Add alias management plus input filtering skeleton

Some of the alias stuff was kind of stolen from earlier figuring-out
Bill did. More Bill code is also on the way. :^)

1 files changed, 112 insertions, 0 deletions

diff --git a/src/alias.c b/src/alias.c
new file mode 100644
index 0000000..7db5907
--- /dev/null
+++ b/src/alias.c
@@ -0,0 +1,112 @@
+/*
+ * Copyright © 2022 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED “AS IS” AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdbool.h>
+#include <string.h>
+
+#include "alias.h"
+#include "con_.h"
+#include "dbg.h"
+#include "errmsg.h"
+#include "extmalloc.h"
+#include "mem.h"
+#include "x86.h"
+
+struct alias **_alias_head;
+
+void alias_rm(const char *name) {
+	for (struct alias **p = _alias_head; *p; p = &(*p)->next) {
+		if (!strcmp((*p)->name, name)) {
+			struct alias *next = (*p)->next;
+			extfree((*p)->value); extfree(*p);
+			*p = next;
+			return;
+		}
+	}
+}
+
+DEF_CCMD_HERE(sst_alias_remove, "Remove a command alias", 0) {
+	if (cmd->argc != 2) {
+		con_warn("usage: sst_alias_remove name");
+		return;
+	}
+	if (strlen(cmd->argv[1]) > 31) {
+		con_warn("invalid alias name (too long)");
+		return;
+	}
+	alias_rm(cmd->argv[1]);
+}
+
+void alias_nuke(void) {
+	for (struct alias *p = alias_head; p;) {
+		struct alias *next = p->next;
+		extfree(p->value); extfree(p);
+		p = next;
+	}
+	alias_head = 0;
+}
+
+DEF_CCMD_HERE(sst_alias_clear, "Remove all command aliases", 0) {
+	if (cmd->argc != 1) {
+		con_warn("usage: sst_alias_clear");
+		return;
+	}
+	alias_nuke();
+}
+
+// XXX: same as in demorec, might want some abstraction for this
+#define NEXT_INSN(p, tgt) do { \
+	int _len = x86_len(p); \
+	if (_len == -1) { \
+		errmsg_errorx("unknown or invalid instruction looking for %s", tgt); \
+		return false; \
+	} \
+	(p) += _len; \
+} while (0)
+
+static bool find_alias_head(con_cmdcb alias_cb) {
+#ifdef _WIN32
+	for (uchar *p = (uchar *)alias_cb; p - (uchar *)alias_cb < 64;) {
+		// alias command with no args calls ConMsg() then loads the head pointer
+		// that asm looks like: call <reg>; mov <reg>, dword ptr [x]
+		// (we don't care about the exact registers)
+		if (p[0] == X86_MISCMW && (p[1] & 0xF0) == 0xD0 &&
+				p[2] == X86_MOVRMW && (p[3] & 0xC7) == 0x05) {
+			_alias_head = mem_loadptr(p + 4);
+			return true;
+		}
+		NEXT_INSN(p, "load of alias list");
+	}
+#else
+#warning TODO(linux): check whether linux is equivalent!
+#endif
+	return false;
+}
+
+bool alias_init(void) {
+	struct con_cmd *cmd_alias = con_findcmd("alias");
+	if (!cmd_alias) {
+		errmsg_warnx("couldn't find \"alias\" command");
+		return false;
+	}
+	if (!find_alias_head(con_getcmdcb(cmd_alias))) {
+		errmsg_warnx("couldn't find alias list");
+		return false;
+	};
+	return true;
+}
+
+// vi: sw=4 ts=4 noet tw=80 cc=80