[PATCH 01/13] gdbsupport: remove uses of vsprintf

[Simon Marchi]

When building on macOS, I get:

      CXX      common-utils.o
    /Users/smarchi/src/binutils-gdb/gdbsupport/common-utils.cc:106:3: error: 'vsprintf' is deprecated: This function is provided for compatibility reasons only.  Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use vsnprintf(3) instead. [-Werror,-Wdeprecated-declarations]
      106 |   vsprintf (&str[0], fmt, vp);
          |   ^
    /Users/smarchi/src/binutils-gdb/gdbsupport/common-utils.cc:128:3: error: 'vsprintf' is deprecated: This function is provided for compatibility reasons only.  Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use vsnprintf(3) instead. [-Werror,-Wdeprecated-declarations]
      128 |   vsprintf (&str[0], fmt, args);
          |   ^
    /Users/smarchi/src/binutils-gdb/gdbsupport/common-utils.cc:166:3: error: 'vsprintf' is deprecated: This function is provided for compatibility reasons only.  Due to security concerns inherent in the design of sprintf(3), it is highly recommended that you use vsnprintf(3) instead. [-Werror,-Wdeprecated-declarations]
      166 |   vsprintf (&str[curr_size], fmt, args);
          |   ^

We know that those calls should be safe because we computed the size that
fmt+args take just before, and allocated that many bytes.  But I also
don't see a real downside in switching those calls to use vsnprintf and
double check that everything went right.

Change the type of the existing "size" variable in "string_vprintf" to
"int", since that's what vsnprintf returns.

Change-Id: I589d9a170fdd15cc31b44b76689c6d8c324e340a
---
 gdbsupport/common-utils.cc | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/gdbsupport/common-utils.cc b/gdbsupport/common-utils.cc
index 3ae3afcc380b..f31699be13a1 100644
--- a/gdbsupport/common-utils.cc
+++ b/gdbsupport/common-utils.cc
@@ -92,10 +92,9 @@ std::string
 string_printf (const char* fmt, ...)
 {
   va_list vp;
-  int size;
 
   va_start (vp, fmt);
-  size = vsnprintf (NULL, 0, fmt, vp);
+  int size = vsnprintf (NULL, 0, fmt, vp);
   va_end (vp);
 
   std::string str (size, '\0');
@@ -103,7 +102,8 @@ string_printf (const char* fmt, ...)
   /* C++11 and later guarantee std::string uses contiguous memory and
      always includes the terminating '\0'.  */
   va_start (vp, fmt);
-  vsprintf (&str[0], fmt, vp);
+  int ret = vsnprintf (&str[0], size + 1, fmt, vp);
+  gdb_assert (ret == size);
   va_end (vp);
 
   return str;
@@ -115,17 +115,17 @@ std::string
 string_vprintf (const char* fmt, va_list args)
 {
   va_list vp;
-  size_t size;
 
   va_copy (vp, args);
-  size = vsnprintf (NULL, 0, fmt, vp);
+  int size = vsnprintf (NULL, 0, fmt, vp);
   va_end (vp);
 
   std::string str (size, '\0');
 
   /* C++11 and later guarantee std::string uses contiguous memory and
      always includes the terminating '\0'.  */
-  vsprintf (&str[0], fmt, args);
+  int ret = vsnprintf (&str[0], size + 1, fmt, args);
+  gdb_assert (ret == size);
 
   return str;
 }
@@ -152,10 +152,9 @@ std::string &
 string_vappendf (std::string &str, const char *fmt, va_list args)
 {
   va_list vp;
-  int grow_size;
 
   va_copy (vp, args);
-  grow_size = vsnprintf (NULL, 0, fmt, vp);
+  int grow_size = vsnprintf (NULL, 0, fmt, vp);
   va_end (vp);
 
   size_t curr_size = str.size ();
@@ -163,7 +162,8 @@ string_vappendf (std::string &str, const char *fmt, va_list args)
 
   /* C++11 and later guarantee std::string uses contiguous memory and
      always includes the terminating '\0'.  */
-  vsprintf (&str[curr_size], fmt, args);
+  int ret = vsnprintf (&str[curr_size], grow_size + 1, fmt, args);
+  gdb_assert (ret == grow_size);
 
   return str;
 }
-- 
2.55.0