From 7239dbcf2dff792f408c60fe3e278f707fdf497b Mon Sep 17 00:00:00 2001
From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Tue, 5 Mar 2013 15:46:34 +0100
Subject: [PATCH] Use dynamically-sized selected[] array for -P PATH

While at it, added a small optimization of not remembering
the path twice if it happens to be the same.

   text	   data	    bss	    dec	    hex	filename
 245111	    680	  10860	 256651	  3ea8b	strace_old
 245075	    680	   9804	 255559	  3e647	strace

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
---
 defs.h      |  2 +-
 pathtrace.c | 43 +++++++++++++++++++------------------------
 strace.1    |  2 +-
 strace.c    |  4 +---
 4 files changed, 22 insertions(+), 29 deletions(-)

diff --git a/defs.h b/defs.h
index 6bfa916a..1d607c70 100644
--- a/defs.h
+++ b/defs.h
@@ -601,7 +601,7 @@ extern int clearbpt(struct tcb *);
 
 extern const char *signame(int);
 extern int is_restart_error(struct tcb *);
-extern int pathtrace_select(const char *);
+extern void pathtrace_select(const char *);
 extern int pathtrace_match(struct tcb *);
 extern const char *getfdpath(struct tcb *, int);
 
diff --git a/pathtrace.c b/pathtrace.c
index 83d79d37..19110348 100644
--- a/pathtrace.c
+++ b/pathtrace.c
@@ -37,8 +37,8 @@
 
 #include "syscall.h"
 
-#define MAXSELECTED  256	/* max number of "selected" paths */
-static const char *selected[MAXSELECTED];	/* paths selected for tracing */
+static const char **selected = NULL; /* paths selected for tracing */
+static unsigned num_selected = 0;
 
 /*
  * Return true if specified path matches one that we're tracing.
@@ -46,11 +46,9 @@ static const char *selected[MAXSELECTED];	/* paths selected for tracing */
 static int
 pathmatch(const char *path)
 {
-	unsigned int i;
+	unsigned i;
 
-	for (i = 0; i < ARRAY_SIZE(selected); ++i) {
-		if (selected[i] == NULL)
-			return 0;
+	for (i = 0; i < num_selected; ++i) {
 		if (strcmp(path, selected[i]) == 0)
 			return 1;
 	}
@@ -84,21 +82,19 @@ fdmatch(struct tcb *tcp, int fd)
  * Add a path to the set we're tracing.
  * Secifying NULL will delete all paths.
  */
-static int
+static void
 storepath(const char *path)
 {
-	unsigned int i;
+	unsigned i;
 
-	for (i = 0; i < ARRAY_SIZE(selected); ++i) {
-		if (!selected[i]) {
-			selected[i] = path;
-			return 0;
-		}
-	}
+	if (pathmatch(path))
+		return; /* already in table */
 
-	fprintf(stderr, "Max trace paths exceeded, only using first %u\n",
-		(unsigned int) ARRAY_SIZE(selected));
-	return -1;
+	i = num_selected++;
+	selected = realloc(selected, num_selected * sizeof(selected[0]));
+	if (!selected)
+		die_out_of_memory();
+	selected[i] = path;
 }
 
 /*
@@ -126,28 +122,27 @@ getfdpath(struct tcb *tcp, int fd)
  * Add a path to the set we're tracing.  Also add the canonicalized
  * version of the path.  Secifying NULL will delete all paths.
  */
-int
+void
 pathtrace_select(const char *path)
 {
 	char *rpath;
 
-	if (storepath(path))
-		return -1;
+	storepath(path);
 
 	rpath = realpath(path, NULL);
 
 	if (rpath == NULL)
-		return 0;
+		return;
 
 	/* if realpath and specified path are same, we're done */
 	if (strcmp(path, rpath) == 0) {
 		free(rpath);
-		return 0;
+		return;
 	}
 
 	fprintf(stderr, "Requested path '%s' resolved into '%s'\n",
 		path, rpath);
-	return storepath(rpath);
+	storepath(rpath);
 }
 
 /*
@@ -159,7 +154,7 @@ pathtrace_match(struct tcb *tcp)
 {
 	const struct_sysent *s;
 
-	if (selected[0] == NULL)
+	if (!selected)
 		return 1;
 
 	s = tcp->s_ent;
diff --git a/strace.1 b/strace.1
index 63b604c8..00ca03c4 100644
--- a/strace.1
+++ b/strace.1
@@ -517,7 +517,7 @@ Trace only system calls accessing
 .I path.
 Multiple
 .B \-P
-options can be used to specify up to 256 paths.
+options can be used to specify several paths.
 .TP
 .BI "\-s " strsize
 Specify the maximum string size to print (the default is 32).  Note
diff --git a/strace.c b/strace.c
index 319dff2f..9ec354da 100644
--- a/strace.c
+++ b/strace.c
@@ -1649,9 +1649,7 @@ init(int argc, char *argv[])
 			break;
 		case 'P':
 			tracing_paths = 1;
-			if (pathtrace_select(optarg)) {
-				error_msg_and_die("Failed to select path '%s'", optarg);
-			}
+			pathtrace_select(optarg);
 			break;
 		case 's':
 			i = string_to_uint(optarg);
-- 
2.40.0