alloc == 0 || len+1 <= str_alloc);
-  ASSERT (len+1 <=  /* size recommended to applications */
-	  mpz_sizeinbase (mpq_numref(q), ABS(base)) +
-	  mpz_sizeinbase (mpq_denref(q), ABS(base)) + 3);
+  ASSERT (len+1 <= 3 + /* size recommended to applications */
+	  (ABS(base) < 2 ?
+	   mpz_sizeinbase (mpq_numref(q), 10) +
+	   mpz_sizeinbase (mpq_denref(q), 10)
+	   : mpz_sizeinbase (mpq_numref(q), ABS(base)) +
+	   mpz_sizeinbase (mpq_denref(q), ABS(base))));
 
   if (str_alloc != 0)
     __GMP_REALLOCATE_FUNC_MAYBE_TYPE (str, str_alloc, len+1, char);