[builtin/printf] Fix integer truncation by using mops::BigInt

I think we still have a year 2038 problem to fix.  Can test that.

Author: Andy C

builtin/printf_osh.py

@@ -299,29 +299,27 @@ def _Percent(self, pr, part, varargs, locs):
             # %(...)T and %d share this complex integer conversion logic
 
             if match.LooksLikeInteger(s):
-                # note: spaces like ' -42 ' accepted and normalized
-                # TODO: use mops.FromStr()
-                # And mylib.hex_lower() etc. may have to change
-                d = int(s)
+                # Note: spaces like ' -42 ' accepted and normalized
+                d = mops.FromStr(s)
 
             else:
                 # 'a is interpreted as the ASCII value of 'a'
                 if len(s) >= 1 and s[0] in '\'"':
                     if len(s) == 1:
                         # NUL after quote
-                        d = 0
+                        d = mops.ZERO
                     else:
                         # TODO: utf-8 decode s[1:] to be more
                         # correct.  Probably depends on issue #366,
                         # a utf-8 library.
-                        d = ord(s[1])
+                        d = mops.IntWiden(ord(s[1]))
 
                 # No argument means -1 for %(...)T as in Bash #
                 # Reference Manual 4.2 "If no argument is
                 # specified, conversion behaves as if -1 had been
                 # given."
                 elif not has_arg and part.type.id == Id.Format_Time:
-                    d = -1
+                    d = mops.MINUS_ONE
 
                 else:
                     if has_arg:
@@ -361,33 +359,34 @@ def _Percent(self, pr, part, varargs, locs):
                 #   used: -1 represents the current time, and -2 represents the
                 #   time the shell was invoked." from
                 #   https://www.gnu.org/software/bash/manual/html_node/Bash-Builtins.html#index-printf
-                if d == -1:  # the current time
+                if mops.Equal(d, mops.MINUS_ONE):  # -1 is current time
+                    # TODO: 2038 problem
                     ts = time_.time()
-                elif d == -2:  # the shell start time
+                elif mops.Equal(d, mops.MINUS_TWO):  # -2 is shell start time
                     ts = self.shell_start_time
                 else:
-                    ts = d
+                    ts = mops.BigTruncate(d)
 
                 s = time_.strftime(typ[1:-2], time_.localtime(ts))
                 if precision >= 0:
                     s = s[:precision]  # truncate
 
             else:  # typ in 'diouxX'
                 # Disallowed because it depends on 32- or 64- bit
-                if d < 0 and typ in 'ouxX':
+                if mops.Greater(mops.ZERO, d) and typ in 'ouxX':
+                    # TODO: Don't truncate it
                     e_die(
-                        "Can't format negative number %d with %%%s" % (d, typ),
-                        part.type)
+                        "Can't format negative number with %%%s: %d" %
+                        (typ, mops.BigTruncate(d)), part.type)
 
-                big_d = mops.IntWiden(d)
                 if typ == 'o':
-                    s = mops.ToOctal(big_d)
+                    s = mops.ToOctal(d)
                 elif typ == 'x':
-                    s = mops.ToHexLower(big_d)
+                    s = mops.ToHexLower(d)
                 elif typ == 'X':
-                    s = mops.ToHexUpper(big_d)
+                    s = mops.ToHexUpper(d)
                 else:  # diu
-                    s = mops.ToStr(big_d)  # without spaces like ' -42 '
+                    s = mops.ToStr(d)  # without spaces like ' -42 '
 
                 # There are TWO different ways to ZERO PAD, and they differ on
                 # the negative sign!  See spec/builtin-printf

mycpp/gc_mops.cc

@@ -13,6 +13,7 @@ namespace mops {
 const BigInt ZERO = BigInt{0};
 const BigInt ONE = BigInt{1};
 const BigInt MINUS_ONE = BigInt{-1};
+const BigInt MINUS_TWO = BigInt{-2};  // for printf
 
 static const int kInt64BufSize = 32;  // more than twice as big as kIntBufSize
 

mycpp/gc_mops.h

@@ -21,6 +21,7 @@ typedef int64_t BigInt;
 extern const BigInt ZERO;
 extern const BigInt ONE;
 extern const BigInt MINUS_ONE;
+extern const BigInt MINUS_TWO;
 
 BigStr* ToStr(BigInt b);
 BigStr* ToOctal(BigInt b);

mycpp/mops.py

@@ -49,6 +49,7 @@ def __hash__(self):
 ZERO = BigInt(0)
 ONE = BigInt(1)
 MINUS_ONE = BigInt(-1)
+MINUS_TWO = BigInt(-2)  # for printf
 
 
 def ToStr(b):

spec/builtin-printf.test.sh

@@ -357,7 +357,7 @@ printf '[%X]\n' \'ab # extra chars ignored
 
 #### unsigned / octal / hex big
 
-for big in $(( 1 << 32 )) $(( 1 << 63 )); do
+for big in $(( 1 << 32 )) $(( (1 << 63) - 1 )); do
   printf '[%u]\n' $big
   printf '[%o]\n' $big
   printf '[%x]\n' $big
@@ -371,10 +371,10 @@ done
 [100000000]
 [100000000]
 
-[9223372036854775808]
-[1000000000000000000000]
-[8000000000000000]
-[8000000000000000]
+[9223372036854775807]
+[777777777777777777777]
+[7fffffffffffffff]
+[7FFFFFFFFFFFFFFF]
 
 ## END