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authorPřemysl Janouch <p.janouch@gmail.com>2017-01-17 14:45:10 +0100
committerPřemysl Janouch <p.janouch@gmail.com>2017-01-17 14:46:38 +0100
commitbf7eae8bf6344ae6c6af2d0fbb926c345f22a309 (patch)
treeea8a29fb5fa6371fe0f33666e10313e084af2943
parent101c58a13657485ea19f29e8cfbafe550e816562 (diff)
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Add field highlighting using Lua plugins
-rw-r--r--hex.c547
1 files changed, 547 insertions, 0 deletions
diff --git a/hex.c b/hex.c
index cf719e9..fded810 100644
--- a/hex.c
+++ b/hex.c
@@ -68,6 +68,14 @@ enum
#include "tui.c"
#include "termo.h"
+#ifdef HAVE_LUA
+#include <lua.h>
+#include <lualib.h>
+#include <lauxlib.h>
+
+#include <dirent.h>
+#endif // HAVE_LUA
+
#define APP_TITLE PROGRAM_NAME ///< Left top corner
// --- Utilities ---------------------------------------------------------------
@@ -157,6 +165,12 @@ static struct app_context
struct poller_fd tty_event; ///< Terminal input event
struct poller_fd signal_event; ///< Signal FD event
+#ifdef HAVE_LUA
+ lua_State *L; ///< Lua state
+ int ref_format; ///< Reference to "string.format"
+ struct str_map coders; ///< Map of coders by name
+#endif // HAVE_LUA
+
// Data:
char *message; ///< Last logged message
@@ -777,6 +791,492 @@ app_on_refresh (void *user_data)
refresh ();
}
+// --- Lua ---------------------------------------------------------------------
+
+#ifdef HAVE_LUA
+
+static void *
+app_lua_alloc (void *ud, void *ptr, size_t o_size, size_t n_size)
+{
+ (void) ud;
+ (void) o_size;
+
+ if (n_size)
+ return realloc (ptr, n_size);
+
+ free (ptr);
+ return NULL;
+}
+
+static int
+app_lua_panic (lua_State *L)
+{
+ // XXX: we might be able to do something better
+ print_fatal ("Lua panicked: %s", lua_tostring (L, -1));
+ lua_close (L);
+ exit (EXIT_FAILURE);
+ return 0;
+}
+
+static bool
+app_lua_getfield (lua_State *L, int idx, const char *name,
+ int expected, bool optional)
+{
+ int found = lua_getfield (L, idx, name);
+ if (found == expected)
+ return true;
+ if (optional && found == LUA_TNIL)
+ return false;
+
+ const char *message = optional
+ ? "invalid field \"%s\" (found: %s, expected: %s or nil)"
+ : "invalid or missing field \"%s\" (found: %s, expected: %s)";
+ return luaL_error (L, message, name,
+ lua_typename (L, found), lua_typename (L, expected));
+}
+
+static int
+app_lua_error_handler (lua_State *L)
+{
+ luaL_traceback (L, L, luaL_checkstring (L, 1), 1);
+ return 1;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+struct app_lua_coder
+{
+ int ref_detect; ///< Reference to the "detect" method
+ int ref_decode; ///< Reference to the "decode" method
+};
+
+static void
+app_lua_coder_free (void *coder)
+{
+ struct app_lua_coder *self = coder;
+ luaL_unref (g_ctx.L, LUA_REGISTRYINDEX, self->ref_decode);
+ luaL_unref (g_ctx.L, LUA_REGISTRYINDEX, self->ref_detect);
+}
+
+static int
+app_lua_register (lua_State *L)
+{
+ luaL_checktype (L, 1, LUA_TTABLE);
+
+ (void) app_lua_getfield (L, 1, "type", LUA_TSTRING, false);
+ const char *type = lua_tostring (L, -1);
+ if (str_map_find (&g_ctx.coders, type))
+ luaL_error (L, "a coder has already been registered for `%s'", type);
+
+ (void) app_lua_getfield (L, 1, "detect", LUA_TFUNCTION, true);
+ (void) app_lua_getfield (L, 1, "decode", LUA_TFUNCTION, false);
+
+ struct app_lua_coder *coder = xcalloc (1, sizeof *coder);
+ coder->ref_decode = luaL_ref (L, LUA_REGISTRYINDEX);
+ coder->ref_detect = luaL_ref (L, LUA_REGISTRYINDEX);
+ str_map_set (&g_ctx.coders, type, coder);
+ return 0;
+}
+
+static luaL_Reg app_lua_library[] =
+{
+ { "register", app_lua_register },
+ { NULL, NULL }
+};
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+#define XLUA_CHUNK_METATABLE "chunk"
+
+struct app_lua_chunk
+{
+ int64_t offset; ///< Offset from start of file
+ int64_t len; ///< Length of the sequence
+
+ int64_t position; ///< Read position in the sequence
+ enum endianity endianity; ///< Read endianity
+};
+
+static struct app_lua_chunk *
+app_lua_chunk_new (lua_State *L)
+{
+ struct app_lua_chunk *chunk = lua_newuserdata (L, sizeof *chunk);
+ luaL_setmetatable (L, XLUA_CHUNK_METATABLE);
+ memset (chunk, 0, sizeof *chunk);
+ return chunk;
+}
+
+static int
+app_lua_chunk_len (lua_State *L)
+{
+ struct app_lua_chunk *self = luaL_checkudata (L, 1, XLUA_CHUNK_METATABLE);
+ lua_pushinteger (L, self->len);
+ return 0;
+}
+
+/// Create a new subchunk following Lua's string.sub() semantics.
+/// An implication is that it is not possible to go extend a chunk's bounds.
+static int
+app_lua_chunk_call (lua_State *L)
+{
+ struct app_lua_chunk *self = luaL_checkudata (L, 1, XLUA_CHUNK_METATABLE);
+ lua_Integer start = luaL_optinteger (L, 2, 1);
+ lua_Integer end = luaL_optinteger (L, 3, -1);
+
+ if (start < 0) start += self->len + 1;
+ if (end < 0) end += self->len + 1;
+
+ start = MAX (start, 1);
+ end = MIN (end, self->len);
+
+ struct app_lua_chunk *clone = app_lua_chunk_new (L);
+ clone->position = 0;
+ clone->endianity = self->endianity;
+ if (start > end)
+ {
+ // "start" can be too high and "end" can be too low;
+ // the length is zero, so the offset doesn't matter much anyway
+ clone->offset = self->offset;
+ clone->len = 0;
+ }
+ else
+ {
+ clone->offset = self->offset + start - 1;
+ clone->len = end - start + 1;
+ }
+ return 1;
+}
+
+static int
+app_lua_chunk_index (lua_State *L)
+{
+ struct app_lua_chunk *self = luaL_checkudata (L, 1, XLUA_CHUNK_METATABLE);
+ const char *key = luaL_checkstring (L, 2);
+ if (luaL_getmetafield (L, 1, key))
+ return 1;
+
+ if (!strcmp (key, "offset"))
+ lua_pushinteger (L, self->offset);
+ else if (!strcmp (key, "endianity"))
+ lua_pushstring (L, self->endianity == ENDIANITY_LE ? "le" : "be");
+ else if (!strcmp (key, "position"))
+ lua_pushinteger (L, self->position + 1);
+ else if (!strcmp (key, "eof"))
+ lua_pushboolean (L, self->position >= self->len);
+ else
+ return luaL_argerror (L, 2, "not a readable property");
+ return 1;
+}
+
+static int
+app_lua_chunk_newindex (lua_State *L)
+{
+ struct app_lua_chunk *self = luaL_checkudata (L, 1, XLUA_CHUNK_METATABLE);
+ const char *key = luaL_checkstring (L, 2);
+ if (!strcmp (key, "endianity"))
+ {
+ // Needs to be in the enum order
+ const char *options[] = { "le", "be" };
+ self->endianity = luaL_checkoption (L, 3, options[0], options);
+ }
+ else if (!strcmp (key, "position"))
+ {
+ lua_Integer position = luaL_checkinteger (L, 3) - 1;
+ if (position < 1 || position > self->len + 1)
+ return luaL_error (L, "position out of range: %" PRId64, position);
+ self->position = position - 1;
+ }
+ else
+ return luaL_argerror (L, 2, "not a writable property");
+ return 0;
+}
+
+static void
+app_lua_mark (int64_t offset, int64_t len, const char *desc)
+{
+ ARRAY_RESERVE (g_ctx.marks, 1);
+ g_ctx.marks[g_ctx.marks_len++] =
+ (struct mark) { offset, len, g_ctx.mark_strings.len };
+
+ str_append (&g_ctx.mark_strings, desc);
+ str_append_c (&g_ctx.mark_strings, 0);
+}
+
+static int
+app_lua_chunk_mark (lua_State *L)
+{
+ struct app_lua_chunk *self = luaL_checkudata (L, 1, XLUA_CHUNK_METATABLE);
+ app_lua_mark (self->offset, self->len, luaL_checkstring (L, 2));
+ return 0;
+}
+
+/// Try to detect any registered type in the data and return its name
+static int
+app_lua_chunk_identify (lua_State *L)
+{
+ (void) luaL_checkudata (L, 1, XLUA_CHUNK_METATABLE);
+
+ struct str_map_iter iter;
+ str_map_iter_init (&iter, &g_ctx.coders);
+ struct app_lua_coder *coder;
+ while ((coder = str_map_iter_next (&iter)))
+ {
+ lua_rawgeti (L, LUA_REGISTRYINDEX, coder->ref_detect);
+
+ // Clone the chunk first to reset its read position
+ lua_pushcfunction (L, app_lua_chunk_call);
+ lua_pushvalue (L, 1);
+ lua_call (L, 1, 1);
+
+ lua_call (L, 1, 1);
+ if (lua_toboolean (L, -1))
+ {
+ lua_pushstring (L, iter.link->key);
+ return 1;
+ }
+ lua_pop (L, 1);
+ }
+ return 0;
+}
+
+static int
+app_lua_chunk_decode (lua_State *L)
+{
+ (void) luaL_checkudata (L, 1, XLUA_CHUNK_METATABLE);
+ const char *type = luaL_optstring (L, 2, NULL);
+ // TODO: further arguments should be passed to the decoding function
+
+ if (!type)
+ {
+ lua_pushcfunction (L, app_lua_chunk_identify);
+ lua_pushvalue (L, 1);
+ lua_call (L, 1, 1);
+ type = lua_tostring (L, -1);
+ }
+ // Can't identify -> can't decode, nothing to do here
+ if (!type)
+ return 0;
+
+ // While we could call "detect" here, just to be sure, some kinds may not
+ // even be detectable and it's better to leave it up to the plugin
+
+ struct app_lua_coder *coder = str_map_find (&g_ctx.coders, type);
+ if (!coder)
+ return luaL_error (L, "unknown type: %s", type);
+
+ lua_rawgeti (L, LUA_REGISTRYINDEX, coder->ref_decode);
+ lua_pushvalue (L, 1);
+ // TODO: the chunk could remember the name of the coder and prepend it
+ // to all marks set from the callback; then reset it back to NULL
+ lua_call (L, 1, 0);
+ return 0;
+}
+
+static int
+app_lua_chunk_read (lua_State *L)
+{
+ struct app_lua_chunk *self = luaL_checkudata (L, 1, XLUA_CHUNK_METATABLE);
+ lua_Integer len = luaL_checkinteger (L, 2);
+ if (len < 0)
+ return luaL_argerror (L, 2, "invalid read length");
+
+ int64_t start = self->offset + self->position;
+ // XXX: or just return a shorter string in this case?
+ if (start + len > g_ctx.data_offset + g_ctx.data_len)
+ return luaL_argerror (L, 2, "chunk is too short");
+
+ lua_pushlstring (L, (char *) g_ctx.data + (start - g_ctx.data_offset), len);
+ self->position += len;
+ return 1;
+}
+
+/// Mark a field that has just been read from the chunk and advance position:
+/// - the second argument, if present, is a simple format string for marking;
+/// - the third argument, if present, is a filtering function.
+///
+/// I am aware of how ugly the implicit "string.format" is. Convenience wins.
+static void
+app_lua_chunk_finish_read
+ (lua_State *L, struct app_lua_chunk *self, int64_t len)
+{
+ int n_args = lua_gettop (L) - 1;
+ if (n_args < 2)
+ return;
+
+ // Prepare <string.format>, <format>, <value>
+ lua_rawgeti (L, LUA_REGISTRYINDEX, g_ctx.ref_format);
+ lua_pushvalue (L, 2);
+
+ int pre_filter_top = lua_gettop (L);
+ lua_pushvalue (L, -3);
+
+ // Transform the value if a filtering function is provided
+ if (n_args >= 3)
+ {
+ lua_pushvalue (L, 3);
+ lua_insert (L, -2);
+ lua_call (L, 1, LUA_MULTRET);
+ int n_ret = lua_gettop (L) - pre_filter_top;
+
+ // When no value has been returned, keep the old one
+ if (n_ret < 1)
+ lua_pushvalue (L, pre_filter_top - 2);
+
+ // Forward multiple return values to "string.format"
+ if (n_ret > 1)
+ {
+ lua_pushvalue (L, pre_filter_top - 1);
+ lua_insert (L, -n_ret - 1);
+ lua_call (L, n_ret, 1);
+ }
+ }
+
+ lua_call (L, 2, 1);
+ app_lua_mark (self->offset + self->position, len, lua_tostring (L, -1));
+ self->position += len;
+ lua_pop (L, 1);
+}
+
+static int
+app_lua_chunk_cstring (lua_State *L)
+{
+ struct app_lua_chunk *self = luaL_checkudata (L, 1, XLUA_CHUNK_METATABLE);
+ void *s = g_ctx.data + (self->offset - g_ctx.data_offset) + self->position;
+
+ void *nil;
+ if (!(nil = memchr (s, '\0', self->len - self->position)))
+ return luaL_error (L, "unexpected EOF");
+
+ lua_pushlstring (L, s, nil - s);
+ app_lua_chunk_finish_read (L, self, nil - s + 1);
+ return 1;
+}
+
+/// Decode "len" bytes as a number starting at the current position in "self"
+static uint64_t
+app_lua_chunk_decode_int (lua_State *L, struct app_lua_chunk *self, size_t len)
+{
+ if (self->position + (int64_t) len > self->len)
+ return luaL_error (L, "unexpected EOF");
+
+ void *s = g_ctx.data + (self->offset - g_ctx.data_offset) + self->position;
+ return app_decode (s, len, self->endianity);
+}
+
+#define APP_LUA_CHUNK_INT(name, type) \
+ static int \
+ app_lua_chunk_ ## name (lua_State *L) \
+ { \
+ struct app_lua_chunk *self = \
+ luaL_checkudata (L, 1, XLUA_CHUNK_METATABLE); \
+ type v = app_lua_chunk_decode_int (L, self, sizeof v); \
+ lua_pushinteger (L, v); \
+ app_lua_chunk_finish_read (L, self, sizeof v); \
+ return 1; \
+ }
+
+APP_LUA_CHUNK_INT (u8, uint8_t) APP_LUA_CHUNK_INT (s8, int8_t)
+APP_LUA_CHUNK_INT (u16, uint16_t) APP_LUA_CHUNK_INT (s16, int16_t)
+APP_LUA_CHUNK_INT (u32, uint32_t) APP_LUA_CHUNK_INT (s32, int32_t)
+APP_LUA_CHUNK_INT (u64, uint64_t) APP_LUA_CHUNK_INT (s64, int64_t)
+
+static luaL_Reg app_lua_chunk_table[] =
+{
+ { "__len", app_lua_chunk_len },
+ { "__call", app_lua_chunk_call },
+ { "__index", app_lua_chunk_index },
+ { "__newindex", app_lua_chunk_newindex },
+ { "mark", app_lua_chunk_mark },
+ { "identify", app_lua_chunk_identify },
+ { "decode", app_lua_chunk_decode },
+
+ { "read", app_lua_chunk_read },
+ { "cstring", app_lua_chunk_cstring },
+ { "u8", app_lua_chunk_u8 },
+ { "s8", app_lua_chunk_s8 },
+ { "u16", app_lua_chunk_u16 },
+ { "s16", app_lua_chunk_s16 },
+ { "u32", app_lua_chunk_u32 },
+ { "s32", app_lua_chunk_s32 },
+ { "u64", app_lua_chunk_u64 },
+ { "s64", app_lua_chunk_s64 },
+ { NULL, NULL }
+};
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+static void
+app_lua_load_plugins (const char *plugin_dir)
+{
+ DIR *dir;
+ if (!(dir = opendir (plugin_dir)))
+ {
+ if (errno != ENOENT)
+ print_error ("cannot open directory `%s': %s",
+ plugin_dir, strerror (errno));
+ return;
+ }
+
+ struct dirent *iter;
+ while ((errno = 0, iter = readdir (dir)))
+ {
+ const char *dot = strrchr (iter->d_name, '.');
+ if (!dot || strcmp (dot, ".lua"))
+ continue;
+
+ char *path = xstrdup_printf ("%s/%s", plugin_dir, iter->d_name);
+ lua_pushcfunction (g_ctx.L, app_lua_error_handler);
+ if (luaL_loadfile (g_ctx.L, path)
+ || lua_pcall (g_ctx.L, 0, 0, -2))
+ exit_fatal ("Lua: %s", lua_tostring (g_ctx.L, -1));
+ lua_pop (g_ctx.L, 1);
+ free (path);
+ }
+ if (errno)
+ exit_fatal ("readdir: %s", strerror (errno));
+ closedir (dir);
+}
+
+static void
+app_lua_init (void)
+{
+ if (!(g_ctx.L = lua_newstate (app_lua_alloc, NULL)))
+ exit_fatal ("Lua initialization failed");
+
+ str_map_init (&g_ctx.coders);
+ g_ctx.coders.free = app_lua_coder_free;
+
+ lua_atpanic (g_ctx.L, app_lua_panic);
+ luaL_openlibs (g_ctx.L);
+ luaL_checkversion (g_ctx.L);
+
+ // I don't want to reimplement this and the C function is not exported
+ hard_assert (lua_getglobal (g_ctx.L, LUA_STRLIBNAME));
+ hard_assert (lua_getfield (g_ctx.L, -1, "format"));
+ g_ctx.ref_format = luaL_ref (g_ctx.L, LUA_REGISTRYINDEX);
+
+ luaL_newlib (g_ctx.L, app_lua_library);
+ lua_setglobal (g_ctx.L, PROGRAM_NAME);
+
+ luaL_newmetatable (g_ctx.L, XLUA_CHUNK_METATABLE);
+ luaL_setfuncs (g_ctx.L, app_lua_chunk_table, 0);
+ lua_pop (g_ctx.L, 1);
+
+ struct str_vector v;
+ str_vector_init (&v);
+ get_xdg_data_dirs (&v);
+ for (size_t i = 0; i < v.len; i++)
+ {
+ char *path = xstrdup_printf
+ ("%s/%s", v.vector[i], PROGRAM_NAME "/plugins");
+ app_lua_load_plugins (path);
+ free (path);
+ }
+ str_vector_free (&v);
+}
+
+#endif // HAVE_LUA
+
// --- Actions -----------------------------------------------------------------
/// Checks what items are visible and returns if fixes were needed
@@ -1299,12 +1799,16 @@ main (int argc, char *argv[])
{ 'o', "offset", NULL, 0, "offset within the file" },
{ 's', "size", NULL, 0, "size limit (1G by default)" },
+#ifdef HAVE_LUA
+ { 't', "type", NULL, 0, "force interpretation as the given type" },
+#endif // HAVE_LUA
{ 0, NULL, NULL, 0, NULL }
};
struct opt_handler oh;
opt_handler_init (&oh, argc, argv, opts, "[FILE]", "Hex viewer.");
int64_t size_limit = 1 << 30;
+ const char *forced_type = NULL;
int c;
while ((c = opt_handler_get (&oh)) != -1)
@@ -1328,6 +1832,9 @@ main (int argc, char *argv[])
if (!decode_size (optarg, &size_limit))
exit_fatal ("invalid size limit specified");
break;
+ case 't':
+ forced_type = optarg;
+ break;
default:
print_error ("wrong options");
opt_handler_usage (&oh, stderr);
@@ -1337,6 +1844,21 @@ main (int argc, char *argv[])
argc -= optind;
argv += optind;
+#ifdef HAVE_LUA
+ // We do it at this questionable location to catch plugin failure before
+ // we read potentially hundreds of megabytes of data in
+ app_lua_init ();
+
+ if (forced_type && !strcmp (forced_type, "list"))
+ {
+ struct str_map_iter iter;
+ str_map_iter_init (&iter, &g_ctx.coders);
+ while (str_map_iter_next (&iter))
+ puts (iter.link->key);
+ exit (EXIT_SUCCESS);
+ }
+#endif // HAVE_LUA
+
// When no filename is given, read from stdin and replace it with the tty
int input_fd;
if (argc == 0)
@@ -1399,6 +1921,26 @@ main (int argc, char *argv[])
print_warning ("failed to set the locale");
app_init_context ();
+#ifdef HAVE_LUA
+ // TODO: eventually we should do this in a separate thread after load
+ // as it may take a long time (-> responsivity) and once we allow the user
+ // to edit the file, each change will need a background rescan
+ lua_pushcfunction (g_ctx.L, app_lua_error_handler);
+ lua_pushcfunction (g_ctx.L, app_lua_chunk_decode);
+
+ struct app_lua_chunk *chunk = app_lua_chunk_new (g_ctx.L);
+ chunk->offset = g_ctx.data_offset;
+ chunk->len = g_ctx.data_len;
+
+ if (forced_type)
+ lua_pushstring (g_ctx.L, forced_type);
+ else
+ lua_pushnil (g_ctx.L);
+ if (lua_pcall (g_ctx.L, 2, 0, -4))
+ exit_fatal ("Lua: decoding failed: %s", lua_tostring (g_ctx.L, -1));
+
+ lua_pop (g_ctx.L, 1);
+#endif // HAVE_LUA
app_flatten_marks ();
app_load_configuration ();
@@ -1418,5 +1960,10 @@ main (int argc, char *argv[])
endwin ();
g_log_message_real = log_message_stdio;
app_free_context ();
+
+#ifdef HAVE_LUA
+ str_map_free (&g_ctx.coders);
+#endif // HAVE_LUA
+
return 0;
}