[PATCH 2/2] utils: Work around mingw strto*l bug with 0x

[Eric Blake <eblake@redhat.com>]

Mingw recognizes that "0x" has value 0 without setting errno, but
fails to advance endptr to the trailing garbage 'x'.  This in turn
showed up in our recent testsuite additions for qemu_strtosz (commit
1657ba44b4 utils: Enhance testsuite for do_strtosz()); adjust our
remaining tests to show that we now work around this windows bug.

This patch intentionally fails check-syntax for use of strtol.

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 tests/unit/test-cutils.c | 54 ++++++++++++++++++++++++++++++++++++++++
 util/cutils.c            | 29 +++++++++++++++------
 2 files changed, 75 insertions(+), 8 deletions(-)

diff --git a/tests/unit/test-cutils.c b/tests/unit/test-cutils.c
index 5908de4fd041..98671f1ac30e 100644
--- a/tests/unit/test-cutils.c
+++ b/tests/unit/test-cutils.c
@@ -378,6 +378,15 @@ static void test_qemu_strtoi_hex(void)
     g_assert_cmpint(err, ==, 0);
     g_assert_cmpint(res, ==, 0x123);
     g_assert(endptr == str + strlen(str));
+
+    str = "0x";
+    res = 999;
+    endptr = &f;
+    err = qemu_strtoi(str, &endptr, 16, &res);
+
+    g_assert_cmpint(err, ==, 0);
+    g_assert_cmpint(res, ==, 0);
+    g_assert(endptr == str + 1);
 }

 static void test_qemu_strtoi_max(void)
@@ -669,6 +678,15 @@ static void test_qemu_strtoui_hex(void)
     g_assert_cmpint(err, ==, 0);
     g_assert_cmphex(res, ==, 0x123);
     g_assert(endptr == str + strlen(str));
+
+    str = "0x";
+    res = 999;
+    endptr = &f;
+    err = qemu_strtoui(str, &endptr, 16, &res);
+
+    g_assert_cmpint(err, ==, 0);
+    g_assert_cmphex(res, ==, 0);
+    g_assert(endptr == str + 1);
 }

 static void test_qemu_strtoui_max(void)
@@ -955,6 +973,15 @@ static void test_qemu_strtol_hex(void)
     g_assert_cmpint(err, ==, 0);
     g_assert_cmpint(res, ==, 0x123);
     g_assert(endptr == str + strlen(str));
+
+    str = "0x";
+    res = 999;
+    endptr = &f;
+    err = qemu_strtol(str, &endptr, 16, &res);
+
+    g_assert_cmpint(err, ==, 0);
+    g_assert_cmpint(res, ==, 0);
+    g_assert(endptr == str + 1);
 }

 static void test_qemu_strtol_max(void)
@@ -1244,6 +1271,15 @@ static void test_qemu_strtoul_hex(void)
     g_assert_cmpint(err, ==, 0);
     g_assert_cmphex(res, ==, 0x123);
     g_assert(endptr == str + strlen(str));
+
+    str = "0x";
+    res = 999;
+    endptr = &f;
+    err = qemu_strtoul(str, &endptr, 16, &res);
+
+    g_assert_cmpint(err, ==, 0);
+    g_assert_cmphex(res, ==, 0);
+    g_assert(endptr == str + 1);
 }

 static void test_qemu_strtoul_max(void)
@@ -1528,6 +1564,15 @@ static void test_qemu_strtoi64_hex(void)
     g_assert_cmpint(err, ==, 0);
     g_assert_cmpint(res, ==, 0x123);
     g_assert(endptr == str + strlen(str));
+
+    str = "0x";
+    endptr = &f;
+    res = 999;
+    err = qemu_strtoi64(str, &endptr, 16, &res);
+
+    g_assert_cmpint(err, ==, 0);
+    g_assert_cmpint(res, ==, 0);
+    g_assert(endptr == str + 1);
 }

 static void test_qemu_strtoi64_max(void)
@@ -1815,6 +1860,15 @@ static void test_qemu_strtou64_hex(void)
     g_assert_cmpint(err, ==, 0);
     g_assert_cmphex(res, ==, 0x123);
     g_assert(endptr == str + strlen(str));
+
+    str = "0x";
+    endptr = &f;
+    res = 999;
+    err = qemu_strtou64(str, &endptr, 16, &res);
+
+    g_assert_cmpint(err, ==, 0);
+    g_assert_cmphex(res, ==, 0);
+    g_assert(endptr == str + 1);
 }

 static void test_qemu_strtou64_max(void)
diff --git a/util/cutils.c b/util/cutils.c
index b425ed6570c3..ee908486da44 100644
--- a/util/cutils.c
+++ b/util/cutils.c
@@ -396,9 +396,22 @@ int qemu_strtosz_metric(const char *nptr, const char **end, uint64_t *result)
  * Helper function for error checking after strtol() and the like
  */
 static int check_strtox_error(const char *nptr, char *ep,
-                              const char **endptr, int libc_errno)
+                              const char **endptr, bool check_zero,
+                              int libc_errno)
 {
     assert(ep >= nptr);
+
+    /* Windows has a bug in that it fails to parse 0 from "0x" in base 16 */
+    if (check_zero && ep == nptr && libc_errno == 0) {
+        char *tmp;
+
+        errno = 0;
+        if (strtol(nptr, &tmp, 10) == 0 && errno == 0 &&
+            (*tmp == 'x' || *tmp == 'X')) {
+            ep = tmp;
+        }
+    }
+
     if (endptr) {
         *endptr = ep;
     }
@@ -465,7 +478,7 @@ int qemu_strtoi(const char *nptr, const char **endptr, int base,
     } else {
         *result = lresult;
     }
-    return check_strtox_error(nptr, ep, endptr, errno);
+    return check_strtox_error(nptr, ep, endptr, lresult == 0, errno);
 }

 /**
@@ -524,7 +537,7 @@ int qemu_strtoui(const char *nptr, const char **endptr, int base,
             *result = lresult;
         }
     }
-    return check_strtox_error(nptr, ep, endptr, errno);
+    return check_strtox_error(nptr, ep, endptr, lresult == 0, errno);
 }

 /**
@@ -566,7 +579,7 @@ int qemu_strtol(const char *nptr, const char **endptr, int base,

     errno = 0;
     *result = strtol(nptr, &ep, base);
-    return check_strtox_error(nptr, ep, endptr, errno);
+    return check_strtox_error(nptr, ep, endptr, *result == 0, errno);
 }

 /**
@@ -613,7 +626,7 @@ int qemu_strtoul(const char *nptr, const char **endptr, int base,
     if (errno == ERANGE) {
         *result = -1;
     }
-    return check_strtox_error(nptr, ep, endptr, errno);
+    return check_strtox_error(nptr, ep, endptr, *result == 0, errno);
 }

 /**
@@ -639,7 +652,7 @@ int qemu_strtoi64(const char *nptr, const char **endptr, int base,
     QEMU_BUILD_BUG_ON(sizeof(int64_t) != sizeof(long long));
     errno = 0;
     *result = strtoll(nptr, &ep, base);
-    return check_strtox_error(nptr, ep, endptr, errno);
+    return check_strtox_error(nptr, ep, endptr, *result == 0, errno);
 }

 /**
@@ -668,7 +681,7 @@ int qemu_strtou64(const char *nptr, const char **endptr, int base,
     if (errno == ERANGE) {
         *result = -1;
     }
-    return check_strtox_error(nptr, ep, endptr, errno);
+    return check_strtox_error(nptr, ep, endptr, *result == 0, errno);
 }

 /**
@@ -708,7 +721,7 @@ int qemu_strtod(const char *nptr, const char **endptr, double *result)

     errno = 0;
     *result = strtod(nptr, &ep);
-    return check_strtox_error(nptr, ep, endptr, errno);
+    return check_strtox_error(nptr, ep, endptr, false, errno);
 }

 /**
-- 
2.30.2