[gcc r13-4455] analyzer: add test coverage for string ops

[gcc r13-4455] analyzer: add test coverage for string ops

[David Malcolm]

https://gcc.gnu.org/g:5cb7d28dcfb11a2810db55b0bbd71fe562bdc2a3

commit r13-4455-g5cb7d28dcfb11a2810db55b0bbd71fe562bdc2a3
Author: David Malcolm <dmalcolm@redhat.com>
Date:   Thu Dec 1 21:28:55 2022 -0500

    analyzer: add test coverage for string ops
    
    gcc/testsuite/ChangeLog:
            * gcc.dg/analyzer/string-ops-concat-pair.c: New test.
            * gcc.dg/analyzer/string-ops-dup.c: New test.
    
    Signed-off-by: David Malcolm <dmalcolm@redhat.com>

Diff:
---
 .../gcc.dg/analyzer/string-ops-concat-pair.c       | 67 ++++++++++++++++++++++
 gcc/testsuite/gcc.dg/analyzer/string-ops-dup.c     | 61 ++++++++++++++++++++
 2 files changed, 128 insertions(+)

diff --git a/gcc/testsuite/gcc.dg/analyzer/string-ops-concat-pair.c b/gcc/testsuite/gcc.dg/analyzer/string-ops-concat-pair.c
new file mode 100644
index 00000000000..f5bcd67594f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/string-ops-concat-pair.c
@@ -0,0 +1,67 @@
+typedef __SIZE_TYPE__ size_t;
+#define NULL ((void *)0)
+
+/* Concatenating a pair of strings.  */
+
+/* Correct but poor implementation with repeated __builtin_strlen calls.  */
+
+char *
+alloc_dup_of_concatenated_pair_1_correct (const char *x, const char *y)
+{
+  size_t sz = __builtin_strlen (x) + __builtin_strlen (y) + 1;
+  char *result = __builtin_malloc (sz);
+  if (!result)
+    return NULL;
+  __builtin_memcpy (result, x, __builtin_strlen (x));
+  __builtin_memcpy (result + __builtin_strlen (x), y, __builtin_strlen (y));
+  result[__builtin_strlen(x) + __builtin_strlen (y)] = '\0';
+  return result;
+}
+
+/* Incorrect version: forgetting to add space for terminator.  */
+
+char *
+alloc_dup_of_concatenated_pair_1_incorrect (const char *x, const char *y)
+{
+  /* Forgetting to add space for the terminator here.  */
+  size_t sz = __builtin_strlen (x) + __builtin_strlen (y);
+  char *result = __builtin_malloc (sz);
+  if (!result)
+    return NULL;
+  __builtin_memcpy (result, x, __builtin_strlen (x));
+  __builtin_memcpy (result + __builtin_strlen (x), y, __builtin_strlen (y));
+  result[__builtin_strlen(x) + __builtin_strlen (y)] = '\0'; /* { dg-warning "heap-based buffer overflow" "PR analyzer/105899" { xfail *-*-* } } */
+  return result;
+}
+
+/* As above, but only calling __builtin_strlen once on each input.  */
+
+char *
+alloc_dup_of_concatenated_pair_2_correct (const char *x, const char *y)
+{
+  size_t len_x = __builtin_strlen (x);
+  size_t len_y = __builtin_strlen (y);
+  size_t sz = len_x + len_y + 1;
+  char *result = __builtin_malloc (sz);
+  if (!result)
+    return NULL;
+  __builtin_memcpy (result, x, len_x);
+  __builtin_memcpy (result + len_x, y, len_y);
+  result[len_x + len_y] = '\0';
+  return result;
+}
+
+char *
+alloc_dup_of_concatenated_pair_2_incorrect (const char *x, const char *y)
+{
+  size_t len_x = __builtin_strlen (x);
+  size_t len_y = __builtin_strlen (y);
+  size_t sz = len_x + len_y; /* Forgetting to add space for the terminator.  */
+  char *result = __builtin_malloc (sz); /* { dg-message "capacity: 'len_x \\+ len_y' bytes" } */
+  if (!result)
+    return NULL;
+  __builtin_memcpy (result, x, len_x);
+  __builtin_memcpy (result + len_x, y, len_y);
+  result[len_x + len_y] = '\0'; /* { dg-warning "heap-based buffer overflow" } */
+  return result;
+}
diff --git a/gcc/testsuite/gcc.dg/analyzer/string-ops-dup.c b/gcc/testsuite/gcc.dg/analyzer/string-ops-dup.c
new file mode 100644
index 00000000000..44c4e9dc67e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/string-ops-dup.c
@@ -0,0 +1,61 @@
+typedef __SIZE_TYPE__ size_t;
+#define NULL ((void *)0)
+
+/* Duplicating a string.  */
+
+/* Correct but poor implementation with repeated __builtin_strlen calls.  */
+
+char *
+alloc_dup_1_correct (const char *x)
+{
+  size_t sz = __builtin_strlen (x) + 1;
+  char *result = __builtin_malloc (sz);
+  if (!result)
+    return NULL;
+  __builtin_memcpy (result, x, __builtin_strlen (x));
+  result[__builtin_strlen(x)] = '\0';
+  return result;
+}
+
+/* Incorrect version: forgetting to add space for terminator.  */
+
+char *
+alloc_dup_1_incorrect (const char *x, const char *y)
+{
+  /* Forgetting to add space for the terminator here.  */
+  size_t sz = __builtin_strlen (x) + 1;
+  char *result = __builtin_malloc (sz);
+  if (!result)
+    return NULL;
+  __builtin_memcpy (result, x, __builtin_strlen (x));
+  result[__builtin_strlen(x)] = '\0'; /* { dg-warning "heap-based buffer overflow" "PR analyzer/105899" { xfail *-*-* } } */
+  return result;
+}
+
+/* As above, but only calling __builtin_strlen once.  */
+
+char *
+alloc_dup_2_correct (const char *x)
+{
+  size_t len_x = __builtin_strlen (x);
+  size_t sz = len_x + 1;
+  char *result = __builtin_malloc (sz);
+  if (!result)
+    return NULL;
+  __builtin_memcpy (result, x, len_x);
+  result[len_x] = '\0';
+  return result;
+}
+
+char *
+alloc_dup_of_concatenated_pair_2_incorrect (const char *x, const char *y)
+{
+  size_t len_x = __builtin_strlen (x);
+  size_t sz = len_x; /* Forgetting to add space for the terminator.  */
+  char *result = __builtin_malloc (sz); /* { dg-message "capacity: 'len_x' bytes" } */
+  if (!result)
+    return NULL;
+  __builtin_memcpy (result, x, len_x);
+  result[len_x] = '\0'; /* { dg-warning "heap-based buffer overflow" } */
+  return result;
+}