[glibc] time: Remove alloca() from getdate

[glibc] time: Remove alloca() from getdate

[Siddhesh Poyarekar]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=21f0b087ee10391433d8279e7c6f104fb9ea0eef

commit 21f0b087ee10391433d8279e7c6f104fb9ea0eef
Author: Joe Simmons-Talbott <josimmon@redhat.com>
Date:   Wed May 3 12:40:05 2023 -0400

    time: Remove alloca() from getdate
    
    Reduce the usage of alloca() to the bare minimum to avoid the potential
    for stack overflow.  Use __strndup to simplify the code.
    
    Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

Diff:
---
 time/getdate.c | 23 +++++------------------
 1 file changed, 5 insertions(+), 18 deletions(-)

diff --git a/time/getdate.c b/time/getdate.c
index c5c8378707..1dcbd77188 100644
--- a/time/getdate.c
+++ b/time/getdate.c
@@ -26,7 +26,6 @@
 #include <unistd.h>
 #include <sys/stat.h>
 #include <ctype.h>
-#include <alloca.h>
 
 #define TM_YEAR_BASE 1900
 
@@ -153,26 +152,14 @@ __getdate_r (const char *string, struct tm *tp)
 
   if (inlen < oldlen)
     {
-      bool using_malloc = false;
-
-      if (__libc_use_alloca (inlen + 1))
-	instr = alloca (inlen + 1);
-      else
+      instr = __strndup(string, inlen);
+      if (instr == NULL)
 	{
-	  instr = malloc (inlen + 1);
-	  if (instr == NULL)
-	    {
-	      fclose (fp);
-	      return 6;
-	    }
-	  using_malloc = true;
+	  fclose(fp);
+	  return 6;
 	}
-      memcpy (instr, string, inlen);
-      instr[inlen] = '\0';
-      string = instr;
 
-      if (!using_malloc)
-	instr = NULL;
+      string = instr;
     }
 
   line = NULL;