initial

.gitignore

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+bin/

Makefile

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+TARGET=d
+BUILDDIR=bin/
+PREFIX=/usr/local/bin/
+SOURCES=$(wildcard src/*.c)
+MAIN=main.c
+override CFLAGS+=-Werror -Wall -g -fPIC -O2 -DNDEBUG -ftrapv -Wfloat-equal -Wundef -Wwrite-strings -Wuninitialized -pedantic -std=c11
+override LDFLAGS+=-ledit
+
+all: main.c
+	mkdir -p $(BUILDDIR)
+	$(CC) $(MAIN) $(SOURCES) -o $(BUILDDIR)$(TARGET) $(CFLAGS) $(LDFLAGS)
+
+install: all
+	install $(BUILDDIR)$(TARGET) $(PREFIX)$(TARGET)
+
+uninstall:
+	rm -rf $(PREFIX)$(TARGET)

README.md

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+# d
+
+Yet another WIP.
+
+A dead simple debugger. Not very pretty.

main.c

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+#include "src/debugger.h"
+
+int main(int argc, char** argv) {
+  if (argc != 2) {
+    printf("usage: %s PROGRAM\n", argv[0]);
+    return 1;
+  }
+
+  debug(argv[1]);
+
+  return 0;
+}

src/debugger.c

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+#include "debugger.h"
+
+void run_target(char* program) {
+  if (ptrace(PTRACE_TRACEME, 0, 0, 0) < 0) perror("Error while creating child: ptrace failed");
+  else execl(program, program, NULL);
+}
+
+void debug_continue(pid_t pid) {
+  int status;
+  ptrace(PTRACE_CONT, pid, NULL, 0);
+
+  waitpid(pid, &status, 0);
+}
+
+void debug_loop(char* command, pid_t pid) {
+  if (!strcmp(command, "c")) {
+    debug_continue(pid);
+  } else {
+    printf("%s: Unknown command\n", command);
+  }
+}
+
+void run_debugger(pid_t pid) {
+  int status;
+  char* line = NULL;
+
+  waitpid(pid, &status, 0);
+
+  while((line = readline("minidbg> ")) != NULL) {
+    debug_loop(line, pid);
+    add_history(line);
+    free(line);
+  }
+}
+
+void debug(char* program) {
+  pid_t pid = fork();
+
+  if (!pid) run_target(program);
+  else if (pid > 0) run_debugger(pid);
+  else perror("Error while creating debugger: unable to fork.");
+}

src/debugger.h

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+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <editline/readline.h>
+#include <sys/ptrace.h>
+#include <sys/wait.h>
+
+#ifdef __APPLE__
+#define PTRACE_TRACEME PT_TRACE_ME
+#define PTRACE_CONT PT_CONTINUE
+#define DATA 0
+#else
+#define DATA NULL
+#endif
+
+void debug(char*);