[PATCH 08/73] options, lib: Harden warning buffers and command-line option parsing

[Bart Van Assche <bvanassche@acm.org>]

Fix buffer sizing and command-line option parsing safety in lib.c and
options.c:
- Enlarge the warning buffer in do_warn(), format with vsnprintf(),
  track warning counts without underflowing fmax_warnings, and allocate
  oversized add_pre_buffer() strings dynamically.
- Reject trailing characters and honor OPT_INVERSE in
  handle_switch_setval(), and diagnose missing arguments in -G,
  -include, -imacros, and -MF/-MQ/-MT switches.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 lib.c     | 24 ++++++++++++++++++++----
 options.c | 19 +++++++++++--------
 2 files changed, 31 insertions(+), 12 deletions(-)

diff --git a/lib.c b/lib.c
index e282a4fb4d54..ff8efb157f39 100644
--- a/lib.c
+++ b/lib.c
@@ -128,13 +128,13 @@ static const char *show_stream_name(struct position pos)
 
 static void do_warn(const char *type, struct position pos, const char * fmt, va_list args)
 {
-	static char buffer[512];
+	static char buffer[4096];
 
 	/* Shut up warnings if position is bad_token.pos */
 	if (pos.type == TOKEN_BAD)
 		return;
 
-	vsprintf(buffer, fmt, args);	
+	vsnprintf(buffer, sizeof(buffer), fmt, args);
 
 	fflush(stdout);
 	fprintf(stderr, "%s:%d:%d: %s%s%s\n",
@@ -181,6 +181,7 @@ static void do_error(struct position pos, const char * fmt, va_list args)
 void warning(struct position pos, const char * fmt, ...)
 {
 	va_list args;
+	static unsigned int warnings = 0;
 
 	if (Wsparse_error) {
 		va_start(args, fmt);
@@ -194,9 +195,13 @@ void warning(struct position pos, const char * fmt, ...)
 		return;
 	}
 
-	if (!--fmax_warnings) {
+	if (++warnings > fmax_warnings) {
+		static int once = 0;
 		show_info = 0;
+		if (once)
+			return;
 		fmt = "too many warnings";
+		once = 1;
 	}
 
 	va_start(args, fmt);
@@ -256,11 +261,22 @@ void add_pre_buffer(const char *fmt, ...)
 	unsigned int size;
 	struct token *begin, *end;
 	char buffer[4096];
+	char *buf = buffer;
 
 	va_start(args, fmt);
 	size = vsnprintf(buffer, sizeof(buffer), fmt, args);
 	va_end(args);
-	begin = tokenize_buffer(buffer, size, &end);
+	if (size >= sizeof(buffer)) {
+		buf = malloc(size + 1);
+		if (!buf)
+			die("out of memory");
+		va_start(args, fmt);
+		vsnprintf(buf, size + 1, fmt, args);
+		va_end(args);
+	}
+	begin = tokenize_buffer(buf, size, &end);
+	if (buf != buffer)
+		free(buf);
 	*pre_buffer_next = begin;
 	pre_buffer_next = &end->next;
 }
diff --git a/options.c b/options.c
index 6ee4d878a473..5aa3290e07da 100644
--- a/options.c
+++ b/options.c
@@ -315,7 +315,9 @@ static void handle_onoff_switch_finalize(const struct flag flags[])
 
 static int handle_switch_setval(const char *arg, const char *opt, const struct flag *flag, int options)
 {
-	*(flag->flag) = flag->mask;
+	if (*opt != '\0')
+		return 0;
+	*(flag->flag) = (options & OPT_INVERSE) ? 0 : flag->mask;
 	return 1;
 }
 
@@ -548,7 +550,7 @@ static char **handle_switch_f(char *arg, char **next)
 
 static char **handle_switch_G(char *arg, char **next)
 {
-	if (!strcmp(arg, "G") && *next)
+	if (!strcmp(arg, "G") && next[1])
 		return next + 1; // "-G 0"
 	else
 		return next;     // "-G0" or (bogus) terminal "-G"
@@ -599,11 +601,12 @@ static void add_cmdline_include(char *filename)
 
 static char **handle_switch_i(char *arg, char **next)
 {
-	if (*next && !strcmp(arg, "include"))
-		add_cmdline_include(*++next);
-	else if (*next && !strcmp(arg, "imacros"))
-		add_cmdline_include(*++next);
-	else if (*next && !strcmp(arg, "isystem")) {
+	if (!strcmp(arg, "include") || !strcmp(arg, "imacros")) {
+		char *path = *++next;
+		if (!path)
+			die("missing argument for -%s option", arg);
+		add_cmdline_include(path);
+	} else if (*next && !strcmp(arg, "isystem")) {
 		char *path = *++next;
 		if (!path)
 			die("missing argument for -isystem option");
@@ -620,7 +623,7 @@ static char **handle_switch_i(char *arg, char **next)
 static char **handle_switch_M(char *arg, char **next)
 {
 	if (!strcmp(arg, "MF") || !strcmp(arg,"MQ") || !strcmp(arg,"MT")) {
-		if (!*next)
+		if (!next[1])
 			die("missing argument for -%s option", arg);
 		return next + 1;
 	}