Replace the use of warnx() with direct output to stderr using _write().

This reduces the size of a statically-linked binary by approximately 100KB
in a trivial "return (0)" test application.  readelf -S was used to verify
that the .text section was reduced and that using strlen() saved a few
more bytes over using sizeof().  Since the section of code is only called
when environ is corrupt (program bug), I went with fewer bytes over fewer
cycles.

I made minor edits to the submitted patch to make the output resemble
warnx().

Submitted by:	kib bz
Approved by:	wes (mentor)
MFC after:	5 days

1 files changed, 36 insertions, 12 deletions

diff --git a/lib/libc/stdlib/getenv.c b/lib/libc/stdlib/getenv.c
index 2b7757ed3374..74595b2eae47 100644
--- a/lib/libc/stdlib/getenv.c
+++ b/lib/libc/stdlib/getenv.c
@@ -23,23 +23,25 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+
+#include "namespace.h"
 #include <sys/types.h>
-#include <err.h>
 #include <errno.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdlib.h>
 #include <string.h>
+#include <unistd.h>
+#include "un-namespace.h"
 
 
-#include <sys/cdefs.h>
-__FBSDID("$FreeBSD$");
-
-
-static const char CorruptEnvFindMsg[] =
-    "environment corrupt; unable to find %.*s";
+static const char CorruptEnvFindMsg[] = "environment corrupt; unable to find ";
 static const char CorruptEnvValueMsg[] =
-    "environment corrupt; missing value for %s";
+    "environment corrupt; missing value for ";
 
 
 /*
@@ -97,6 +99,26 @@ static void __attribute__ ((destructor)) __clean_env_destructor(void);
 
 
 /*
+ * A simple version of warnx() to avoid the bloat of including stdio in static
+ * binaries.
+ */
+static void
+__env_warnx(const char *msg, const char *name, size_t nameLen)
+{
+	static const char nl[] = "\n";
+	static const char progSep[] = ": ";
+
+	_write(STDERR_FILENO, _getprogname(), strlen(_getprogname()));
+	_write(STDERR_FILENO, progSep, sizeof(progSep) - 1);
+	_write(STDERR_FILENO, msg, strlen(msg));
+	_write(STDERR_FILENO, name, nameLen);
+	_write(STDERR_FILENO, nl, sizeof(nl) - 1);
+
+	return;
+}
+
+
+/*
  * Inline strlen() for performance.  Also, perform check for an equals sign.
  * Cheaper here than peforming a strchr() later.
  */
@@ -341,7 +363,8 @@ __build_env(void)
 			envVars[envNdx].valueSize =
 			    strlen(envVars[envNdx].value);
 		} else {
-			warnx(CorruptEnvValueMsg, envVars[envNdx].name);
+			__env_warnx(CorruptEnvValueMsg, envVars[envNdx].name,
+			    strlen(envVars[envNdx].name));
 			errno = EFAULT;
 			goto Failure;
 		}
@@ -356,8 +379,8 @@ __build_env(void)
 		activeNdx = envVarsTotal - 1;
 		if (__findenv(envVars[envNdx].name, nameLen, &activeNdx,
 		    false) == NULL) {
-			warnx(CorruptEnvFindMsg, (int)nameLen,
-			    envVars[envNdx].name);
+			__env_warnx(CorruptEnvFindMsg, envVars[envNdx].name,
+			    nameLen);
 			errno = EFAULT;
 			goto Failure;
 		}
@@ -527,7 +550,8 @@ __merge_environ(void)
 		if (origEnviron != NULL)
 			for (env = origEnviron; *env != NULL; env++) {
 				if ((equals = strchr(*env, '=')) == NULL) {
-					warnx(CorruptEnvValueMsg, *env);
+					__env_warnx(CorruptEnvValueMsg, *env,
+					    strlen(*env));
 					errno = EFAULT;
 					return (-1);
 				}