[PATCH v3 01/24] xen/ctype: introduce is_console_printable()

[Denis Mukhin via B4 Relay <devnull+dmukhin.ford.com@xxxxxxxxxx>]

From: Denis Mukhin <dmukhin@xxxxxxxx>

There are several console drivers which have same checks w.r.t. printable
characters. The check is moved to new is_console_printable() function and
re-used in the UART emulation / guest logging code.

Also, MISRA rule 21.13 for ctype.h has been exploited while working on
the code change, reference the rule from ctype.h for future engineers.

Signed-off-by: Denis Mukhin <dmukhin@xxxxxxxx>
---
 xen/arch/arm/vuart.c       | 3 +--
 xen/arch/x86/hvm/hvm.c     | 3 +--
 xen/drivers/char/console.c | 2 +-
 xen/include/xen/ctype.h    | 7 +++++++
 4 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/vuart.c b/xen/arch/arm/vuart.c
index 
d5ba483f1e63245e545346ad5045098152b8c152..98a65b99385a2a119725bab8634ed7cf9d926d68
 100644
--- a/xen/arch/arm/vuart.c
+++ b/xen/arch/arm/vuart.c
@@ -79,8 +79,7 @@ static void vuart_print_char(struct vcpu *v, char c)
     struct domain *d = v->domain;
     struct vuart *uart = &d->arch.vuart;
 
-    /* Accept only printable characters, newline, and horizontal tab. */
-    if ( !isprint(c) && (c != '\n') && (c != '\t') )
+    if ( !is_console_printable(c) )
         return ;
 
     spin_lock(&uart->lock);
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 
922c9b3af64d9132022d37627c54af092275e9cf..c4f1df248c1a7b2b3e5c45cef154e7ca80018dfc
 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -561,8 +561,7 @@ static int cf_check hvm_print_line(
     if ( dir != IOREQ_WRITE )
         return X86EMUL_UNHANDLEABLE;
 
-    /* Accept only printable characters, newline, and horizontal tab. */
-    if ( !isprint(c) && (c != '\n') && (c != '\t') )
+    if ( !is_console_printable(c) )
         return X86EMUL_OKAY;
 
     spin_lock(&cd->pbuf_lock);
diff --git a/xen/drivers/char/console.c b/xen/drivers/char/console.c
index 
7da8c5296f3b62c6c45131c58fe5cf0e393e9ef3..4cb397116b44935214801c496b30e44c9399c59a
 100644
--- a/xen/drivers/char/console.c
+++ b/xen/drivers/char/console.c
@@ -674,7 +674,7 @@ static long 
guest_console_write(XEN_GUEST_HANDLE_PARAM(char) buffer,
                 c = *kin++;
                 if ( c == '\n' )
                     break;
-                if ( isprint(c) || c == '\t' )
+                if ( is_console_printable(c) )
                     *kout++ = c;
             } while ( --kcount > 0 );
 
diff --git a/xen/include/xen/ctype.h b/xen/include/xen/ctype.h
index 
773ac27aa44ac65e76e87cdec960450804310249..ceb8f028ddc80b3b688f13422c0362199a03ba9e
 100644
--- a/xen/include/xen/ctype.h
+++ b/xen/include/xen/ctype.h
@@ -4,6 +4,8 @@
 /*
  * NOTE! This ctype does not handle EOF like the standard C
  * library is required to.
+ *
+ * See Rule 21.13 in docs/misra/rules.rst.
  */
 
 #define _U     0x01    /* upper */
@@ -51,4 +53,9 @@ static inline unsigned char __toupper(unsigned char c)
 #define tolower(c) ((char)__tolower(c))
 #define toupper(c) ((char)__toupper(c))
 
+static inline unsigned is_console_printable(unsigned char c)
+{
+       return isprint(c) || c == '\n' || c == '\t';
+}
+
 #endif

-- 
2.34.1