imrat: fix an inconsistency in reading string values (#62)

Make mp_rat_read_cstring more consistent with mp_int_read_cstring.
Add some tests for that.

Updates #57

Makefile

@@ -45,7 +45,7 @@ DFLAGSY=-g -DDEBUG=1
 
 # --- end of configuration section ---
 
-TARGETS=bintest bug-swap imtest imtimer rtest
+TARGETS=bintest bug-swap bug-qread imtest imtimer rtest
 HDRS=imath.h imrat.h iprime.h imdrover.h rsamath.h gmp_compat.h
 SRCS=$(HDRS:.h=.c) $(TARGETS:=.c)
 OBJS=$(SRCS:.c=.o)
@@ -79,7 +79,7 @@ objs: $(OBJS)
 check: test gmp-compat-test
 	@ echo "Completed running imath and gmp-compat unit tests"
 
-test: imtest pi bug-swap doc.md
+test: imtest pi bug-swap bug-qread doc.md
 	@ echo ""
 	@ echo "Running tests, you should not see any 'FAILED' lines here."
 	@ echo "If you do, please see doc.txt for how to report a bug."
@@ -100,7 +100,7 @@ docker-test: docker-image
 $(EXAMPLES):%: imath.o imrat.o iprime.o %.o
 	$(CC) $(CFLAGS) -o $@ $^ $(LIBS)
 
-$(TARGETS):%: imath.o %.o
+$(TARGETS):%: imath.o imrat.o %.o
 	$(CC) $(CFLAGS) -o $@ $^ $(LIBS)
 
 examples: $(EXAMPLES)

imrat.c

@@ -669,16 +669,18 @@ mp_result mp_rat_read_cstring(mp_rat r, mp_size radix, const char *str,
   }
 
   /* Skip whitespace between numerator and (possible) separator */
-  while (isspace((unsigned char)*endp)) {
-    ++endp;
+  char *sp = endp;
+  while (isspace((unsigned char)*sp)) {
+    ++sp;
   }
 
   /* If there is no separator, we will stop reading at this point. */
-  if (*endp != '/') {
+  if (*sp != '/') {
     mp_int_set_value(MP_DENOM_P(r), 1);
     if (end != NULL) *end = endp;
     return res;
   }
+  endp = sp;
 
   ++endp; /* skip separator */
   if ((res = mp_int_read_cstring(MP_DENOM_P(r), radix, endp, end)) != MP_OK) {

tests/bug-qread.c

@@ -0,0 +1,38 @@
+#include <stdio.h>
+
+#include "imrat.h"
+
+struct test {
+  char* input;
+  int radix;
+  mp_result want;
+};
+
+int main(int arch, char* argv[]) {
+  struct test tests[] = {
+    {"123", 10, 0},
+    {"  1ca", 16, 0},
+    {"1010", 2, 0},
+    {"123 ", 10, -5}, /* MP_TRUNC */
+    {"123/456", 8, 0},
+    {"123 / 456", 8, 0},
+    {"123 /", 8, -4}, /* MP_UNDEF */
+    {" -5/-3", 10, 0},
+    {NULL, 10, 0},
+  };
+
+  int errs = 0;
+  for (int i = 0; tests[i].input != NULL; i++) {
+    mpq_t value;
+    mp_rat_init(&value);
+
+    mp_result got = mp_rat_read_cstring(&value, tests[i].radix, tests[i].input, NULL);
+    if (got != tests[i].want) {
+      printf("ERROR: test %d: input \"%s\": got \"%s\", want \"%s\"\n",
+             i+1, tests[i].input, mp_error_string(got), mp_error_string(tests[i].want));
+    }
+  }
+  printf("REGRESSION: mp_rat_read_cstring inconsistent space handling: %s\n",
+         errs ? "FAILED" : "OK");
+  return !errs;
+}

tests/test.sh

@@ -58,7 +58,7 @@ pitest 4096 10 pi4096-10.txt
 echo ""
 echo "-- Running regression tests"
 
-for bug in bug-swap ; do
+for bug in bug-qread bug-swap ; do
     ../${bug}
 done