analyzer: support for creat, dup, dup2 and dup3 [PR106298]

This patch extends the state machine in sm-fd.cc to support
creat, dup, dup2 and dup3 functions.

Lightly tested on x86_64 Linux.

gcc/analyzer/ChangeLog:
	PR analyzer/106298
	* sm-fd.cc (fd_state_machine::on_open): Add
	creat, dup, dup2 and dup3 functions.
	(enum dup): New.
	(fd_state_machine::valid_to_unchecked_state): New.
	(fd_state_machine::on_creat): New.
	(fd_state_machine::on_dup): New.

gcc/testsuite/ChangeLog:
	PR analyzer/106298
	* gcc.dg/analyzer/fd-1.c: Add tests for 'creat'.
	* gcc.dg/analyzer/fd-2.c: Likewise.
	* gcc.dg/analyzer/fd-4.c: Likewise.
	* gcc.dg/analyzer/fd-dup-1.c: New tests.

Signed-off-by: Immad Mir <mirimmad@outlook.com>

5 files changed, 415 insertions, 4 deletions

diff --git a/gcc/analyzer/sm-fd.cc b/gcc/analyzer/sm-fd.cc
index ed923ade100..8bb76d72b05 100644
--- a/gcc/analyzer/sm-fd.cc
+++ b/gcc/analyzer/sm-fd.cc
@@ -69,6 +69,14 @@ enum access_directions
   DIRS_WRITE
 };
 
+/* An enum for distinguishing between dup, dup2 and dup3.  */
+enum dup
+{
+  DUP_1,
+  DUP_2,
+  DUP_3
+};
+
 class fd_state_machine : public state_machine
 {
 public:
@@ -114,7 +122,9 @@ public:
   bool is_readonly_fd_p (state_t s) const;
   bool is_writeonly_fd_p (state_t s) const;
   enum access_mode get_access_mode_from_flag (int flag) const;
-
+  /* Function for one-to-one correspondence between valid
+     and unchecked states.  */
+  state_t valid_to_unchecked_state (state_t state) const;
   /* State for a constant file descriptor (>= 0) */
   state_t m_constant_fd;
 
@@ -147,6 +157,8 @@ public:
 private:
   void on_open (sm_context *sm_ctxt, const supernode *node, const gimple *stmt,
 		const gcall *call) const;
+  void on_creat (sm_context *sm_ctxt, const supernode *node, const gimple *stmt,
+		const gcall *call) const;
   void on_close (sm_context *sm_ctxt, const supernode *node, const gimple *stmt,
 		 const gcall *call) const;
   void on_read (sm_context *sm_ctxt, const supernode *node, const gimple *stmt,
@@ -170,6 +182,9 @@ private:
 			   const gimple *stmt, const gcall *call,
 			   const tree callee_fndecl, const char *attr_name,
 			   access_directions fd_attr_access_dir) const;
+  void check_for_dup (sm_context *sm_ctxt, const supernode *node,
+       const gimple *stmt, const gcall *call, const tree callee_fndecl,
+       enum dup kind) const;
 };
 
 /* Base diagnostic class relative to fd_state_machine.  */
@@ -723,6 +738,20 @@ fd_state_machine::is_constant_fd_p (state_t state) const
   return (state == m_constant_fd);
 }
 
+fd_state_machine::state_t
+fd_state_machine::valid_to_unchecked_state (state_t state) const
+{
+  if (state == m_valid_read_write)
+    return m_unchecked_read_write;
+  else if (state == m_valid_write_only)
+    return m_unchecked_write_only;
+  else if (state == m_valid_read_only)
+    return m_unchecked_read_only;
+  else
+    gcc_unreachable ();
+  return NULL;
+}
+
 bool
 fd_state_machine::on_stmt (sm_context *sm_ctxt, const supernode *node,
 			   const gimple *stmt) const
@@ -736,6 +765,11 @@ fd_state_machine::on_stmt (sm_context *sm_ctxt, const supernode *node,
 	    return true;
 	  } //  "open"
 
+	if (is_named_call_p (callee_fndecl, "creat", call, 2))
+	  {
+	    on_creat (sm_ctxt, node, stmt, call);
+	  } // "creat"
+
 	if (is_named_call_p (callee_fndecl, "close", call, 1))
 	  {
 	    on_close (sm_ctxt, node, stmt, call);
@@ -754,6 +788,23 @@ fd_state_machine::on_stmt (sm_context *sm_ctxt, const supernode *node,
 	    return true;
 	  } // "read"
 
+	if (is_named_call_p (callee_fndecl, "dup", call, 1))
+	  {
+	    check_for_dup (sm_ctxt, node, stmt, call, callee_fndecl, DUP_1);
+	    return true;
+	  }
+
+	if (is_named_call_p (callee_fndecl, "dup2", call, 2))
+	  {
+	    check_for_dup (sm_ctxt, node, stmt, call, callee_fndecl, DUP_2);
+	    return true;
+	  }
+
+	if (is_named_call_p (callee_fndecl, "dup3", call, 3))
+	  {
+	    check_for_dup (sm_ctxt, node, stmt, call, callee_fndecl, DUP_3);
+	    return true;
+	  }
 
 	{
 	  // Handle __attribute__((fd_arg))
@@ -900,6 +951,78 @@ fd_state_machine::on_open (sm_context *sm_ctxt, const supernode *node,
 }
 
 void
+fd_state_machine::on_creat (sm_context *sm_ctxt, const supernode *node,
+			    const gimple *stmt, const gcall *call) const
+{
+  tree lhs = gimple_call_lhs (call);
+  if (lhs)
+    sm_ctxt->on_transition (node, stmt, lhs, m_start, m_unchecked_write_only);
+  else
+    sm_ctxt->warn (node, stmt, NULL_TREE, new fd_leak (*this, NULL_TREE));
+}
+
+void
+fd_state_machine::check_for_dup (sm_context *sm_ctxt, const supernode *node,
+				 const gimple *stmt, const gcall *call,
+				 const tree callee_fndecl, enum dup kind) const
+{
+  tree lhs = gimple_call_lhs (call);
+  tree arg_1 = gimple_call_arg (call, 0);
+  state_t state_arg_1 = sm_ctxt->get_state (stmt, arg_1);
+  if (state_arg_1 == m_stop)
+    return;
+  if (!(is_constant_fd_p (state_arg_1) || is_valid_fd_p (state_arg_1)))
+    {
+      check_for_open_fd (sm_ctxt, node, stmt, call, callee_fndecl,
+			 DIRS_READ_WRITE);
+      if (kind == DUP_1)
+	return;
+    }
+  switch (kind)
+    {
+    case DUP_1:
+      if (lhs)
+	{
+	  if (is_constant_fd_p (state_arg_1))
+	    sm_ctxt->set_next_state (stmt, lhs, m_unchecked_read_write);
+	  else
+	    sm_ctxt->set_next_state (stmt, lhs,
+				     valid_to_unchecked_state (state_arg_1));
+	}
+      break;
+
+    case DUP_2:
+    case DUP_3:
+      tree arg_2 = gimple_call_arg (call, 1);
+      state_t state_arg_2 = sm_ctxt->get_state (stmt, arg_2);
+      tree diag_arg_2 = sm_ctxt->get_diagnostic_tree (arg_2);
+      if (state_arg_2 == m_stop)
+	return;
+      /* Check if -1 was passed as second argument to dup2.  */
+      if (!(is_constant_fd_p (state_arg_2) || is_valid_fd_p (state_arg_2)))
+	{
+	  sm_ctxt->warn (
+	      node, stmt, arg_2,
+	      new fd_use_without_check (*this, diag_arg_2, callee_fndecl));
+	  return;
+	}
+      /* dup2 returns value of its second argument on success.But, the
+      access mode of the returned file descriptor depends on the duplicated
+      file descriptor i.e the first argument.  */
+      if (lhs)
+	{
+	  if (is_constant_fd_p (state_arg_1))
+	    sm_ctxt->set_next_state (stmt, lhs, m_unchecked_read_write);
+	  else
+	    sm_ctxt->set_next_state (stmt, lhs,
+				     valid_to_unchecked_state (state_arg_1));
+	}
+
+      break;
+    }
+}
+
+void
 fd_state_machine::on_close (sm_context *sm_ctxt, const supernode *node,
 			    const gimple *stmt, const gcall *call) const
 {
@@ -964,6 +1087,8 @@ fd_state_machine::check_for_open_fd (
 	}
       switch (callee_fndecl_dir)
 	{
+	case DIRS_READ_WRITE:
+	  break;
 	case DIRS_READ:
 	  if (is_writeonly_fd_p (state))
 	    {
@@ -984,8 +1109,6 @@ fd_state_machine::check_for_open_fd (
 				 *this, diag_arg, DIRS_READ, callee_fndecl));
 	    }
 	  break;
-	default:
-	  gcc_unreachable ();
 	}
     }
 }
diff --git a/gcc/testsuite/gcc.dg/analyzer/fd-1.c b/gcc/testsuite/gcc.dg/analyzer/fd-1.c
index 8a72e63833c..5b85a3316e8 100644
--- a/gcc/testsuite/gcc.dg/analyzer/fd-1.c
+++ b/gcc/testsuite/gcc.dg/analyzer/fd-1.c
@@ -3,6 +3,13 @@ int open(const char *, int mode);
 #define O_WRONLY 1
 #define O_RDWR 2
 
+typedef enum {
+  S_IRWXU
+  // etc
+} mode_t;
+
+int creat (const char *, mode_t mode);
+
 void
 test_1 (const char *path)
 {
@@ -37,3 +44,17 @@ void test_4 (const char *path)
   /* { dg-message "\\(1\\) leaks here" "" { target *-*-* } .-1 } */
 }
 
+void 
+test_5 (const char *path, mode_t mode)
+{
+  creat (path, mode); /* { dg-warning "leak of file descriptor \\\[CWE-775\\\]" } */
+}
+
+void
+test_6 (const char *path, mode_t mode)
+{
+  int fd = creat (path, mode);
+  return; /* { dg-warning "leak of file descriptor 'fd' \\\[CWE-775\\\]" } */
+}
+
+
diff --git a/gcc/testsuite/gcc.dg/analyzer/fd-2.c b/gcc/testsuite/gcc.dg/analyzer/fd-2.c
index d794b460a2e..10c9ecdb09d 100644
--- a/gcc/testsuite/gcc.dg/analyzer/fd-2.c
+++ b/gcc/testsuite/gcc.dg/analyzer/fd-2.c
@@ -5,6 +5,13 @@ void close(int fd);
 #define O_RDWR 2
 #define STDIN 0
 
+typedef enum {
+  S_IRWXU
+  // etc
+} mode_t;
+
+int creat (const char *, mode_t mode);
+
 void 
 test_1 (const char *path)
 {
@@ -46,4 +53,12 @@ test_4 ()
     int fd = -1;
     close(fd);
     close(fd);
+}
+
+void
+test_5 (const char *path, mode_t mode)
+{
+    int fd = creat (path, mode);
+    close(fd);
+    close(fd); /* { dg-warning "double 'close' of file descriptor 'fd' \\\[CWE-1341\\\]" "warning" } */
 }
\ No newline at end of file
diff --git a/gcc/testsuite/gcc.dg/analyzer/fd-4.c b/gcc/testsuite/gcc.dg/analyzer/fd-4.c
index ecd787caff7..6b8fca5408f 100644
--- a/gcc/testsuite/gcc.dg/analyzer/fd-4.c
+++ b/gcc/testsuite/gcc.dg/analyzer/fd-4.c
@@ -9,6 +9,12 @@ int read (int fd, void *buf, int nbytes);
 #define O_WRONLY 1
 #define O_RDWR 2
 
+typedef enum {
+  S_IRWXU
+  // etc
+} mode_t;
+
+int creat (const char *, mode_t mode);
 
 void
 test_1 (const char *path, void *buf)
@@ -69,4 +75,27 @@ test_5 (const char *path)
     int fd = open (path, O_RDWR);
     close(fd);
     printf("%d", fd); /* { dg-bogus "'printf' on a closed file descriptor 'fd'" } */
-}
\ No newline at end of file
+}
+
+
+void
+test_6 (const char *path, mode_t mode, void *buf)
+{
+  int fd = creat (path, mode);
+  if (fd != -1)
+  {
+    read (fd, buf, 1); /* { dg-warning "'read' on write-only file descriptor 'fd'" } */
+    close(fd);
+  }
+}
+
+void
+test_7 (const char *path, mode_t mode, void *buf)
+{
+  int fd = creat (path, mode);
+  if (fd != -1)
+  {
+    write (fd, buf, 1);
+    close(fd);
+  }
+}
diff --git a/gcc/testsuite/gcc.dg/analyzer/fd-dup-1.c b/gcc/testsuite/gcc.dg/analyzer/fd-dup-1.c
new file mode 100644
index 00000000000..eba2570568f
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/fd-dup-1.c
@@ -0,0 +1,223 @@
+int open(const char *, int mode);
+void close(int fd);
+int dup (int old_fd);
+int dup2 (int old_fd, int new_fd);
+int dup3 (int old_fd, int new_fd, int flags);
+int write (int fd, void *buf, int nbytes);
+int read (int fd, void *buf, int nbytes);
+#define O_RDONLY 0
+#define O_WRONLY 1
+#define O_RDWR 2
+
+void test_1 (const char *path)
+{
+    int old_fd = open (path, O_RDWR);
+    int new_fd = dup (old_fd); /* { dg-warning "'dup' on possibly invalid file descriptor 'old_fd'" } */
+    close(old_fd);
+    close(new_fd);
+}
+
+void test_2 (const char *path)
+{
+    int old_fd = open (path, O_RDWR);
+    if (old_fd != -1)
+    {
+        int new_fd = dup (old_fd); 
+        close(old_fd);
+        return; /* { dg-warning "leak of file descriptor 'new_fd' \\\[CWE-775\\\]" } */
+    }
+}
+
+void test_3 (const char *path, void *buf)
+{
+    int old_fd = open (path, O_RDWR);
+    if (old_fd != -1)
+    {
+        int new_fd = dup (old_fd);
+        write (new_fd, buf, 1); /* { dg-warning "'write' on possibly invalid file descriptor 'new_fd'" } */
+        close (new_fd);
+        close(old_fd);
+    }
+}
+
+
+void test_5 (const char *path, void *buf)
+{
+    int old_fd = open (path, O_RDWR);
+    if (old_fd != -1)
+    {
+        int new_fd = dup (old_fd);
+        if (new_fd != -1)
+        {
+            write (new_fd, buf, 1); 
+            close (new_fd);
+            
+        }
+        close(old_fd);
+    }
+}
+
+
+void test_7 (const char *path)
+{
+    int old_fd = open (path, O_RDWR);
+    dup2 (old_fd, 4); /* { dg-warning "'dup2' on possibly invalid file descriptor 'old_fd'" } */
+    close(old_fd);
+}
+
+void test_8 (const char *path)
+{
+    int old_fd = open (path, O_RDWR);
+    int new_fd = open (path, O_RDWR);
+    if (old_fd != -1)
+    {
+        dup2 (old_fd, new_fd); /* { dg-warning "'dup2' on possibly invalid file descriptor 'new_fd'" } */
+        close (old_fd);
+    }
+    close (new_fd);
+}
+
+void test_9 (const char *path, void *buf)
+{
+    int old_fd = open (path, O_RDWR);
+    
+    if (old_fd != -1)
+    {
+        int new_fd = open (path, O_RDWR);
+        if (new_fd != -1)
+        {
+            int lhs = dup2 (old_fd, new_fd);
+            write (lhs, buf, 1); /* { dg-warning "'write' on possibly invalid file descriptor 'lhs'" } */
+            close(new_fd);
+            close(lhs);
+    }
+        close(old_fd);        
+    }
+}
+
+void test_10 (const char *path, int flags)
+{
+    int old_fd = open (path, O_RDWR);
+    int new_fd = open (path, O_RDWR);
+    if (old_fd != -1)
+    {
+        dup3 (old_fd, new_fd, flags); /* { dg-warning "'dup3' on possibly invalid file descriptor 'new_fd'" } */
+        close(old_fd);
+        
+    }
+    close(new_fd);
+}
+
+void test_11 (const char *path, int flags)
+{
+    int old_fd = open (path, O_RDWR);
+    int new_fd = open (path, O_RDWR);
+    if (new_fd != -1)
+    {
+        dup3 (old_fd, new_fd, flags); /* { dg-warning "'dup3' on possibly invalid file descriptor 'old_fd'" } */
+        close(new_fd);
+        
+    }
+    close(old_fd);
+}
+
+void test_12 (const char *path, void *buf)
+{
+    int old_fd = open (path, O_RDONLY);
+    if (old_fd != -1)
+    {
+        int new_fd = dup (old_fd);
+        if (new_fd != -1)
+        {
+            write (new_fd, buf, 1); /* { dg-warning "'write' on read-only file descriptor 'new_fd'" } */
+            close(new_fd);
+        }
+        close(old_fd);
+    }
+}
+
+void test_13 (const char *path, void *buf)
+{
+    int old_fd = open (path, O_WRONLY);
+    if (old_fd != -1)
+    {
+        int new_fd = dup (old_fd);
+        if (new_fd != -1)
+        {
+            read (new_fd, buf, 1); /* { dg-warning "'read' on write-only file descriptor 'new_fd'" } */
+            close(new_fd);
+        }
+        close(old_fd);
+    }
+}
+
+void test_14 (const char *path, void *buf)
+{
+    int old_fd = open (path, O_RDWR);
+    if (old_fd != -1)
+    {
+        int new_fd = dup (old_fd);
+        if (new_fd != -1)
+        {
+            write (new_fd, buf, 1);
+            read (new_fd, buf, 1);
+            close(new_fd);
+        }
+        close(old_fd);
+    }
+}
+
+void test_15 (void *buf)
+{
+    int fd = dup(0);
+    read (fd, buf, 1); /* { dg-warning "'read' on possibly invalid file descriptor 'fd'" } */
+    close(fd);
+}
+
+void test_16 (void *buf)
+{
+    int fd = dup(1);
+    if (fd != -1)
+    {
+        write (fd, buf, 1);
+        close (fd);
+    }
+}
+
+void test_17 (const char *path)
+{
+    int fd = open (path, O_RDWR);
+    close(fd);
+    dup (fd); /* { dg-warning "'dup' on closed file descriptor 'fd'" }  */
+    dup2 (fd, 4); /* { dg-warning "'dup2' on closed file descriptor 'fd'" }  */
+}
+
+void
+test_18 (const char *path, void *buf)
+{
+    int fd = open (path, O_RDWR);
+    if (fd != -1)
+    {
+        int fd2 = dup2 (fd, 3);
+        read (fd2, buf, 1); /* { dg-warning "'read' on possibly invalid file descriptor 'fd2'" } */
+        close(fd);
+        close(fd2);
+    }
+}
+
+void
+test_19 (const char *path, void *buf)
+{
+    int fd = open (path, O_WRONLY);
+    if (fd != -1)
+    {
+        int fd2 = dup2 (fd, 4);
+        if (fd2 != -1)
+        {
+            read (fd2, buf, 1); /* { dg-warning "'read' on write-only file descriptor 'fd2'" } */
+            close(fd2);
+        }
+        close (fd);
+    }
+    
+}
\ No newline at end of file