Minimize unsafe C functions usage

Replace calls to `sprintf` and `strcpy` by the safer options `snprintf`
and `safe_strcpy` in the following directories:

- libmysqld
- mysys
- sql-common
- strings

All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the
BSD-new license. I am contributing on behalf of my employer
Amazon Web Services, Inc.

4 files changed, 13 insertions, 9 deletions

diff --git a/mysys/my_atomic_writes.c b/mysys/my_atomic_writes.c
index b383af11ba8..357448d10d2 100644
--- a/mysys/my_atomic_writes.c
+++ b/mysys/my_atomic_writes.c
@@ -112,7 +112,7 @@ static my_bool test_if_shannon_card_exists()
     char path[32];
     struct stat stat_buff;
 
-    sprintf(path, "/dev/df%c", dev_part);
+    snprintf(path, sizeof(path), "/dev/df%c", dev_part);
 #ifdef TEST_SHANNON
     if (lstat(path, &stat_buff) < 0)
     {
@@ -121,8 +121,10 @@ static my_bool test_if_shannon_card_exists()
     }
 #endif
     shannon_devices[shannon_found_devices].st_dev= stat_buff.st_rdev;
-    sprintf(shannon_devices[shannon_found_devices].dev_name, "/dev/sct%c",
-            dev_part);
+    snprintf(shannon_devices[shannon_found_devices].dev_name,
+             sizeof(shannon_devices[shannon_found_devices].dev_name),
+             "/dev/sct%c",
+             dev_part);
 
 #ifdef TEST_SHANNON
     printf("%s(): i=%d, stat_buff.st_dev=0x%lx, stat_buff.st_rdev=0x%lx, st_rdev=0x%lx, dev_name=%s\n",
@@ -145,13 +147,15 @@ static my_bool test_if_shannon_card_exists()
 
     for (dev_no= 1 ; dev_no < 9 ; dev_no++)
     {
-      sprintf(path, "/dev/df%c%d", dev_part, dev_no);
+      snprintf(path, sizeof(path), "/dev/df%c%d", dev_part, dev_no);
       if (lstat(path, &stat_buff) < 0)
         break;
 
       shannon_devices[shannon_found_devices].st_dev= stat_buff.st_rdev;
-      sprintf(shannon_devices[shannon_found_devices].dev_name, "/dev/sct%c%d",
-              dev_part, dev_no);
+      snprintf(shannon_devices[shannon_found_devices].dev_name,
+               sizeof(shannon_devices[shannon_found_devices].dev_name),
+               "/dev/sct%c%d",
+               dev_part, dev_no);
 
 #ifdef TEST_SHANNON
       printf("%s(): i=%d, st_dev=0x%lx, st_rdev=0x%lx, dev_name=%s\n",
diff --git a/mysys/my_conio.c b/mysys/my_conio.c
index 04750635dd3..ec30b9dc6c7 100644
--- a/mysys/my_conio.c
+++ b/mysys/my_conio.c
@@ -50,7 +50,7 @@ int my_pthread_auto_mutex_lock(HANDLE* ph, const char* name, int id, int time)
   DWORD res;
   char tname[FN_REFLEN];
   
-  sprintf(tname, "%s-%08X", name, id);
+  snprintf(tname, sizeof(tname), "%s-%08X", name, id);
   
   *ph= CreateMutex(NULL, FALSE, tname);
   if (*ph == NULL)
diff --git a/mysys/my_likely.c b/mysys/my_likely.c
index c6fca5b7146..b63e5f4211e 100644
--- a/mysys/my_likely.c
+++ b/mysys/my_likely.c
@@ -77,7 +77,7 @@ void end_my_likely(FILE *out)
   if (!(likely_file= out))
   {
     char name[80];
-    sprintf(name, "/tmp/unlikely-%lu.out", (ulong) getpid());
+    snprintf(name, sizeof(name), "/tmp/unlikely-%lu.out", (ulong) getpid());
     if ((likely_file= my_fopen(name, O_TRUNC | O_WRONLY, MYF(MY_WME))))
       do_close= 1;
     else
diff --git a/mysys/my_thr_init.c b/mysys/my_thr_init.c
index 66c2543c51d..57ac2d228fb 100644
--- a/mysys/my_thr_init.c
+++ b/mysys/my_thr_init.c
@@ -426,7 +426,7 @@ const char *my_thread_name(void)
   if (!tmp->name[0])
   {
     my_thread_id id= my_thread_dbug_id();
-    sprintf(name_buff,"T@%lu", (ulong) id);
+    snprintf(name_buff, sizeof(name_buff), "T@%lu", (ulong) id);
     strmake_buf(tmp->name, name_buff);
   }
   return tmp->name;