ld.so: Consolidate 2 strtouls into _dl_strtoul [BZ #21528]

There are 2 minimal strtoul implementations in ld.so:

1. __strtoul_internal in elf/dl-minimal.c.
2. tunables_strtoul in elf/dl-tunables.c.

This patch adds _dl_strtoul to replace them.  Tested builds with and
without --enable-tunables.

	[BZ #21528]
	* elf/dl-minimal.c (__strtoul_internal): Removed.
	(strtoul): Likewise.
	* elf/dl-misc.c (_dl_strtoul): New function.
	* elf/dl-tunables.c (tunables_strtoul): Removed.
	(tunable_initialize): Replace tunables_strtoul with _dl_strtoul.
	* elf/rtld.c (process_envvars): Likewise.
	* sysdeps/unix/sysv/linux/dl-librecon.h (_dl_osversion_init):
	Likewise.
	* sysdeps/generic/ldsodefs.h (_dl_strtoul): New prototype.

1 files changed, 84 insertions, 0 deletions

diff --git a/elf/dl-misc.c b/elf/dl-misc.c
index c5d3e0e7c5..c469b5a365 100644
--- a/elf/dl-misc.c
+++ b/elf/dl-misc.c
@@ -360,3 +360,87 @@ _dl_higher_prime_number (unsigned long int n)
 
   return *low;
 }
+
+/* A stripped down strtoul-like implementation for very early use.  It
+   does not set errno if the result is outside bounds because it may get
+   called before errno may have been set up.  */
+
+uint64_t
+internal_function
+_dl_strtoul (const char *nptr, char **endptr)
+{
+  uint64_t result = 0;
+  bool positive = true;
+  unsigned max_digit;
+
+  while (*nptr == ' ' || *nptr == '\t')
+    ++nptr;
+
+  if (*nptr == '-')
+    {
+      positive = false;
+      ++nptr;
+    }
+  else if (*nptr == '+')
+    ++nptr;
+
+  if (*nptr < '0' || *nptr > '9')
+    {
+      if (endptr != NULL)
+	*endptr = (char *) nptr;
+      return 0UL;
+    }
+
+  int base = 10;
+  max_digit = 9;
+  if (*nptr == '0')
+    {
+      if (nptr[1] == 'x' || nptr[1] == 'X')
+	{
+	  base = 16;
+	  nptr += 2;
+	}
+      else
+	{
+	  base = 8;
+	  max_digit = 7;
+	}
+    }
+
+  while (1)
+    {
+      int digval;
+      if (*nptr >= '0' && *nptr <= '0' + max_digit)
+        digval = *nptr - '0';
+      else if (base == 16)
+        {
+	  if (*nptr >= 'a' && *nptr <= 'f')
+	    digval = *nptr - 'a' + 10;
+	  else if (*nptr >= 'A' && *nptr <= 'F')
+	    digval = *nptr - 'A' + 10;
+	  else
+	    break;
+	}
+      else
+        break;
+
+      if (result >= (UINT64_MAX - digval) / base)
+	{
+	  if (endptr != NULL)
+	    *endptr = (char *) nptr;
+	  return UINT64_MAX;
+	}
+      result *= base;
+      result += digval;
+      ++nptr;
+    }
+
+  if (endptr != NULL)
+    *endptr = (char *) nptr;
+
+  /* Avoid 64-bit multiplication.  */
+  if (!positive)
+    result = -result;
+
+  return result;
+}