8365896: Remove unnecessary explicit buffer nul-termination after using os::snprintf

Reviewed-by: dholmes, coleenp

Author: Arraying

src/hotspot/cpu/zero/frame_zero.cpp

@@ -245,8 +245,6 @@ void frame::zero_print_on_error(int           frame_index,
     os::snprintf_checked(fieldbuf, buflen, "word[%d]", offset);
     os::snprintf_checked(valuebuf, buflen, PTR_FORMAT, *addr);
     zeroframe()->identify_word(frame_index, offset, fieldbuf, valuebuf, buflen);
-    fieldbuf[buflen - 1] = '\0';
-    valuebuf[buflen - 1] = '\0';
 
     // Print the result
     st->print_cr(" " PTR_FORMAT ": %-21s = %s", p2i(addr), fieldbuf, valuebuf);

src/hotspot/os/aix/os_aix.cpp

@@ -1054,7 +1054,7 @@ static void* dll_load_library(const char *filename, int *eno, char *ebuf, int eb
       error_report = "dlerror returned no error description";
     }
     if (ebuf != nullptr && ebuflen > 0) {
-      os::snprintf_checked(ebuf, ebuflen - 1, "%s, LIBPATH=%s, LD_LIBRARY_PATH=%s : %s",
+      os::snprintf_checked(ebuf, ebuflen, "%s, LIBPATH=%s, LD_LIBRARY_PATH=%s : %s",
                            filename, ::getenv("LIBPATH"), ::getenv("LD_LIBRARY_PATH"), error_report);
     }
     Events::log_dll_message(nullptr, "Loading shared library %s failed, %s", filename, error_report);

src/hotspot/os/aix/porting_aix.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright (c) 2012, 2024 SAP SE. All rights reserved.
+ * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1154,7 +1155,7 @@ bool os::pd_dll_unload(void* libhandle, char* ebuf, int ebuflen) {
         error_report = "dlerror returned no error description";
       }
       if (ebuf != nullptr && ebuflen > 0) {
-        os::snprintf_checked(ebuf, ebuflen - 1, "%s", error_report);
+        os::snprintf_checked(ebuf, ebuflen, "%s", error_report);
       }
       assert(false, "os::pd_dll_unload() ::dlclose() failed");
     }

src/hotspot/os/bsd/os_bsd.cpp

@@ -2483,7 +2483,7 @@ bool os::pd_dll_unload(void* libhandle, char* ebuf, int ebuflen) {
       error_report = "dlerror returned no error description";
     }
     if (ebuf != nullptr && ebuflen > 0) {
-      os::snprintf_checked(ebuf, ebuflen - 1, "%s", error_report);
+      os::snprintf_checked(ebuf, ebuflen, "%s", error_report);
     }
   }
 

src/hotspot/os/linux/os_linux.cpp

@@ -5338,7 +5338,7 @@ bool os::pd_dll_unload(void* libhandle, char* ebuf, int ebuflen) {
       error_report = "dlerror returned no error description";
     }
     if (ebuf != nullptr && ebuflen > 0) {
-      os::snprintf_checked(ebuf, ebuflen - 1, "%s", error_report);
+      os::snprintf_checked(ebuf, ebuflen, "%s", error_report);
     }
   }
 

src/hotspot/os/linux/os_perf_linux.cpp

@@ -705,11 +705,9 @@ bool SystemProcessInterface::SystemProcesses::ProcessIterator::is_valid_entry(st
 
   if (atoi(entry->d_name) != 0) {
     jio_snprintf(buffer, PATH_MAX, "/proc/%s", entry->d_name);
-    buffer[PATH_MAX - 1] = '\0';
 
     if (is_dir(buffer)) {
       jio_snprintf(buffer, PATH_MAX, "/proc/%s/stat", entry->d_name);
-      buffer[PATH_MAX - 1] = '\0';
       if (fsize(buffer, size) != OS_ERR) {
         return true;
       }
@@ -724,7 +722,6 @@ void SystemProcessInterface::SystemProcesses::ProcessIterator::get_exe_name() {
   char  buffer[PATH_MAX];
 
   jio_snprintf(buffer, PATH_MAX, "/proc/%s/stat", _entry->d_name);
-  buffer[PATH_MAX - 1] = '\0';
   if ((fp = os::fopen(buffer, "r")) != nullptr) {
     if (fgets(buffer, PATH_MAX, fp) != nullptr) {
       char* start, *end;
@@ -752,7 +749,6 @@ char* SystemProcessInterface::SystemProcesses::ProcessIterator::get_cmdline() {
   char* cmdline = nullptr;
 
   jio_snprintf(buffer, PATH_MAX, "/proc/%s/cmdline", _entry->d_name);
-  buffer[PATH_MAX - 1] = '\0';
   if ((fp = os::fopen(buffer, "r")) != nullptr) {
     size_t size = 0;
     char   dummy;
@@ -787,7 +783,6 @@ char* SystemProcessInterface::SystemProcesses::ProcessIterator::get_exe_path() {
   char buffer[PATH_MAX];
 
   jio_snprintf(buffer, PATH_MAX, "/proc/%s/exe", _entry->d_name);
-  buffer[PATH_MAX - 1] = '\0';
   return os::realpath(buffer, _exePath, PATH_MAX);
 }
 
@@ -1001,7 +996,6 @@ int64_t NetworkPerformanceInterface::NetworkPerformance::read_counter(const char
     return -1;
   }
 
-  buf[num_bytes] = '\0';
   int64_t value = strtoll(buf, nullptr, 10);
 
   return value;

src/hotspot/os/windows/os_windows.cpp

@@ -1827,12 +1827,12 @@ void * os::dll_load(const char *name, char *ebuf, int ebuflen) {
   }
 
   if (lib_arch_str != nullptr) {
-    os::snprintf_checked(ebuf, ebuflen - 1,
+    os::snprintf_checked(ebuf, ebuflen,
                          "Can't load %s-bit .dll on a %s-bit platform",
                          lib_arch_str, running_arch_str);
   } else {
     // don't know what architecture this dll was build for
-    os::snprintf_checked(ebuf, ebuflen - 1,
+    os::snprintf_checked(ebuf, ebuflen,
                          "Can't load this .dll (machine code=0x%x) on a %s-bit platform",
                          lib_arch, running_arch_str);
   }

src/hotspot/share/cds/filemap.cpp

@@ -117,7 +117,6 @@ template <int N> static void get_header_version(char (&header_version) [N]) {
 
     // Append the hash code as eight hex digits.
     os::snprintf_checked(&header_version[JVM_IDENT_MAX-9], 9, "%08x", hash);
-    header_version[JVM_IDENT_MAX-1] = 0;  // Null terminate.
   }
 
   assert(header_version[JVM_IDENT_MAX-1] == 0, "must be");

src/hotspot/share/runtime/reflection.cpp

@@ -546,7 +546,7 @@ char* Reflection::verify_class_access_msg(const Klass* current_class,
         size_t len = 100 + strlen(current_class_name) + 2*strlen(module_from_name) +
           strlen(new_class_name) + 2*strlen(module_to_name);
         msg = NEW_RESOURCE_ARRAY(char, len);
-        jio_snprintf(msg, len - 1,
+        jio_snprintf(msg, len,
           "class %s (in module %s) cannot access class %s (in module %s) because module %s does not read module %s",
           current_class_name, module_from_name, new_class_name,
           module_to_name, module_from_name, module_to_name);
@@ -557,7 +557,7 @@ char* Reflection::verify_class_access_msg(const Klass* current_class,
         size_t len = 160 + strlen(current_class_name) + 2*strlen(module_from_name) +
           strlen(new_class_name) + 2*sizeof(uintx);
         msg = NEW_RESOURCE_ARRAY(char, len);
-        jio_snprintf(msg, len - 1,
+        jio_snprintf(msg, len,
           "class %s (in module %s) cannot access class %s (in unnamed module @0x%zx) because module %s does not read unnamed module @0x%zx",
           current_class_name, module_from_name, new_class_name, uintx(identity_hash),
           module_from_name, uintx(identity_hash));
@@ -573,7 +573,7 @@ char* Reflection::verify_class_access_msg(const Klass* current_class,
         size_t len = 118 + strlen(current_class_name) + 2*strlen(module_from_name) +
           strlen(new_class_name) + 2*strlen(module_to_name) + strlen(package_name);
         msg = NEW_RESOURCE_ARRAY(char, len);
-        jio_snprintf(msg, len - 1,
+        jio_snprintf(msg, len,
           "class %s (in module %s) cannot access class %s (in module %s) because module %s does not export %s to module %s",
           current_class_name, module_from_name, new_class_name,
           module_to_name, module_to_name, package_name, module_from_name);
@@ -584,7 +584,7 @@ char* Reflection::verify_class_access_msg(const Klass* current_class,
         size_t len = 170 + strlen(current_class_name) + strlen(new_class_name) +
           2*strlen(module_to_name) + strlen(package_name) + 2*sizeof(uintx);
         msg = NEW_RESOURCE_ARRAY(char, len);
-        jio_snprintf(msg, len - 1,
+        jio_snprintf(msg, len,
           "class %s (in unnamed module @0x%zx) cannot access class %s (in module %s) because module %s does not export %s to unnamed module @0x%zx",
           current_class_name, uintx(identity_hash), new_class_name, module_to_name,
           module_to_name, package_name, uintx(identity_hash));

src/hotspot/share/services/diagnosticFramework.cpp

@@ -208,7 +208,7 @@ void DCmdParser::parse(CmdLine* line, char delim, TRAPS) {
 
         strncpy(argbuf, iter.key_addr(), len);
         argbuf[len] = '\0';
-        jio_snprintf(buf, buflen - 1, "Unknown argument '%s' in diagnostic command.", argbuf);
+        jio_snprintf(buf, buflen, "Unknown argument '%s' in diagnostic command.", argbuf);
 
         THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), buf);
       }
@@ -236,15 +236,15 @@ void DCmdParser::check(TRAPS) {
   GenDCmdArgument* arg = _arguments_list;
   while (arg != nullptr) {
     if (arg->is_mandatory() && !arg->has_value()) {
-      jio_snprintf(buf, buflen - 1, "The argument '%s' is mandatory.", arg->name());
+      jio_snprintf(buf, buflen, "The argument '%s' is mandatory.", arg->name());
       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), buf);
     }
     arg = arg->next();
   }
   arg = _options;
   while (arg != nullptr) {
     if (arg->is_mandatory() && !arg->has_value()) {
-      jio_snprintf(buf, buflen - 1, "The option '%s' is mandatory.", arg->name());
+      jio_snprintf(buf, buflen, "The option '%s' is mandatory.", arg->name());
       THROW_MSG(vmSymbols::java_lang_IllegalArgumentException(), buf);
     }
     arg = arg->next();