commit 654cd8331b3dafb2027a3062104c6e9934af1935
author Elliott Hughes <enh@google.com> Thu Aug 30 16:00:42 2018 -0700
committer Elliott Hughes <enh@google.com> Thu Aug 30 16:00:42 2018 -0700
tree 82562a68054fbcbe65259cd594290278ca94f8fc
parent 003521af4760215c9c3b8ba80c88dd3b3c87ab67

Add the %m GNU extension to printf/wprintf.

And remove the local hack from syslog(3).

Bug: http://b/112776560
Test: ran tests
Change-Id: I5807e729a978df26187ea0ee255bba4ca74220c8

libc/stdio/vfwprintf.cpp

diff --git a/libc/stdio/vfwprintf.cpp b/libc/stdio/vfwprintf.cpp
index 1c3b80d..19cce17 100644
--- a/libc/stdio/vfwprintf.cpp
+++ b/libc/stdio/vfwprintf.cpp
@@ -43,6 +43,7 @@
 #include "printf_common.h"
 
 int FUNCTION_NAME(FILE* fp, const CHAR_TYPE* fmt0, va_list ap) {
+  int caller_errno = errno;
   int n, n2;
   CHAR_TYPE* cp;   /* handy char pointer (short term usage) */
   CHAR_TYPE sign;  /* sign prefix (' ', '+', '-', or \0) */
@@ -436,6 +437,16 @@
         break;
       case 'n':
         __fortify_fatal("%%n not allowed on Android");
+      case 'm':
+        free(convbuf);
+        convbuf = helpers::mbsconv(strerror(caller_errno), prec);
+        if (convbuf == nullptr) {
+            fp->_flags |= __SERR;
+            goto error;
+        } else {
+            cp = convbuf;
+        }
+        goto string;
       case 'O':
         flags |= LONGINT;
         __BIONIC_FALLTHROUGH;
@@ -474,6 +485,7 @@
             cp = convbuf;
           }
         }
+  string:
         if (prec >= 0) {
           size = CHAR_TYPE_STRNLEN(cp, prec);
         } else {