build: assume standard snprintf()

Stop detecting standard `snprintf()`, and expect it to be available.

Except for the only known platform where it's missing: Visual Studio
2013 and older, where we keep using the existing local implementation.

`snprintf()` was already required to build examples and tests.

Closes #2326

CMakeLists.txt

@@ -312,7 +312,6 @@ include(PickyWarnings)
 # Keep this synced with src/libssh2_setup.h
 if(WIN32)
   if(MINGW)
-    set(HAVE_SNPRINTF 1)
     set(HAVE_UNISTD_H 1)
     set(HAVE_INTTYPES_H 1)
     set(HAVE_SYS_TIME_H 1)
@@ -330,11 +329,6 @@ if(WIN32)
       set(HAVE_STRTOLL 0)
       set(HAVE_STRTOI64 1)
     endif()
-    if(MSVC_VERSION GREATER_EQUAL 1900)
-      set(HAVE_SNPRINTF 1)
-    else()
-      set(HAVE_SNPRINTF 0)
-    endif()
   endif()
   set(HAVE_POLL 0)
   set(HAVE_SELECT 1)
@@ -372,7 +366,6 @@ if(NOT HAVE_STRTOLL)
   # Try _strtoi64() if strtoll() is not available
   check_symbol_exists("_strtoi64" "stdlib.h" HAVE_STRTOI64)
 endif()
-check_symbol_exists("snprintf" "stdio.h" HAVE_SNPRINTF)
 if(NOT WIN32)
   check_symbol_exists("explicit_bzero" "string.h" HAVE_EXPLICIT_BZERO)
   check_symbol_exists("explicit_memset" "string.h" HAVE_EXPLICIT_MEMSET)

configure.ac

@@ -409,7 +409,7 @@ case $host in
     ;;
 esac
 
-AC_CHECK_FUNCS(gettimeofday select strtoll explicit_bzero explicit_memset memset_s snprintf)
+AC_CHECK_FUNCS(gettimeofday select strtoll explicit_bzero explicit_memset memset_s)
 
 dnl Check for select() into ws2_32 for Msys/Mingw
 if test "$ac_cv_func_select" != "yes"; then

os400/libssh2_config.h

@@ -120,10 +120,6 @@
 /* Use OS/400 Qc3 */
 #define LIBSSH2_OS400QC3
 
-/* Use our platform-specific local implementation:
-   _libssh2_os400_snprintf */
-#define HAVE_SNPRINTF 1
-
 /* Define to the subdirectory in which libtool stores uninstalled libraries.
  */
 #define LT_OBJDIR ".libs/"

src/libssh2_config_cmake.h.in

@@ -49,7 +49,6 @@
 #cmakedefine HAVE_GETTIMEOFDAY
 #cmakedefine HAVE_STRTOLL
 #cmakedefine HAVE_STRTOI64
-#cmakedefine HAVE_SNPRINTF
 #cmakedefine HAVE_EXPLICIT_BZERO
 #cmakedefine HAVE_EXPLICIT_MEMSET
 #cmakedefine HAVE_MEMSET_S

src/libssh2_priv.h

@@ -138,12 +138,12 @@
 #define SSH2_PRINTF(fmt, arg)
 #endif
 
-/* Use local implementation when not available */
-#ifdef HAVE_SNPRINTF
-#define ssh2_snprintf snprintf
-#else
+/* Use local implementation with <VS2015 */
+#if defined(_MSC_VER) && _MSC_VER < 1900
 int ssh2_snprintf(char *cp, size_t cp_max_len, const char *fmt, ...)
     SSH2_PRINTF(3, 4);
+#else
+#define ssh2_snprintf snprintf
 #endif
 
 #ifndef SSH2_FALLTHROUGH

src/libssh2_setup.h

@@ -25,7 +25,6 @@
 #elif defined(_WIN32)
 
 #define HAVE_SELECT
-#define HAVE_SNPRINTF
 
 #ifdef __MINGW32__
 #  define HAVE_UNISTD_H
@@ -40,9 +39,6 @@
 #  else
 #    define HAVE_STRTOI64
 #  endif
-#  if _MSC_VER < 1900
-#    undef HAVE_SNPRINTF
-#  endif
 #endif
 
 #endif /* HAVE_CONFIG_H */
@@ -91,8 +87,6 @@
      /* we cannot access our internal snprintf() implementation in examples and
         tests when linking to a shared libssh2. */
 #    if _MSC_VER < 1900
-#      undef HAVE_SNPRINTF
-#      define HAVE_SNPRINTF
 #      define snprintf _snprintf
 #    endif
 #  endif

src/misc.c

@@ -51,7 +51,7 @@
 
 /* snprintf is not in pre-VS2015 CRTs and _snprintf dangerously incompatible.
    We provide a safe wrapper for these environments */
-#ifndef HAVE_SNPRINTF
+#if defined(_MSC_VER) && _MSC_VER < 1900
 #include <stdarg.h>
 
 /* Want safe, 'n += snprintf(b + n ...)' like function. Returns number of chars

vms/libssh2_config.h

@@ -29,7 +29,6 @@ typedef unsigned int socklen_t; /* missing in headers on VMS */
 #define HAVE_ARPA_INET_H
 
 #define HAVE_GETTIMEOFDAY 1
-#define HAVE_SNPRINTF 1
 
 #define POSIX_C_SOURCE