[PATCH] filedescriptor attribute
Immad Mir
mirimmad@outlook.com
Tue Jul 12 17:31:36 GMT 2022
---
gcc/analyzer/sm-fd.cc | 231 ++++++++++++++++++++++++---
gcc/c-family/c-attribs.cc | 63 ++++++++
gcc/testsuite/gcc.dg/analyzer/fd-5.c | 44 +++++
gcc/testsuite/gcc.dg/analyzer/fd-6.c | 4 +
4 files changed, 322 insertions(+), 20 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/analyzer/fd-5.c
create mode 100644 gcc/testsuite/gcc.dg/analyzer/fd-6.c
diff --git a/gcc/analyzer/sm-fd.cc b/gcc/analyzer/sm-fd.cc
index 8e4300b06e2..bdc807160cc 100644
--- a/gcc/analyzer/sm-fd.cc
+++ b/gcc/analyzer/sm-fd.cc
@@ -39,10 +39,13 @@ along with GCC; see the file COPYING3. If not see
#include "analyzer/analyzer-selftests.h"
#include "tristate.h"
#include "selftest.h"
+#include "stringpool.h"
+#include "attribs.h"
#include "analyzer/call-string.h"
#include "analyzer/program-point.h"
#include "analyzer/store.h"
#include "analyzer/region-model.h"
+#include "bitmap.h"
#if ENABLE_ANALYZER
@@ -59,6 +62,13 @@ enum access_mode
WRITE_ONLY
};
+enum fd_access_direction
+{
+ DIR_READ_WRITE,
+ DIR_READ,
+ DIR_WRITE
+};
+
class fd_state_machine : public state_machine
{
public:
@@ -104,6 +114,8 @@ 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;
+ void inform_filedescriptor_attribute (tree callee_fndecl, int arg,
+ fd_access_direction fd_dir) const;
/* State for a constant file descriptor (>= 0) */
state_t m_constant_fd;
@@ -146,7 +158,7 @@ private:
void check_for_open_fd (sm_context *sm_ctxt, const supernode *node,
const gimple *stmt, const gcall *call,
const tree callee_fndecl,
- enum access_direction access_fn) const;
+ enum fd_access_direction access_fn) const;
void make_valid_transitions_on_condition (sm_context *sm_ctxt,
const supernode *node,
@@ -156,6 +168,12 @@ private:
const supernode *node,
const gimple *stmt,
const svalue *lhs) const;
+ bitmap get_fd_attrs (const char *attr_name, tree callee_fndecl) const;
+ void check_for_fd_attrs (sm_context *sm_ctxt, const supernode *node,
+ const gimple *stmt, const gcall *call,
+ const tree callee_fndecl, bitmap argmap,
+ fd_access_direction fd_attr_access_dir) const;
+
};
/* Base diagnostic class relative to fd_state_machine. */
@@ -294,10 +312,10 @@ class fd_access_mode_mismatch : public fd_diagnostic
{
public:
fd_access_mode_mismatch (const fd_state_machine &sm, tree arg,
- enum access_direction fd_dir,
- const tree callee_fndecl)
+ enum fd_access_direction fd_dir,
+ const tree callee_fndecl, bool attr, int arg_idx)
: fd_diagnostic (sm, arg), m_fd_dir (fd_dir),
- m_callee_fndecl (callee_fndecl)
+ m_callee_fndecl (callee_fndecl), m_attr (attr), m_arg_idx (arg_idx)
{
}
@@ -317,19 +335,27 @@ public:
bool
emit (rich_location *rich_loc) final override
{
+ bool warned;
switch (m_fd_dir)
{
case DIR_READ:
- return warning_at (rich_loc, get_controlling_option (),
+ warned = warning_at (rich_loc, get_controlling_option (),
"%qE on %<read-only%> file descriptor %qE",
m_callee_fndecl, m_arg);
+ break;
case DIR_WRITE:
- return warning_at (rich_loc, get_controlling_option (),
+ warned = warning_at (rich_loc, get_controlling_option (),
"%qE on %<write-only%> file descriptor %qE",
m_callee_fndecl, m_arg);
+ break;
default:
gcc_unreachable ();
}
+ if (warned && m_attr)
+ {
+ m_sm.inform_filedescriptor_attribute (m_callee_fndecl, m_arg_idx, m_fd_dir);
+ }
+ return warned;
}
bool
@@ -359,8 +385,10 @@ public:
}
private:
- enum access_direction m_fd_dir;
+ enum fd_access_direction m_fd_dir;
const tree m_callee_fndecl;
+ bool m_attr;
+ int m_arg_idx;
};
class double_close : public fd_diagnostic
@@ -422,8 +450,9 @@ class fd_use_after_close : public fd_diagnostic
{
public:
fd_use_after_close (const fd_state_machine &sm, tree arg,
- const tree callee_fndecl)
- : fd_diagnostic (sm, arg), m_callee_fndecl (callee_fndecl)
+ const tree callee_fndecl, bool attr, int arg_idx)
+ : fd_diagnostic (sm, arg), m_callee_fndecl (callee_fndecl), m_attr (attr),
+ m_arg_idx (arg_idx)
{
}
@@ -439,12 +468,27 @@ public:
return OPT_Wanalyzer_fd_use_after_close;
}
+ bool
+ subclass_equal_p (const pending_diagnostic &base_other) const override
+ {
+ const fd_use_after_close &sub_other
+ = (const fd_use_after_close &)base_other;
+ return (same_tree_p (m_arg, sub_other.m_arg)
+ && m_callee_fndecl == sub_other.m_callee_fndecl
+ && m_attr == sub_other.m_attr
+ && m_arg_idx == sub_other.m_arg_idx);
+ }
+
bool
emit (rich_location *rich_loc) final override
{
- return warning_at (rich_loc, get_controlling_option (),
+ bool warned;
+ warned = warning_at (rich_loc, get_controlling_option (),
"%qE on closed file descriptor %qE", m_callee_fndecl,
m_arg);
+ if (warned && m_attr)
+ m_sm.inform_filedescriptor_attribute (m_callee_fndecl, m_arg_idx, DIR_READ_WRITE);
+ return warned;
}
label_text
@@ -466,17 +510,19 @@ public:
describe_final_event (const evdesc::final_event &ev) final override
{
if (m_first_close_event.known_p ())
- return ev.formatted_print (
- "%qE on closed file descriptor %qE; %qs was at %@", m_callee_fndecl,
- m_arg, "close", &m_first_close_event);
- else
- return ev.formatted_print ("%qE on closed file descriptor %qE",
- m_callee_fndecl, m_arg);
+ return ev.formatted_print (
+ "%qE on closed file descriptor %qE; %qs was at %@", m_callee_fndecl,
+ m_arg, "close", &m_first_close_event);
+ else
+ return ev.formatted_print ("%qE on closed file descriptor %qE",
+ m_callee_fndecl, m_arg);
}
private:
diagnostic_event_id_t m_first_close_event;
const tree m_callee_fndecl;
+ bool m_attr;
+ int m_arg_idx;
};
class unchecked_use_of_fd : public fd_diagnostic
@@ -543,8 +589,38 @@ public:
private:
diagnostic_event_id_t m_first_open_event;
const tree m_callee_fndecl;
+
};
+/* Issue a note regarding misuse of a file descriptor.
+ ARG_IDX here is 0-based.
+ */
+void
+fd_state_machine::inform_filedescriptor_attribute (
+ tree callee_fndecl, int arg_idx, fd_access_direction fd_dir) const
+{
+ switch (fd_dir)
+ {
+ case READ_WRITE:
+ inform (DECL_SOURCE_LOCATION (callee_fndecl),
+ "argument %d of %qD must be an open file descriptor", arg_idx + 1,
+ callee_fndecl);
+ break;
+ case DIR_WRITE:
+ inform (DECL_SOURCE_LOCATION (callee_fndecl),
+ "argument %d of %qD must be a read-only file descriptor",
+ arg_idx + 1, callee_fndecl);
+ break;
+ case DIR_READ:
+ inform (DECL_SOURCE_LOCATION (callee_fndecl),
+ "argument %d of %qD must be a write-only file descriptor",
+ arg_idx + 1, callee_fndecl);
+ break;
+ }
+}
+
+
+
fd_state_machine::fd_state_machine (logger *logger)
: state_machine ("file-descriptor", logger),
m_constant_fd (add_state ("fd-constant")),
@@ -647,11 +723,124 @@ fd_state_machine::on_stmt (sm_context *sm_ctxt, const supernode *node,
on_read (sm_ctxt, node, stmt, call, callee_fndecl);
return true;
} // "read"
+
+ // Handle __attribute__((filedescriptor))
+ {
+ bitmap argmap = get_fd_attrs ("accesses_fd", callee_fndecl);
+ if (argmap)
+ check_for_fd_attrs (sm_ctxt, node, stmt, call, callee_fndecl, argmap, DIR_READ_WRITE);
+
+ bitmap read_argmap = get_fd_attrs ("reads_from_fd", callee_fndecl);
+ if(read_argmap)
+ check_for_fd_attrs (sm_ctxt, node, stmt, call, callee_fndecl, read_argmap, DIR_READ);
+
+ bitmap write_argmap = get_fd_attrs ("writes_to_fd", callee_fndecl);
+ if (write_argmap)
+ check_for_fd_attrs (sm_ctxt, node, stmt, call, callee_fndecl, write_argmap, DIR_WRITE);
+
+ return true;
+ }
+
}
return false;
}
+void
+fd_state_machine::check_for_fd_attrs (sm_context *sm_ctxt,
+ const supernode *node, const gimple *stmt,
+ const gcall *call,
+ const tree callee_fndecl, bitmap argmap,
+ fd_access_direction fd_attr_access_dir) const
+{
+ for (unsigned i = 0; i < gimple_call_num_args (stmt); i++)
+ {
+ unsigned int arg_idx = i;
+ tree arg = gimple_call_arg (stmt, i);
+ tree diag_arg = sm_ctxt->get_diagnostic_tree (arg);
+ state_t state = sm_ctxt->get_state (stmt, arg);
+ if (TREE_CODE (TREE_TYPE (arg)) != INTEGER_TYPE)
+ continue;
+ if (bitmap_bit_p (argmap, arg_idx)) // check if the arg is any of the file
+ // descriptor attributes
+ {
+
+ if (is_closed_fd_p (state))
+ {
+
+ sm_ctxt->warn (node, stmt, arg,
+ new fd_use_after_close (*this, diag_arg,
+ callee_fndecl, true,
+ arg_idx));
+ continue;
+ }
+ else
+ {
+ if (!(is_valid_fd_p (state) || (state == m_stop)))
+ {
+ if (!is_constant_fd_p (state))
+ sm_ctxt->warn (node, stmt, arg,
+ new unchecked_use_of_fd (*this, diag_arg,
+ callee_fndecl));
+ }
+ }
+ }
+ switch (fd_attr_access_dir)
+ {
+ case DIR_READ:
+ if (bitmap_bit_p (argmap, arg_idx)) // check if the arg is marked by
+ // reads_from_fd attribute
+ {
+ if (is_writeonly_fd_p (state))
+ {
+ sm_ctxt->warn (node, stmt, arg,
+ new fd_access_mode_mismatch (*this, diag_arg,
+ DIR_WRITE,
+ callee_fndecl, true, i));
+ }
+ }
+ break;
+ case DIR_WRITE:
+ if (bitmap_bit_p (argmap, arg_idx)) // check if the arg is marked by
+ // writes_to_fd attribute
+ {
+ if (is_readonly_fd_p (state))
+ {
+ sm_ctxt->warn (node, stmt, arg,
+ new fd_access_mode_mismatch (
+ *this, diag_arg, DIR_READ, callee_fndecl, true, i));
+ }
+ }
+ break;
+ default:
+ gcc_unreachable ();
+ }
+ }
+}
+
+bitmap
+fd_state_machine::get_fd_attrs (const char *attr_name, tree callee_fndecl) const
+{
+ bitmap argmap = NULL;
+ tree attrs = TYPE_ATTRIBUTES (TREE_TYPE (callee_fndecl));
+ attrs = lookup_attribute (attr_name, attrs);
+ if (!attrs)
+ return argmap;
+
+ if (!TREE_VALUE (attrs))
+ return argmap;
+
+ argmap = BITMAP_ALLOC (NULL);
+
+ for (tree idx = TREE_VALUE (attrs); idx; idx = TREE_CHAIN (idx))
+ {
+ unsigned int val = TREE_INT_CST_LOW (TREE_VALUE (idx)) - 1;
+ bitmap_set_bit (argmap, val);
+ }
+ return argmap;
+}
+
+
void
fd_state_machine::on_open (sm_context *sm_ctxt, const supernode *node,
const gimple *stmt, const gcall *call) const
@@ -729,7 +918,7 @@ void
fd_state_machine::check_for_open_fd (
sm_context *sm_ctxt, const supernode *node, const gimple *stmt,
const gcall *call, const tree callee_fndecl,
- enum access_direction callee_fndecl_dir) const
+ enum fd_access_direction callee_fndecl_dir) const
{
tree arg = gimple_call_arg (call, 0);
tree diag_arg = sm_ctxt->get_diagnostic_tree (arg);
@@ -738,7 +927,7 @@ fd_state_machine::check_for_open_fd (
if (is_closed_fd_p (state))
{
sm_ctxt->warn (node, stmt, arg,
- new fd_use_after_close (*this, diag_arg, callee_fndecl));
+ new fd_use_after_close (*this, diag_arg, callee_fndecl, false, -1));
}
else
@@ -758,7 +947,7 @@ fd_state_machine::check_for_open_fd (
tree diag_arg = sm_ctxt->get_diagnostic_tree (arg);
sm_ctxt->warn (node, stmt, arg,
new fd_access_mode_mismatch (
- *this, diag_arg, DIR_WRITE, callee_fndecl));
+ *this, diag_arg, DIR_WRITE, callee_fndecl, false, -1));
}
break;
@@ -769,9 +958,11 @@ fd_state_machine::check_for_open_fd (
tree diag_arg = sm_ctxt->get_diagnostic_tree (arg);
sm_ctxt->warn (node, stmt, arg,
new fd_access_mode_mismatch (
- *this, diag_arg, DIR_READ, callee_fndecl));
+ *this, diag_arg, DIR_READ, callee_fndecl, false, -1));
}
break;
+ default:
+ gcc_unreachable ();
}
}
}
diff --git a/gcc/c-family/c-attribs.cc b/gcc/c-family/c-attribs.cc
index c8d96723f4c..84f29987bc6 100644
--- a/gcc/c-family/c-attribs.cc
+++ b/gcc/c-family/c-attribs.cc
@@ -173,6 +173,10 @@ static tree handle_objc_nullability_attribute (tree *, tree, tree, int, bool *);
static tree handle_signed_bool_precision_attribute (tree *, tree, tree, int,
bool *);
static tree handle_retain_attribute (tree *, tree, tree, int, bool *);
+static tree handle_accesses_fd_attribute (tree *, tree, tree, int, bool *);
+static tree handle_reads_from_fd_attribute (tree *, tree, tree, int, bool *);
+static tree handle_writes_to_fd_attribute (tree *, tree, tree, int, bool *);
+
/* Helper to define attribute exclusions. */
#define ATTR_EXCL(name, function, type, variable) \
@@ -427,6 +431,12 @@ const struct attribute_spec c_common_attribute_table[] =
handle_tls_model_attribute, NULL },
{ "nonnull", 0, -1, false, true, true, false,
handle_nonnull_attribute, NULL },
+ { "accesses_fd", 0, -1, false, true, true, false,
+ handle_accesses_fd_attribute, NULL},
+ { "reads_from_fd", 0, -1, false, true, true, false,
+ handle_reads_from_fd_attribute, NULL},
+ { "writes_to_fd", 0, -1, false, true, true, false,
+ handle_writes_to_fd_attribute, NULL},
{ "nonstring", 0, 0, true, false, false, false,
handle_nonstring_attribute, NULL },
{ "nothrow", 0, 0, true, false, false, false,
@@ -4521,6 +4531,59 @@ handle_nonnull_attribute (tree *node, tree name,
return NULL_TREE;
}
+/* Handle the "accesses_fd" attribute */
+static tree
+handle_accesses_fd_attribute (tree *node, tree name, tree args,
+ int ARG_UNUSED (flags), bool *no_add_attrs)
+{
+ tree type = *node;
+ if (!args)
+ {
+ if (!prototype_p (type))
+ {
+ error ("%qE attribute without arguments on a non-prototype", name);
+ *no_add_attrs = true;
+ }
+ return NULL_TREE;
+ }
+
+ for (int i = 1; args; ++i)
+ {
+ tree pos = TREE_VALUE (args);
+ tree next = TREE_CHAIN (args);
+ if (tree val = positional_argument (type, name, pos, INTEGER_TYPE,
+ next || i > 1 ? i : 0))
+ TREE_VALUE (args) = val;
+ else
+ {
+ *no_add_attrs = true;
+ break;
+ }
+ args = next;
+ }
+}
+
+
+
+static tree
+handle_reads_from_fd_attribute (tree *node, tree name, tree ARG_UNUSED (args),
+ int ARG_UNUSED (flags), bool *no_add_attrs)
+{
+ // TODO: valiadate usage of this attribute
+ return NULL_TREE;
+}
+
+static tree
+handle_writes_to_fd_attribute (tree *node, tree name, tree ARG_UNUSED (args),
+ int ARG_UNUSED (flags), bool *no_add_attrs)
+{
+ // TODO: validate usage of this attribute
+ return NULL_TREE;
+}
+
+
+
+
/* Handle the "nonstring" variable attribute. */
static tree
diff --git a/gcc/testsuite/gcc.dg/analyzer/fd-5.c b/gcc/testsuite/gcc.dg/analyzer/fd-5.c
new file mode 100644
index 00000000000..e597ba2367a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/fd-5.c
@@ -0,0 +1,44 @@
+int open(const char *, int mode);
+void close(int fd);
+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 f (int fd) __attribute__((accesses_fd(1))); /* { dg-message "argument 1 of 'f' must be an open file descriptor" } */
+
+void
+test_1 (const char *path)
+{
+ int fd = open (path, O_RDWR);
+ close(fd);
+ f(fd); /* { dg-warning "'f' on closed file descriptor 'fd'" } */
+ /* { dg-message "\\(3\\) 'f' on closed file descriptor 'fd'; 'close' was at \\(2\\)" "" { target *-*-* } .-1 } */
+}
+
+void g (int fd) __attribute__((reads_from_fd(1))); /* { dg-message "argument 1 of 'g' must be a read-only file descriptor" } */
+
+void
+test_2 (const char *path)
+{
+ int fd = open (path, O_WRONLY);
+ if (fd != -1)
+ {
+ g (fd); /* { dg-warning "'g' on 'write-only' file descriptor 'fd'" } */
+ }
+ close (fd);
+}
+
+void h (int fd) __attribute__((writes_to_fd(1))); /* { dg-message "argument 1 of 'h' must be a write-only file descriptor" } */
+void
+test_3 (const char *path)
+{
+ int fd = open (path, O_RDONLY);
+ if (fd != -1)
+ {
+ h (fd); /* { dg-warning "'h' on 'read-only' file descriptor 'fd'" } */
+ }
+ close(fd);
+}
\ No newline at end of file
diff --git a/gcc/testsuite/gcc.dg/analyzer/fd-6.c b/gcc/testsuite/gcc.dg/analyzer/fd-6.c
new file mode 100644
index 00000000000..9c0b55086a9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/analyzer/fd-6.c
@@ -0,0 +1,4 @@
+
+int not_a_fn __attribute__ ((accesses_fd(1))); /* { dg-warning "'accesses_fd' attribute only applies to function types" } */
+
+void f (char *p) __attribute__ ((accesses_fd(1))); /* { dg-warning "'accesses_fd' attribute argument value '1' refers to parameter type 'char \\\*'" } */
\ No newline at end of file
--
2.25.1
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