Added optimization to Makefile (can be set/overruled using OPT).

Added flag to display all warnings during compiling.
Added status checks when parsing user/group IDs for Linux.
Make sure Linux drops original user's groups when running as another user.

Author: Jesse Smith

Makefile

@@ -5,9 +5,10 @@ PREFIX?=/usr/local
 MANDIR?=$(DESTDIR)$(PREFIX)/man
 SYSCONFDIR?=$(DESTDIR)$(PREFIX)/etc
 OBJECTS=doas.o env.o execvpe.o reallocarray.o y.tab.o
+OPT?=-O2
 # Can set GLOBAL_PATH here to set PATH for target user.
 # TARGETPATH=-DGLOBAL_PATH=\"/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:\"
-CFLAGS+=-DUSE_PAM -DDOAS_CONF=\"${SYSCONFDIR}/doas.conf\" $(TARGETPATH)
+CFLAGS+=-Wall $(OPT) -DUSE_PAM -DDOAS_CONF=\"${SYSCONFDIR}/doas.conf\" $(TARGETPATH)
 LDFLAGS+=-lpam
 UNAME_S := $(shell uname -s)
 ifeq ($(UNAME_S),Linux)

doas.c

@@ -85,19 +85,25 @@ static int
 parseuid(const char *s, uid_t *uid)
 {
 	struct passwd *pw;
-	const char *errstr;
+	#if !defined(__linux__) && !defined(__NetBSD__)
+	const char *errstr = NULL;
+        #else
+        int status;
+        #endif
 
 	if ((pw = getpwnam(s)) != NULL) {
 		*uid = pw->pw_uid;
 		return 0;
 	}
 	#if !defined(__linux__) && !defined(__NetBSD__)
 	*uid = strtonum(s, 0, UID_MAX, &errstr);
-	#else
-	sscanf(s, "%d", uid);
-	#endif
 	if (errstr)
 		return -1;
+	#else
+	status = sscanf(s, "%d", uid);
+        if (status != 1)
+           return -1;
+	#endif
 	return 0;
 }
 
@@ -117,19 +123,25 @@ static int
 parsegid(const char *s, gid_t *gid)
 {
 	struct group *gr;
-	const char *errstr;
+	#if !defined(__linux__) && !defined(__NetBSD__)
+	const char *errstr = NULL;
+        #else
+        int status;
+        #endif
 
 	if ((gr = getgrnam(s)) != NULL) {
 		*gid = gr->gr_gid;
 		return 0;
 	}
 	#if !defined(__linux__) && !defined(__NetBSD__)
 	*gid = strtonum(s, 0, GID_MAX, &errstr);
-	#else
-	sscanf(s, "%d", gid);
-	#endif
 	if (errstr)
 		return -1;
+	#else
+	status = sscanf(s, "%d", gid);
+        if (status != 1)
+            return -1;
+	#endif
 	return 0;
 }